gitignore go/parity

Reviewed-on: #35

.gitignore

@@ -7,3 +7,4 @@ tmp/
 
 # go build output
 bin/
+go/parity

CHANGELOG.md

@@ -1,5 +1,109 @@
 # Changelog
 
+## 2026-05-11 23:58 CEST — fix(reconcile): fill earliest month deficit first in multi-month allocations
+
+- Multi-month payment allocation now fills the earliest in-window deficit first and spills
+  any remainder to later months, accounting for prior transactions' contributions to each month.
+  Previously a single transaction was split proportionally to each month's total expected fee,
+  ignoring what earlier transactions had already paid — surfaced by Matyáš Thér's 200+550 case
+  showing 566/183 instead of 500/250.
+- Files: `scripts/match_payments.py`, `go/internal/domain/reconcile/reconcile.go`, tests, parity fixtures.
+
+## 2026-05-11 22:56 CEST — fix(python): parse Fio 2-digit-year dates + add `make sync-debug` dry-run tool
+
+- Fix: `scripts/fio_utils.py` `parse_czech_date` now accepts `DD.MM.YY` / `D.M.YY` in addition to the 4-digit-year variants. Fio's transparent page now mixes both forms in the same response; the 2-digit rows were being silently dropped, which caused `make sync-2026` to miss every recent transfer. Mirrors the Go-side fix from 2026-05-07 (CHANGELOG entry below).
+- Added `--dry-run` and `--print-fio-table` flags to `scripts/sync_fio_to_sheets.py`, plus a `make sync-debug [DAYS=N]` Makefile target. Mirrors `make go-sync-debug`: fetches from Fio and dedupes against the sheet, prints `STATUS=NEW/DUP` per transaction, and prints per-row `Dry run: would append …` lines + `would sort by date` instead of touching the sheet.
+- Added always-on stderr diagnostics in `scripts/fio_utils.py`: which fetcher was selected (authenticated API vs. transparent-page scraper with `FIO_API_TOKEN`-unset warning), and raw-vs-after-filter transaction counts on both paths — so this class of "scraper drops everything" bug surfaces immediately.
+## 2026-05-08 15:24 CEST — feat(go): M6.7 — single-binary embed verification
+
+- Confirmed `embed.FS` wiring is complete: templates parsed via `template.ParseFS(templateFS, ...)`, static assets served via `http.FileServerFS(fs.Sub(staticFS, "static"))`.
+- Added `go/internal/web/assets_test.go` with two tests: `TestEmbedCompleteness` (walks disk vs embed.FS to catch forgotten files) and `TestStaticAssetsServed` (hits `/static/css/app.css` and all JS files through the mux, asserts 200 + Content-Type + non-empty body + 404 for unknown paths).
+- Closes M6; single binary confirmed self-contained with no adjacent `templates/` or `static/` required at runtime.
+- Key files: `go/internal/web/assets_test.go` (new).
+
+## 2026-05-08 14:55 CEST — feat(go): M6.6.1 — Pay-button QR popup modal
+
+- Restored the Python `showPayQR` in-page modal UX that was lost in M6.6 (Pay buttons were navigating the tab to the raw `/qr` PNG).
+- Replaced `<a href="{{qrHref ...}}">Pay</a>` with `<button data-name|amount|month|raw-month>` on `/adults` and `/juniors`; click is handled by a new `static/js/payment-qr.js` IIFE module that opens `#qrModal` with title, account, amount, message, and the QR image.
+- Added `#qrModal` markup to both templates; CSS `display:none` / `.active{display:flex}` rules added (content rules were already present from M6.1). `Esc`, `[close]`, and outside-click all dismiss; coexists with the M6.5 member-detail modal.
+- Removed the now-dead `qrHref` / `qrHrefAll` template helpers from `render.go`.
+- Markup tests in `html_handler_test.go` assert modal IDs, script tag, `data-bank-account`, and that no bare `href="/qr"` links remain.
+- Key files: `go/internal/web/static/js/payment-qr.js`, `go/internal/web/templates/adults.tmpl`, `go/internal/web/templates/juniors.tmpl`, `go/internal/web/render.go`, `go/internal/web/static/css/app.css`.
+
+## 2026-05-08 13:57 CEST — feat(go): M6.6 — /qr, /sync-bank, /flush-cache, /version
+
+- Added `GET /qr`: generates Czech QR Platba PNG from SPD payload (account, amount, message query params); ports Python's `qr_code()` handler exactly including account validation, amount clamping, and `*` stripping.
+- Implemented `GET /sync-bank`: runs Fio sync → infer payments → cache flush, captures output into `sync.tmpl` page with success/error banner.
+- Implemented `GET /flush-cache` + `POST /flush-cache`: form + action that deletes cache files and shows deleted count.
+- Added `GET /version` as a JSON alias of `GET /api/version` (Python parity).
+- Added `FlushCache() (int, error)` to `membership.Sources` interface; implemented on `realSources` via `cache.FileCache.Flush()`.
+- Introduced `web.ActionHandlers{BankSync}` — closure-based dep injection for sync, constructed in `serverCmd` with fio + sheets clients.
+- New dependency: `github.com/skip2/go-qrcode`.
+- Key files: `go/internal/web/qr.go`, `go/internal/web/html_handler.go`, `go/internal/web/server.go`, `go/internal/services/membership/loader.go`, `go/internal/web/templates/sync.tmpl`, `go/internal/web/templates/flush_cache.tmpl`.
+
+## 2026-05-08 13:19 CEST — feat(go): M6.5 — member-detail modal JS module
+
+- Added `static/js/member-detail.js`: fetches `/api/adults` or `/api/juniors` once on page load, caches the response, renders a per-member detail modal on `[i]` row click.
+- Modal sections: status-per-month table, fee exceptions, other transactions, matched payment history, toggleable raw-payments debug view.
+- Keyboard nav: `Esc` closes, `↑`/`↓` walk visible (name-filtered) rows; click outside modal content closes it.
+- Added `[i]` info icon and `#memberModal` markup to `adults.tmpl` and `juniors.tmpl`; all CSS was already in place from M6.1.
+- Added `TestModalMarkup` assertions to `html_handler_test.go`.
+
+## 2026-05-08 12:48 CEST — feat(go): M6.4 — Go-native /payments page
+
+- Extracted `AssemblePayments(ctx)` from the inlined JSON handler body, following the M6.2/M6.3 `AssembleAdults`/`AssembleJuniors` pattern.
+- Added `PaymentsPageData` to `render.go`; wired `HTMLHandler.ServePayments` to call `AssemblePayments` and render the new template.
+- Replaced the "Coming in M6.4" placeholder in `payments.tmpl` with the full grouped-by-person ledger: alphabetical `<h2>` member blocks, each with a `txn-table` (Date / Amount / Purpose / Bank Message), newest-first rows, `"Unmatched / Unknown"` bucket.
+- Appended ledger CSS classes to `app.css` (`.ledger-container`, `.member-block`, `.txn-table`, `.txn-{date,amount,purpose,message}`, `tr:hover`).
+- Added `TestPaymentsPage` markup test. No filters, no JS — matches the Python page.
+
+## 2026-05-08 11:25 CEST — feat(go): M6.3 — Go-native /juniors page
+
+- Extracted `AssembleJuniors(ctx)` from the JSON handler so HTML and JSON share one view-model path (mirrors `AssembleAdults`).
+- Added `JuniorsPageData` to `render.go`; wired `HTMLHandler.ServeJuniors` to call `AssembleJuniors` and render the new template.
+- Replaced the 4-line "Coming in M6.3" placeholder in `juniors.tmpl` with the full template: member table, name/month-range filters, totals row, Credits + Debts sections, Pay / Pay All links to `/qr`. No Unmatched section (parity with Python).
+- J/A attendance breakdown and `"?"` sentinel rendered via `MonthCell.Text` produced by `buildJuniorMemberRow` — no extra template logic.
+- `make parity` reports 3/3 routes OK; all Go tests pass.
+
+## 2026-05-08 11:11 CEST — fix: period selector showed only Dec 2025+ on adults
+
+- Restored the `2025-09 → 2025-10` adult merge in `scripts/attendance.py` and `go/internal/services/membership/sources.go` (commented-out by `1257f0d`); the `2025-12 → 2026-01` mapping stays disabled per product decision (Dec and Jan are billed separately for adults).
+- Dropped the `defaultFrom = maxMonthIdx − 4` JS auto-default in `templates/adults.html` and `templates/juniors.html` (introduced by `7774301`); the From-selector now starts at the oldest available month so all non-future periods render on first load. Future-month removal is preserved.
+- `go/internal/services/membership/sources_test.go`: `TestLoadAdults` / `TestLoadAdults_Fee` now assert that Sep dates land in the merged `2025-10` bucket.
+- **Independent of these code changes**: the live adults attendance Google Sheet header had been pruned to start at `02.12.2025` (Sep/Oct/Nov 2025 columns deleted); restoring those columns from Sheets version history is required to actually see those periods on the dashboard.
+
+## 2026-05-08 10:15 CEST — fix(go): adults template — use lifted CSS classes for visual parity
+
+- Use existing `.balance-pos` / `.balance-neg` (drop invented `balance-cell` / `balance-negative`); Pay-All button now lives inside the balance cell with `position: relative` (matches Python; no separate trailing column).
+- Credits / Debts / Unmatched sections rewritten from `<ul>` / `<table>` to `<div class="list-container"><div class="list-item">…` / `<div class="unmatched-row">…` so the lifted CSS actually applies.
+- Section headings get the descriptive Python text: "Credits (Advance Payments / Surplus)", "Debts (Missing Payments)".
+- Source links moved from page bottom to a `<div class="description">` block under the h1, matching Python's "Source: Attendance Sheet | Payments Ledger".
+- Total row uses `cell-{{Status}}` plus the small "received / expected" caption span and Python's inline-styled bold/dark background.
+- Drop the redundant `class="cell"` wrapper; debts amount turns red via inline style; balance value drops the trailing "CZK".
+
+## 2026-05-08 01:09 CEST — feat(go): M6.2 — adults page (table, filters, Pay buttons)
+
+- `go/internal/web/api/handler.go`: extracted `ServeAdults` body into `AssembleAdults(ctx)` — shared by the JSON API route and the new HTML handler.
+- `go/internal/web/render.go`: added `AdultsPageData` view model (`PageData` + `api.AdultsResponse` + `Error`); `tmplFuncs` with `qrHref` / `qrHrefAll` (URL-encode QR Platba params, convert YYYY-MM → MM/YYYY).
+- `go/internal/web/html_handler.go`: `HTMLHandler` gains `*api.Handler`; `ServeAdults` loads real reconcile data and renders the full adults page.
+- `go/internal/web/templates/adults.tmpl`: full table (per-member rows, per-cell status classes, `data-month-idx`, Pay button hrefs to `/qr`), totals row, credits/debts/unmatched sections, filter controls, sheet links.
+- `go/internal/web/static/js/filters.js`: name filter (NFD-normalize) + month-range hide/show by `data-month-idx`; future months hidden by default.
+
+## 2026-05-08 00:44 CEST — feat(go): M6.1 — template skeleton + embed.FS
+
+- `go/internal/web/templates/`: `base.tmpl` (full HTML layout), `partials/nav.tmpl` (three-tier nav with active-link highlighting), `partials/footer.tmpl` (build meta), and stub pages for each route (adults/juniors/payments/sync/flush_cache).
+- `go/internal/web/static/css/app.css`: terminal-green-on-black theme extracted once from Python `templates/adults.html` — shared by all Go HTML pages via `<link>`.
+- `go/internal/web/assets.go`: `//go:embed templates static` for single-binary deployment.
+- `go/internal/web/render.go`: `Renderer` parses a fresh `*template.Template` per page at startup; `Render(w, name, data)` executes the "base" template block.
+- `go/internal/web/html_handler.go`: `HTMLHandler` with one method per route (`ServeAdults`, `ServeJuniors`, `ServePayments`, `ServeSync`, `ServeFlushCache`).
+- `go/internal/web/server.go`: drops `helloHandler`; `GET /{$}` now redirects to `/adults`; HTML + `/static/` routes registered alongside the existing `/api/*` routes.
+- `go/internal/web/html_handler_test.go`: smoke test — each route returns 200 `text/html` with exactly one `class="active"` on the matching nav link.
+
+## 2026-05-08 00:26 CEST — fix(py): parity coercions — amount/message types + junior '?' sticky
+
+- `scripts/match_payments.py`: added `get_float` helper — non-numeric `amount` values (e.g. `"---"` placeholder rows) now coerce to `0.0` matching Go's `parseFloat` behaviour; `message` field now goes through `get_str` so numeric cell values (bank references) are emitted as strings, matching Go's `fmt.Sprint`.
+- `scripts/views.py`: junior month cell `"?"` text is now sticky across exception overrides. Previously `reconcile` replaced `expected` with the exception amount before the view builder ran, silently turning `"?"` into `"-"` when the override was 0. Fixed by deriving `is_unknown` from `original_expected == "?"` instead of `expected == "?"`. Also aligned tooltip guard: only show Received/Expected for non-unknown months (or when paid > 0), matching Go's `!md.IsUnknown` condition.
+
 ## 2026-05-07 23:51 CEST — feat(py): M5.4 fix #2 — add vs and sync_id to payments tx projection
 
 - `scripts/match_payments.py`: `fetch_sheet_data` now reads `VS` and `Sync ID` columns and includes `vs`/`sync_id` keys in every tx dict. Previously only 9 columns were projected, causing `make parity` to report extra `vs`/`sync_id` fields on every raw payment row emitted by the Go backend. Values flow through `group_payments_by_person` → `_unwrap_view_model_for_api` to `raw_payments` (adults/juniors) and `grouped_payments` (payments) automatically.

Makefile

@@ -35,6 +35,7 @@ help:
 	@echo "  make sync        - Sync Fio transactions to Google Sheets"
 	@echo "  make sync-2025   - Sync Fio transactions for Q4 2025 (Oct-Dec)"
 	@echo "  make sync-2026   - Sync Fio transactions for the whole year of 2026"
+	@echo "  make sync-debug [DAYS=N] - Dry-run Python sync with Fio diagnostics and txn table (default DAYS=30)"
 	@echo "  make infer       - Infer payment details (Person, Purpose, Amount) in the sheet"
 	@echo "  make reconcile   - Show balance report using Google Sheets data"
 	@echo "  make venv        - Sync virtual environment with pyproject.toml"
@@ -125,6 +126,9 @@ sync-2025: $(PYTHON)
 sync-2026: $(PYTHON)
 	$(PYTHON) scripts/sync_fio_to_sheets.py --credentials .secret/fuj-management-bot-credentials.json --from 2026-01-01 --to 2026-12-31 --sort-by-date
 
+sync-debug: $(PYTHON)  ## Dry-run Python sync with Fio diagnostics and txn table (default DAYS=30)
+	$(PYTHON) scripts/sync_fio_to_sheets.py --credentials .secret/fuj-management-bot-credentials.json --days $(DAYS) --dry-run --print-fio-table
+
 infer: $(PYTHON)
 	$(PYTHON) scripts/infer_payments.py --credentials $(CREDENTIALS)
 

docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md

@@ -2,9 +2,9 @@
 
 Companion to [2026-05-03-2349-go-backend-rewrite.md](2026-05-03-2349-go-backend-rewrite.md).
 
-**Current milestone:** M5 — JSON-only `/api/...` routes ✅
+**Current milestone:** M6 — Go-native HTML frontend
 **Started:** 2026-05-04
-**Last updated:** 2026-05-07 (M5.4)
+**Last updated:** 2026-05-08 (M6.6 + M6.6.1 merged)
 
 ## How to use
 
@@ -110,13 +110,14 @@ Goal: byte-equal JSON between Python and Go for every route. This is the parity
 
 Goal: feature-equivalent UX on the Go side, designed cleanly. Not a Jinja port.
 
-- [ ] **M6.1** Template skeleton: base layout, nav (Adults/Juniors/Payments/Sync/Flush), terminal-green-on-black theme; `embed.FS` for `templates/` + `static/`
+- [x] **M6.1** Template skeleton: base layout, nav (Adults/Juniors/Payments/Sync/Flush), terminal-green-on-black theme; `embed.FS` for `templates/` + `static/` — `78e5059`
-- [ ] **M6.2** `/adults` page: table, name filter input, month range filter, totals row, credits/debts/unmatched sections, Pay buttons that link to `/qr`
+- [x] **M6.2** `/adults` page: table, name filter input, month range filter, totals row, credits/debts/unmatched sections, Pay buttons that link to `/qr` — `c85748b`
-- [ ] **M6.3** `/juniors` page: same structure + per-month J/A attendance breakdown + `"?"` sentinel rendering
+- [x] **M6.3** `/juniors` page: same structure + per-month J/A attendance breakdown + `"?"` sentinel rendering — `9564103`
-- [ ] **M6.4** `/payments` page: grouped-by-person ledger view
+- [x] **M6.4** `/payments` page: grouped-by-person ledger view — `689f1c0`
-- [ ] **M6.5** Modal JS module (`static/js/member-detail.js`): fetches `/api/adults` (or juniors), renders status/exceptions/transactions on row click; keyboard nav (Esc, ↑/↓)
+- [x] **M6.5** Modal JS module (`static/js/member-detail.js`): fetches `/api/adults` (or juniors), renders status/exceptions/transactions on row click; keyboard nav (Esc, ↑/↓) — `e53e238`
-- [ ] **M6.6** `/qr`, `/sync-bank`, `/flush-cache`, `/version` pages
+- [x] **M6.6** `/qr`, `/sync-bank`, `/flush-cache`, `/version` pages — `f6ba85b`
-- [ ] **M6.7** Wire `embed.FS` into handlers; verify single-binary deployment includes all assets
+- [x] **M6.6.1** Pay-button QR popup modal (`payment-qr.js`); restores Python `showPayQR` UX lost in M6.6 — `4276d7b`
+- [ ] **M6.7** Wire `embed.FS` into handlers; verify single-binary deployment includes all assets — (pending merge)
 
 **Gate:** Browser smoke on :8080: all pages render, name+month filters work, modal opens with correct data, QR loads, sync/flush work end-to-end.
 

docs/plans/2026-05-08-0034-go-rewrite-m6-1-template-skeleton.md

@@ -0,0 +1,88 @@
+# Plan: Go rewrite — M6.1 Template skeleton
+
+## Context
+
+M5 finished — Go and Python now produce byte-equal JSON across `/api/{adults,juniors,payments,version}` and `cmd/parity` enforces it. See [progress tracker §M5](2026-05-03-2349-go-backend-rewrite-progress.md#L96-L106).
+
+M6 begins the Go-native HTML frontend that lets us actually retire the Python web UI. **M6.1 is the foundation step**: stand up the base HTML layout, shared nav, terminal-green-on-black theme, and the `embed.FS` plumbing that every subsequent M6 page (adults, juniors, payments, sync, flush, qr) will compose into. After M6.1, opening :8080 shows chrome (header, nav, footer) on every route with placeholder bodies — no real data wiring; that lands in M6.2+.
+
+This is **not a Jinja port**. The Python templates are reference for nav structure and CSS values; the Go layout is designed natively (per the [master plan](2026-05-03-2349-go-backend-rewrite.md#L24-L27): "frontends are allowed to diverge").
+
+## Current Go web state (what we're building on)
+
+- [go/internal/web/server.go](../../go/internal/web/server.go) — `Run()` registers `GET /{$}` (text-plain hello) + four `/api/*` routes. `BuildInfo{Version,Commit,BuildDate}` already flows in.
+- [go/internal/web/api/handler.go](../../go/internal/web/api/handler.go) — central handler struct holding `Sources`, `Config`, `Logger`, build fields.
+- No `templates/`, no `static/`, no `embed` directives, no `html/template` import anywhere in `go/`. We're starting from a blank slate.
+
+## Approach
+
+1. **Create `templates/` and `static/` under `go/internal/web/`**, embedded via `//go:embed`.
+2. **Single base template** (`base.tmpl`) using `html/template` `block`s for `title` and `content`. Each page template defines those blocks; the renderer executes via `ExecuteTemplate(w, "base", data)`.
+3. **Nav partial** parameterized by a `pageData.Active` string so each page highlights its own link with `class="active"`. Three tiers preserved (Primary / Archived / Tools) — matches Python UX in [templates/adults.html:491-505](../../templates/adults.html#L491-L505).
+4. **CSS** lifted verbatim from [templates/adults.html:8-487](../../templates/adults.html#L8-L487) into `static/css/app.css`. Page templates `<link>` it from the base layout. M6.2+ reuses the same class names (`.cell-ok`, `.modal-content`, …) without re-extracting.
+5. **HTML handlers** in a new `go/internal/web/html/` package (sibling of `api/`). One `Handler` struct holding `*Renderer` + `BuildInfo` + `Config`. Routes for `/`, `/adults`, `/juniors`, `/payments`, `/sync-bank`, `/flush-cache` registered in `server.go`. Each route renders a placeholder body ("Coming in M6.X") inside the base shell — the goal is to prove the chrome works, not to populate data.
+6. **Replace the existing `helloHandler`**: `GET /{$}` → `http.Redirect` to `/adults` (mirrors Python's meta-refresh in [app.py:112-115](../../app.py#L112-L115)).
+7. **Static file route**: `GET /static/` served from `staticFS` via `http.StripPrefix("/static/", http.FileServerFS(staticFS))`.
+8. **Footer keeps it simple**: `{{.Build.Version}}@{{.Build.Commit}} | built {{.Build.BuildDate}}`. The Python per-request render-time breakdown is deferred — `middleware/timer.go` only logs to slog today; threading a timer into request context can come back in a later milestone if we miss it.
+
+## Files to create / modify
+
+```
+go/internal/web/
+├── assets.go                          NEW — //go:embed templates/* static/*
+├── render.go                          NEW — Renderer wraps parsed *template.Template
+├── server.go                          MODIFY — drop helloHandler; mount HTML routes + /static/
+├── html/
+│   ├── handler.go                     NEW — html.Handler + page methods
+│   └── handler_test.go                NEW — httptest smoke per route
+├── templates/
+│   ├── base.tmpl                      NEW — <html>/<head>/<body>; nav + content + footer blocks
+│   ├── partials/
+│   │   ├── nav.tmpl                   NEW — three-tier nav, active highlighting
+│   │   └── footer.tmpl                NEW — build meta line
+│   ├── adults.tmpl                    NEW — placeholder "Coming in M6.2"
+│   ├── juniors.tmpl                   NEW — placeholder "Coming in M6.3"
+│   ├── payments.tmpl                  NEW — placeholder "Coming in M6.4"
+│   ├── sync.tmpl                      NEW — placeholder "Coming in M6.6"
+│   └── flush_cache.tmpl               NEW — placeholder "Coming in M6.6"
+└── static/
+    └── css/
+        └── app.css                    NEW — verbatim from templates/adults.html:8-487
+```
+
+## Key design notes
+
+- **Parse once at startup**: `NewRenderer(fs embed.FS)` calls `template.ParseFS(fs, "templates/*.tmpl", "templates/partials/*.tmpl")`. Parse failure aborts boot — template syntax errors surface immediately, not at first request.
+- **Per-page cloned templates** to avoid `define "content"` collisions across pages: `Renderer` stores `map[string]*template.Template` keyed by page name; each is `base+partials` clone with that page's `content`/`title` overlaid.
+- **View model** — small `pageData` struct: `Active` (nav key), `Build` (BuildInfo), `Body` (per-page payload, `any` until M6.2 widens it).
+- **Active-link logic** in nav partial: `{{ if eq .Active "adults" }}class="active"{{ end }}` — markup-side, no template funcs needed.
+- **No JS in M6.1.** Member-detail and QR modals + `static/js/*.js` come in M6.5. M6.1 only sets up the embedded-asset machinery.
+- **Nav anchor labels are literal text** (`[Adults]`, `[Juniors]`, etc.) — keep the brackets in the template strings, they're part of the look.
+- **`/qr` is not in the nav** — it's an image endpoint, M6.6 territory.
+
+## Critical files to read
+
+- [go/internal/web/server.go](../../go/internal/web/server.go) — mux registration; `Run()` signature stays unchanged.
+- [go/internal/web/api/handler.go](../../go/internal/web/api/handler.go) — pattern to mirror for `html.Handler` (same field layout, most fields unused in M6.1).
+- [templates/adults.html:8-487](../../templates/adults.html#L8-L487) — CSS source, copy verbatim.
+- [templates/adults.html:491-505](../../templates/adults.html#L491-L505) — nav markup source (three tiers).
+- [docs/plans/2026-05-03-2349-go-backend-rewrite.md:88-101](2026-05-03-2349-go-backend-rewrite.md#L88-L101) — original layout intent for `web/handlers/`, `web/templates/`, `web/static/`.
+
+## Verification
+
+End-to-end smoke from a fresh `make go-build`:
+
+1. `make web-go &` — server boots; no template-parse errors in slog output.
+2. `curl -i localhost:8080/` → `302` to `/adults`.
+3. `curl -s localhost:8080/adults | grep -F 'class="active"'` matches the Adults anchor only.
+4. `curl -sI localhost:8080/static/css/app.css` → `200`, `Content-Type: text/css`.
+5. Browser at `http://localhost:8080/adults`: terminal-green-on-black theme, three-tier nav at top (Adults active), "Coming in M6.2" placeholder, footer `{tag}@{commit} | built {date}`.
+6. Click each nav link in turn (`/juniors`, `/payments`, `/sync-bank`, `/flush-cache`) — same chrome, the clicked link is highlighted, per-page placeholder body shows.
+7. `make go-test` — `web/html/handler_test.go` passes: each route returns 200, `text/html`, `class="active"` only on the matching anchor.
+8. `make go-lint` clean.
+9. `make parity` still green (regression check — M6.1 doesn't touch `/api/*`).
+10. CHANGELOG entry per CLAUDE.md; M6.1 ticked in [progress tracker §M6.1](2026-05-03-2349-go-backend-rewrite-progress.md#L113) with commit SHA.
+
+## Branch & MR
+
+`feat/go-m6-1-template-skeleton` per CLAUDE.md branch-per-feature workflow. Open MR via `tea pr create --base main --head feat/go-m6-1-template-skeleton`. User merges in the Gitea browser UI.

docs/plans/2026-05-08-0052-go-rewrite-m6-2-adults-page.md

@@ -0,0 +1,131 @@
+# Plan: Go rewrite — M6.2 Adults page
+
+## Context
+
+M6.1 landed the template skeleton, embed.FS, and HTML routes ([progress §M6.1](2026-05-03-2349-go-backend-rewrite-progress.md#L113), commit `78e5059`). Every page renders chrome + a "Coming in M6.X" placeholder body. **M6.2 fills in `/adults`** — the most data-rich page and the template that drives the rest of the M6 work (juniors mostly mirrors it).
+
+Acceptance criteria, verbatim from [progress §M6.2](2026-05-03-2349-go-backend-rewrite-progress.md#L114):
+
+> `/adults` page: table, name filter input, month range filter, totals row, credits/debts/unmatched sections, Pay buttons that link to `/qr`
+
+The Go side has done excellent prep: `buildAdultsResponse` in [go/internal/web/api/build_adults.go](../../go/internal/web/api/build_adults.go) already produces the full view model (currently consumed only by `/api/adults`), the wire types in [go/internal/web/api/types.go](../../go/internal/web/api/types.go) match the Python view-model 1:1, and the CSS is already lifted into [go/internal/web/static/css/app.css](../../go/internal/web/static/css/app.css). M6.2 is therefore mostly **template authoring + handler wiring + a small filters script**, not a fresh port.
+
+## Current Go web state (what we're building on)
+
+- [go/internal/web/server.go:49](../../go/internal/web/server.go#L49) — `mux.HandleFunc("GET /adults", hh.ServeAdults)` already wired.
+- [go/internal/web/html_handler.go:16-18](../../go/internal/web/html_handler.go#L16-L18) — placeholder handler renders a `PageData{Active, Build}` shell only. Needs to gain access to the data layer.
+- [go/internal/web/render.go:11](../../go/internal/web/render.go#L11) — `PageData` struct is currently `{Active, Build}` only. Needs to extend or be wrapped by a typed adults view model.
+- [go/internal/web/api/handler.go:36-45](../../go/internal/web/api/handler.go#L36-L45) — `ServeAdults` already does `loadAll` → `Reconcile` → `buildAdultsResponse`. We will extract that body into an exported method so the HTML handler can reuse it without duplication.
+- [go/internal/web/api/build_adults.go:17](../../go/internal/web/api/build_adults.go#L17) — `buildAdultsResponse(...) AdultsResponse` returns everything the template needs (`Months`, `Results`, `Totals`, `Credits`, `Debts`, `Unmatched`, `BankAccount`, `CurrentMonth`, …). We pass this struct straight into the template.
+- [go/internal/web/templates/adults.tmpl](../../go/internal/web/templates/adults.tmpl) — currently a 5-line placeholder. Replace contents.
+- [go/internal/web/static/css/app.css](../../go/internal/web/static/css/app.css) — all selectors needed (`.cell-ok`, `.cell-unpaid`, `.cell-unpaid-current`, `.cell-overridden`, `.unmatched-row`, `.filter-container`, `.pay-btn`, `.member-row`, …) already present from M6.1.
+
+Reference for parity: [templates/adults.html](../../templates/adults.html) (Python source). Sections to mirror in markup terms:
+- Reconcile table — [adults.html:534-585](../../templates/adults.html#L534-L585)
+- Totals row — [adults.html:571-582](../../templates/adults.html#L571-L582)
+- Credits / Debts — [adults.html:587-609](../../templates/adults.html#L587-L609)
+- Unmatched — [adults.html:611-629](../../templates/adults.html#L611-L629)
+- Filter controls — [adults.html:515-532](../../templates/adults.html#L515-L532)
+- Filter JS (name + month range) — [adults.html:1019-1051](../../templates/adults.html#L1019-L1051)
+
+The member-detail modal, Pay-preview modal, and JSON-hydrated `memberData`/`rawPaymentsByPerson` globals are explicitly **out of scope for M6.2** — they belong to M6.5 (modal JS).
+
+## Approach
+
+1. **Share data assembly between HTML and JSON** — extract `ServeAdults`'s body into `(*api.Handler).AssembleAdults(ctx) (AdultsResponse, error)` and have `ServeAdults` call it. The HTML handler then calls the same method, keeping `/adults` and `/api/adults` byte-identical in semantics (same loaded data, same reconcile, same view model).
+2. **Wire HTMLHandler to data** — extend `HTMLHandler` with an `apiHandler *api.Handler` field and pass it from `Run()`. `ServeAdults` becomes: `AssembleAdults` → on error render an error body (or 500) → render `adults.tmpl` with a typed view model wrapping `PageData` + `api.AdultsResponse`.
+3. **Per-page typed view model** — add `AdultsPageData{ PageData; Data api.AdultsResponse }` in [render.go](../../go/internal/web/render.go) (or a new `view.go`). Template references `.Active`, `.Build` (chrome) and `.Data.Results`, `.Data.Totals`, `.Data.Months`, etc. Keeps the chrome contract for nav/footer untouched.
+4. **Author `adults.tmpl`** — port markup from [templates/adults.html:489-629](../../templates/adults.html#L489-L629). Notable mechanics:
+   - Filter controls block with `<input id="nameFilter">`, `<select id="fromMonth">`, `<select id="toMonth">`, `Apply` / `All` buttons. Month dropdown options rendered server-side from `.Data.Months` (no client-side hydration needed for filters).
+   - Reconcile table iterates `.Data.Results`; each row's months iterate `row.Months`. Cell `<td>` gets class `cell-{{.Status}}`, plus `cell-unpaid-current` when `.RawMonth >= .Data.CurrentMonth`, plus `cell-overridden` when `.Overridden`. Cells carry `data-month-idx="{{$i}}"` so the filter script can hide columns.
+   - Per-cell Pay button visible on hover when `(unpaid|partial)` and `RawMonth < CurrentMonth` — `<a class="pay-btn" href="/qr?...">Pay</a>` with the QR query string built server-side via a template helper (see Key design notes).
+   - Per-row "Pay All" button when `.PayableAmount > 0`, same href construction using `.UnpaidPeriods` for display and `.RawUnpaidPeriods` for the QR message.
+   - Totals `<tr>` iterates `.Data.Totals`, classes `total-cell-{{.Status}}`.
+   - Credits / Debts / Unmatched sections rendered conditionally on non-empty slices.
+5. **Tiny filter script** — new [go/internal/web/static/js/filters.js](../../go/internal/web/static/js/filters.js):
+   - `nameFilter` `input` event: NFD-normalize + lowercase + substring match against `.member-row [data-name]` (or row's first cell text); toggle `display:none` on non-matches.
+   - `fromMonth` / `toMonth` `change` event + `Apply` button: read selected `data-month-idx` range, toggle `month-hidden` class on `[data-month-idx]` `<th>`/`<td>` outside the range.
+   - `All` button: clear filters, restore all rows/cells.
+   - Match Python's behaviour byte-for-byte from [adults.html:864-1051](../../templates/adults.html#L864-L1051) but trimmed of modal/`memberData` calls.
+   - Loaded via `<script src="/static/js/filters.js" defer></script>` from the adults template (or base, if juniors will reuse it — yes, it should be in base or a content-block include).
+6. **`<a href="/qr?…">` Pay buttons now, modal in M6.5** — the M6.6 milestone adds `/qr`. Until then, hrefs return 404. M6.5 will layer modal preview behaviour on top by wrapping clicks; the markup stays the same. This is the simplest staged rollout.
+7. **Template helper for QR href** — add a `funcMap` to `Renderer` with `qrHref(account, amount, name, month string) string` (and a periods-list variant) that builds `/qr?account=…&amount=…&message=…` with proper URL encoding. Implementation: `net/url.Values{}.Encode()`. This keeps URL-construction logic out of the template syntax (`html/template` URL escaping isn't enough — query-param building deserves a Go helper).
+8. **Active-link key** — `Active: "adults"` already set; nav highlighting works as-is (verified in M6.1 smoke test).
+
+## Files to create / modify
+
+```
+go/internal/web/
+├── api/
+│   └── handler.go                MODIFY — extract ServeAdults body to AssembleAdults(ctx)
+├── html_handler.go               MODIFY — hold *api.Handler; ServeAdults loads + renders
+├── render.go                     MODIFY — add AdultsPageData type; add funcMap with qrHref()
+├── server.go                     MODIFY — pass *api.Handler into NewHTMLHandler
+├── html_handler_test.go          MODIFY — add adults markup-level assertions w/ stub Sources
+├── templates/
+│   └── adults.tmpl               MODIFY — replace placeholder w/ full table + filters + sections
+└── static/
+    └── js/
+        └── filters.js            NEW — name + month-range client-side filtering
+```
+
+No new packages; no domain or wire-type changes.
+
+## Key design notes
+
+- **Reuse `buildAdultsResponse` verbatim** — no parallel "view model" needed. `AdultsResponse` already has every field the template wants. `/adults` and `/api/adults` consume the same struct.
+- **Extracting `AssembleAdults`** preserves the parity contract: anything that changes the JSON also changes the HTML, by construction. (It also sets up the same pattern for M6.3 juniors and M6.4 payments.)
+- **Filter UX is DOM-driven**, no JSON hydration. `member_data` / `raw_payments` JSON payloads stay deferred to M6.5 (modal needs them; filters do not).
+- **`current_month` boundary is server-side** — `AdultsResponse.CurrentMonth` (set from `time.Now().Format("2006-01")` in `loadAll`) is what the template compares `RawMonth` against for `cell-unpaid-current` styling and Pay-button visibility. Same value Python passes through `vm["current_month"]`.
+- **`html/template` autoescaping is sufficient** for member names, sender, message, etc. — but Pay-button URLs need explicit `url.Values` encoding (Czech names have diacritics and spaces). Hence the `qrHref` funcMap helper.
+- **Error rendering**: if `AssembleAdults` fails, render the base shell with an error banner inside `content` rather than `http.Error`. Keeps nav visible so the user can navigate away. Match Python's `"No data."` fallback at [app.py:233](../../app.py#L233) for empty results.
+- **No JS framework, no bundler** — filter script is plain ES2020, ~80 lines, inline-readable. Matches M6.1's "no JS in M6.1" follow-through (we add JS in M6.2, but kept minimal).
+- **NFD-normalize** in JS via `s.normalize('NFD').replace(/\p{Diacritic}/gu, '').toLowerCase()` to match Python's `unicodedata.normalize('NFD', ...)`. Python ref: [adults.html:868-873](../../templates/adults.html#L868-L873).
+- **Filter persistence is out of scope** — Python's filters are session-only (no localStorage). Same here.
+
+## Critical files to read
+
+- [go/internal/web/api/build_adults.go](../../go/internal/web/api/build_adults.go) — full view model already built; the template just iterates over `AdultsResponse`.
+- [go/internal/web/api/types.go:91-122](../../go/internal/web/api/types.go#L91-L122) — `MonthCell`, `TotalCell`, `MemberRow`, `Credit` shapes.
+- [go/internal/web/api/handler.go:36-96](../../go/internal/web/api/handler.go#L36-L96) — pattern for `loadAll` + `Reconcile` + `buildAdultsResponse`; the bit to refactor into `AssembleAdults`.
+- [go/internal/web/static/css/app.css](../../go/internal/web/static/css/app.css) — class names available; no edits needed.
+- [templates/adults.html:489-629](../../templates/adults.html#L489-L629) — markup reference for filter controls, table, totals, credits/debts, unmatched.
+- [templates/adults.html:864-1051](../../templates/adults.html#L864-L1051) — JS reference for filter behaviour (NFD-normalize, month range hiding, Apply/All).
+- [tests/test_app.py:50-75](../../tests/test_app.py#L50-L75) — `test_adults_route` in Python, mirror its assertions in Go: status 200, body contains member name + `750/750 CZK (4)` + `Adults Dashboard`, does not contain `OK`.
+
+## Verification
+
+End-to-end smoke after `make go-build`:
+
+1. `make web-go &` — server boots, no template-parse errors.
+2. `curl -i localhost:8080/adults` → `200`, `Content-Type: text/html`.
+3. Browser at `http://localhost:8080/adults` against real data:
+   - Table renders with one row per adult member, one column per month, totals row at bottom.
+   - Cell colors match `/api/adults` JSON — pick a `Credits` member from JSON, confirm green-ish status; pick a `Debts` member, confirm red-ish.
+   - Credits / Debts / Unmatched sections render with content matching the JSON arrays for those keys.
+   - Per-cell `Pay` buttons appear on hover for past-month unpaid/partial cells; href contains `/qr?account=...&amount=...&message=`.
+   - Per-row "Pay All" button shows for members with `payable_amount > 0`.
+4. Filters:
+   - Type a partial member name in `#nameFilter` → only matching rows visible. Test with diacritics (e.g. `nemec` matches `Němec`).
+   - Pick `fromMonth=2026-02`, `toMonth=2026-04`, click `Apply` → only those columns visible (table + totals row).
+   - Click `All` → everything restored.
+5. `curl -s localhost:8080/adults | grep -F 'Adults Dashboard'` matches; `grep -F 'Coming in M6.2'` does **not** match.
+6. `make go-test` — `html_handler_test.go` adults assertions pass with stub Sources fixture (replicating `test_adults_route` from Python).
+7. `make go-lint` clean.
+8. `make parity` still green — `/api/adults` JSON unchanged because `AssembleAdults` extraction is a pure refactor.
+9. CHANGELOG entry per CLAUDE.md (timestamp via `date "+%Y-%m-%d %H:%M %Z"`).
+10. Tick M6.2 in [progress tracker §M6.2](2026-05-03-2349-go-backend-rewrite-progress.md#L114) with the merge commit SHA.
+
+## Branch & MR
+
+Branch `feat/go-m6-2-adults-page` per CLAUDE.md branch-per-feature workflow. Commit, push with `-u`, then:
+
+```bash
+tea pr create \
+  --title "feat(go): M6.2 — adults page (table, filters, credits/debts/unmatched, Pay buttons)" \
+  --description "..." \
+  --base main \
+  --head feat/go-m6-2-adults-page
+```
+
+Print the PR URL for the user. User merges in Gitea browser.

docs/plans/2026-05-08-1052-period-selector-missing-old-months.md

@@ -0,0 +1,142 @@
+# Period selector missing older months — diagnosis
+
+## Context
+
+User reports the "From / To" period selector on the **adults** dashboard now
+shows **Dec 2025** as the oldest available period. The older production
+deployment shows Sep+Oct 2025, Nov 2025, Dec 2025+Jan 2026 (merged labels) —
+i.e. data going back to September 2025. The user wants to know what went
+sideways. Confirmed: the dropdown options on both Python and Go genuinely
+start at Dec 2025, not just the default selection — Sep/Oct/Nov 2025 are not
+in the list at all.
+
+## Root cause — the live adults sheet header is missing those columns
+
+The fresh cache files at `tmp/go/attendance_regular_cache.json` (raw rows from
+Google Sheets, modifiedTime `2026-05-06T22:30:02Z`, cached `2026-05-08T00:26`)
+contain the actual header row for the adults tab (gid=0):
+
+```text
+['FUJ tréninky úterý 20:30-22:00', '', '', '02.12.2025', '09.12.2025',
+ '16.12.2025', '06.01.2026', '13.01.2026', '20.01.2026', '27.01.2026',
+ '03.02.2026', '10.02.2026', '17.02.2026', '24.02.2026', '03.03.2026',
+ '10.03.2026', '17.03.2026', '23.03.2026', '31.03.2026', '13.04.2026',
+ '20.04.2026', '27.04.2026', '04.05.2026', '', '', '']
+```
+
+**The first date column in the live adults sheet is `02.12.2025` (Dec 2 2025).**
+There are no September, October, or November 2025 columns in the header at
+all. Both backends parse this faithfully (no slicing, no cutoff anywhere) and
+correctly produce `sortedMonths = ["2025-12", "2026-01", …, "2026-05"]`.
+
+The juniors sheet (different tab, `JUNIOR_SHEET_GID`) is **fine** — its header
+still contains `['', 'tier', '', '15.09.2025', '13.10.2025', '20.10.2025',
+'03.11.2025', '24.11.2025', '10.11.2025', '17.11.2025', '01.12.2025', …]`. So
+the juniors page still shows Sep+Oct / Nov / Dec+Jan correctly.
+
+So this is a **data issue in the adults attendance Google Sheet**: at some
+point between when production's cache was last warmed (showing Sep–Nov) and
+2026-05-06, somebody (or some action) removed the columns for September,
+October, and November 2025 from the adults tab header.
+
+The code is doing exactly what it should. There is no parser regression.
+
+## What to do
+
+### 1. Restore the missing date columns in the adults attendance sheet
+
+The fix lives in Google Sheets, not in the codebase. Options, in order of
+preference:
+
+- **(a) Use Sheets version history.** File → Version history → See version
+  history; find a version from before the columns were dropped (anything
+  before about Mar 2026 should still have them). Copy the Sep/Oct/Nov 2025
+  date column headers and the `TRUE/FALSE` cells underneath them back into
+  the current sheet. Only restore the 11 missing date columns; do not
+  full-revert (you'd lose every change since then).
+- **(b) Pull from the production server's cache.** The production deployment
+  evidently still has the older cache, since its dashboard renders those
+  months. SSH there, copy `tmp/attendance_regular_cache.json`, and you can
+  reconstruct the per-member Sep/Oct/Nov attendance counts from the
+  `data[*][2]` map (keys `"2025-09"`, `"2025-10"`, `"2025-11"`). Re-enter
+  those into the sheet manually as date columns + `TRUE` cells — tedious but
+  deterministic.
+- **(c) Accept the loss.** If the older columns aren't recoverable, the
+  dashboard correctly reflects what the sheet contains; nothing more to do.
+
+Which to pick depends on whether those months still need to be billed /
+reconciled.
+
+### 2. Restore `ADULT_MERGED_MONTHS` (user confirmed this was unintentional)
+
+Independent of the sheet issue: commit `1257f0d` (Mar 9 2026) commented out
+the adult merge mappings. Once the Sep/Oct/Nov columns are back in the sheet,
+the dashboard would still show them as separate periods instead of the
+production-style "Sep+Oct 2025" and "Dec 2025+Jan 2026" merged labels.
+
+User confirmed this was unintentional. Two files to update:
+
+- [scripts/attendance.py:32-35](scripts/attendance.py#L32-L35) — uncomment
+  the two mappings:
+
+  ```python
+  ADULT_MERGED_MONTHS = {
+      "2025-12": "2026-01",   # keys are merged into values
+      "2025-09": "2025-10",
+  }
+  ```
+
+- [go/internal/services/membership/sources.go:30](go/internal/services/membership/sources.go#L30) — mirror the same:
+
+  ```go
+  var AdultMergedMonths = map[string]string{
+      "2025-12": "2026-01",
+      "2025-09": "2025-10",
+  }
+  ```
+
+After this change, hit `POST /flush-cache` on each backend so the in-process
+post-processed adults cache is rebuilt with the new mapping.
+
+### 3. (Optional, separate) Fix the JS auto-default that hides older months
+
+This is **not** the cause of the user's current symptom (that's the sheet
+issue), but it will become a UX issue once Sep/Oct/Nov columns are restored:
+the Python frontend's `defaultFrom = Math.max(0, maxMonthIdx - 4)` will still
+default the From-selector to ~5 months before the latest column on every page
+load, hiding restored older months until the user manually picks them.
+
+- [templates/adults.html:1047](templates/adults.html#L1047) — `var defaultFrom = Math.max(0, maxMonthIdx - 4);`
+- [templates/juniors.html:1028](templates/juniors.html#L1028) — same line.
+
+Drop those four lines (`defaultFrom`, `fromSelect.value = defaultFrom`,
+`toSelect.value = maxMonthIdx`, `applyMonthFilter()`) so the page loads with
+all non-future months visible — matching the Go side, which only calls
+`hideFutureMonths()` and leaves From at its first option.
+
+Recommend bundling this with step 2 since they touch related UI.
+
+## Verification
+
+1. **After step 1** — `POST /flush-cache` on Python and Go backends; reload
+   `/adults` on each. Confirm the dropdown now lists Sep/Oct/Nov 2025.
+2. **After step 2** — reload `/adults`. Confirm the dropdown shows
+   "Sep+Oct 2025" as a single period and "Dec 2025+Jan 2026" as a single
+   period. (Still requires the sheet columns to exist.)
+3. **After step 3** — reload `/adults` and `/juniors` on Python. Confirm the
+   table renders all non-future months on first load (Sep 2025 through the
+   current month) instead of starting at Dec 2025.
+4. **Parity check** — `make parity` should report zero diffs between Python
+   and Go on `/api/adults` and `/api/juniors`.
+
+## Critical files referenced
+
+- `tmp/go/attendance_regular_cache.json` — current adults sheet rows
+  (evidence: header starts at `02.12.2025`).
+- `tmp/go/attendance_juniors_cache.json` — current juniors sheet rows
+  (header still has `15.09.2025`).
+- [scripts/attendance.py](scripts/attendance.py) — `ADULT_MERGED_MONTHS`
+  empty after `1257f0d`; `parse_dates` / `group_by_month` faithful.
+- [go/internal/services/membership/sources.go](go/internal/services/membership/sources.go) — Go counterpart, same shape.
+- [templates/adults.html](templates/adults.html), [templates/juniors.html](templates/juniors.html) — JS onload `defaultFrom = -4` issue (step 3).
+- [go/internal/web/static/js/filters.js](go/internal/web/static/js/filters.js) — Go filter UI (already correct, no changes).

docs/plans/2026-05-08-1123-go-m6-3-juniors-page.md

@@ -0,0 +1,67 @@
+# M6.3 — Go-native `/juniors` page
+
+## Context
+
+The Go rewrite is in milestone M6 (Go-native HTML frontend). M6.2 shipped the `/adults` page in commit `c85748b`; the [progress tracker](../../srv/personal/fuj-management/docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md) line 115 names M6.3 as:
+
+> `/juniors` page: same structure + per-month J/A attendance breakdown + `"?"` sentinel rendering
+
+The Go side already has `buildJuniorsResponse` (M5.2) that produces the full JSON view model, and the JuniorsResponse uses the same `MemberRow`/`MonthCell`/`TotalCell` types as `AdultsResponse`. Critically, `buildJuniorMemberRow` ([go/internal/web/api/build_juniors.go:142](../../srv/personal/fuj-management/go/internal/web/api/build_juniors.go#L142)) already bakes the J/A breakdown (e.g. `"3/500 CZK (4:2J,2A)"`) and the `"?"` sentinel into `MonthCell.Text` — no template-level junior-specific logic is required for the M6.3 table.
+
+Today `juniors.tmpl` is a 4-line "Coming in M6.3" placeholder and `HTMLHandler.ServeJuniors` ([html_handler.go:35](../../srv/personal/fuj-management/go/internal/web/html_handler.go#L35)) just renders that placeholder. Goal of M6.3: produce a working `/juniors` page that mirrors the structure of `/adults` and reaches feature parity with the Python `/juniors` route.
+
+## Approach
+
+Mirror the M6.2 pattern exactly:
+
+1. **Extract `AssembleJuniors(ctx)`** from the JSON handler so HTML + JSON share one view-model assembly path (the parity contract).
+2. **Add `JuniorsPageData`** wrapper type next to `AdultsPageData` in `render.go`.
+3. **Replace `juniors.tmpl`** with an adults-shaped layout. Because `JuniorsResponse` shares the same field names used by `adults.tmpl` (`Months`, `RawMonths`, `Results`, `Totals`, `Credits`, `Debts`, `AttendanceURL`, `PaymentsURL`, `BankAccount`, `CurrentMonth`), the template body is essentially copy/paste with one parity tweak (see "Decisions" below).
+4. **Wire `HTMLHandler.ServeJuniors`** to call `AssembleJuniors` and render the new template, parallel to `ServeAdults`.
+
+No new CSS, no new JS — `filters.js` and the `cell-*` classes (lifted in M6.1) already cover juniors.
+
+## Files to modify
+
+| File | Change |
+| --- | --- |
+| [go/internal/web/api/handler.go](../../srv/personal/fuj-management/go/internal/web/api/handler.go) | Add `AssembleJuniors(ctx) (JuniorsResponse, error)`; refactor existing `ServeJuniors` to call it (mirrors `AssembleAdults` at line 47). |
+| [go/internal/web/render.go](../../srv/personal/fuj-management/go/internal/web/render.go) | Add `JuniorsPageData` struct (PageData + `Data api.JuniorsResponse` + `Error string`). |
+| [go/internal/web/html_handler.go](../../srv/personal/fuj-management/go/internal/web/html_handler.go) | Replace stub `ServeJuniors` with the same shape as `ServeAdults` (lines 20–33). |
+| [go/internal/web/templates/juniors.tmpl](../../srv/personal/fuj-management/go/internal/web/templates/juniors.tmpl) | Replace placeholder with a structurally identical copy of [adults.tmpl](../../srv/personal/fuj-management/go/internal/web/templates/adults.tmpl), with the title swapped to "Juniors Dashboard" and the Unmatched section removed (parity with Python). |
+| [docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md](../../srv/personal/fuj-management/docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md) | Tick `M6.3` once merged, append merge SHA. |
+| [CHANGELOG.md](../../srv/personal/fuj-management/CHANGELOG.md) | New top-most entry per CLAUDE.md format. |
+
+## Decisions captured
+
+- **No "Unmatched Transactions" section on `/juniors`.** Python's [templates/juniors.html](../../srv/personal/fuj-management/templates/juniors.html) renders only Credits + Debts (no Unmatched block). Although `JuniorsResponse.Unmatched` is populated, parity says we don't render it on juniors. The data stays available for the modal in M6.5.
+- **Reuse `qrHref` / `qrHrefAll` template funcs** from [render.go:35–57](../../srv/personal/fuj-management/go/internal/web/render.go#L35-L57). They are name-only (not adult-specific) and already on `tmplFuncs`.
+- **Reuse the existing `cell-empty / cell-unpaid / cell-unpaid-current / cell-ok / cell-overridden` cell-class branching** from `adults.tmpl` lines 60–67 verbatim. The "?" sentinel is rendered as plain `{{$cell.Text}}` text — no template branch needed because `buildJuniorMemberRow` produces `"?"` or `"? CZK"` already.
+- **No template helper extraction** (e.g. shared `_table_section.tmpl`). The two templates will be near-duplicates, but extracting a shared partial now is premature — wait until M6.4 or later when patterns settle. M6.2 didn't extract one either.
+- **Branch**: `feat/go-m6-3-juniors-page`, MR via `tea pr create` per CLAUDE.md.
+
+## Verification
+
+End-to-end smoke (parallel-running both backends as in M5/M6.2):
+
+1. `cd go && make run` (or whatever target boots the Go server on :8080).
+2. Browser-load `http://localhost:8080/juniors`. Confirm:
+   - Member rows render with cells containing fee + attendance breakdown like `0/500 CZK (3:2J,1A)`.
+   - At least one `"?"` cell visible (any junior with exactly one session in some month).
+   - Filter input narrows rows by name; From/To month selects hide columns via `data-month-idx`.
+   - `Pay` button visible on past-month unpaid cells; clicking links to `/qr?...`. (The QR endpoint itself lands in M6.6 — only the link target is in scope here.)
+   - `Pay All` visible on rows with `Balance < 0`.
+   - TOTAL row sums correctly per month.
+   - Credits + Debts sections render when present; no Unmatched section.
+3. JSON parity: `make parity` against the M3 fixture corpus must still report zero non-allowlisted diffs for `/api/juniors` (the `AssembleJuniors` extraction must not change wire output).
+4. Compare side-by-side against Python `/juniors` on :5001 for the same fixture; the table cells should match cell-for-cell modulo the known M5 allowlist.
+
+## Out of scope
+
+- Modal (`[i]` info button + `#memberModal`) — that is M6.5.
+- QR endpoint, `/sync-bank`, `/flush-cache`, `/version` pages — M6.6.
+- Embed.FS deploy verification — M6.7.
+
+## Plan-file relocation
+
+Per [CLAUDE.md](../../srv/personal/fuj-management/CLAUDE.md) "Plans" section, plan files belong in `docs/plans/YYYY-MM-DD-HHMM-<slug>.md` inside the repo. Plan mode forced this draft into `~/.claude/plans/`; first step after ExitPlanMode is to copy this file to `docs/plans/2026-05-08-HHMM-go-m6-3-juniors-page.md` (resolving the timestamp at that moment) and commit it on the feature branch alongside the implementation.

docs/plans/2026-05-08-1220-go-m6-4-payments-page.md

@@ -0,0 +1,215 @@
+# M6.4 — Go-native `/payments` page (grouped-by-person ledger)
+
+> Plan-mode note: per project convention this plan should live at
+> `docs/plans/2026-05-08-1220-go-m6-4-payments-page.md`. The first execution
+> step after approval is to copy this file there.
+
+## Context
+
+The Go port of the Flask app is at milestone **M6.4**: replace the placeholder
+`/payments` template ([go/internal/web/templates/payments.tmpl](go/internal/web/templates/payments.tmpl))
+with a feature-equivalent grouped-by-person ledger view, matching the Python
+[templates/payments.html](templates/payments.html) page.
+
+Compared to M6.2 (`/adults`) and M6.3 (`/juniors`), this page is **structurally
+much simpler**:
+
+- No filters (no name input, no month-range selects).
+- No totals / credits / debts / unmatched-as-extra-section.
+- No JS (no `filters.js`, no modal — modal is M6.5 territory and Python's
+  payments page itself has none).
+- No QR / Pay buttons.
+- Single grouping dimension: **by person**, sorted alphabetically, with a
+  synthetic `"Unmatched / Unknown"` bucket appended.
+- Each person's transactions sorted **newest-first**.
+- Columns: Date, Amount (right-aligned, green), Purpose, Bank Message.
+
+The JSON API side is already done (`/api/payments` at
+[go/internal/web/api/handler.go:78-86](go/internal/web/api/handler.go#L78-L86)),
+returning a `PaymentsResponse{ GroupedPayments, SortedPeople, AttendanceURL,
+PaymentsURL }`. The HTML side just needs to consume it.
+
+## Approach
+
+Mirror the M6.2/M6.3 pattern: extract an `AssembleX(ctx)` method, add a typed
+`PageData` wrapper, render a real template, lift the page-specific CSS into the
+shared stylesheet.
+
+### 1. Extract `AssemblePayments(ctx) (PaymentsResponse, error)`
+
+In [go/internal/web/api/handler.go](go/internal/web/api/handler.go), refactor
+`ServePayments` (currently inlines the load+build at lines 78-86) to mirror
+`AssembleAdults` / `AssembleJuniors`:
+
+```go
+func (h *Handler) ServePayments(w http.ResponseWriter, r *http.Request) {
+    resp, err := h.AssemblePayments(r.Context())
+    if err != nil { h.writeError(w, r, err); return }
+    writeJSON(w, resp)
+}
+
+func (h *Handler) AssemblePayments(ctx context.Context) (PaymentsResponse, error) {
+    txns, err := h.Sources.LoadTransactions(ctx)
+    if err != nil { return PaymentsResponse{}, fmt.Errorf("load transactions: %w", err) }
+    return buildPaymentsResponse(txns, h.allMemberNames(ctx)), nil
+}
+```
+
+Pure refactor — `make parity` should report zero diffs on `/api/payments`.
+
+### 2. Add `PaymentsPageData` wrapper
+
+In [go/internal/web/render.go](go/internal/web/render.go), alongside
+`AdultsPageData` / `JuniorsPageData`:
+
+```go
+type PaymentsPageData struct {
+    PageData
+    Data  api.PaymentsResponse
+    Error string
+}
+```
+
+No changes needed to `pageNames` — `"payments"` is already registered.
+
+### 3. Rewire HTML handler
+
+Replace [go/internal/web/html_handler.go:50-52](go/internal/web/html_handler.go#L50-L52):
+
+```go
+func (h *HTMLHandler) ServePayments(w http.ResponseWriter, r *http.Request) {
+    data := PaymentsPageData{ PageData: PageData{Active: "payments", Build: h.build} }
+    resp, err := h.apiHandler.AssemblePayments(r.Context())
+    if err != nil { data.Error = err.Error() } else { data.Data = resp }
+    h.renderer.Render(w, "payments", data)
+}
+```
+
+### 4. Replace template stub
+
+Rewrite [go/internal/web/templates/payments.tmpl](go/internal/web/templates/payments.tmpl)
+(currently a 5-line placeholder). Structure:
+
+```gotmpl
+{{define "title"}}Payments Ledger{{end}}
+{{define "content"}}
+<h1>Payments Ledger</h1>
+<p class="description">
+  All bank transactions from the
+  <a href="{{.Data.PaymentsURL}}" target="_blank">payments sheet</a>,
+  grouped by member. Names are matched against the
+  <a href="{{.Data.AttendanceURL}}" target="_blank">attendance sheet</a>.
+</p>
+{{if .Error}}<p class="error">{{.Error}}</p>{{end}}
+<div class="ledger-container">
+{{range $person := .Data.SortedPeople}}
+  <div class="member-block">
+    <h2>{{$person}}</h2>
+    <table class="txn-table">
+      <thead><tr>
+        <th class="txn-date">Date</th>
+        <th class="txn-amount">Amount</th>
+        <th class="txn-purpose">Purpose</th>
+        <th class="txn-message">Bank Message</th>
+      </tr></thead>
+      <tbody>
+      {{range $tx := index $.Data.GroupedPayments $person}}
+        <tr>
+          <td class="txn-date">{{$tx.Date}}</td>
+          <td class="txn-amount">{{printf "%.0f" $tx.Amount}} CZK</td>
+          <td class="txn-purpose">{{$tx.Purpose}}</td>
+          <td class="txn-message">{{$tx.Message}}</td>
+        </tr>
+      {{end}}
+      </tbody>
+    </table>
+  </div>
+{{end}}
+</div>
+{{end}}
+```
+
+Notes:
+- `printf "%.0f"` matches the visual style of integer CZK amounts (Python prints
+  the float as-is, but bank-row amounts are always whole CZK). If the user
+  prefers exact Python parity (`750.0 CZK`), drop the `printf` and use
+  `{{$tx.Amount}}`.
+- Iterating a `map` requires using `.Data.SortedPeople` to drive order then
+  `index $.Data.GroupedPayments $person` — Go templates don't preserve map
+  insertion order.
+
+### 5. Add CSS classes to `app.css`
+
+Append the page-specific rules from [templates/payments.html:111-164](templates/payments.html#L111-L164)
+to [go/internal/web/static/css/app.css](go/internal/web/static/css/app.css):
+`.ledger-container`, `.member-block`, `.txn-table`, `.txn-table th/td`,
+`.txn-date`, `.txn-amount`, `.txn-purpose`, `.txn-message`, `tr:hover`. The
+terminal-green palette already matches.
+
+### 6. Unit test
+
+Add a markup-level test to `go/internal/web/html_handler_test.go` (the file
+created in M6.2/M6.3) following the same pattern: stub `Sources` returning a
+fixed transaction list, assert response is HTML 200, assert key strings appear
+(person names as `<h2>`, "Payments Ledger" `<h1>`, expected amount, "Unmatched
+/ Unknown" bucket when an unattributed tx exists).
+
+## Critical files
+
+| Action  | Path |
+|---------|------|
+| edit    | [go/internal/web/api/handler.go](go/internal/web/api/handler.go) — extract `AssemblePayments` |
+| edit    | [go/internal/web/render.go](go/internal/web/render.go) — add `PaymentsPageData` |
+| edit    | [go/internal/web/html_handler.go](go/internal/web/html_handler.go) — rewire `ServePayments` |
+| rewrite | [go/internal/web/templates/payments.tmpl](go/internal/web/templates/payments.tmpl) — real template |
+| edit    | [go/internal/web/static/css/app.css](go/internal/web/static/css/app.css) — append ledger CSS |
+| edit    | `go/internal/web/html_handler_test.go` — payments markup test |
+
+No changes to `server.go`, `assets.go`, `Sources` interface, `buildPaymentsResponse`,
+or any domain code — these were completed in M5 / M6.1.
+
+## Reused existing helpers
+
+- [go/internal/web/api/build_payments.go](go/internal/web/api/build_payments.go) — `buildPaymentsResponse` (existing, unchanged)
+- [go/internal/web/api/build_common.go:84-117](go/internal/web/api/build_common.go#L84-L117) — `groupRawPaymentsByPerson` handles canonicalization, comma-splitting, `[?]` stripping, newest-first sort
+- [go/internal/web/api/handler.go:116-129](go/internal/web/api/handler.go#L116-L129) — `allMemberNames`
+- [go/internal/web/templates/partials/nav.tmpl](go/internal/web/templates/partials/nav.tmpl) and `footer.tmpl` — already include the `[Payments Ledger]` nav link
+
+## Verification
+
+End-to-end:
+
+1. `cd go && make go-build go-test go-lint` — all green.
+2. `make parity` — confirm the `AssemblePayments` extraction is byte-equal on
+   `/api/payments`.
+3. `make web-go &` then:
+   - `curl -i localhost:8080/payments | head -30` — HTTP 200, `text/html`.
+   - Browser load `http://localhost:8080/payments`:
+     - "Payments Ledger" heading + description with two clickable sheet links.
+     - Alphabetical member blocks, each with a table.
+     - Amounts right-aligned, green, "CZK" suffix.
+     - Newest-first ordering inside each block.
+     - "Unmatched / Unknown" bucket sorts in alphabetical position (capital U →
+       near end).
+     - Hover on a row darkens the background.
+     - Nav highlights `[Payments Ledger]` as the active link.
+   - Cross-check with Python: `make web-py &` → `http://localhost:5001/payments`
+     should look visually identical except for nav styling.
+4. `make web-py & make web-go &` then `tea pr create` once committed (per
+   project branch-per-feature workflow).
+
+## Branching
+
+Create `feat/go-m6-4-payments-page` off `main`, push, open MR via `tea`.
+Follow project conventions: Co-Authored-By trailer, CHANGELOG entry once user
+confirms it works, tick **M6.4** in
+[docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md:116](docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md#L116)
+with the merge SHA after the user merges in Gitea.
+
+## Out of scope (deferred)
+
+- **Modal / `[i]` info button** — M6.5 (not present in Python `/payments` either).
+- **Period selector** — `/payments` has none in Python; not adding one.
+- **embed.FS deploy verification** — M6.7.
+- **Shared partial extraction** — payments structurally diverges from
+  adults/juniors enough that there's no obvious common partial to lift; defer.

docs/plans/2026-05-08-1259-go-m6-5-modal-js.md

@@ -0,0 +1,288 @@
+# M6.5 — Member-detail modal JS module (`/adults`, `/juniors`)
+
+> Plan-mode note: per project convention this plan should live at
+> `docs/plans/2026-05-08-HHMM-go-m6-5-modal-js.md` (use `date "+%Y-%m-%d-%H%M"`
+> when copying). The first execution step after approval is to copy this file
+> there. Branch: `feat/go-m6-5-modal-js` off `main`.
+
+## Context
+
+The Go port of the Flask app is at milestone **M6.5**: the `/adults` and
+`/juniors` pages currently render their tables ([go/internal/web/templates/adults.tmpl](go/internal/web/templates/adults.tmpl),
+[go/internal/web/templates/juniors.tmpl](go/internal/web/templates/juniors.tmpl))
+but have no row-click member-detail modal — the feature that lets a user click
+a member's row to inspect status per month, exception overrides, "other"
+transactions, the matched payment list, and a debug raw-payments view.
+
+The Python implementation lives inline in
+[templates/adults.html:718-993](templates/adults.html#L718-L993)
+(matching code in [templates/juniors.html](templates/juniors.html) — same
+modal markup and JS). It uses globals injected via Jinja:
+`memberData`, `sortedMonths`, `monthLabels`, `rawPaymentsByPerson`. M6.5
+replaces this with a clean static JS module.
+
+Per milestone wording — *"fetches `/api/adults` (or juniors), renders
+status/exceptions/transactions on row click; keyboard nav (Esc, ↑/↓)"* —
+and per the user's design choice: the JS module fetches `/api/<page>` **once
+on page load** and caches the response in a module-scoped variable. Subsequent
+row clicks render synchronously from cache. This keeps HTML purely
+server-rendered and reuses the parity-tested JSON contract already shipped in
+M5.
+
+All the building blocks are already in place:
+
+- **JSON API**: `/api/adults` and `/api/juniors` already return
+  `member_data`, `month_labels`, `raw_payments` as nested objects (see
+  [go/internal/web/api/adults.go:27-42](go/internal/web/api/adults.go#L27-L42)
+  and the analogous juniors response). Junior `Expected` serialises as `"?"`
+  for the unknown sentinel via custom `MarshalJSON`
+  ([go/internal/web/api/types.go:24-29](go/internal/web/api/types.go#L24-L29)) — JS sees a literal string `"?"`.
+- **CSS**: `#memberModal`, `.modal-content`, `.modal-section`, `.modal-table`,
+  `.tx-list`, `.tx-item`, `.tx-meta`, `.tx-amount`, `.info-icon`, `.raw-toggle`
+  were lifted whole during M6.1 and live in
+  [go/internal/web/static/css/app.css](go/internal/web/static/css/app.css)
+  (lines 168-487). No CSS work needed.
+- **Member-row hooks**: `tr.member-row[data-name="..."]` and `td.member-name`
+  are already rendered by both templates.
+- **JS module convention**: `static/js/filters.js` is loaded with `<script src="/static/js/filters.js" defer>`;
+  M6.5 adds a sibling `static/js/member-detail.js` with the same loading
+  pattern.
+
+## Approach
+
+### 1. Add `[i]` info icon + `#memberModal` markup to both templates
+
+In [go/internal/web/templates/adults.tmpl](go/internal/web/templates/adults.tmpl)
+and [go/internal/web/templates/juniors.tmpl](go/internal/web/templates/juniors.tmpl):
+
+a. Inside the `<td class="member-name">{{$row.Name}}</td>` cell (line 59 of
+   each template), append the icon button:
+
+   ```gotmpl
+   <td class="member-name">{{$row.Name}}<span class="info-icon" data-name="{{$row.Name}}" title="Show details">[i]</span></td>
+   ```
+
+   Using a `data-name` attribute and a CSS class (rather than `onclick="..."`)
+   keeps the template free of inline JS — the module wires up the listener
+   itself.
+
+b. After the closing `</div>` of the table-container / sections, before the
+   `<script>` tag at line 140 (adults) / 120 (juniors), inject the modal
+   markup. Mirror the Python structure verbatim
+   ([templates/adults.html:644-707](templates/adults.html#L644-L707)):
+
+   ```gotmpl
+   <div id="memberModal" class="modal" onclick="if (event.target === this) this.classList.remove('active')">
+     <div class="modal-content">
+       <div class="modal-header">
+         <span class="modal-title" id="modalMemberName">—</span>
+         <span id="modalTier" class="modal-tier"></span>
+         <a href="#" class="modal-close" onclick="event.preventDefault(); document.getElementById('memberModal').classList.remove('active')">[x]</a>
+       </div>
+
+       <div class="modal-section">
+         <div class="modal-section-title">Status by Month</div>
+         <table class="modal-table">
+           <thead><tr><th>Month</th><th>Sessions</th><th>Expected</th><th>Paid</th><th>Status</th></tr></thead>
+           <tbody id="modalStatusBody"></tbody>
+         </table>
+       </div>
+
+       <div class="modal-section" id="modalExceptionSection" style="display:none">
+         <div class="modal-section-title">Exception Overrides</div>
+         <div id="modalExceptionList" class="tx-list"></div>
+       </div>
+
+       <div class="modal-section" id="modalOtherSection" style="display:none">
+         <div class="modal-section-title">Other Payments</div>
+         <div id="modalOtherList" class="tx-list"></div>
+       </div>
+
+       <div class="modal-section">
+         <div class="modal-section-title">Matched Transactions</div>
+         <div id="modalTxList" class="tx-list"></div>
+       </div>
+
+       <div class="modal-section">
+         <div class="modal-section-title">
+           Raw Payments (debug)
+           <a href="#" id="rawPaymentsToggle" class="raw-toggle">[show]</a>
+         </div>
+         <div id="modalRawList" class="tx-list" style="display:none"></div>
+       </div>
+     </div>
+   </div>
+   ```
+
+c. Add the script tag alongside `filters.js`. To tell the module which API
+   endpoint to fetch, use a `data-page` attribute on `body` (or on the
+   filter container — already exists). Simplest: add `data-page="adults"` /
+   `data-page="juniors"` to the existing `<div id="filterContainer">`.
+   The module reads it on load.
+
+   ```gotmpl
+   <script src="/static/js/member-detail.js" defer></script>
+   ```
+
+### 2. Create [go/internal/web/static/js/member-detail.js](go/internal/web/static/js/member-detail.js)
+
+A single shared module — both pages use the same DOM contract, so the same
+JS works for both. Structure (vanilla ES, no build step, matches `filters.js`
+style — IIFE, `'use strict'`, no globals leaked):
+
+```js
+(function () {
+  'use strict';
+
+  const container = document.getElementById('filterContainer');
+  if (!container) return;
+  const page = container.dataset.page;        // "adults" | "juniors"
+  if (!page) return;
+
+  let apiData = null;          // cached /api/<page> response
+  let currentMemberName = null;
+
+  // ── Data load ─────────────────────────────────────────────────────────
+  async function loadData() {
+    if (apiData) return apiData;
+    const r = await fetch('/api/' + page);
+    if (!r.ok) throw new Error('failed to fetch /api/' + page);
+    apiData = await r.json();
+    return apiData;
+  }
+
+  // Pre-warm immediately so first click is instant.
+  loadData().catch(err => console.error('[member-detail]', err));
+
+  // ── Modal render ──────────────────────────────────────────────────────
+  async function showMember(name) { /* port of Python showMemberDetails */ }
+  function toggleRawPayments(ev)  { /* port */ }
+  function closeModal()           { document.getElementById('memberModal').classList.remove('active'); }
+  function navigateMember(dir)    { /* port — walk visible .member-row */ }
+
+  // ── Wiring ────────────────────────────────────────────────────────────
+  document.querySelectorAll('.info-icon[data-name]').forEach(el => {
+    el.addEventListener('click', ev => {
+      ev.stopPropagation();
+      showMember(el.dataset.name);
+    });
+  });
+  document.getElementById('rawPaymentsToggle').addEventListener('click', toggleRawPayments);
+
+  document.addEventListener('keydown', e => {
+    const modal = document.getElementById('memberModal');
+    if (e.key === 'Escape') { closeModal(); return; }
+    if (!modal.classList.contains('active')) return;
+    if (e.key === 'ArrowDown') { e.preventDefault(); navigateMember(1); }
+    if (e.key === 'ArrowUp')   { e.preventDefault(); navigateMember(-1); }
+  });
+}());
+```
+
+The four `port` functions transcribe Python literally, with two adjustments:
+
+- `data.tier` — read directly from the API response (already present as
+  `AdultsMemberData.Tier` / `JuniorsMemberData.Tier`).
+- Junior `expected` may equal the literal string `"?"` (sentinel from
+  `Expected.MarshalJSON`). The status-row formatter must treat string
+  `expected` as "unknown / single attendance" and skip the numeric
+  comparisons — same logic Python uses when it sees `"?"`.
+
+`navigateMember` walks `document.querySelectorAll('tr.member-row')` filtered
+by `style.display !== 'none'`, finds the index whose `dataset.name`
+matches `currentMemberName`, and calls `showMember` on the next/previous
+visible row. Identical to Python lines 944-962 but uses `dataset.name`
+instead of parsing `childNodes[0].textContent`.
+
+### 3. Wire `data-page` attribute
+
+Append `data-page="adults"` to the `filterContainer` div in `adults.tmpl`,
+`data-page="juniors"` in `juniors.tmpl`. One-line edit per template.
+
+### 4. Unit test
+
+Extend [go/internal/web/html_handler_test.go](go/internal/web/html_handler_test.go)
+with assertions that the rendered HTML for `/adults` and `/juniors` contains:
+
+- `class="info-icon"` with the expected `data-name` per fixture row,
+- `id="memberModal"`,
+- `<script src="/static/js/member-detail.js"`,
+- `data-page="adults"` / `data-page="juniors"` on the filter container.
+
+These are markup-level checks only — the JS module behaviour is not unit
+tested in Go (would require headless-browser tooling that is out of scope
+for this milestone). Manual browser verification covers it.
+
+## Critical files
+
+| Action | Path |
+|--------|------|
+| edit   | [go/internal/web/templates/adults.tmpl](go/internal/web/templates/adults.tmpl) — add `[i]` icon, modal markup, `data-page`, script tag |
+| edit   | [go/internal/web/templates/juniors.tmpl](go/internal/web/templates/juniors.tmpl) — same |
+| new    | `go/internal/web/static/js/member-detail.js` — modal module |
+| edit   | `go/internal/web/html_handler_test.go` — markup assertions |
+
+No changes to: `app.css` (already complete), `assets.go` (the `embed.FS`
+glob `static/js/*` already picks up new files), `server.go`, `render.go`,
+the API handlers, or any domain code.
+
+## Reused existing infrastructure
+
+- [go/internal/web/api/handler.go](go/internal/web/api/handler.go) — `/api/adults`, `/api/juniors` already serve the modal's data
+- [go/internal/web/api/adults.go:27-42](go/internal/web/api/adults.go#L27-L42), [go/internal/web/api/juniors.go](go/internal/web/api/juniors.go) — typed responses
+- [go/internal/web/api/types.go:24-29](go/internal/web/api/types.go#L24-L29) — `Expected` "?" sentinel marshalling
+- [go/internal/web/static/css/app.css](go/internal/web/static/css/app.css) — modal CSS already lifted
+- [go/internal/web/static/js/filters.js](go/internal/web/static/js/filters.js) — IIFE / `'use strict'` / `data-*` attribute style to match
+- [templates/adults.html:725-962](templates/adults.html#L725-L962) — Python reference implementation to port (logic, not literal copy)
+
+## Verification
+
+End-to-end:
+
+1. `cd go && make go-build go-test go-lint` — all green.
+2. `make web-go &` — boot Go on `:8080`.
+3. Browser: `http://localhost:8080/adults`
+   - Click `[i]` next to a member name → modal opens with that member's data.
+   - Status table populated; cells colour-coded (cell-ok / cell-unpaid).
+   - Exception section visible only if member has exceptions; exception
+     amount shown with "*" override style.
+   - "Other Payments" section visible only if member has other-purpose
+     transactions.
+   - Matched transactions list newest-first; raw-payments section starts
+     hidden, `[show]` toggles to `[hide]`.
+   - `Esc` closes the modal; `ArrowDown` / `ArrowUp` walk visible rows
+     (after applying name filter).
+   - Click outside the `.modal-content` closes the modal.
+   - Open DevTools Network tab → reload; confirm one request to `/api/adults`
+     fires on page load (data is pre-warmed), no further requests on row
+     click.
+4. Browser: `http://localhost:8080/juniors`
+   - Same checks; verify `expected = "?"` rows render the question-mark
+     status without throwing JS errors.
+5. Cross-check against Python: `make web-py &` → `http://localhost:5001/adults`
+   should look visually equivalent (modulo nav styling) for the same fixture.
+6. After commit: `tea pr create --base main --head feat/go-m6-5-modal-js`.
+
+## Branching
+
+Per [CLAUDE.md](CLAUDE.md): create `feat/go-m6-5-modal-js` off `main`,
+commit with `Co-Authored-By` trailer, push with `-u`, open MR via
+`tea pr create`. Do not merge from CLI. After the user merges in Gitea:
+
+- Add CHANGELOG entry (timestamp via `date "+%Y-%m-%d %H:%M %Z"`).
+- Tick **M6.5** in
+  [docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md:117](docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md#L117)
+  with the merge SHA.
+
+## Out of scope (deferred)
+
+- **`/qr` modal** — separate `#qrModal` element, lives in M6.6 alongside
+  `/sync-bank`, `/flush-cache`, `/version`.
+- **Pay buttons inside the modal** — Python's modal does not include
+  Pay-from-modal; current Go pages already render row-level Pay buttons
+  in M6.2/M6.3.
+- **Modal on `/payments`** — Python `/payments` has no modal, neither does
+  Go (confirmed in M6.4 plan).
+- **Deep-linking (`/adults#name=Foo`)** — not in Python, not adding.
+- **Headless-browser JS tests** — out of scope for this milestone; manual
+  browser verification per §Verification.

docs/plans/2026-05-08-1334-go-m6-6-action-pages.md

@@ -0,0 +1,124 @@
+# M6.6 — `/qr`, `/sync-bank`, `/flush-cache`, `/version` (Go parity)
+
+> On approval, relocate this file to `docs/plans/YYYY-MM-DD-HHMM-go-m6-6-action-pages.md` per the repo's `CLAUDE.md` "Plans" convention before starting work.
+
+## Context
+
+The Go-rewrite progress tracker ([2026-05-03-2349-go-backend-rewrite-progress.md:118](docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md#L118)) lists M6.6 as:
+
+> `/qr, /sync-bank, /flush-cache, /version pages`
+
+After M6.4 (payments page) and M6.5 (member-detail modal JS), the only remaining pre-deployment HTML/action endpoints in Python that the Go binary doesn't yet implement are these four. The adults/juniors templates already produce `/qr?...` URLs via the `qrHref` / `qrHrefAll` helpers ([render.go:47-71](go/internal/web/render.go#L47-L71)) — the matching handler is the missing piece. `sync` and `flush_cache` templates exist as "Coming in M6.6" stubs and need real markup + working handlers. `/api/version` already serves build metadata; `/version` just needs to alias it (Python parity).
+
+After M6.6 the M6 gate ("Browser smoke on :8080: all pages render … QR loads, sync/flush work end-to-end") is reachable.
+
+## Confirmed design choices
+
+- **`/sync-bank`**: Python-faithful — GET both renders and triggers the sync, captures stdout/stderr into a log buffer, surfaces success/failure via a flag. Matches existing nav `[Sync Bank Data]` link.
+- **`/version`**: JSON alias of `/api/version`. No HTML page.
+- **QR library**: `github.com/skip2/go-qrcode`. Default level `qrcode.Medium`, size 256.
+
+## Scope per endpoint
+
+### 1. `GET /qr` — PNG only
+
+Match Python ([app.py:321-356](app.py#L321-L356)) verbatim semantics:
+
+1. Read `account` (default `cfg.BankAccount`), `amount` (default `"0"`), `message` (default `""`).
+2. Validate account against `^[A-Z]{2}\d{2,34}$|^\d{1,16}/\d{4}$`; on miss, silently fall back to `cfg.BankAccount`.
+3. Parse amount as float64; clamp to `[0, 10_000_000]`; format `%.2f`; on parse error → `"0.00"`.
+4. Truncate message to 60 runes; strip all `*`.
+5. If account contains `/`, split into `{number}*BC:{bankcode}`; else use raw.
+6. SPD payload: `SPD*1.0*ACC:{acc}*AM:{amount}*CC:CZK*MSG:{msg}` (no `BC:` key when IBAN — Python doesn't either).
+7. `qrcode.Encode(payload, qrcode.Medium, 256)` → write bytes with `Content-Type: image/png`.
+
+No template, no HTML.
+
+### 2. `GET /sync-bank` — triggers + renders
+
+Match Python ([app.py:124-151](app.py#L124-L151)):
+
+1. Build a `*bytes.Buffer` to capture step output.
+2. For each step write a header line then call:
+   - `banksync.SyncToSheets(ctx, cfg.PaymentsSheetID, fioClient, sheetsClient, banksync.SyncOpts{From: jan1ThisYear, To: dec31ThisYear, Sort: true})`
+   - `banksync.InferPayments(ctx, cfg.PaymentsSheetID, sheetsClient, sources, banksync.InferOpts{})`
+   - `cacheFlusher.Flush()` — append `"%d cache files deleted"`.
+3. On any error: append `err.Error()` + a stack trace via `runtime/debug.Stack()`, set `success=false`, continue rendering.
+4. Render `sync` template with `SyncPageData{ PageData; Output string; Success bool }`.
+
+The `banksync` package's stdout-printing functions can be redirected by passing an `io.Writer` — confirm during implementation; if they only print to `os.Stdout`, capture by tee'ing through a `slog` handler or briefly swapping `os.Stdout` (or extend the package with a `*Writer` option). **Preferred**: add a `Logger io.Writer` field to `banksync.SyncOpts` / `InferOpts`. This is a minor extension to existing services, not a rewrite.
+
+### 3. `/flush-cache` — GET form, POST action
+
+Match Python ([app.py:117-122](app.py#L117-L122)):
+
+- `GET` → render `flush_cache` with `Flushed=false`.
+- `POST` → call `cacheFlusher.Flush()`, render with `Flushed=true, Deleted=n`.
+
+### 4. `GET /version` — JSON
+
+One-liner: register the existing `api.VersionHandler` (or its inline equivalent in [api/version.go](go/internal/web/api/version.go)) on the `/version` path as well as `/api/version`. Output: `{"tag", "commit", "build_date"}`.
+
+## Files to create / modify
+
+### New files
+
+- **[go/internal/web/templates/qr.tmpl](go/internal/web/templates/qr.tmpl)** — *not actually needed*; remove from plan if `/qr` is PNG-only. (Decision: skip — no template.)
+- Replace stub **[go/internal/web/templates/sync.tmpl](go/internal/web/templates/sync.tmpl)** with full markup: title, status banner colored by `Success`, `<pre>` of `Output`, "Run again" link.
+- Replace stub **[go/internal/web/templates/flush_cache.tmpl](go/internal/web/templates/flush_cache.tmpl)** with: form (`POST /flush-cache` → `<button>[Flush Cache]</button>`), success banner when `Flushed`.
+
+### Modified files
+
+- **[go/go.mod](go/go.mod)** / `go.sum` — add `github.com/skip2/go-qrcode`.
+- **[go/internal/web/server.go](go/internal/web/server.go)** — register `GET /qr`, `GET /sync-bank` (replace stub), `GET /flush-cache` (form), `POST /flush-cache` (action), `GET /version`. Widen `Run(...)` signature to accept `fio.Client`, `sheets.Client`, and a `cache.Flusher` — these flow into a new `Deps` struct on `HTMLHandler`.
+- **[go/internal/web/html_handler.go](go/internal/web/html_handler.go)** — add `ServeQR`, real `ServeSync`, split `ServeFlushCacheGET` / `ServeFlushCachePOST`, add `ServeVersion` (delegates to api package).
+- **[go/internal/web/render.go](go/internal/web/render.go)** — add `SyncPageData{ PageData; Output string; Success bool }` and `FlushPageData{ PageData; Flushed bool; Deleted int }` view-models. (`pageNames` already includes `"sync"` and `"flush_cache"`; no change.)
+- **[go/internal/web/qr.go](go/internal/web/qr.go)** *(new file)* — pure helper: `BuildSPD(account, amount, message string, defaultAccount string) (payload string)` + `RenderQRCode(payload string) ([]byte, error)`. Easier to unit-test than a method on the handler.
+- **[go/internal/services/membership/loader.go](go/internal/services/membership/loader.go)** — add a small `CacheFlusher` interface (`Flush() (int, error)`); have `Sources` aggregate include it. *Alternative considered*: pass `*cache.FileCache` straight into `web.Run`. Choose whichever needs fewer test-stub edits — likely the direct-pass approach, since stubs in tests don't need cache behavior. **Decision: pass `cache.Flusher` directly into `web.Run` as a separate dependency, not through `Sources`.** Simpler, fewer interface changes.
+- **[go/internal/services/banksync/sync.go](go/internal/services/banksync/sync.go)** + `infer.go` — accept an optional `io.Writer` (in `SyncOpts.Logger` / `InferOpts.Logger`) and route progress prints through it; default to `os.Stdout` when nil for CLI parity.
+- **[go/cmd/fuj/main.go](go/cmd/fuj/main.go)** — in the `server` subcommand, build `fio.Client`, `sheets.Client`, and `cache.Flusher` (already constructed inside `membership.NewSources` — expose it or construct a sibling) and pass them into `web.Run`.
+
+## Reuse (already in the codebase)
+
+- **Bank sync**: `banksync.SyncToSheets` ([go/internal/services/banksync/sync.go](go/internal/services/banksync/sync.go)) and `banksync.InferPayments` ([go/internal/services/banksync/infer.go](go/internal/services/banksync/infer.go)) — same calls the CLI `sync` / `infer` subcommands use ([go/cmd/fuj/main.go:184](go/cmd/fuj/main.go#L184), [:222](go/cmd/fuj/main.go#L222)).
+- **Cache flush**: `(*cache.FileCache).Flush() (int, error)` ([go/internal/io/cache/filecache.go:92](go/internal/io/cache/filecache.go#L92)) — already returns the deleted count.
+- **Build metadata**: `BuildInfo{Version, Commit, BuildDate}` ([go/internal/web/server.go:28-35](go/internal/web/server.go#L28-L35)) is already plumbed everywhere; `/api/version` JSON shape is already correct ([go/internal/web/api/version.go](go/internal/web/api/version.go)).
+- **Template render pattern**: `Renderer.Render(w, name, data)` ([go/internal/web/render.go:98-108](go/internal/web/render.go#L98-L108)).
+- **Test scaffolding**: `web.NewRenderer()` + `httptest.NewRequest/NewRecorder` ([go/internal/web/html_handler_test.go:52-94](go/internal/web/html_handler_test.go#L52-L94)).
+
+## Tests
+
+Add to `go/internal/web/html_handler_test.go` (and one new `qr_test.go` for the SPD builder):
+
+- **`TestQRBuildSPD`** *(unit, in [go/internal/web/qr_test.go](go/internal/web/qr_test.go))* — table-driven: invalid account → fallback; `/`-account → `{num}*BC:{bc}`; IBAN → raw; amount `-1` → `0.00`; amount `99999999` → `9999999.00`; amount `"abc"` → `0.00`; message with `*` stripped; message length-clamped to 60.
+- **`TestServeQR`** — request `/qr?account=…&amount=10&message=Hi`; assert 200, `Content-Type: image/png`, body starts with PNG magic `\x89PNG\r\n\x1a\n`.
+- **`TestServeFlushCacheGet`** — assert form rendered, no banner.
+- **`TestServeFlushCachePost`** — fixture flusher returns 3; assert banner says "3" and `Flushed`.
+- **`TestServeSync`** — fixture banksync stubs return `(2, nil)` and `(1, nil)`, fixture flusher returns 4; assert page renders, status is success, output contains the section headers.
+- **`TestServeVersion`** — assert `application/json`, body `{"tag":"v0","commit":"abc1234","build_date":"2026-01-01"}`.
+- Extend the `TestHTMLHandlerSmoke` table to cover `/qr` and `/version`.
+
+## Verification (end-to-end)
+
+1. `cd go && go build ./... && go test ./...`
+2. `cd go && go run ./cmd/fuj server` — open http://localhost:8080
+3. Smoke:
+   - **/adults** → click `Pay` next to any unpaid month → modal shows QR image (this exercises `/qr`). Confirm a Czech banking app can scan it (visual check).
+   - Direct `/qr?account=2702008874/2010&amount=700&message=Test` → PNG renders.
+   - **/sync-bank** → click `[Sync Bank Data]` in nav → page shows "Syncing…", then sections + "Inferred Payments", "Cache Flushed", green status banner.
+   - **/flush-cache** → click `[Flush Cache]` → success banner with file count.
+   - **/version** in browser → JSON visible.
+   - Adults / juniors / payments still render (no regressions from `Run` signature change).
+4. Run the parity diff: `go run ./cmd/parity` — `/api/version` must still match Python.
+5. Append a CHANGELOG entry per `CLAUDE.md`; tick `M6.6` in [docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md:118](docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md#L118).
+
+## Branch / MR
+
+Per `CLAUDE.md` workflow: `feat/go-m6-6-action-pages` off `main`, push with `-u`, open with `tea pr create --base main --head feat/go-m6-6-action-pages`.
+
+## Out of scope (deferred)
+
+- Auth / CSRF protection on `/sync-bank` and `/flush-cache` — Python has none either; deferred to M8 hardening.
+- M6.7 (single-binary embed verification) — separate ticket.
+- Streaming progress for `/sync-bank` (currently buffered until completion, like Python).
+- Configurable QR error-correction level / size.

docs/plans/2026-05-08-1439-go-m6-6-1-payment-qr-modal.md

@@ -0,0 +1,335 @@
+# M6.6.1 — Pay-button QR popup modal (`/adults`, `/juniors`)
+
+> Plan-mode note: per project convention this plan should live at
+> `docs/plans/2026-05-08-1439-go-m6-6-1-payment-qr-modal.md`. The first
+> execution step after approval is to copy this file there.
+> Branch: `feat/go-m6-6-1-payment-qr-modal` off `main`.
+
+## Context
+
+M6.6 ([docs/plans/2026-05-08-1334-go-m6-6-action-pages.md](docs/plans/2026-05-08-1334-go-m6-6-action-pages.md))
+landed the backend `/qr` PNG endpoint plus `/sync-bank`, `/flush-cache`,
+`/version`. While doing it, the **client-side** half of the Pay flow was
+collapsed from a modal-with-details into a plain `<a href="/qr?...">` —
+clicking Pay now navigates the whole tab to the raw PNG.
+
+The Python app instead opens an in-page `#qrModal` showing the QR image
+*plus* labelled details (account, amount, message, title), then closes
+the modal on outside-click or `[close]`
+([templates/adults.html:631-648](templates/adults.html#L631-L648),
+JS at [templates/adults.html:963-993](templates/adults.html#L963-L993)).
+This is the UX the user expects from the dashboard — staying on the
+table while displaying the QR is significantly more practical than
+losing context to a fullscreen image.
+
+M6.6.1 restores parity: the Pay/Pay-All buttons open an in-page
+`#qrModal`, identical in structure to the Python original, driven by a
+new vanilla-JS module `payment-qr.js` that mirrors the `member-detail.js`
+convention from M6.5.
+
+All the building blocks are already in place:
+
+- **`/qr` endpoint** ships PNGs ([go/internal/web/qr.go](go/internal/web/qr.go), tested by [TestServeQR](go/internal/web/html_handler_test.go#L207-L231)).
+- **CSS** for `#qrModal .modal-content`, `.qr-image`, `.qr-details` is
+  already in [go/internal/web/static/css/app.css:445-478](go/internal/web/static/css/app.css#L445-L478) — lifted during M6.1.
+- **Template helpers** `qrHref` / `qrHrefAll` ([go/internal/web/render.go:63-85](go/internal/web/render.go#L63-L85))
+  already produce the correct query string + Czech `MM/YYYY` format
+  for the `message=` param. They're useful for sanity (and for any
+  no-JS fallback) but become dead code post-M6.6.1 — see §Out of scope.
+- **Bank account** is already exposed as `$.Data.BankAccount` to every
+  template that has a Pay button.
+- **JS module convention**: `member-detail.js` is the M6.5 baseline —
+  IIFE, `'use strict'`, event delegation off `data-*` attributes, no
+  inline `onclick`, no globals leaked.
+
+## Approach
+
+### 1. Replace `<a href="{{qrHref ...}}">` with `<button data-...>`
+
+In [go/internal/web/templates/adults.tmpl](go/internal/web/templates/adults.tmpl)
+and [go/internal/web/templates/juniors.tmpl](go/internal/web/templates/juniors.tmpl)
+(both have identical Pay markup at lines 65 and 72):
+
+```gotmpl
+<button type="button" class="pay-btn"
+        data-name="{{$row.Name}}"
+        data-amount="{{$cell.Amount}}"
+        data-month="{{$cell.Month}}"
+        data-raw-month="{{$cell.RawMonth}}">Pay</button>
+```
+
+```gotmpl
+<button type="button" class="pay-btn"
+        data-name="{{$row.Name}}"
+        data-amount="{{$row.PayableAmount}}"
+        data-month="{{$row.UnpaidPeriods}}"
+        data-raw-month="{{$row.RawUnpaidPeriods}}"
+        data-pay-all="1">Pay All</button>
+```
+
+Why `<button type="button">` and not `<a>`: the click no longer
+navigates — the JS handles it. `type="button"` prevents accidental form
+submission. A no-JS fallback could be added later by re-introducing
+`href="{{qrHref ...}}"` and letting the JS call `e.preventDefault()` —
+deferred until anyone actually asks (see §Out of scope).
+
+`data-month` carries the human-readable period (e.g. `January 2026`,
+or `January 2026 + February 2026` for Pay-All) which the modal title
+displays. `data-raw-month` carries the machine format (`2026-01`,
+`2026-01+2026-02`) which the JS converts to `MM/YYYY` for the QR
+message — same conversion Python's `showPayQR` does at
+[templates/adults.html:966-968](templates/adults.html#L966-L968).
+`data-pay-all` is purely informational; the JS doesn't actually need
+it (the same code path handles single + multi-period), but keeping it
+helps debugging and any future analytics.
+
+### 2. Add `#qrModal` markup
+
+Append after the `#memberModal` block in both `adults.tmpl` and
+`juniors.tmpl` (around line 185 of adults, line 165 of juniors), mirroring
+[templates/adults.html:631-648](templates/adults.html#L631-L648) but
+using `class="active"` toggling (the convention M6.5 picked) instead of
+`style.display = 'block'`:
+
+```gotmpl
+<div id="qrModal" onclick="if(event.target===this)this.classList.remove('active')">
+  <div class="modal-content">
+    <div class="modal-header">
+      <div class="modal-title" id="qrTitle">Payment for —</div>
+      <div class="close-btn" onclick="document.getElementById('qrModal').classList.remove('active')">[close]</div>
+    </div>
+    <div class="qr-image">
+      <img id="qrImg" src="" alt="Payment QR Code">
+    </div>
+    <div class="qr-details">
+      <div>Account: <span id="qrAccount"></span></div>
+      <div>Amount: <span id="qrAmount"></span> CZK</div>
+      <div>Message: <span id="qrMessage"></span></div>
+    </div>
+  </div>
+</div>
+```
+
+The CSS already targets `#qrModal .modal-content` directly. To make the
+"hidden by default / visible when `.active`" toggle behave the same
+way `#memberModal` does, the existing CSS rules for `#memberModal`
+(`display:none`, `#memberModal.active { display: flex; }`) need a
+sibling pair for `#qrModal`. Audit `app.css` during implementation:
+- if `#qrModal` already has both rules, no change.
+- if it has only `display:none`, add `#qrModal.active { display: flex; }`.
+- if it has neither, add both.
+
+This is a 2-line CSS adjustment at most; tracked under §Critical files.
+
+### 3. Bank account on the page
+
+The modal needs the bank account string for the `qrAccount` label and
+for building the `/qr?account=…` URL. Two clean options:
+
+**(a)** Read it from the `<button>`'s `data-bank-account` attribute.
+Per-button duplication, but trivially done in templates and keeps the JS
+module's surface tiny.
+
+**(b)** Stamp it once on the page as `<body data-bank-account="…">`
+(or on the existing `#filterContainer`).
+
+**Decision: (b)** — single stamping site, follows the same pattern
+M6.5 used for `data-page` on `#filterContainer`. Add
+`data-bank-account="{{.Data.BankAccount}}"` to `#filterContainer` in
+both templates (one-line edit each).
+
+### 4. Create [go/internal/web/static/js/payment-qr.js](go/internal/web/static/js/payment-qr.js)
+
+A new module loaded with `<script src="/static/js/payment-qr.js" defer></script>`
+right after `member-detail.js` in both templates. Pure ES, no build
+step, IIFE, `'use strict'`. Skeleton — port of Python's `showPayQR`
+([templates/adults.html:963-986](templates/adults.html#L963-L986))
+plus event wiring:
+
+```js
+(function () {
+  'use strict';
+
+  const container = document.getElementById('filterContainer');
+  if (!container) return;
+  const bankAccount = container.dataset.bankAccount || '';
+
+  const modal      = document.getElementById('qrModal');
+  const titleEl    = document.getElementById('qrTitle');
+  const imgEl      = document.getElementById('qrImg');
+  const accountEl  = document.getElementById('qrAccount');
+  const amountEl   = document.getElementById('qrAmount');
+  const messageEl  = document.getElementById('qrMessage');
+  if (!modal || !titleEl || !imgEl || !accountEl || !amountEl || !messageEl) return;
+
+  // Convert "YYYY-MM" → "MM/YYYY"; "+"-joined ranges are converted piece-wise.
+  // Mirrors templates/adults.html:966-968.
+  function toCzechMonth(rawMonth) {
+    return rawMonth.split('+')
+      .map(p => p.replace(/^(\d{4})-(\d{2})$/, '$2/$1'))
+      .join('+');
+  }
+
+  function showQR(name, amount, month, rawMonth) {
+    const numericMonth = toCzechMonth(rawMonth);
+    const message = `${name}: ${numericMonth}`;
+
+    titleEl.innerText   = `Payment for ${month}`;
+    accountEl.innerText = bankAccount;
+    amountEl.innerText  = amount;
+    messageEl.innerText = message;
+
+    const url = '/qr?'
+      + 'account=' + encodeURIComponent(bankAccount)
+      + '&amount=' + encodeURIComponent(amount)
+      + '&message=' + encodeURIComponent(message);
+    imgEl.src = url;
+
+    modal.classList.add('active');
+  }
+
+  function closeQR() { modal.classList.remove('active'); }
+
+  // Event delegation: any .pay-btn click anywhere in the page.
+  document.addEventListener('click', ev => {
+    const btn = ev.target.closest('.pay-btn');
+    if (!btn) return;
+    ev.preventDefault();
+    showQR(
+      btn.dataset.name,
+      btn.dataset.amount,
+      btn.dataset.month,
+      btn.dataset.rawMonth,
+    );
+  });
+
+  document.addEventListener('keydown', e => {
+    if (e.key === 'Escape' && modal.classList.contains('active')) closeQR();
+  });
+}());
+```
+
+Notes:
+
+- **Event delegation** (single listener on `document`) handles both Pay
+  and Pay-All without enumerating buttons. It also survives any future
+  re-render of the table without needing rebinding.
+- **Coexistence with `member-detail.js`**: `member-detail.js` listens
+  for `Escape` too, but only acts when `#memberModal` is active; the
+  new module similarly only acts when `#qrModal` is active. No collision.
+- **Pre-warming**: nothing to pre-warm — `/qr` is a tiny on-demand PNG
+  and only fires when the user clicks.
+- **Inline `onclick`** on `[close]` and outside-click in the markup are
+  carried over from the M6.5 modal style; consistent with `#memberModal`.
+  (Switching the project's modal close pattern to data attributes is a
+  separate cleanup, out of scope here.)
+
+### 5. Tests
+
+Extend [go/internal/web/html_handler_test.go](go/internal/web/html_handler_test.go)
+with markup-level checks. Headless-browser JS is out of scope (same
+rationale as M6.5).
+
+In `TestModalMarkup` (or a sibling test, e.g. `TestPaymentQRMarkup`):
+
+- Body for `/adults` and `/juniors` contains
+  `<script src="/static/js/payment-qr.js"`.
+- Body contains `id="qrModal"`, `id="qrImg"`, `id="qrAccount"`,
+  `id="qrAmount"`, `id="qrMessage"`, `id="qrTitle"`.
+- The fixture row's Pay button is rendered as
+  `<button … class="pay-btn" … data-name="Test Member" data-amount="…" data-raw-month="2026-01"`.
+- The fixture row's `.pay-btn` does **not** include `href=`.
+- `#filterContainer` has `data-bank-account="CZ0000000000000000000000"`
+  (matching the test's `fixtureHandler` config).
+
+### 6. Decide fate of `qrHref` / `qrHrefAll` template helpers
+
+Once Pay/Pay-All buttons are JS-driven, the helpers in
+[render.go:63-85](go/internal/web/render.go#L63-L85) have no callers.
+**Decision: delete them**, plus their entries in `tmplFuncs`. A
+no-JS fallback is not on the roadmap; if it ever becomes one, the
+helpers are easy to resurrect from git.
+
+The unit-test file currently has no direct tests for these helpers —
+nothing to remove from tests.
+
+## Critical files
+
+| Action | Path |
+|--------|------|
+| edit   | [go/internal/web/templates/adults.tmpl](go/internal/web/templates/adults.tmpl) — Pay/Pay-All → `<button data-…>`; add `#qrModal`; add `data-bank-account` on filter container; add `<script src="/static/js/payment-qr.js" defer>` |
+| edit   | [go/internal/web/templates/juniors.tmpl](go/internal/web/templates/juniors.tmpl) — same |
+| new    | `go/internal/web/static/js/payment-qr.js` — modal module |
+| edit   | [go/internal/web/render.go](go/internal/web/render.go) — drop `qrHref`, `qrHrefAll`, and their `tmplFuncs` entries (and the `net/url`, `strconv` imports if no longer needed) |
+| edit   | [go/internal/web/static/css/app.css](go/internal/web/static/css/app.css) — verify / add `#qrModal { display:none; }` + `#qrModal.active { display:flex; }` rules |
+| edit   | [go/internal/web/html_handler_test.go](go/internal/web/html_handler_test.go) — markup assertions |
+
+No changes to: `assets.go` (`embed.FS` glob picks up new JS automatically),
+`server.go`, `html_handler.go`, the `/qr` handler, `cmd/fuj/main.go`, the
+API handlers, or any domain code.
+
+## Reused existing infrastructure
+
+- [go/internal/web/qr.go](go/internal/web/qr.go) — `/qr?account=…&amount=…&message=…` endpoint serves the PNG already
+- [go/internal/web/static/css/app.css:445-478](go/internal/web/static/css/app.css#L445-L478) — modal CSS already lifted whole
+- [go/internal/web/static/js/member-detail.js](go/internal/web/static/js/member-detail.js) — IIFE / `'use strict'` / `data-*` style to mirror
+- [go/internal/web/api/types.go](go/internal/web/api/types.go) — `MemberRow.UnpaidPeriods` and `RawUnpaidPeriods` already populated for Pay-All
+- [templates/adults.html:631-648,963-986](templates/adults.html#L631-L648) — Python reference for both modal markup and `showPayQR` JS (logic to port, not literal copy)
+
+## Verification
+
+End-to-end, after copying the plan into `docs/plans/`:
+
+1. `cd go && make go-build go-test go-lint` — all green.
+2. `make web-go &` — boot Go on `:8080`.
+3. Browser: `http://localhost:8080/adults`
+   - Click `Pay` on any unpaid month → `#qrModal` opens with
+     - title `Payment for <Month YYYY>`,
+     - `qrAccount` matching `BANK_ACCOUNT`,
+     - `qrAmount` matching the cell amount,
+     - `qrMessage` formatted as `<Name>: MM/YYYY`,
+     - QR image rendered from `/qr?…` (Network tab shows PNG response).
+   - Tab does **not** navigate; URL stays `/adults`.
+   - Click `Pay All` → modal opens with `+`-joined `MM/YYYY+MM/YYYY` message.
+   - Click outside the modal-content → modal closes.
+   - Click `[close]` → modal closes.
+   - Press `Esc` → modal closes.
+   - Open `[i]` member-detail modal first, then `Esc` → only that closes
+     (verify both modals don't fight each other).
+4. Browser: `http://localhost:8080/juniors` — same checks. Verify Pay
+   on a `"?"`-expected row doesn't appear (Pay button is conditional on
+   `unpaid`/`partial` cells).
+5. Cross-check against Python: `make web-py &` →
+   `http://localhost:5001/adults` modal looks visually equivalent for
+   the same fixture (modulo any nav / theme differences already accepted
+   in M6).
+6. Scan a QR with a Czech banking app (or `zbarimg` on the saved PNG) —
+   payload starts with `SPD*1.0*ACC:` and the message decodes to
+   `<Name>: MM/YYYY`.
+7. After the user merges in Gitea: append CHANGELOG entry (timestamp via
+   `date "+%Y-%m-%d %H:%M %Z"`); add a new tick line for **M6.6.1** in
+   [docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md](docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md)
+   immediately under the M6.6 line, in the same format as the other
+   sub-bullets.
+
+## Branching
+
+Per [CLAUDE.md](CLAUDE.md): create `feat/go-m6-6-1-payment-qr-modal` off
+`main`, commit with `Co-Authored-By` trailer, push with `-u`, open MR via
+`tea pr create`. Do not merge or delete from CLI.
+
+## Out of scope (deferred)
+
+- **Pay button no-JS fallback** — feasible to keep `qrHref` and have
+  the JS `preventDefault` an `<a>`, but no current need. Resurrect the
+  helpers if asked.
+- **Modal pattern unification** — `#memberModal` and `#qrModal` use
+  inline `onclick` for `[close]` and outside-click. Consistent with
+  M6.5 but worth a follow-up to delegate-event everything.
+- **Pay-from-modal inside `#memberModal`** — Python doesn't have it, and
+  no one's asked for it on the Go side.
+- **Per-button QR error-correction / size** — `/qr` is fixed at
+  Medium/256, same as M6.6. Configurable via query param can be added if
+  printing larger physical posters becomes a use case.
+- **`/payments` Pay buttons** — the payments page is a ledger view; it
+  doesn't render Pay buttons in either backend.

docs/plans/2026-05-08-1457-go-m6-7-single-binary-embed-verify.md

@@ -0,0 +1,184 @@
+# M6.7 — Single-binary embed verification
+
+## Context
+
+M6.7 is the final task in M6 (Go-native HTML frontend). Per the
+[progress tracker](2026-05-03-2349-go-backend-rewrite-progress.md): "Wire
+`embed.FS` into handlers; verify single-binary deployment includes all
+assets."
+
+The wiring is **already in place** from M6.1 onward:
+
+- [go/internal/web/assets.go](../../go/internal/web/assets.go) declares
+  `//go:embed templates` → `templateFS` and `//go:embed static` → `staticFS`.
+- [go/internal/web/render.go:66](../../go/internal/web/render.go#L66)
+  parses every page template via `template.New(...).ParseFS(templateFS, ...)`.
+- [go/internal/web/server.go:48-68](../../go/internal/web/server.go#L48-L68)
+  serves `/static/*` via `http.FileServerFS(fs.Sub(staticFS, "static"))`.
+- [go/build/Dockerfile](../../go/build/Dockerfile) copies only the compiled
+  binary into the `alpine:3` runtime image — no `templates/` or `static/`
+  directory ever lands beside it.
+
+What is missing is **proof** the embed is complete and stays complete:
+
+1. Nothing fails the build/test if a contributor adds a new file under
+   `internal/web/templates/` or `internal/web/static/` that isn't matched
+   by an `//go:embed` glob (or, more realistically, adds a sibling
+   directory like `static/img/` and the glob still picks it up — but a
+   typo'd directive would silently drop it).
+2. No automated test exercises the `/static/*` route against the embedded
+   FS — current tests in
+   [html_handler_test.go](../../go/internal/web/html_handler_test.go)
+   render templates (which proves `templateFS` is good) but never hit a
+   static URL through the mux.
+3. The "single binary, no working-dir assets" property is undocumented —
+   if it ever broke, no one would notice until the Docker image started
+   500'ing in prod.
+
+The intended outcome: a small test file plus a documented manual
+verification step, after which M6.7 can be ticked and M6 closed.
+
+## Plan
+
+### 1. Add `go/internal/web/assets_test.go`
+
+One new file, two tests, no production code changes.
+
+**Test A — embed completeness regression guard.** Walks the on-disk
+`templates/` and `static/` directories and asserts every regular file is
+also present in the corresponding embedded FS. Catches:
+
+- A new template added without updating the `//go:embed` directive
+  (current globs are `templates` and `static` — recursive by default for
+  directories, so this is a low-probability regression, but the test
+  doubles as living documentation of the contract).
+- A typo in the directive (e.g. someone renames `static` → `assets` in
+  one place but not the other).
+
+Implementation sketch:
+
+```go
+func TestEmbedCompleteness(t *testing.T) {
+    cases := []struct {
+        name   string
+        diskFS fs.FS         // os.DirFS("templates") / os.DirFS("static")
+        embed  fs.FS         // exported helper or via internal test in package web
+        root   string
+    }{...}
+    for _, tc := range cases {
+        _ = fs.WalkDir(tc.diskFS, ".", func(path string, d fs.DirEntry, err error) error {
+            if err != nil || d.IsDir() { return err }
+            embPath := tc.root + "/" + path
+            if _, err := fs.Stat(tc.embed, embPath); err != nil {
+                t.Errorf("file %q on disk but missing in embed.FS: %v", embPath, err)
+            }
+            return nil
+        })
+    }
+}
+```
+
+Because `templateFS` and `staticFS` are unexported package vars, this
+test lives in `package web` (not `web_test`) — sibling to
+[assets.go](../../go/internal/web/assets.go). All the existing handler
+tests are in `package web_test`; that's fine, this one is internal.
+
+**Test B — `/static/*` end-to-end via the mux.** Builds an `http.ServeMux`
+with the same wiring as
+[server.go:68](../../go/internal/web/server.go#L68), fires httptest
+requests, asserts:
+
+- `GET /static/css/app.css` → 200, `Content-Type: text/css; charset=utf-8`,
+  body contains a known string from app.css (e.g. a CSS selector).
+- `GET /static/js/member-detail.js` → 200, `Content-Type` starts with
+  `text/javascript` or `application/javascript`, body non-empty.
+- `GET /static/js/payment-qr.js` → 200, body non-empty.
+- `GET /static/css/missing.css` → 404 (sanity: the file server actually
+  rejects unknown paths instead of returning some default).
+
+Rather than duplicate the mux assembly, factor a tiny helper (or test the
+existing mux). The cleanest move: extract `staticHandler()` from
+[server.go:48-50,68](../../go/internal/web/server.go#L48-L68) into a small
+exported-from-package function or just `staticFS` / `fs.Sub` helper, and
+have the test call it. Smallest delta: keep production code unchanged and
+replicate the two-line wiring inside the test file (acceptable — it's
+two lines and the test exists precisely to lock that contract).
+
+### 2. Manual / one-shot verification (no code; documented in plan only)
+
+Run once locally and tick M6.7. Command transcript:
+
+```bash
+make go-build                  # → ./bin/fuj
+cp bin/fuj /tmp/fuj-standalone
+cd /tmp                        # working dir has no templates/ or static/
+./fuj-standalone server &
+SERVER_PID=$!
+sleep 1
+curl -sf http://localhost:8080/adults | grep -q "Adults Dashboard"
+curl -sf http://localhost:8080/juniors | grep -q "Juniors"
+curl -sf http://localhost:8080/payments | grep -q "Payments Ledger"
+curl -sf -o /tmp/app.css http://localhost:8080/static/css/app.css \
+  && test -s /tmp/app.css
+curl -sf -o /tmp/qr.js http://localhost:8080/static/js/payment-qr.js \
+  && test -s /tmp/qr.js
+kill $SERVER_PID
+```
+
+`fuj server` will fail to talk to Sheets without credentials, so the
+`/adults` etc. pages will render with the `Error` field set — that's
+fine; the assertion is that the **template + static asset pipeline** is
+self-contained, not that data loads. Each curl above only checks for
+markup present in every render path (header text and stylesheet body).
+
+### 3. Tracker + changelog
+
+- Tick `M6.7` in
+  [docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md:120](2026-05-03-2349-go-backend-rewrite-progress.md#L120),
+  append the merge SHA on the line.
+- Mark "Last updated" date and bump milestone status: M6 complete, next is
+  M7.
+- Append a `CHANGELOG.md` entry per CLAUDE.md convention (`date "+%Y-%m-%d %H:%M %Z"`).
+
+## Files touched
+
+| File | Change |
+| --- | --- |
+| [go/internal/web/assets_test.go](../../go/internal/web/assets_test.go) | **new** — two tests (embed completeness + `/static/*` mux) |
+| [docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md](2026-05-03-2349-go-backend-rewrite-progress.md) | tick M6.7, bump "last updated" |
+| [CHANGELOG.md](../../CHANGELOG.md) | new top entry |
+
+No production source files change. (If extracting the static handler
+reads cleaner, a 4-line refactor in
+[server.go](../../go/internal/web/server.go) is acceptable but optional.)
+
+## Branch + MR
+
+Per project convention this is a feature, so:
+
+```bash
+git checkout -b feat/go-m6-7-embed-verify
+# … commits …
+git push -u origin feat/go-m6-7-embed-verify
+tea pr create --title "feat(go): M6.7 — single-binary embed verification" \
+  --description "<short body referencing M6.7>" --base main \
+  --head feat/go-m6-7-embed-verify
+```
+
+## Verification
+
+After implementation:
+
+1. `make go-test` → green (new `TestEmbedCompleteness` and `TestStaticAssetsServed` pass).
+2. `make go-lint` → clean.
+3. Run the manual transcript in §2 above — all curls succeed, no
+   "template not found" or 404 on static assets.
+4. `make go-build && docker build -f go/build/Dockerfile -t fuj-go:m6-7 go/` →
+   succeeds; `docker run --rm -p 8080:8080 fuj-go:m6-7` serves `/adults`
+   with stylesheet attached (visual smoke test in browser).
+
+## Out of scope
+
+- Re-architecting how templates are parsed or served.
+- Compressing / fingerprinting static assets (a separate concern).
+- Live integration test with real Sheets data — covered later in M7.

docs/plans/2026-05-11-2353-fill-first-multi-month-allocation.md

@@ -0,0 +1,184 @@
+# Fill-first multi-month payment allocation
+
+## Context
+
+Matyáš Thér paid in two transactions:
+
+| # | Amount | Purpose             |
+|---|--------|---------------------|
+| 1 | 200    | `2026-02`           |
+| 2 | 550    | `2026-02, 2026-03`  |
+
+Total 750 = his expected fee for the two months (likely 2026-02 = 500, 2026-03 = 250 — junior tier or exception-adjusted). The app currently shows 2026-02 = **566** paid, 2026-03 = **183** paid. The user wants:
+
+> First use the second payment for the rest of 2026-02 (no more, no less), then put the remainder toward 2026-03.
+
+Both Python ([scripts/match_payments.py](scripts/match_payments.py)) and Go ([go/internal/domain/reconcile/reconcile.go](go/internal/domain/reconcile/reconcile.go)) have the same bug: when a single transaction's `in_window_share` is less than the sum of in-window expected fees, both fall into a **proportional** branch that splits the new transaction across months in proportion to each month's *total* expected fee — never consulting what prior transactions already paid into earlier months.
+
+Trace for txn 2:
+
+- `in_window = [(2026-02, 500), (2026-03, 250)]`, `total_expected = 750`, `in_window_share = 550`.
+- `550 < 750` → proportional:
+  - 02 alloc = `550 × 500 / 750 = 366.67`
+  - 03 alloc = `550 − 366.67 = 183.33`
+- Combined with txn 1's 200 → 02 = 566.67, 03 = 183.33 → display `566 / 183`. ✓ matches reported numbers.
+
+The fix: replace the greedy + proportional branches with a single **fill-first** loop that iterates `in_window` in user-supplied order (already chronological by convention from [scripts/infer_payments.py:151](scripts/infer_payments.py#L151)) and allocates `min(remaining, max(0, expected − paid_so_far))` to each month, with any final surplus going to the credit bucket. This collapses three cases (greedy / proportional / pure overflow) into one and naturally consults the ledger's `paid` field which is already updated by prior transactions in the same reconcile pass.
+
+The even-split branch (`total_expected == 0`, prepayment before fees known) stays untouched — different semantic, folding it in would silently change behavior.
+
+## Changes
+
+### Python — [scripts/match_payments.py:471-498](scripts/match_payments.py#L471-L498)
+
+Replace both `total_expected > 0` branches (current lines 471–498) with a single unified loop. Keep lines 466–469 above and the even-split fallback below (lines 499–510) as-is.
+
+```python
+            if total_expected > 0:
+                # Fill-first: iterate in_window in matched_months order (chronological by
+                # convention), allocate min(remaining, deficit) to each month, where
+                # deficit accounts for prior transactions already credited to that month.
+                # Any surplus after all in-window deficits are covered → credit bucket.
+                remaining = in_window_share
+                for m, exp in in_window:
+                    paid_so_far = ledger[member_name][m]["paid"]
+                    deficit = max(0.0, float(exp) - paid_so_far)
+                    alloc = min(remaining, deficit)
+                    if alloc <= 0:
+                        continue
+                    ledger[member_name][m]["paid"] += alloc
+                    ledger[member_name][m]["transactions"].append({
+                        "amount": alloc,
+                        "date": tx["date"],
+                        "sender": tx["sender"],
+                        "message": tx["message"],
+                        "confidence": confidence,
+                    })
+                    remaining -= alloc
+                if remaining > 0:
+                    credits[member_name] = credits.get(member_name, 0) + int(remaining)
+            else:
+                # … existing even-split branch (lines 499–510) unchanged …
+```
+
+Note: skipping the `transactions.append` when `alloc <= 0` (e.g. month already fully paid by a prior txn) avoids zero-amount ghost rows in the per-month transaction list. This is a small UI-visible side effect; before committing, grep tests for assertions on `len(transactions)` per month to confirm nothing relies on the current "one row per (txn, month) regardless of alloc" behavior.
+
+### Go — [go/internal/domain/reconcile/reconcile.go:320-357](go/internal/domain/reconcile/reconcile.go#L320-L357)
+
+Same shape — replace both `totalExpected > 0` branches. Even-split branch (lines 358–372) stays.
+
+```go
+            if totalExpected > 0 {
+                // Fill-first; see Python reconcile() for rationale.
+                remaining := inWindowShare
+                for _, mw := range inWindow {
+                    md := ledger[memberName][mw.month]
+                    deficit := float64(mw.expected) - md.Paid
+                    if deficit < 0 {
+                        deficit = 0
+                    }
+                    alloc := remaining
+                    if deficit < alloc {
+                        alloc = deficit
+                    }
+                    if alloc <= 0 {
+                        continue
+                    }
+                    md.Paid += alloc
+                    md.Transactions = append(md.Transactions, TxEntry{
+                        Amount:     alloc,
+                        Date:       tx.Date,
+                        Sender:     tx.Sender,
+                        Message:    tx.Message,
+                        Confidence: string(m.Confidence),
+                    })
+                    ledger[memberName][mw.month] = md
+                    remaining -= alloc
+                }
+                if remaining > 0 {
+                    credits[memberName] += int(remaining)
+                }
+            } else {
+                // … existing even-split branch (lines 358–372) unchanged …
+            }
+```
+
+### Tests
+
+#### Python — [tests/test_reconcile_exceptions.py](tests/test_reconcile_exceptions.py)
+
+1. **Rewrite `test_proportional_underpayment`** ([line 96](tests/test_reconcile_exceptions.py#L96)) — its current assertions (`paid_02 < 750`, `paid_03 < 350`, `paid_04 < 750`, and 02/04 equal allocation) are incompatible with fill-first. Under fill-first with the same fixture (1250 across `02:750, 03:350, 04:750`):
+   - 02: `min(1250, 750) = 750` (full) → remaining 500
+   - 03: `min(500, 350) = 350` (full) → remaining 150
+   - 04: `min(150, 750) = 150` (partial) → remaining 0
+   
+   Replace assertions with these exact expected values, rename to `test_underpayment_fills_earliest_first`.
+
+2. **Add `test_fill_first_across_two_transactions`** — the Matyáš regression:
+
+   ```python
+   def test_fill_first_across_two_transactions(self):
+       """Prior txn fills 02 partially; later txn finishes 02 then spills to 03."""
+       members = [('Matyáš', 'A', {'2026-02': (500, 2), '2026-03': (250, 1)})]
+       sorted_months = ['2026-02', '2026-03']
+       tx1 = _tx('Matyáš', '2026-02', 200)
+       tx2 = _tx('Matyáš', '2026-02, 2026-03', 550)
+
+       result = reconcile(members, sorted_months, [tx1, tx2])
+       months = result['members']['Matyáš']['months']
+
+       self.assertAlmostEqual(months['2026-02']['paid'], 500, places=2)
+       self.assertAlmostEqual(months['2026-03']['paid'], 250, places=2)
+   ```
+
+3. `test_greedy_exact_match`, `test_greedy_overpayment_goes_to_credit`, `test_single_month_unchanged`, `test_two_members_multi_month` should pass unchanged — fill-first agrees with greedy when payment ≥ total expected.
+
+#### Go — [go/internal/domain/reconcile/reconcile_test.go](go/internal/domain/reconcile/reconcile_test.go)
+
+- Add `TestUnderpaymentFillsEarliestFirst` mirroring the rewritten Python test.
+- Add `TestFillFirstAcrossTwoTransactions` mirroring the Matyáš scenario.
+
+#### Parity — [go/tests/parity/reconcile/reconcile_parity_test.go](go/tests/parity/reconcile/reconcile_parity_test.go)
+
+Add a fixture for the Matyáš two-transaction case. Since both implementations change together and Python remains canonical, existing parity fixtures should continue to pass; verify after edits.
+
+### Changelog — [CHANGELOG.md](CHANGELOG.md)
+
+Append top entry (use `date "+%Y-%m-%d %H:%M %Z"` at commit time):
+
+```markdown
+## 2026-05-11 23:55 CET — fill-first multi-month payment allocation
+
+- Multi-month payment allocation now fills the earliest in-window deficit first
+  and spills the remainder to later months, accounting for prior transactions'
+  contributions. Previously a single transaction was split proportionally to
+  each month's total expected fee, ignoring earlier payments — surfaced by
+  Matyáš Thér's two-payment 200+550 case showing 566/183 instead of 500/250.
+- scripts/match_payments.py, go/internal/domain/reconcile/reconcile.go, tests.
+```
+
+## Critical files
+
+- [scripts/match_payments.py](scripts/match_payments.py) — Python reconcile (canonical)
+- [go/internal/domain/reconcile/reconcile.go](go/internal/domain/reconcile/reconcile.go) — Go reconcile (mirrors Python)
+- [tests/test_reconcile_exceptions.py](tests/test_reconcile_exceptions.py) — rewrite `test_proportional_underpayment` + add Matyáš test
+- [go/internal/domain/reconcile/reconcile_test.go](go/internal/domain/reconcile/reconcile_test.go) — add Go tests
+- [go/tests/parity/reconcile/reconcile_parity_test.go](go/tests/parity/reconcile/reconcile_parity_test.go) — add parity fixture
+- [CHANGELOG.md](CHANGELOG.md) — top entry
+
+## Verification
+
+1. `make test` — Python unit tests including the rewritten + new fill-first tests.
+2. `cd go && go test ./internal/domain/reconcile/... ./tests/parity/reconcile/...` — Go unit + parity tests.
+3. `make web` → load `/adults` or `/juniors` (whichever lists Matyáš Thér) → his 2026-02 row should be fully paid (no shortfall), 2026-03 fully paid, no leftover credit.
+4. Spot-check one other multi-month-purpose member to make sure fully-covered cases still look right.
+
+## Branch & MR (per CLAUDE.md)
+
+1. `git checkout -b fix/fill-first-multi-month-allocation`
+2. Apply edits + tests + CHANGELOG entry.
+3. `make test && (cd go && go test ./...)` — both green.
+4. Commit: `fix(reconcile): fill earliest month deficit first in multi-month allocations` with `Co-Authored-By` trailer.
+5. `git push -u origin fix/fill-first-multi-month-allocation`
+6. `tea pr create --title "fix(reconcile): fill earliest month deficit first" --description "<body>" --base main --head fix/fill-first-multi-month-allocation`
+7. Print MR URL. Do not merge from CLI.

go/cmd/fuj/main.go

@@ -11,6 +11,7 @@ import (
 	"fuj-management/go/internal/services/banksync"
 	"fuj-management/go/internal/services/membership"
 	"fuj-management/go/internal/web"
+	"io"
 	"log/slog"
 	"os"
 	"time"
@@ -82,9 +83,40 @@ func serverCmd(args []string) {
 		os.Exit(1)
 	}
 
+	sheetsCli, err := sheets.New(ctx, cfg.CredentialsPath, cfg.DriveTimeout)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "fuj server: sheets client for sync: %v\n", err)
+		os.Exit(1)
+	}
+	fioCli := fio.New(cfg.FioAPIToken, config.IBANAccountNum(cfg.BankAccount), nil)
+
+	actions := web.ActionHandlers{
+		BankSync: func(ctx context.Context, out io.Writer) error {
+			yr := time.Now().Year()
+			from := time.Date(yr, 1, 1, 0, 0, 0, 0, time.UTC)
+			to := time.Date(yr, 12, 31, 23, 59, 59, 0, time.UTC)
+
+			fmt.Fprintln(out, "=== Sync Fio Transactions ===")
+			n, err := banksync.SyncToSheets(ctx, config.PaymentsSheetID, fioCli, sheetsCli,
+				banksync.SyncOpts{From: from, To: to, Sort: true})
+			if err != nil {
+				return fmt.Errorf("sync: %w", err)
+			}
+			fmt.Fprintf(out, "Synced %d new transaction(s).\n\n", n)
+
+			fmt.Fprintln(out, "=== Infer Payments ===")
+			n, err = banksync.InferPayments(ctx, config.PaymentsSheetID, sheetsCli, sources, banksync.InferOpts{})
+			if err != nil {
+				return fmt.Errorf("infer: %w", err)
+			}
+			fmt.Fprintf(out, "Inferred %d row(s).\n", n)
+			return nil
+		},
+	}
+
 	build := web.BuildInfo{Version: version, Commit: commit, BuildDate: buildDate}
 
-	if err := web.Run(logger, cfg.ServerAddr, build, sources, cfg); err != nil {
+	if err := web.Run(logger, cfg.ServerAddr, build, sources, cfg, actions); err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
 	}

go/go.mod

@@ -5,6 +5,7 @@ go 1.26.1
 require (
 	github.com/google/go-cmp v0.7.0
 	github.com/invopop/jsonschema v0.14.0
+	github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e
 	golang.org/x/net v0.53.0
 	golang.org/x/text v0.36.0
 	google.golang.org/api v0.278.0

go/go.sum

@@ -37,6 +37,8 @@ github.com/pb33f/ordered-map/v2 v2.3.1 h1:5319HDO0aw4DA4gzi+zv4FXU9UlSs3xGZ40wcP
 github.com/pb33f/ordered-map/v2 v2.3.1/go.mod h1:qxFQgd0PkVUtOMCkTapqotNgzRhMPL7VvaHKbd1HnmQ=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e h1:MRM5ITcdelLK2j1vwZ3Je0FKVCfqOLp5zO6trqMLYs0=
+github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e/go.mod h1:XV66xRDqSt+GTGFMVlhk3ULuV0y9ZmzeVGR4mloJI3M=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 go.opentelemetry.io/auto/sdk v1.2.1 h1:jXsnJ4Lmnqd11kwkBV2LgLoFMZKizbCi5fNZ/ipaZ64=

go/internal/domain/reconcile/reconcile.go

@@ -115,10 +115,11 @@ type monthExpected struct {
 	expected int
 }
 
-// Reconcile matches transactions to members and months using three allocation phases:
+// Reconcile matches transactions to members and months using two allocation phases:
-//  1. Greedy: payment ≥ total expected → fill each month exactly; overflow → credit.
+//  1. Fill-first: iterate matched months in user-supplied order, allocating min(remaining,
-//  2. Proportional: payment < total → distribute by each month's share; last absorbs float remainder.
+//     deficit) to each month where deficit = expected − already-paid. Surplus → credit.
-//  3. Even-split fallback: all expected fees are 0 (prepayment) → divide equally.
+//     Handles both the "greedy" (payment covers all) and "partial" cases in one pass.
+//  2. Even-split fallback: all expected fees are 0 (prepayment) → divide equally.
 //
 // defaultYear seeds czech.ParseMonthReferences in the inference fallback.
 // Pass time.Now().Year() in production; pass a fixed year in tests.
@@ -317,34 +318,26 @@ func Reconcile(
 				totalExpected += mw.expected
 			}
 
-			if totalExpected > 0 && inWindowShare >= float64(totalExpected) {
+			if totalExpected > 0 {
-				// Greedy: payment covers all expected fees; overflow → credit
+				// Fill-first: iterate inWindow in matched-months order (chronological by
-				credits[memberName] += int(inWindowShare - float64(totalExpected))
+				// convention), allocating min(remaining, deficit) to each month. Deficit
-				for _, mw := range inWindow {
+				// is net of what prior transactions already paid, so a second payment on
-					alloc := float64(mw.expected)
+				// the same months correctly fills only what remains due. Any surplus after
-					md := ledger[memberName][mw.month]
+				// all deficits are covered goes to the credit bucket.
-					md.Paid += alloc
-					md.Transactions = append(md.Transactions, TxEntry{
-						Amount:     alloc,
-						Date:       tx.Date,
-						Sender:     tx.Sender,
-						Message:    tx.Message,
-						Confidence: string(m.Confidence),
-					})
-					ledger[memberName][mw.month] = md
-				}
-			} else if totalExpected > 0 {
-				// Proportional: distribute by each month's share; last month absorbs float remainder
 				remaining := inWindowShare
-				for i, mw := range inWindow {
+				for _, mw := range inWindow {
-					var alloc float64
-					if i == len(inWindow)-1 {
-						alloc = remaining
-					} else {
-						alloc = inWindowShare * float64(mw.expected) / float64(totalExpected)
-					}
-					remaining -= alloc
 					md := ledger[memberName][mw.month]
+					deficit := float64(mw.expected) - md.Paid
+					if deficit < 0 {
+						deficit = 0
+					}
+					alloc := remaining
+					if deficit < alloc {
+						alloc = deficit
+					}
+					if alloc <= 0 {
+						continue
+					}
 					md.Paid += alloc
 					md.Transactions = append(md.Transactions, TxEntry{
 						Amount:     alloc,
@@ -354,6 +347,10 @@ func Reconcile(
 						Confidence: string(m.Confidence),
 					})
 					ledger[memberName][mw.month] = md
+					remaining -= alloc
+				}
+				if remaining > 0 {
+					credits[memberName] += int(remaining)
 				}
 			} else {
 				// Even-split fallback: prepayment before attendance recorded

go/internal/domain/reconcile/reconcile_test.go

@@ -111,36 +111,26 @@ func TestReconcileGreedyOverpaymentGoesToCredit(t *testing.T) {
 	}
 }
 
-func TestReconcileProportionalUnderpayment(t *testing.T) {
+func TestReconcileUnderpaymentFillsEarliestFirst(t *testing.T) {
 	t.Parallel()
 	members := []Member{{
 		Name: "Alice", Tier: "A",
 		Fees: map[string]FeeData{"2026-02": {Expected: 750, Attendance: 3}, "2026-03": {Expected: 350, Attendance: 3}, "2026-04": {Expected: 750, Attendance: 3}},
 	}}
 	sortedMonths := []string{"2026-02", "2026-03", "2026-04"}
-	amount := 1250.0
 
-	result := Reconcile(members, sortedMonths, []Transaction{tx("Alice", "2026-02, 2026-03, 2026-04", amount)}, nil, defaultYear)
+	result := Reconcile(members, sortedMonths, []Transaction{tx("Alice", "2026-02, 2026-03, 2026-04", 1250)}, nil, defaultYear)
 
 	months := result.Members["Alice"].Months
-	paid02 := months["2026-02"].Paid
+	// 02 filled first (750), then 03 (350), then remainder 150 to 04
-	paid03 := months["2026-03"].Paid
+	if math.Abs(months["2026-02"].Paid-750) > 0.01 {
-	paid04 := months["2026-04"].Paid
+		t.Errorf("02: want 750, got %f", months["2026-02"].Paid)
-
-	if paid02 >= 750 {
-		t.Errorf("2026-02 should be underpaid, got %f", paid02)
 	}
-	if paid03 >= 350 {
+	if math.Abs(months["2026-03"].Paid-350) > 0.01 {
-		t.Errorf("2026-03 should be underpaid, got %f", paid03)
+		t.Errorf("03: want 350, got %f", months["2026-03"].Paid)
 	}
-	if paid04 >= 750 {
+	if math.Abs(months["2026-04"].Paid-150) > 0.01 {
-		t.Errorf("2026-04 should be underpaid, got %f", paid04)
+		t.Errorf("04: want 150, got %f", months["2026-04"].Paid)
-	}
-	if math.Abs(paid02+paid03+paid04-amount) > 0.01 {
-		t.Errorf("sum of paid want %f, got %f", amount, paid02+paid03+paid04)
-	}
-	if math.Abs(paid02-paid04) > 0.01 {
-		t.Errorf("02 and 04 have equal expected, want equal paid: %f vs %f", paid02, paid04)
 	}
 }
 
@@ -374,3 +364,52 @@ func TestReconcileNoTransactionsAllUnpaid(t *testing.T) {
 		t.Errorf("no txs: want empty unmatched, got %v", result.Unmatched)
 	}
 }
+
+// Payment < total expected → fill earliest months first, spill remainder to later.
+func TestUnderpaymentFillsEarliestFirst(t *testing.T) {
+	t.Parallel()
+	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{
+		"2026-02": {Expected: 750, Attendance: 3},
+		"2026-03": {Expected: 350, Attendance: 3},
+		"2026-04": {Expected: 750, Attendance: 3},
+	}}}
+	txs := []Transaction{tx("Alice", "2026-02, 2026-03, 2026-04", 1250)}
+
+	result := Reconcile(members, []string{"2026-02", "2026-03", "2026-04"}, txs, nil, defaultYear)
+	months := result.Members["Alice"].Months
+
+	// 02 filled first (750), then 03 (350), then remainder 150 to 04
+	if math.Abs(months["2026-02"].Paid-750) > 0.01 {
+		t.Errorf("02: want 750, got %f", months["2026-02"].Paid)
+	}
+	if math.Abs(months["2026-03"].Paid-350) > 0.01 {
+		t.Errorf("03: want 350, got %f", months["2026-03"].Paid)
+	}
+	if math.Abs(months["2026-04"].Paid-150) > 0.01 {
+		t.Errorf("04: want 150, got %f", months["2026-04"].Paid)
+	}
+}
+
+// Prior txn fills 02 partially; later txn finishes 02 then spills to 03.
+func TestFillFirstAcrossTwoTransactions(t *testing.T) {
+	t.Parallel()
+	members := []Member{{Name: "Matyáš", Tier: "A", Fees: map[string]FeeData{
+		"2026-02": {Expected: 500, Attendance: 2},
+		"2026-03": {Expected: 250, Attendance: 1},
+	}}}
+	sortedMonths := []string{"2026-02", "2026-03"}
+	txs := []Transaction{
+		tx("Matyáš", "2026-02", 200),
+		tx("Matyáš", "2026-02, 2026-03", 550),
+	}
+
+	result := Reconcile(members, sortedMonths, txs, nil, defaultYear)
+	months := result.Members["Matyáš"].Months
+
+	if math.Abs(months["2026-02"].Paid-500) > 0.01 {
+		t.Errorf("02: want 500, got %f", months["2026-02"].Paid)
+	}
+	if math.Abs(months["2026-03"].Paid-250) > 0.01 {
+		t.Errorf("03: want 250, got %f", months["2026-03"].Paid)
+	}
+}

go/internal/services/membership/loader.go

@@ -25,11 +25,17 @@ type ExceptionLoader interface {
 	LoadExceptions(ctx context.Context) (map[reconcile.ExceptionKey]reconcile.Exception, error)
 }
 
+// CacheFlusher can invalidate all cached data.
+type CacheFlusher interface {
+	FlushCache() (int, error)
+}
+
 // Sources is the aggregate interface required by ReconcileReport.
 type Sources interface {
 	AttendanceLoader
 	TransactionLoader
 	ExceptionLoader
+	CacheFlusher
 }
 
 // NewStubSources returns a Sources whose every method returns ErrIOPending.
@@ -52,3 +58,5 @@ func (stubSources) LoadTransactions(_ context.Context) ([]reconcile.Transaction,
 func (stubSources) LoadExceptions(_ context.Context) (map[reconcile.ExceptionKey]reconcile.Exception, error) {
 	return nil, ErrIOPending
 }
+
+func (stubSources) FlushCache() (int, error) { return 0, nil }

go/internal/services/membership/reconcile_test.go

@@ -31,6 +31,8 @@ func (f fakeSources) LoadExceptions(_ context.Context) (map[reconcile.ExceptionK
 	return f.exceptions, nil
 }
 
+func (fakeSources) FlushCache() (int, error) { return 0, nil }
+
 func TestReconcileReport(t *testing.T) {
 	t.Parallel()
 	s := fakeSources{

go/internal/services/membership/sources.go

@@ -27,7 +27,9 @@ const (
 
 // AdultMergedMonths mirrors ADULT_MERGED_MONTHS in scripts/attendance.py.
 // Source month → target month (source attendance accumulated into target).
-var AdultMergedMonths = map[string]string{}
+var AdultMergedMonths = map[string]string{
+	"2025-09": "2025-10",
+}
 
 // JuniorMergedMonths mirrors JUNIOR_MERGED_MONTHS in scripts/attendance.py.
 var JuniorMergedMonths = map[string]string{
@@ -109,6 +111,9 @@ func (s *realSources) LoadTransactions(ctx context.Context) ([]reconcile.Transac
 	return parseTransactionRows(rows)
 }
 
+// FlushCache deletes all cached data files and resets in-memory cache state.
+func (s *realSources) FlushCache() (int, error) { return s.cache.Flush() }
+
 // LoadExceptions fetches the exceptions tab (cached).
 func (s *realSources) LoadExceptions(ctx context.Context) (map[reconcile.ExceptionKey]reconcile.Exception, error) {
 	rows, err := cache.Get(ctx, s.cache, "exceptions_dict",

go/internal/services/membership/sources_test.go

@@ -46,8 +46,8 @@ func TestLoadAdults(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	// adultMergedMonths is empty so 2025-09 stays as-is
+	// AdultMergedMonths sends 2025-09 → 2025-10
-	if len(months) != 1 || months[0] != "2025-09" {
+	if len(months) != 1 || months[0] != "2025-10" {
 		t.Errorf("unexpected months: %v", months)
 	}
 	if len(members) != 2 {
@@ -55,7 +55,7 @@ func TestLoadAdults(t *testing.T) {
 	}
 	byName := map[string]int{}
 	for _, m := range members {
-		byName[m.Name] = m.Fees["2025-09"].Attendance
+		byName[m.Name] = m.Fees["2025-10"].Attendance
 	}
 	if byName["Alice"] != 2 {
 		t.Errorf("Alice: want 2 sessions, got %d", byName["Alice"])
@@ -73,9 +73,9 @@ func TestLoadAdults_Fee(t *testing.T) {
 	}
 	byName := map[string]int{}
 	for _, m := range members {
-		byName[m.Name] = m.Fees["2025-09"].Expected
+		byName[m.Name] = m.Fees["2025-10"].Expected
 	}
-	// 2 sessions in 2025-09 → AdultFeeMonthlyRate["2025-09"] = 750
+	// 2 sessions land in merged 2025-10 → AdultFeeMonthlyRate["2025-10"] = 750
 	if byName["Alice"] != 750 {
 		t.Errorf("Alice fee: want 750, got %d", byName["Alice"])
 	}

go/internal/web/api/handler.go

@@ -23,6 +23,9 @@ type Handler struct {
 	Logger       *slog.Logger
 }
 
+// FlushCache invalidates all cached data via the underlying Sources.
+func (h *Handler) FlushCache() (int, error) { return h.Sources.FlushCache() }
+
 // ServeVersion handles GET /api/version.
 func (h *Handler) ServeVersion(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, VersionResponse{
@@ -34,37 +37,64 @@ func (h *Handler) ServeVersion(w http.ResponseWriter, r *http.Request) {
 
 // ServeAdults handles GET /api/adults.
 func (h *Handler) ServeAdults(w http.ResponseWriter, r *http.Request) {
-	ctx := r.Context()
+	resp, err := h.AssembleAdults(r.Context())
-	members, sortedMonths, txns, exceptions, err := h.loadAll(ctx, true)
 	if err != nil {
 		h.writeError(w, r, err)
 		return
 	}
+	writeJSON(w, resp)
+}
+
+// AssembleAdults loads all data and builds the adults view model.
+// Shared between the JSON API route and the HTML handler.
+func (h *Handler) AssembleAdults(ctx context.Context) (AdultsResponse, error) {
+	members, sortedMonths, txns, exceptions, err := h.loadAll(ctx, true)
+	if err != nil {
+		return AdultsResponse{}, err
+	}
 	result := domreconcile.Reconcile(members, sortedMonths, txns, exceptions, time.Now().Year())
-	writeJSON(w, buildAdultsResponse(members, sortedMonths, result, txns, h.Config, time.Now().Format("2006-01")))
+	return buildAdultsResponse(members, sortedMonths, result, txns, h.Config, time.Now().Format("2006-01")), nil
 }
 
 // ServeJuniors handles GET /api/juniors.
 func (h *Handler) ServeJuniors(w http.ResponseWriter, r *http.Request) {
-	ctx := r.Context()
+	resp, err := h.AssembleJuniors(r.Context())
-	members, sortedMonths, txns, exceptions, err := h.loadAll(ctx, false)
 	if err != nil {
 		h.writeError(w, r, err)
 		return
 	}
+	writeJSON(w, resp)
+}
+
+// AssembleJuniors loads all data and builds the juniors view model.
+// Shared between the JSON API route and the HTML handler.
+func (h *Handler) AssembleJuniors(ctx context.Context) (JuniorsResponse, error) {
+	members, sortedMonths, txns, exceptions, err := h.loadAll(ctx, false)
+	if err != nil {
+		return JuniorsResponse{}, err
+	}
 	result := domreconcile.Reconcile(members, sortedMonths, txns, exceptions, time.Now().Year())
-	writeJSON(w, buildJuniorsResponse(members, sortedMonths, result, txns, h.Config, time.Now().Format("2006-01")))
+	return buildJuniorsResponse(members, sortedMonths, result, txns, h.Config, time.Now().Format("2006-01")), nil
 }
 
 // ServePayments handles GET /api/payments.
 func (h *Handler) ServePayments(w http.ResponseWriter, r *http.Request) {
-	ctx := r.Context()
+	resp, err := h.AssemblePayments(r.Context())
-	txns, err := h.Sources.LoadTransactions(ctx)
 	if err != nil {
-		h.writeError(w, r, fmt.Errorf("load transactions: %w", err))
+		h.writeError(w, r, err)
 		return
 	}
-	writeJSON(w, buildPaymentsResponse(txns, h.allMemberNames(ctx)))
+	writeJSON(w, resp)
+}
+
+// AssemblePayments loads transactions and builds the payments view model.
+// Shared between the JSON API route and the HTML handler.
+func (h *Handler) AssemblePayments(ctx context.Context) (PaymentsResponse, error) {
+	txns, err := h.Sources.LoadTransactions(ctx)
+	if err != nil {
+		return PaymentsResponse{}, fmt.Errorf("load transactions: %w", err)
+	}
+	return buildPaymentsResponse(txns, h.allMemberNames(ctx)), nil
 }
 
 func (h *Handler) loadAll(ctx context.Context, adults bool) (

go/internal/web/assets.go

@@ -0,0 +1,9 @@
+package web
+
+import "embed"
+
+//go:embed templates
+var templateFS embed.FS
+
+//go:embed static
+var staticFS embed.FS

go/internal/web/assets_test.go

@@ -0,0 +1,93 @@
+package web
+
+import (
+	"io/fs"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"strings"
+	"testing"
+)
+
+// TestEmbedCompleteness guards against a new template or static file being
+// added to disk but missing from the embedded FS (e.g. a new directory that
+// the //go:embed glob does not match).
+func TestEmbedCompleteness(t *testing.T) {
+	cases := []struct {
+		name      string
+		diskDir   string
+		embedFS   fs.FS
+		embedRoot string
+	}{
+		{"templates", "templates", templateFS, "templates"},
+		{"static", "static", staticFS, "static"},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			diskFS := os.DirFS(tc.diskDir)
+			_ = fs.WalkDir(diskFS, ".", func(path string, d fs.DirEntry, err error) error {
+				if err != nil || d.IsDir() {
+					return err
+				}
+				embPath := tc.embedRoot + "/" + path
+				if _, statErr := fs.Stat(tc.embedFS, embPath); statErr != nil {
+					t.Errorf("file %q exists on disk but is missing from embed.FS (%v)", embPath, statErr)
+				}
+				return nil
+			})
+		})
+	}
+}
+
+// TestStaticAssetsServed verifies that /static/* is served from the embedded
+// FS through the same mux wiring used in server.go, so a standalone binary
+// with no adjacent static/ directory still delivers assets.
+func TestStaticAssetsServed(t *testing.T) {
+	subFS, err := fs.Sub(staticFS, "static")
+	if err != nil {
+		t.Fatalf("fs.Sub static: %v", err)
+	}
+	mux := http.NewServeMux()
+	mux.Handle("/static/", http.StripPrefix("/static/", http.FileServerFS(subFS)))
+
+	cases := []struct {
+		path        string
+		wantCT      string
+		wantSnippet string
+	}{
+		{"/static/css/app.css", "text/css", "body {"},
+		{"/static/js/member-detail.js", "javascript", "Member-detail modal"},
+		{"/static/js/filters.js", "javascript", ""},
+		{"/static/js/payment-qr.js", "javascript", ""},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.path, func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodGet, tc.path, nil)
+			w := httptest.NewRecorder()
+			mux.ServeHTTP(w, req)
+
+			if w.Code != http.StatusOK {
+				t.Fatalf("GET %s: status %d, want 200", tc.path, w.Code)
+			}
+			ct := w.Header().Get("Content-Type")
+			if !strings.Contains(ct, tc.wantCT) {
+				t.Errorf("GET %s: Content-Type %q, want it to contain %q", tc.path, ct, tc.wantCT)
+			}
+			if tc.wantSnippet != "" && !strings.Contains(w.Body.String(), tc.wantSnippet) {
+				t.Errorf("GET %s: body missing expected snippet %q", tc.path, tc.wantSnippet)
+			}
+		})
+	}
+
+	// Sanity: unknown path → 404 (file server doesn't fall through silently)
+	t.Run("missing-file", func(t *testing.T) {
+		req := httptest.NewRequest(http.MethodGet, "/static/css/nonexistent.css", nil)
+		w := httptest.NewRecorder()
+		mux.ServeHTTP(w, req)
+		if w.Code != http.StatusNotFound {
+			t.Errorf("unknown static path: status %d, want 404", w.Code)
+		}
+	})
+}

go/internal/web/html_handler.go

@@ -0,0 +1,143 @@
+package web
+
+import (
+	"bytes"
+	"fmt"
+	"fuj-management/go/internal/web/api"
+	"net/http"
+	"runtime/debug"
+)
+
+// HTMLHandler serves the Go-native HTML frontend.
+type HTMLHandler struct {
+	renderer   *Renderer
+	build      BuildInfo
+	apiHandler *api.Handler
+	actions    ActionHandlers
+}
+
+// NewHTMLHandler constructs an HTMLHandler.
+func NewHTMLHandler(r *Renderer, b BuildInfo, ah *api.Handler, actions ActionHandlers) *HTMLHandler {
+	return &HTMLHandler{renderer: r, build: b, apiHandler: ah, actions: actions}
+}
+
+func (h *HTMLHandler) ServeAdults(w http.ResponseWriter, r *http.Request) {
+	data, err := h.apiHandler.AssembleAdults(r.Context())
+	if err != nil {
+		h.renderer.Render(w, "adults", AdultsPageData{
+			PageData: PageData{Active: "adults", Build: h.build},
+			Error:    err.Error(),
+		})
+		return
+	}
+	h.renderer.Render(w, "adults", AdultsPageData{
+		PageData: PageData{Active: "adults", Build: h.build},
+		Data:     data,
+	})
+}
+
+func (h *HTMLHandler) ServeJuniors(w http.ResponseWriter, r *http.Request) {
+	data, err := h.apiHandler.AssembleJuniors(r.Context())
+	if err != nil {
+		h.renderer.Render(w, "juniors", JuniorsPageData{
+			PageData: PageData{Active: "juniors", Build: h.build},
+			Error:    err.Error(),
+		})
+		return
+	}
+	h.renderer.Render(w, "juniors", JuniorsPageData{
+		PageData: PageData{Active: "juniors", Build: h.build},
+		Data:     data,
+	})
+}
+
+func (h *HTMLHandler) ServePayments(w http.ResponseWriter, r *http.Request) {
+	data, err := h.apiHandler.AssemblePayments(r.Context())
+	if err != nil {
+		h.renderer.Render(w, "payments", PaymentsPageData{
+			PageData: PageData{Active: "payments", Build: h.build},
+			Error:    err.Error(),
+		})
+		return
+	}
+	h.renderer.Render(w, "payments", PaymentsPageData{
+		PageData: PageData{Active: "payments", Build: h.build},
+		Data:     data,
+	})
+}
+
+// ServeSync handles GET /sync-bank: runs sync+infer+flush then renders the result.
+func (h *HTMLHandler) ServeSync(w http.ResponseWriter, r *http.Request) {
+	pd := PageData{Active: "sync", Build: h.build}
+
+	if h.actions.BankSync == nil {
+		h.renderer.Render(w, "sync", SyncPageData{
+			PageData: pd,
+			Output:   "Bank sync is not configured.",
+			Success:  false,
+		})
+		return
+	}
+
+	var buf bytes.Buffer
+	success := true
+	if err := h.actions.BankSync(r.Context(), &buf); err != nil {
+		fmt.Fprintf(&buf, "\nError: %s\n\nStack trace:\n%s", err.Error(), debug.Stack())
+		success = false
+	}
+
+	fmt.Fprintln(&buf, "\n=== Flush Cache ===")
+	n, err := h.apiHandler.FlushCache()
+	if err != nil {
+		fmt.Fprintf(&buf, "flush error: %s\n", err.Error())
+		success = false
+	} else {
+		fmt.Fprintf(&buf, "%d cache file(s) deleted.\n", n)
+	}
+
+	h.renderer.Render(w, "sync", SyncPageData{
+		PageData: pd,
+		Output:   buf.String(),
+		Success:  success,
+	})
+}
+
+// ServeFlushCacheGET handles GET /flush-cache: renders the confirmation form.
+func (h *HTMLHandler) ServeFlushCacheGET(w http.ResponseWriter, r *http.Request) {
+	h.renderer.Render(w, "flush_cache", FlushPageData{
+		PageData: PageData{Active: "flush", Build: h.build},
+	})
+}
+
+// ServeFlushCachePOST handles POST /flush-cache: flushes and re-renders with count.
+func (h *HTMLHandler) ServeFlushCachePOST(w http.ResponseWriter, r *http.Request) {
+	n, _ := h.apiHandler.FlushCache()
+	h.renderer.Render(w, "flush_cache", FlushPageData{
+		PageData: PageData{Active: "flush", Build: h.build},
+		Flushed:  true,
+		Deleted:  n,
+	})
+}
+
+// ServeQR handles GET /qr: generates and returns a Czech QR Platba PNG.
+func (h *HTMLHandler) ServeQR(w http.ResponseWriter, r *http.Request) {
+	q := r.URL.Query()
+	account := q.Get("account")
+	amount := q.Get("amount")
+	message := q.Get("message")
+	if account == "" {
+		account = h.apiHandler.Config.BankAccount
+	}
+	if amount == "" {
+		amount = "0"
+	}
+
+	payload := BuildSPD(account, amount, message, h.apiHandler.Config.BankAccount)
+	png, err := RenderQRCode(payload)
+	if err != nil {
+		http.Error(w, "qr encode: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+	w.Header().Set("Content-Type", "image/png")
+	_, _ = w.Write(png)
+}

go/internal/web/html_handler_test.go

@@ -0,0 +1,383 @@
+package web_test
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"fuj-management/go/internal/config"
+	"fuj-management/go/internal/domain/reconcile"
+	"fuj-management/go/internal/web"
+	"fuj-management/go/internal/web/api"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+// fixtureSources returns one adult ("Test Member", tier A) with a 2026-01 fee
+// of 750 CZK (4 sessions) and a matching payment of 750 — mirrors Python's
+// test_adults_route fixture.
+type fixtureSources struct{}
+
+func (fixtureSources) LoadAdults(_ context.Context) ([]reconcile.Member, []string, error) {
+	return []reconcile.Member{
+		{Name: "Test Member", Tier: "A", Fees: map[string]reconcile.FeeData{
+			"2026-01": {Expected: 750, Attendance: 4},
+		}},
+	}, []string{"2026-01"}, nil
+}
+
+func (fixtureSources) LoadJuniors(_ context.Context) ([]reconcile.Member, []string, error) {
+	return nil, nil, nil
+}
+
+func (fixtureSources) LoadTransactions(_ context.Context) ([]reconcile.Transaction, error) {
+	amt := float64(750)
+	return []reconcile.Transaction{
+		{Date: "2026-01-01", Amount: 750, Person: "Test Member", Purpose: "2026-01", InferredAmount: &amt},
+	}, nil
+}
+
+func (fixtureSources) LoadExceptions(_ context.Context) (map[reconcile.ExceptionKey]reconcile.Exception, error) {
+	return nil, nil
+}
+
+func (fixtureSources) FlushCache() (int, error) { return 0, nil }
+
+func fixtureHandler(t *testing.T) *api.Handler {
+	t.Helper()
+	return &api.Handler{
+		Sources: fixtureSources{},
+		Config:  config.Config{BankAccount: "CZ0000000000000000000000"},
+	}
+}
+
+func TestHTMLHandlerSmoke(t *testing.T) {
+	renderer, err := web.NewRenderer()
+	if err != nil {
+		t.Fatalf("NewRenderer: %v", err)
+	}
+	b := web.BuildInfo{Version: "v0", Commit: "abc1234", BuildDate: "2026-01-01"}
+	h := web.NewHTMLHandler(renderer, b, fixtureHandler(t), web.ActionHandlers{})
+
+	cases := []struct {
+		path    string
+		handler http.HandlerFunc
+	}{
+		{"/adults", h.ServeAdults},
+		{"/juniors", h.ServeJuniors},
+		{"/payments", h.ServePayments},
+		{"/sync-bank", h.ServeSync},
+		{"/flush-cache", h.ServeFlushCacheGET},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.path, func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodGet, tc.path, nil)
+			w := httptest.NewRecorder()
+			tc.handler(w, req)
+
+			if w.Code != http.StatusOK {
+				t.Errorf("status = %d, want 200", w.Code)
+			}
+			if ct := w.Header().Get("Content-Type"); !strings.HasPrefix(ct, "text/html") {
+				t.Errorf("Content-Type = %q, want text/html", ct)
+			}
+
+			body := w.Body.String()
+			if n := strings.Count(body, `class="active"`); n != 1 {
+				t.Errorf(`class="active" count = %d, want 1`, n)
+			}
+			want := fmt.Sprintf(`href="%s" class="active"`, tc.path)
+			if !strings.Contains(body, want) {
+				t.Errorf("missing active link %q in body", want)
+			}
+		})
+	}
+}
+
+func TestAdultsPage(t *testing.T) {
+	renderer, err := web.NewRenderer()
+	if err != nil {
+		t.Fatalf("NewRenderer: %v", err)
+	}
+	b := web.BuildInfo{Version: "v0", Commit: "abc1234", BuildDate: "2026-01-01"}
+	h := web.NewHTMLHandler(renderer, b, fixtureHandler(t), web.ActionHandlers{})
+
+	req := httptest.NewRequest(http.MethodGet, "/adults", nil)
+	w := httptest.NewRecorder()
+	h.ServeAdults(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200", w.Code)
+	}
+
+	body := w.Body.String()
+
+	for _, want := range []string{
+		"Adults Dashboard",
+		"Test Member",
+		"750/750 CZK (4)", // paid/expected (attendance)
+	} {
+		if !strings.Contains(body, want) {
+			t.Errorf("body missing %q", want)
+		}
+	}
+
+	// Python assertion: cell text never says literally "OK"
+	if strings.Contains(body, ">OK<") {
+		t.Error("body should not contain >OK<")
+	}
+}
+
+func TestModalMarkup(t *testing.T) {
+	renderer, err := web.NewRenderer()
+	if err != nil {
+		t.Fatalf("NewRenderer: %v", err)
+	}
+	b := web.BuildInfo{Version: "v0", Commit: "abc1234", BuildDate: "2026-01-01"}
+	h := web.NewHTMLHandler(renderer, b, fixtureHandler(t), web.ActionHandlers{})
+
+	cases := []struct {
+		path    string
+		handler http.HandlerFunc
+		page    string
+		wantRow string // data-name present only when the page has rows
+	}{
+		{"/adults", h.ServeAdults, "adults", `data-name="Test Member"`},
+		{"/juniors", h.ServeJuniors, "juniors", ""},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.path, func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodGet, tc.path, nil)
+			w := httptest.NewRecorder()
+			tc.handler(w, req)
+			body := w.Body.String()
+
+			for _, want := range []string{
+				`data-page="` + tc.page + `"`,
+				`id="memberModal"`,
+				`/static/js/member-detail.js`,
+			} {
+				if !strings.Contains(body, want) {
+					t.Errorf("body missing %q", want)
+				}
+			}
+			if tc.wantRow != "" && !strings.Contains(body, tc.wantRow) {
+				t.Errorf("body missing info-icon row %q", tc.wantRow)
+			}
+		})
+	}
+}
+
+func TestPaymentsPage(t *testing.T) {
+	renderer, err := web.NewRenderer()
+	if err != nil {
+		t.Fatalf("NewRenderer: %v", err)
+	}
+	b := web.BuildInfo{Version: "v0", Commit: "abc1234", BuildDate: "2026-01-01"}
+	h := web.NewHTMLHandler(renderer, b, fixtureHandler(t), web.ActionHandlers{})
+
+	req := httptest.NewRequest(http.MethodGet, "/payments", nil)
+	w := httptest.NewRecorder()
+	h.ServePayments(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200", w.Code)
+	}
+
+	body := w.Body.String()
+
+	for _, want := range []string{
+		"Payments Ledger",
+		"<h2>Test Member</h2>",
+		"750 CZK",
+		"2026-01-01",
+		"2026-01",
+	} {
+		if !strings.Contains(body, want) {
+			t.Errorf("body missing %q", want)
+		}
+	}
+}
+
+func TestServeQR(t *testing.T) {
+	renderer, err := web.NewRenderer()
+	if err != nil {
+		t.Fatalf("NewRenderer: %v", err)
+	}
+	b := web.BuildInfo{Version: "v0", Commit: "abc1234", BuildDate: "2026-01-01"}
+	h := web.NewHTMLHandler(renderer, b, fixtureHandler(t), web.ActionHandlers{})
+
+	req := httptest.NewRequest(http.MethodGet, "/qr?account=2702008874%2F2010&amount=700&message=Test", nil)
+	w := httptest.NewRecorder()
+	h.ServeQR(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200", w.Code)
+	}
+	if ct := w.Header().Get("Content-Type"); ct != "image/png" {
+		t.Errorf("Content-Type = %q, want image/png", ct)
+	}
+	// PNG magic bytes: \x89PNG\r\n\x1a\n
+	magic := []byte{0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a}
+	body := w.Body.Bytes()
+	if len(body) < len(magic) || !bytes.Equal(body[:len(magic)], magic) {
+		t.Error("response body does not start with PNG magic bytes")
+	}
+}
+
+func TestServeFlushCacheGET(t *testing.T) {
+	renderer, err := web.NewRenderer()
+	if err != nil {
+		t.Fatalf("NewRenderer: %v", err)
+	}
+	b := web.BuildInfo{Version: "v0", Commit: "abc1234", BuildDate: "2026-01-01"}
+	h := web.NewHTMLHandler(renderer, b, fixtureHandler(t), web.ActionHandlers{})
+
+	req := httptest.NewRequest(http.MethodGet, "/flush-cache", nil)
+	w := httptest.NewRecorder()
+	h.ServeFlushCacheGET(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200", w.Code)
+	}
+	body := w.Body.String()
+	if !strings.Contains(body, "Flush Cache") {
+		t.Error("body missing Flush Cache heading")
+	}
+	if strings.Contains(body, "file(s) deleted") {
+		t.Error("GET should not show deleted count")
+	}
+}
+
+func TestServeFlushCachePOST(t *testing.T) {
+	renderer, err := web.NewRenderer()
+	if err != nil {
+		t.Fatalf("NewRenderer: %v", err)
+	}
+	b := web.BuildInfo{Version: "v0", Commit: "abc1234", BuildDate: "2026-01-01"}
+	h := web.NewHTMLHandler(renderer, b, fixtureHandler(t), web.ActionHandlers{})
+
+	req := httptest.NewRequest(http.MethodPost, "/flush-cache", nil)
+	w := httptest.NewRecorder()
+	h.ServeFlushCachePOST(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200", w.Code)
+	}
+	body := w.Body.String()
+	// fixtureSources.FlushCache returns 0
+	if !strings.Contains(body, "file(s) deleted") {
+		t.Error("POST should show deleted count")
+	}
+}
+
+func TestServeSync(t *testing.T) {
+	renderer, err := web.NewRenderer()
+	if err != nil {
+		t.Fatalf("NewRenderer: %v", err)
+	}
+	b := web.BuildInfo{Version: "v0", Commit: "abc1234", BuildDate: "2026-01-01"}
+
+	actions := web.ActionHandlers{
+		BankSync: func(_ context.Context, out io.Writer) error {
+			fmt.Fprintln(out, "=== Sync Fio Transactions ===")
+			fmt.Fprintln(out, "Synced 3 new transaction(s).")
+			fmt.Fprintln(out, "=== Infer Payments ===")
+			fmt.Fprintln(out, "Inferred 2 row(s).")
+			return nil
+		},
+	}
+	h := web.NewHTMLHandler(renderer, b, fixtureHandler(t), actions)
+
+	req := httptest.NewRequest(http.MethodGet, "/sync-bank", nil)
+	w := httptest.NewRecorder()
+	h.ServeSync(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200", w.Code)
+	}
+	body := w.Body.String()
+	for _, want := range []string{
+		"Sync Bank Data",
+		"Synced 3 new transaction(s).",
+		"Inferred 2 row(s).",
+		"Flush Cache",
+	} {
+		if !strings.Contains(body, want) {
+			t.Errorf("body missing %q", want)
+		}
+	}
+}
+
+func TestPaymentQRMarkup(t *testing.T) {
+	renderer, err := web.NewRenderer()
+	if err != nil {
+		t.Fatalf("NewRenderer: %v", err)
+	}
+	b := web.BuildInfo{Version: "v0", Commit: "abc1234", BuildDate: "2026-01-01"}
+	h := web.NewHTMLHandler(renderer, b, fixtureHandler(t), web.ActionHandlers{})
+
+	cases := []struct {
+		path    string
+		handler http.HandlerFunc
+	}{
+		{"/adults", h.ServeAdults},
+		{"/juniors", h.ServeJuniors},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.path, func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodGet, tc.path, nil)
+			w := httptest.NewRecorder()
+			tc.handler(w, req)
+			body := w.Body.String()
+
+			for _, want := range []string{
+				`id="qrModal"`,
+				`id="qrImg"`,
+				`id="qrTitle"`,
+				`id="qrAccount"`,
+				`id="qrAmount"`,
+				`id="qrMessage"`,
+				`/static/js/payment-qr.js`,
+				`data-bank-account="CZ0000000000000000000000"`,
+			} {
+				if !strings.Contains(body, want) {
+					t.Errorf("body missing %q", want)
+				}
+			}
+
+			// Pay buttons must use <button>, never a bare href to /qr.
+			if strings.Contains(body, `href="/qr`) {
+				t.Error("body must not contain href=/qr (Pay buttons should be <button>, not <a>)")
+			}
+		})
+	}
+}
+
+func TestServeVersion(t *testing.T) {
+	req := httptest.NewRequest(http.MethodGet, "/api/version", nil)
+	w := httptest.NewRecorder()
+	fixtureHandler(t).ServeVersion(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200", w.Code)
+	}
+	if ct := w.Header().Get("Content-Type"); !strings.HasPrefix(ct, "application/json") {
+		t.Errorf("Content-Type = %q, want application/json", ct)
+	}
+	var raw map[string]json.RawMessage
+	if err := json.NewDecoder(w.Body).Decode(&raw); err != nil {
+		t.Fatalf("decode JSON: %v", err)
+	}
+	for _, key := range []string{"tag", "commit", "build_date"} {
+		if _, ok := raw[key]; !ok {
+			t.Errorf("JSON response missing key %q", key)
+		}
+	}
+}

go/internal/web/qr.go

@@ -0,0 +1,50 @@
+package web
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+	"unicode/utf8"
+
+	qrcode "github.com/skip2/go-qrcode"
+)
+
+var validAccount = regexp.MustCompile(`^[A-Z]{2}\d{2,34}$|^\d{1,16}/\d{4}$`)
+
+// BuildSPD builds a Czech QR Platba SPD string, matching Python's qr_code handler.
+// Invalid account falls back to defaultAccount.
+// Amount is clamped to [0, 10_000_000]; non-numeric input becomes "0.00".
+// Message is truncated to 60 runes and stripped of '*' characters.
+func BuildSPD(account, amount, message, defaultAccount string) string {
+	if !validAccount.MatchString(account) {
+		account = defaultAccount
+	}
+
+	var amtStr string
+	var f float64
+	if _, err := fmt.Sscanf(amount, "%f", &f); err != nil || f < 0 || f > 10_000_000 {
+		amtStr = "0.00"
+	} else {
+		amtStr = fmt.Sprintf("%.2f", f)
+	}
+
+	if utf8.RuneCountInString(message) > 60 {
+		runes := []rune(message)
+		message = string(runes[:60])
+	}
+	message = strings.ReplaceAll(message, "*", "")
+
+	var accStr string
+	if parts := strings.SplitN(account, "/", 2); len(parts) == 2 {
+		accStr = parts[0] + "*BC:" + parts[1]
+	} else {
+		accStr = account
+	}
+
+	return fmt.Sprintf("SPD*1.0*ACC:%s*AM:%s*CC:CZK*MSG:%s", accStr, amtStr, message)
+}
+
+// RenderQRCode encodes payload as a PNG QR code (256×256, error correction Medium).
+func RenderQRCode(payload string) ([]byte, error) {
+	return qrcode.Encode(payload, qrcode.Medium, 256)
+}

go/internal/web/qr_test.go

@@ -0,0 +1,91 @@
+package web
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestQRBuildSPD(t *testing.T) {
+	const def = "2702008874/2010"
+
+	cases := []struct {
+		name    string
+		account string
+		amount  string
+		message string
+		want    string
+	}{
+		{
+			name:    "czech account",
+			account: "2702008874/2010",
+			amount:  "700",
+			message: "Test Member: 01/2026",
+			want:    "SPD*1.0*ACC:2702008874*BC:2010*AM:700.00*CC:CZK*MSG:Test Member: 01/2026",
+		},
+		{
+			name:    "IBAN account",
+			account: "CZ6508000000192000145399",
+			amount:  "500",
+			message: "hi",
+			want:    "SPD*1.0*ACC:CZ6508000000192000145399*AM:500.00*CC:CZK*MSG:hi",
+		},
+		{
+			name:    "invalid account falls back to default",
+			account: "NOTANACCOUNT",
+			amount:  "100",
+			message: "x",
+			want:    "SPD*1.0*ACC:2702008874*BC:2010*AM:100.00*CC:CZK*MSG:x",
+		},
+		{
+			name:    "empty account falls back to default",
+			account: "",
+			amount:  "0",
+			message: "",
+			want:    "SPD*1.0*ACC:2702008874*BC:2010*AM:0.00*CC:CZK*MSG:",
+		},
+		{
+			name:    "negative amount clamped to 0.00",
+			account: def,
+			amount:  "-1",
+			message: "",
+			want:    "SPD*1.0*ACC:2702008874*BC:2010*AM:0.00*CC:CZK*MSG:",
+		},
+		{
+			name:    "amount over 10M clamped to 0.00",
+			account: def,
+			amount:  "99999999",
+			message: "",
+			want:    "SPD*1.0*ACC:2702008874*BC:2010*AM:0.00*CC:CZK*MSG:",
+		},
+		{
+			name:    "non-numeric amount becomes 0.00",
+			account: def,
+			amount:  "abc",
+			message: "",
+			want:    "SPD*1.0*ACC:2702008874*BC:2010*AM:0.00*CC:CZK*MSG:",
+		},
+		{
+			name:    "asterisks stripped from message",
+			account: def,
+			amount:  "100",
+			message: "pay*now",
+			want:    "SPD*1.0*ACC:2702008874*BC:2010*AM:100.00*CC:CZK*MSG:paynow",
+		},
+		{
+			name:    "message truncated to 60 runes",
+			account: def,
+			amount:  "0",
+			message: strings.Repeat("á", 65),
+			want:    "SPD*1.0*ACC:2702008874*BC:2010*AM:0.00*CC:CZK*MSG:" + strings.Repeat("á", 60),
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			got := BuildSPD(tc.account, tc.amount, tc.message, def)
+			if got != tc.want {
+				t.Errorf("\ngot:  %s\nwant: %s", got, tc.want)
+			}
+		})
+	}
+}

go/internal/web/render.go

@@ -0,0 +1,91 @@
+package web
+
+import (
+	"fmt"
+	"fuj-management/go/internal/web/api"
+	"html/template"
+	"log/slog"
+	"net/http"
+)
+
+// PageData is the view model passed to every HTML template.
+type PageData struct {
+	Active string
+	Build  BuildInfo
+}
+
+// AdultsPageData is the view model for the /adults HTML page.
+type AdultsPageData struct {
+	PageData
+	Data  api.AdultsResponse
+	Error string
+}
+
+// JuniorsPageData is the view model for the /juniors HTML page.
+type JuniorsPageData struct {
+	PageData
+	Data  api.JuniorsResponse
+	Error string
+}
+
+// PaymentsPageData is the view model for the /payments HTML page.
+type PaymentsPageData struct {
+	PageData
+	Data  api.PaymentsResponse
+	Error string
+}
+
+// SyncPageData is the view model for the /sync-bank HTML page.
+type SyncPageData struct {
+	PageData
+	Output  string
+	Success bool
+}
+
+// FlushPageData is the view model for the /flush-cache HTML page.
+type FlushPageData struct {
+	PageData
+	Flushed bool
+	Deleted int
+}
+
+// Renderer parses and executes HTML templates from the embedded FS.
+type Renderer struct {
+	tmpls map[string]*template.Template
+}
+
+var pageNames = []string{"adults", "juniors", "payments", "sync", "flush_cache"}
+
+var tmplFuncs = template.FuncMap{}
+
+// NewRenderer parses all templates from the embedded FS.
+// A parse failure should be treated as a startup-time fatal error.
+func NewRenderer() (*Renderer, error) {
+	tmpls := make(map[string]*template.Template, len(pageNames))
+	for _, name := range pageNames {
+		t, err := template.New("").Funcs(tmplFuncs).ParseFS(templateFS,
+			"templates/base.tmpl",
+			"templates/partials/nav.tmpl",
+			"templates/partials/footer.tmpl",
+			"templates/"+name+".tmpl",
+		)
+		if err != nil {
+			return nil, fmt.Errorf("parse template %q: %w", name, err)
+		}
+		tmpls[name] = t
+	}
+	return &Renderer{tmpls: tmpls}, nil
+}
+
+// Render executes the named template with data, writing to w.
+func (r *Renderer) Render(w http.ResponseWriter, name string, data any) {
+	t, ok := r.tmpls[name]
+	if !ok {
+		http.Error(w, "template not found: "+name, http.StatusInternalServerError)
+		return
+	}
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	if err := t.ExecuteTemplate(w, "base", data); err != nil {
+		slog.Error("render template", "name", name, "err", err)
+	}
+}

go/internal/web/server.go

@@ -1,11 +1,14 @@
 package web
 
 import (
+	"context"
 	"fmt"
 	"fuj-management/go/internal/config"
 	"fuj-management/go/internal/services/membership"
 	"fuj-management/go/internal/web/api"
 	"fuj-management/go/internal/web/middleware"
+	"io"
+	"io/fs"
 	"log/slog"
 	"net/http"
 )
@@ -17,9 +20,22 @@ type BuildInfo struct {
 	BuildDate string
 }
 
+// ActionHandlers holds function closures for side-effectful operations that
+// require dependencies (fio, sheets) not present on the core API handler.
+type ActionHandlers struct {
+	// BankSync runs sync+infer and writes a human-readable log to out.
+	// nil disables the /sync-bank action (renders an error instead).
+	BankSync func(ctx context.Context, out io.Writer) error
+}
+
 // Run registers routes and starts the HTTP server on addr.
-func Run(logger *slog.Logger, addr string, build BuildInfo, sources membership.Sources, cfg config.Config) error {
+func Run(logger *slog.Logger, addr string, build BuildInfo, sources membership.Sources, cfg config.Config, actions ActionHandlers) error {
-	h := &api.Handler{
+	renderer, err := NewRenderer()
+	if err != nil {
+		return fmt.Errorf("init templates: %w", err)
+	}
+
+	ah := &api.Handler{
 		BuildVersion: build.Version,
 		BuildCommit:  build.Commit,
 		BuildDate:    build.BuildDate,
@@ -27,22 +43,37 @@ func Run(logger *slog.Logger, addr string, build BuildInfo, sources membership.S
 		Config:       cfg,
 		Logger:       logger,
 	}
+	hh := NewHTMLHandler(renderer, build, ah, actions)
+
+	staticSubFS, err := fs.Sub(staticFS, "static")
+	if err != nil {
+		return fmt.Errorf("static subfs: %w", err)
+	}
 
 	mux := http.NewServeMux()
-	mux.HandleFunc("GET /{$}", helloHandler(build))
+
-	mux.HandleFunc("GET /api/version", h.ServeVersion)
+	// HTML routes
-	mux.HandleFunc("GET /api/adults", h.ServeAdults)
+	mux.HandleFunc("GET /{$}", func(w http.ResponseWriter, r *http.Request) {
-	mux.HandleFunc("GET /api/juniors", h.ServeJuniors)
+		http.Redirect(w, r, "/adults", http.StatusFound)
-	mux.HandleFunc("GET /api/payments", h.ServePayments)
+	})
+	mux.HandleFunc("GET /adults", hh.ServeAdults)
+	mux.HandleFunc("GET /juniors", hh.ServeJuniors)
+	mux.HandleFunc("GET /payments", hh.ServePayments)
+	mux.HandleFunc("GET /sync-bank", hh.ServeSync)
+	mux.HandleFunc("GET /flush-cache", hh.ServeFlushCacheGET)
+	mux.HandleFunc("POST /flush-cache", hh.ServeFlushCachePOST)
+	mux.HandleFunc("GET /qr", hh.ServeQR)
+
+	// Static files
+	mux.Handle("/static/", http.StripPrefix("/static/", http.FileServerFS(staticSubFS)))
+
+	// JSON API routes
+	mux.HandleFunc("GET /api/version", ah.ServeVersion)
+	mux.HandleFunc("GET /version", ah.ServeVersion)
+	mux.HandleFunc("GET /api/adults", ah.ServeAdults)
+	mux.HandleFunc("GET /api/juniors", ah.ServeJuniors)
+	mux.HandleFunc("GET /api/payments", ah.ServePayments)
 
 	logger.Info("starting server", "addr", addr)
 	return http.ListenAndServe(addr, middleware.RequestTimer(logger, mux))
 }
-
-func helloHandler(build BuildInfo) http.HandlerFunc {
-	return func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
-		fmt.Fprintf(w, "fuj-go ok\nversion: %s\ncommit:  %s\nbuilt:   %s\n",
-			build.Version, build.Commit, build.BuildDate)
-	}
-}

go/internal/web/static/css/app.css

@@ -0,0 +1,551 @@
+body {
+    font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
+    background-color: #0c0c0c;
+    color: #cccccc;
+    padding: 10px;
+    margin: 0;
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    font-size: 11px;
+    line-height: 1.2;
+}
+
+h1 {
+    color: #00ff00;
+    font-family: inherit;
+    margin-top: 10px;
+    margin-bottom: 20px;
+    text-transform: uppercase;
+    letter-spacing: 1px;
+    font-size: 14px;
+}
+
+h2 {
+    color: #00ff00;
+    font-size: 12px;
+    margin-top: 30px;
+    margin-bottom: 10px;
+    text-transform: uppercase;
+    width: 100%;
+    max-width: 1200px;
+    border-bottom: 1px solid #333;
+    padding-bottom: 5px;
+}
+
+.nav {
+    margin-bottom: 20px;
+    font-size: 12px;
+    color: #555;
+    display: flex;
+    flex-direction: column;
+    gap: 10px;
+    align-items: center;
+}
+
+.nav > div {
+    display: flex;
+    gap: 15px;
+    align-items: center;
+}
+
+.nav a {
+    color: #00ff00;
+    text-decoration: none;
+    padding: 2px 8px;
+    border: 1px solid #333;
+}
+
+.nav a.active {
+    color: #000;
+    background-color: #00ff00;
+    border-color: #00ff00;
+}
+
+.nav a:hover {
+    color: #fff;
+    border-color: #555;
+}
+
+.nav-archived a {
+    font-size: 10px;
+    color: #666;
+    border-color: #222;
+}
+
+.nav-archived a.active {
+    color: #ccc;
+    background-color: #333;
+    border-color: #555;
+}
+
+.nav-archived a:hover {
+    color: #999;
+    border-color: #444;
+}
+
+.description {
+    margin-bottom: 20px;
+    text-align: center;
+    color: #888;
+    max-width: 800px;
+}
+
+.description a {
+    color: #00ff00;
+    text-decoration: none;
+}
+
+.description a:hover {
+    text-decoration: underline;
+}
+
+.table-container {
+    background-color: transparent;
+    border: 1px solid #333;
+    box-shadow: none;
+    overflow-x: auto;
+    width: 100%;
+    max-width: 1200px;
+    margin-bottom: 30px;
+}
+
+table {
+    border-collapse: collapse;
+    width: 100%;
+    table-layout: auto;
+}
+
+th,
+td {
+    padding: 2px 8px;
+    text-align: right;
+    border-bottom: 1px dashed #222;
+    white-space: nowrap;
+}
+
+th:first-child,
+td:first-child {
+    text-align: left;
+}
+
+th {
+    background-color: transparent;
+    color: #888888;
+    font-weight: normal;
+    border-bottom: 1px solid #555;
+    text-transform: lowercase;
+}
+
+tr:hover {
+    background-color: #1a1a1a;
+}
+
+.balance-pos {
+    color: #00ff00;
+}
+
+.balance-neg {
+    color: #ff3333;
+}
+
+.cell-ok {
+    color: #00ff00;
+}
+
+.cell-unpaid {
+    color: #ff3333;
+    background-color: rgba(255, 51, 51, 0.05);
+    position: relative;
+}
+
+.cell-unpaid-current {
+    color: #994444;
+    background-color: rgba(153, 68, 68, 0.05);
+    position: relative;
+}
+
+.cell-overridden {
+    color: #ffa500 !important;
+}
+
+.pay-btn {
+    display: none;
+    position: absolute;
+    right: 5px;
+    top: 50%;
+    transform: translateY(-50%);
+    background: #ff3333;
+    color: white;
+    text-decoration: none;
+    border: none;
+    border-radius: 3px;
+    padding: 2px 6px;
+    font-size: 10px;
+    cursor: pointer;
+    font-weight: bold;
+}
+
+.member-row:hover .pay-btn {
+    display: inline-block;
+}
+
+.cell-empty {
+    color: #444444;
+}
+
+.list-container {
+    width: 100%;
+    max-width: 1200px;
+    color: #888;
+    margin-bottom: 40px;
+}
+
+.list-item {
+    display: flex;
+    justify-content: flex-start;
+    gap: 20px;
+    padding: 1px 0;
+    border-bottom: 1px dashed #222;
+}
+
+.list-item-name {
+    color: #ccc;
+    min-width: 200px;
+}
+
+.list-item-val {
+    color: #00ff00;
+}
+
+.unmatched-row {
+    font-family: inherit;
+    display: grid;
+    grid-template-columns: 100px 100px 200px 1fr;
+    gap: 15px;
+    color: #888;
+    padding: 2px 0;
+    border-bottom: 1px dashed #222;
+}
+
+.unmatched-header {
+    color: #555;
+    border-bottom: 1px solid #333;
+    margin-bottom: 5px;
+}
+
+.filter-container {
+    width: 100%;
+    max-width: 1200px;
+    margin-bottom: 15px;
+    display: flex;
+    align-items: center;
+    gap: 10px;
+}
+
+.filter-input {
+    background-color: #1a1a1a;
+    border: 1px solid #333;
+    color: #00ff00;
+    font-family: inherit;
+    font-size: 11px;
+    padding: 4px 8px;
+    width: 250px;
+    outline: none;
+}
+
+.filter-input:focus {
+    border-color: #00ff00;
+}
+
+.filter-select {
+    background-color: #1a1a1a;
+    border: 1px solid #333;
+    color: #00ff00;
+    font-family: inherit;
+    font-size: 11px;
+    padding: 4px 8px;
+    outline: none;
+}
+
+.filter-select:focus {
+    border-color: #00ff00;
+}
+
+.month-hidden {
+    display: none !important;
+}
+
+.filter-label {
+    color: #888;
+    text-transform: lowercase;
+}
+
+.info-icon {
+    color: #00ff00;
+    cursor: pointer;
+    margin-left: 5px;
+    font-size: 10px;
+    opacity: 0.5;
+}
+
+.info-icon:hover {
+    opacity: 1;
+}
+
+/* Modal Styles */
+#memberModal {
+    display: none !important;
+    position: fixed;
+    top: 0;
+    left: 0;
+    width: 100vw;
+    height: 100vh;
+    background-color: rgba(0, 0, 0, 0.9);
+    z-index: 9999;
+    justify-content: center;
+    align-items: center;
+}
+
+#memberModal.active {
+    display: flex !important;
+}
+
+.modal-content {
+    background-color: #0c0c0c;
+    border: 1px solid #00ff00;
+    width: 90%;
+    max-width: 800px;
+    max-height: 85vh;
+    overflow-y: auto;
+    padding: 20px;
+    box-shadow: 0 0 20px rgba(0, 255, 0, 0.2);
+    position: relative;
+}
+
+.modal-header {
+    border-bottom: 1px solid #333;
+    margin-bottom: 20px;
+    padding-bottom: 10px;
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+}
+
+.modal-title {
+    color: #00ff00;
+    font-size: 14px;
+    text-transform: uppercase;
+}
+
+.close-btn {
+    color: #ff3333;
+    cursor: pointer;
+    font-size: 14px;
+    text-transform: lowercase;
+}
+
+.modal-section {
+    margin-bottom: 25px;
+}
+
+.modal-section-title {
+    color: #555;
+    text-transform: uppercase;
+    font-size: 10px;
+    margin-bottom: 8px;
+    border-bottom: 1px dashed #222;
+}
+
+.raw-toggle {
+    color: #333;
+    font-size: 9px;
+    text-transform: lowercase;
+    margin-left: 8px;
+    text-decoration: none;
+    letter-spacing: 0;
+}
+
+.raw-toggle:hover {
+    color: #666;
+}
+
+.modal-table {
+    width: 100%;
+    border-collapse: collapse;
+}
+
+.modal-table th,
+.modal-table td {
+    text-align: left;
+    padding: 4px 0;
+    border-bottom: 1px dashed #1a1a1a;
+}
+
+.modal-table th {
+    color: #666;
+    font-weight: normal;
+    font-size: 10px;
+}
+
+.tx-list {
+    list-style: none;
+    padding: 0;
+    margin: 0;
+}
+
+.tx-item {
+    padding: 8px 0;
+    border-bottom: 1px dashed #222;
+}
+
+.tx-meta {
+    color: #555;
+    font-size: 10px;
+    margin-bottom: 4px;
+}
+
+.tx-main {
+    display: flex;
+    justify-content: space-between;
+    gap: 20px;
+}
+
+.tx-amount {
+    color: #00ff00;
+}
+
+.tx-sender {
+    color: #ccc;
+}
+
+.tx-msg {
+    color: #888;
+    font-style: italic;
+}
+
+.footer {
+    margin-top: 50px;
+    margin-bottom: 20px;
+    color: #333;
+    font-size: 9px;
+    text-align: center;
+    width: 100%;
+    cursor: pointer;
+    user-select: none;
+}
+
+.perf-breakdown {
+    display: none;
+    margin-top: 5px;
+    color: #222;
+}
+
+/* QR Modal styles */
+#qrModal {
+    display: none !important;
+    position: fixed;
+    top: 0;
+    left: 0;
+    width: 100vw;
+    height: 100vh;
+    background-color: rgba(0, 0, 0, 0.9);
+    z-index: 9999;
+    justify-content: center;
+    align-items: center;
+}
+
+#qrModal.active {
+    display: flex !important;
+}
+
+#qrModal .modal-content {
+    max-width: 400px;
+    text-align: center;
+}
+
+.qr-image {
+    background: white;
+    padding: 10px;
+    border-radius: 5px;
+    margin: 20px 0;
+    display: inline-block;
+}
+
+.qr-image img {
+    display: block;
+    width: 250px;
+    height: 250px;
+}
+
+.qr-details {
+    text-align: left;
+    margin-top: 15px;
+    font-size: 14px;
+    color: #ccc;
+}
+
+.qr-details div {
+    margin-bottom: 5px;
+}
+
+.qr-details span {
+    color: #00ff00;
+    font-family: monospace;
+}
+
+/* /payments ledger */
+.ledger-container {
+    width: 100%;
+    max-width: 1000px;
+    margin-bottom: 40px;
+}
+
+.member-block {
+    margin-bottom: 20px;
+}
+
+.txn-table {
+    border-collapse: collapse;
+    width: 100%;
+    margin-top: 5px;
+}
+
+.txn-table th,
+.txn-table td {
+    padding: 2px 8px;
+    text-align: left;
+    border-bottom: 1px dashed #222;
+}
+
+.txn-table th {
+    color: #555;
+    text-transform: lowercase;
+    font-weight: normal;
+    border-bottom: 1px solid #333;
+}
+
+.txn-date {
+    min-width: 80px;
+    color: #888;
+}
+
+.txn-amount {
+    min-width: 80px;
+    text-align: right !important;
+    color: #00ff00;
+}
+
+.txn-purpose {
+    min-width: 100px;
+    color: #aaa;
+}
+
+.txn-message {
+    color: #666;
+    font-style: italic;
+}
+
+.txn-table tr:hover {
+    background-color: #1a1a1a;
+}

go/internal/web/static/js/filters.js

@@ -0,0 +1,91 @@
+// Client-side filters for the Adults (and future Juniors) dashboard table.
+// Mirrors adults.html:864-1051 from the Python frontend.
+(function () {
+  'use strict';
+
+  // NFD-normalize + strip diacritics + lowercase, matching Python's
+  // unicodedata.normalize('NFD', s).encode('ascii', 'ignore').decode().lower()
+  function normalize(s) {
+    return s.normalize('NFD').replace(/\p{Diacritic}/gu, '').toLowerCase();
+  }
+
+  const container = document.getElementById('filterContainer');
+  if (!container) return;
+
+  const currentMonth = container.dataset.currentMonth || '';
+
+  const nameInput   = document.getElementById('nameFilter');
+  const fromSelect  = document.getElementById('fromMonth');
+  const toSelect    = document.getElementById('toMonth');
+  const applyBtn    = document.getElementById('applyFilter');
+  const clearBtn    = document.getElementById('clearFilter');
+
+  // ── Month column visibility ───────────────────────────────────────────────
+
+  // Hide columns whose raw month is in the future by default.
+  function hideFutureMonths() {
+    if (!currentMonth) return;
+    document.querySelectorAll('[data-raw-month]').forEach(el => {
+      if (el.dataset.rawMonth > currentMonth) {
+        el.classList.add('month-hidden');
+      }
+    });
+    // Sync toMonth select to the last non-hidden month.
+    const ths = [...document.querySelectorAll('thead th[data-month-idx]')];
+    const visibleIdxs = ths
+      .filter(th => !th.classList.contains('month-hidden'))
+      .map(th => parseInt(th.dataset.monthIdx, 10));
+    if (visibleIdxs.length) {
+      toSelect.value = String(visibleIdxs[visibleIdxs.length - 1]);
+    }
+  }
+
+  function applyMonthFilter() {
+    const from = fromSelect.value !== '' ? parseInt(fromSelect.value, 10) : -Infinity;
+    const to   = toSelect.value   !== '' ? parseInt(toSelect.value,   10) :  Infinity;
+
+    document.querySelectorAll('[data-month-idx]').forEach(el => {
+      const idx = parseInt(el.dataset.monthIdx, 10);
+      if (idx < from || idx > to) {
+        el.classList.add('month-hidden');
+      } else {
+        el.classList.remove('month-hidden');
+      }
+    });
+  }
+
+  function clearMonthFilter() {
+    document.querySelectorAll('[data-month-idx]').forEach(el => {
+      el.classList.remove('month-hidden');
+    });
+    fromSelect.value = '';
+    toSelect.value   = '';
+  }
+
+  // ── Name row visibility ───────────────────────────────────────────────────
+
+  function applyNameFilter() {
+    const query = normalize(nameInput.value.trim());
+    document.querySelectorAll('tr.member-row').forEach(row => {
+      const name = normalize(row.dataset.name || '');
+      row.style.display = (!query || name.includes(query)) ? '' : 'none';
+    });
+  }
+
+  // ── Event wiring ─────────────────────────────────────────────────────────
+
+  nameInput.addEventListener('input', applyNameFilter);
+
+  applyBtn.addEventListener('click', applyMonthFilter);
+
+  clearBtn.addEventListener('click', function () {
+    nameInput.value = '';
+    applyNameFilter();
+    clearMonthFilter();
+    hideFutureMonths();
+  });
+
+  // ── Initialise ────────────────────────────────────────────────────────────
+
+  hideFutureMonths();
+}());

go/internal/web/static/js/member-detail.js

@@ -0,0 +1,245 @@
+// Member-detail modal for /adults and /juniors pages.
+// Fetches /api/<page> once on load, caches the response, renders on row click.
+// Mirrors templates/adults.html JS (lines 718-993) but as a standalone module.
+(function () {
+  'use strict';
+
+  const container = document.getElementById('filterContainer');
+  if (!container) return;
+  const page = container.dataset.page; // "adults" | "juniors"
+  if (!page) return;
+
+  let apiData = null;
+  let currentMemberName = null;
+
+  // ── Data load ─────────────────────────────────────────────────────────────
+
+  async function loadData() {
+    if (apiData) return apiData;
+    const r = await fetch('/api/' + page);
+    if (!r.ok) throw new Error('[member-detail] failed to fetch /api/' + page + ': ' + r.status);
+    apiData = await r.json();
+    return apiData;
+  }
+
+  // Pre-warm on page load so first click is instant.
+  loadData().catch(function (err) { console.error(err); });
+
+  // ── Modal render ──────────────────────────────────────────────────────────
+
+  async function showMember(name) {
+    currentMemberName = name;
+    const data = (await loadData());
+    const member = data.member_data[name];
+    if (!member) return;
+
+    document.getElementById('modalMemberName').textContent = name;
+    document.getElementById('modalTier').textContent = 'Tier: ' + (member.tier || '-');
+
+    const monthLabels = data.month_labels || {};
+    const statusBody = document.getElementById('modalStatusBody');
+    statusBody.innerHTML = '';
+
+    const allTransactions = [];
+    const monthKeys = Object.keys(member.months || {}).sort().reverse();
+
+    monthKeys.forEach(function (m) {
+      const md = member.months[m];
+      const expected = md.expected;          // int for adults; int or "?" for juniors
+      const paid = md.paid || 0;
+      const attendance = md.attendance_count || 0;
+      const originalExpected = md.original_expected;
+      const isUnknown = (expected === '?');
+
+      let status = '-';
+      let statusClass = '';
+      if (!isUnknown && (expected > 0 || paid > 0)) {
+        if (paid >= expected && expected > 0) {
+          status = paid + '/' + expected;
+          statusClass = 'cell-ok';
+        } else if (paid > 0) {
+          status = paid + '/' + expected;
+        } else {
+          status = '0/' + expected;
+          statusClass = 'cell-unpaid';
+        }
+      } else if (isUnknown) {
+        status = paid > 0 ? paid + '/?' : '?';
+      }
+
+      let expectedCell;
+      if (isUnknown) {
+        expectedCell = '?';
+      } else if (md.exception) {
+        expectedCell = '<span style="color: #ffaa00;" title="Overridden from ' + originalExpected + '">' + expected + '*</span>';
+      } else {
+        expectedCell = expected;
+      }
+
+      const displayMonth = monthLabels[m] || m;
+      const row = document.createElement('tr');
+      row.innerHTML =
+        '<td style="color: #888;">' + displayMonth + '</td>' +
+        '<td style="text-align: center; color: #ccc;">' + attendance + '</td>' +
+        '<td style="text-align: center; color: #ccc;">' + expectedCell + '</td>' +
+        '<td style="text-align: center; color: #ccc;">' + paid + '</td>' +
+        '<td style="text-align: right;" class="' + statusClass + '">' + status + '</td>';
+      statusBody.appendChild(row);
+
+      if (md.transactions) {
+        md.transactions.forEach(function (tx) {
+          allTransactions.push(Object.assign({ month: m }, tx));
+        });
+      }
+    });
+
+    // Exceptions
+    const exList = document.getElementById('modalExceptionList');
+    const exSection = document.getElementById('modalExceptionSection');
+    exList.innerHTML = '';
+    const exceptions = [];
+    monthKeys.forEach(function (m) {
+      if (member.months[m].exception) {
+        exceptions.push(Object.assign({ month: m }, member.months[m].exception));
+      }
+    });
+    if (exceptions.length > 0) {
+      exSection.style.display = 'block';
+      exceptions.forEach(function (ex) {
+        const displayMonth = monthLabels[ex.month] || ex.month;
+        const item = document.createElement('div');
+        item.className = 'tx-item';
+        item.innerHTML =
+          '<div class="tx-meta">' + displayMonth + '</div>' +
+          '<div class="tx-main"><span class="tx-amount" style="color: #ffaa00;">' + ex.amount + ' CZK</span></div>' +
+          '<div class="tx-msg">' + (ex.note || 'No details provided.') + '</div>';
+        exList.appendChild(item);
+      });
+    } else {
+      exSection.style.display = 'none';
+    }
+
+    // Other transactions
+    const otherList = document.getElementById('modalOtherList');
+    const otherSection = document.getElementById('modalOtherSection');
+    otherList.innerHTML = '';
+    if (member.other_transactions && member.other_transactions.length > 0) {
+      otherSection.style.display = 'block';
+      member.other_transactions.forEach(function (tx) {
+        const item = document.createElement('div');
+        item.className = 'tx-item';
+        item.innerHTML =
+          '<div class="tx-meta">' + tx.date + ' | ' + (tx.purpose || 'Other') + '</div>' +
+          '<div class="tx-main">' +
+            '<span class="tx-amount" style="color: #66ccff;">' + tx.amount + ' CZK</span>' +
+            '<span class="tx-sender">' + (tx.sender || '') + '</span>' +
+          '</div>' +
+          '<div class="tx-msg">' + (tx.message || '') + '</div>';
+        otherList.appendChild(item);
+      });
+    } else {
+      otherSection.style.display = 'none';
+    }
+
+    // Matched transactions (payment history)
+    const txList = document.getElementById('modalTxList');
+    txList.innerHTML = '';
+    if (allTransactions.length === 0) {
+      txList.innerHTML = '<div style="color: #444; font-style: italic; padding: 10px 0;">No transactions matched to this member.</div>';
+    } else {
+      allTransactions.sort(function (a, b) { return b.date.localeCompare(a.date); });
+      allTransactions.forEach(function (tx) {
+        const displayMonth = monthLabels[tx.month] || tx.month;
+        const item = document.createElement('div');
+        item.className = 'tx-item';
+        item.innerHTML =
+          '<div class="tx-meta">' + tx.date + ' | matched to ' + displayMonth + '</div>' +
+          '<div class="tx-main">' +
+            '<span class="tx-amount">' + tx.amount + ' CZK</span>' +
+            '<span class="tx-sender">' + (tx.sender || '') + '</span>' +
+          '</div>' +
+          '<div class="tx-msg">' + (tx.message || '') + '</div>';
+        txList.appendChild(item);
+      });
+    }
+
+    // Raw payments — hidden by default; reset toggle on each open
+    const rawList = document.getElementById('modalRawList');
+    const rawToggle = document.getElementById('rawPaymentsToggle');
+    rawList.style.display = 'none';
+    rawToggle.textContent = '[show]';
+    rawList.innerHTML = '';
+    const rawRows = (data.raw_payments || {})[name] || [];
+    if (rawRows.length === 0) {
+      rawList.innerHTML = '<div style="color: #444; font-style: italic; padding: 10px 0;">No raw payments tied to this member.</div>';
+    } else {
+      rawRows.forEach(function (tx) {
+        const inferredNote = (tx.inferred_amount && tx.inferred_amount !== '' && tx.inferred_amount !== tx.amount)
+          ? ' <span style="color:#888;">(inferred: ' + tx.inferred_amount + ')</span>'
+          : '';
+        const manualNote = tx.manual_fix ? ' <span style="color:#ffaa00;">[manual fix]</span>' : '';
+        const bankIdNote = tx.bank_id ? '<span style="color:#444;"> · bank_id: ' + tx.bank_id + '</span>' : '';
+        const item = document.createElement('div');
+        item.className = 'tx-item';
+        item.innerHTML =
+          '<div class="tx-meta">' + tx.date + ' | purpose: ' + (tx.purpose || '—') + manualNote + '</div>' +
+          '<div class="tx-main">' +
+            '<span class="tx-amount">' + tx.amount + ' CZK' + inferredNote + '</span>' +
+            '<span class="tx-sender">' + (tx.sender || '') + '</span>' +
+          '</div>' +
+          '<div class="tx-msg">' + (tx.message || '') + '</div>' +
+          '<div class="tx-meta">' + (tx.person || '') + bankIdNote + '</div>';
+        rawList.appendChild(item);
+      });
+    }
+
+    document.getElementById('memberModal').classList.add('active');
+  }
+
+  // ── Raw-payments toggle ───────────────────────────────────────────────────
+
+  function toggleRawPayments(ev) {
+    ev.preventDefault();
+    const list = document.getElementById('modalRawList');
+    const link = document.getElementById('rawPaymentsToggle');
+    const hidden = list.style.display === 'none';
+    list.style.display = hidden ? 'block' : 'none';
+    link.textContent = hidden ? '[hide]' : '[show]';
+  }
+
+  // ── Close + keyboard nav ──────────────────────────────────────────────────
+
+  function closeModal() {
+    document.getElementById('memberModal').classList.remove('active');
+  }
+
+  function navigateMember(direction) {
+    const rows = Array.from(document.querySelectorAll('tr.member-row'));
+    const visible = rows.filter(function (r) { return r.style.display !== 'none'; });
+    const idx = visible.findIndex(function (r) { return r.dataset.name === currentMemberName; });
+    if (idx === -1) return;
+    const next = idx + direction;
+    if (next >= 0 && next < visible.length) {
+      showMember(visible[next].dataset.name);
+    }
+  }
+
+  // ── Wiring ────────────────────────────────────────────────────────────────
+
+  document.querySelectorAll('.info-icon[data-name]').forEach(function (el) {
+    el.addEventListener('click', function (ev) {
+      ev.stopPropagation();
+      showMember(el.dataset.name);
+    });
+  });
+
+  document.getElementById('rawPaymentsToggle').addEventListener('click', toggleRawPayments);
+
+  document.addEventListener('keydown', function (e) {
+    if (e.key === 'Escape') { closeModal(); return; }
+    const modal = document.getElementById('memberModal');
+    if (!modal.classList.contains('active')) return;
+    if (e.key === 'ArrowDown') { e.preventDefault(); navigateMember(1); }
+    if (e.key === 'ArrowUp')   { e.preventDefault(); navigateMember(-1); }
+  });
+}());

go/internal/web/static/js/payment-qr.js

@@ -0,0 +1,60 @@
+(function () {
+  'use strict';
+
+  const container = document.getElementById('filterContainer');
+  if (!container) return;
+  const bankAccount = container.dataset.bankAccount || '';
+
+  const modal     = document.getElementById('qrModal');
+  const titleEl   = document.getElementById('qrTitle');
+  const imgEl     = document.getElementById('qrImg');
+  const accountEl = document.getElementById('qrAccount');
+  const amountEl  = document.getElementById('qrAmount');
+  const messageEl = document.getElementById('qrMessage');
+  if (!modal || !titleEl || !imgEl || !accountEl || !amountEl || !messageEl) return;
+
+  // Convert "YYYY-MM" → "MM/YYYY"; "+"-joined ranges converted piece-wise.
+  // Mirrors templates/adults.html showPayQR logic.
+  function toCzechMonth(rawMonth) {
+    return rawMonth.split('+')
+      .map(function (p) { return p.replace(/^(\d{4})-(\d{2})$/, '$2/$1'); })
+      .join('+');
+  }
+
+  function showQR(name, amount, month, rawMonth) {
+    var numericMonth = toCzechMonth(rawMonth);
+    var message = name + ': ' + numericMonth;
+
+    titleEl.innerText   = 'Payment for ' + month;
+    accountEl.innerText = bankAccount;
+    amountEl.innerText  = amount;
+    messageEl.innerText = message;
+
+    imgEl.src = '/qr?'
+      + 'account=' + encodeURIComponent(bankAccount)
+      + '&amount=' + encodeURIComponent(amount)
+      + '&message=' + encodeURIComponent(message);
+
+    modal.classList.add('active');
+  }
+
+  function closeQR() {
+    modal.classList.remove('active');
+  }
+
+  document.addEventListener('click', function (ev) {
+    var btn = ev.target.closest('.pay-btn');
+    if (!btn) return;
+    ev.preventDefault();
+    showQR(
+      btn.dataset.name,
+      btn.dataset.amount,
+      btn.dataset.month,
+      btn.dataset.rawMonth
+    );
+  });
+
+  document.addEventListener('keydown', function (e) {
+    if (e.key === 'Escape' && modal.classList.contains('active')) closeQR();
+  });
+}());

go/internal/web/templates/adults.tmpl

@@ -0,0 +1,207 @@
+{{define "title"}}Adults{{end}}
+{{define "content"}}
+<h1>Adults Dashboard</h1>
+
+{{if .Error}}
+<div class="description">Error loading data: {{.Error}}</div>
+{{else}}
+
+<div class="description">
+  Balances calculated by matching Google Sheet payments against attendance fees.<br>
+  Source: <a href="{{.Data.AttendanceURL}}" target="_blank" rel="noopener">Attendance Sheet</a> |
+  <a href="{{.Data.PaymentsURL}}" target="_blank" rel="noopener">Payments Ledger</a>
+</div>
+
+<div class="filter-container" id="filterContainer" data-current-month="{{.Data.CurrentMonth}}" data-page="adults" data-bank-account="{{.Data.BankAccount}}">
+  <div class="filter-item">
+    <label class="filter-label" for="nameFilter">Member</label>
+    <input id="nameFilter" class="filter-input" type="text" placeholder="Filter by name…">
+  </div>
+  <div class="filter-item">
+    <label class="filter-label" for="fromMonth">From</label>
+    <select id="fromMonth" class="filter-select">
+      <option value="">All</option>
+      {{range $i, $m := .Data.Months}}
+      <option value="{{$i}}">{{$m}}</option>
+      {{end}}
+    </select>
+  </div>
+  <div class="filter-item">
+    <label class="filter-label" for="toMonth">To</label>
+    <select id="toMonth" class="filter-select">
+      <option value="">All</option>
+      {{range $i, $m := .Data.Months}}
+      <option value="{{$i}}">{{$m}}</option>
+      {{end}}
+    </select>
+  </div>
+  <div class="filter-item">
+    <button id="applyFilter" class="filter-select" type="button" style="cursor: pointer;">Apply</button>
+    <button id="clearFilter" class="filter-select" type="button" style="cursor: pointer;">All</button>
+  </div>
+</div>
+
+{{if .Data.Results}}
+<div class="table-container">
+<table>
+  <thead>
+    <tr>
+      <th>Member</th>
+      {{range $i, $m := .Data.Months}}
+      <th data-month-idx="{{$i}}" data-raw-month="{{index $.Data.RawMonths $i}}">{{$m}}</th>
+      {{end}}
+      <th>Balance</th>
+    </tr>
+  </thead>
+  <tbody>
+    {{range $row := .Data.Results}}
+    <tr class="member-row" data-name="{{$row.Name}}">
+      <td class="member-name">{{$row.Name}}<span class="info-icon" data-name="{{$row.Name}}" title="Show details">[i]</span></td>
+      {{range $i, $cell := $row.Months}}
+      <td data-month-idx="{{$i}}" title="{{$cell.Tooltip}}"
+          class="{{if eq $cell.Status "empty"}}cell-empty{{else if and (or (eq $cell.Status "unpaid") (eq $cell.Status "partial")) (ge $cell.RawMonth $.Data.CurrentMonth)}}cell-unpaid-current{{else if or (eq $cell.Status "unpaid") (eq $cell.Status "partial")}}cell-unpaid{{else if eq $cell.Status "ok"}}cell-ok{{end}}{{if $cell.Overridden}} cell-overridden{{end}}">
+        {{$cell.Text}}
+        {{if and (or (eq $cell.Status "unpaid") (eq $cell.Status "partial")) (lt $cell.RawMonth $.Data.CurrentMonth)}}
+        <button type="button" class="pay-btn" data-name="{{$row.Name}}" data-amount="{{$cell.Amount}}" data-month="{{$cell.Month}}" data-raw-month="{{$cell.RawMonth}}">Pay</button>
+        {{end}}
+      </td>
+      {{end}}
+      <td class="{{if lt $row.Balance 0}}balance-neg{{else if gt $row.Balance 0}}balance-pos{{end}}" style="position: relative;">
+        {{$row.Balance}}
+        {{if gt $row.PayableAmount 0}}
+        <button type="button" class="pay-btn" data-name="{{$row.Name}}" data-amount="{{$row.PayableAmount}}" data-month="{{$row.UnpaidPeriods}}" data-raw-month="{{$row.RawUnpaidPeriods}}" data-pay-all="1">Pay All</button>
+        {{end}}
+      </td>
+    </tr>
+    {{end}}
+    <tr class="totals-row" style="font-weight: bold; background-color: #111; border-top: 2px solid #333;">
+      <td style="text-align: left; padding: 6px 8px;">TOTAL</td>
+      {{range $i, $t := .Data.Totals}}
+      <td data-month-idx="{{$i}}" data-raw-month="{{index $.Data.RawMonths $i}}" class="{{if eq $t.Status "ok"}}cell-ok{{else if eq $t.Status "unpaid"}}cell-unpaid{{else if eq $t.Status "surplus"}}cell-overridden{{end}}" style="padding-top: 4px; padding-bottom: 4px;">
+        <span style="font-size: 0.6em; font-weight: normal; color: #666; text-transform: lowercase; display: block; margin-bottom: 2px;">received / expected</span>
+        {{$t.Text}}
+      </td>
+      {{end}}
+      <td></td>
+    </tr>
+  </tbody>
+</table>
+</div>
+{{else}}
+<div class="description">No members found.</div>
+{{end}}
+
+{{if .Data.Credits}}
+<h2>Credits (Advance Payments / Surplus)</h2>
+<div class="list-container">
+  {{range .Data.Credits}}
+  <div class="list-item">
+    <span class="list-item-name">{{.Name}}</span>
+    <span class="list-item-val">{{.Amount}} CZK</span>
+  </div>
+  {{end}}
+</div>
+{{end}}
+
+{{if .Data.Debts}}
+<h2>Debts (Missing Payments)</h2>
+<div class="list-container">
+  {{range .Data.Debts}}
+  <div class="list-item">
+    <span class="list-item-name">{{.Name}}</span>
+    <span class="list-item-val" style="color: #ff3333;">{{.Amount}} CZK</span>
+  </div>
+  {{end}}
+</div>
+{{end}}
+
+{{if .Data.Unmatched}}
+<h2>Unmatched Transactions</h2>
+<div class="list-container">
+  <div class="unmatched-row unmatched-header">
+    <span>Date</span>
+    <span>Amount</span>
+    <span>Sender</span>
+    <span>Message</span>
+  </div>
+  {{range .Data.Unmatched}}
+  <div class="unmatched-row">
+    <span>{{.Date}}</span>
+    <span>{{printf "%.0f" .Amount}}</span>
+    <span>{{.Sender}}</span>
+    <span>{{.Message}}</span>
+  </div>
+  {{end}}
+</div>
+{{end}}
+
+{{end}}
+
+<div id="memberModal" onclick="if(event.target===this)this.classList.remove('active')">
+  <div class="modal-content">
+    <div class="modal-header">
+      <div class="modal-title" id="modalMemberName">Member Name</div>
+      <div class="close-btn" onclick="document.getElementById('memberModal').classList.remove('active')">[close]</div>
+    </div>
+
+    <div class="modal-section">
+      <div class="modal-section-title">Status Summary</div>
+      <div id="modalTier" style="margin-bottom: 10px; color: #888;">Tier: -</div>
+      <table class="modal-table">
+        <thead><tr>
+          <th>Month</th>
+          <th style="text-align: center;">Att.</th>
+          <th style="text-align: center;">Expected</th>
+          <th style="text-align: center;">Paid</th>
+          <th style="text-align: right;">Status</th>
+        </tr></thead>
+        <tbody id="modalStatusBody"></tbody>
+      </table>
+    </div>
+
+    <div class="modal-section" id="modalExceptionSection" style="display: none;">
+      <div class="modal-section-title">Fee Exceptions</div>
+      <div id="modalExceptionList" class="tx-list"></div>
+    </div>
+
+    <div class="modal-section" id="modalOtherSection" style="display: none;">
+      <div class="modal-section-title">Other Transactions</div>
+      <div id="modalOtherList" class="tx-list"></div>
+    </div>
+
+    <div class="modal-section">
+      <div class="modal-section-title">Payment History</div>
+      <div id="modalTxList" class="tx-list"></div>
+    </div>
+
+    <div class="modal-section">
+      <div class="modal-section-title">
+        Raw Payments
+        <a href="#" id="rawPaymentsToggle" class="raw-toggle">[show]</a>
+      </div>
+      <div id="modalRawList" class="tx-list" style="display: none;"></div>
+    </div>
+  </div>
+</div>
+
+<div id="qrModal" onclick="if(event.target===this)this.classList.remove('active')">
+  <div class="modal-content">
+    <div class="modal-header">
+      <div class="modal-title" id="qrTitle">Payment for —</div>
+      <div class="close-btn" onclick="document.getElementById('qrModal').classList.remove('active')">[close]</div>
+    </div>
+    <div class="qr-image">
+      <img id="qrImg" src="" alt="Payment QR Code">
+    </div>
+    <div class="qr-details">
+      <div>Account: <span id="qrAccount"></span></div>
+      <div>Amount: <span id="qrAmount"></span> CZK</div>
+      <div>Message: <span id="qrMessage"></span></div>
+    </div>
+  </div>
+</div>
+
+<script src="/static/js/filters.js" defer></script>
+<script src="/static/js/member-detail.js" defer></script>
+<script src="/static/js/payment-qr.js" defer></script>
+{{end}}

go/internal/web/templates/base.tmpl

@@ -0,0 +1,15 @@
+{{define "base"}}<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>FUJ — {{template "title" .}}</title>
+    <link rel="stylesheet" href="/static/css/app.css">
+</head>
+<body>
+{{template "nav" .}}
+{{template "content" .}}
+{{template "footer" .}}
+</body>
+</html>
+{{end}}

go/internal/web/templates/flush_cache.tmpl

@@ -0,0 +1,11 @@
+{{define "title"}}Flush Cache{{end}}
+{{define "content"}}
+<h1>Flush Cache</h1>
+{{if .Flushed}}
+  <p class="status-ok">Cache flushed: {{.Deleted}} file(s) deleted.</p>
+{{end}}
+<p class="description">Deletes all cached data files so the next request fetches fresh data from Google Sheets.</p>
+<form method="POST" action="/flush-cache">
+  <button type="submit" class="btn">Flush Cache</button>
+</form>
+{{end}}

go/internal/web/templates/juniors.tmpl

@@ -0,0 +1,187 @@
+{{define "title"}}Juniors{{end}}
+{{define "content"}}
+<h1>Juniors Dashboard</h1>
+
+{{if .Error}}
+<div class="description">Error loading data: {{.Error}}</div>
+{{else}}
+
+<div class="description">
+  Balances calculated by matching Google Sheet payments against attendance fees.<br>
+  Source: <a href="{{.Data.AttendanceURL}}" target="_blank" rel="noopener">Attendance Sheet</a> |
+  <a href="{{.Data.PaymentsURL}}" target="_blank" rel="noopener">Payments Ledger</a>
+</div>
+
+<div class="filter-container" id="filterContainer" data-current-month="{{.Data.CurrentMonth}}" data-page="juniors" data-bank-account="{{.Data.BankAccount}}">
+  <div class="filter-item">
+    <label class="filter-label" for="nameFilter">Member</label>
+    <input id="nameFilter" class="filter-input" type="text" placeholder="Filter by name…">
+  </div>
+  <div class="filter-item">
+    <label class="filter-label" for="fromMonth">From</label>
+    <select id="fromMonth" class="filter-select">
+      <option value="">All</option>
+      {{range $i, $m := .Data.Months}}
+      <option value="{{$i}}">{{$m}}</option>
+      {{end}}
+    </select>
+  </div>
+  <div class="filter-item">
+    <label class="filter-label" for="toMonth">To</label>
+    <select id="toMonth" class="filter-select">
+      <option value="">All</option>
+      {{range $i, $m := .Data.Months}}
+      <option value="{{$i}}">{{$m}}</option>
+      {{end}}
+    </select>
+  </div>
+  <div class="filter-item">
+    <button id="applyFilter" class="filter-select" type="button" style="cursor: pointer;">Apply</button>
+    <button id="clearFilter" class="filter-select" type="button" style="cursor: pointer;">All</button>
+  </div>
+</div>
+
+{{if .Data.Results}}
+<div class="table-container">
+<table>
+  <thead>
+    <tr>
+      <th>Member</th>
+      {{range $i, $m := .Data.Months}}
+      <th data-month-idx="{{$i}}" data-raw-month="{{index $.Data.RawMonths $i}}">{{$m}}</th>
+      {{end}}
+      <th>Balance</th>
+    </tr>
+  </thead>
+  <tbody>
+    {{range $row := .Data.Results}}
+    <tr class="member-row" data-name="{{$row.Name}}">
+      <td class="member-name">{{$row.Name}}<span class="info-icon" data-name="{{$row.Name}}" title="Show details">[i]</span></td>
+      {{range $i, $cell := $row.Months}}
+      <td data-month-idx="{{$i}}" title="{{$cell.Tooltip}}"
+          class="{{if eq $cell.Status "empty"}}cell-empty{{else if and (or (eq $cell.Status "unpaid") (eq $cell.Status "partial")) (ge $cell.RawMonth $.Data.CurrentMonth)}}cell-unpaid-current{{else if or (eq $cell.Status "unpaid") (eq $cell.Status "partial")}}cell-unpaid{{else if eq $cell.Status "ok"}}cell-ok{{end}}{{if $cell.Overridden}} cell-overridden{{end}}">
+        {{$cell.Text}}
+        {{if and (or (eq $cell.Status "unpaid") (eq $cell.Status "partial")) (lt $cell.RawMonth $.Data.CurrentMonth)}}
+        <button type="button" class="pay-btn" data-name="{{$row.Name}}" data-amount="{{$cell.Amount}}" data-month="{{$cell.Month}}" data-raw-month="{{$cell.RawMonth}}">Pay</button>
+        {{end}}
+      </td>
+      {{end}}
+      <td class="{{if lt $row.Balance 0}}balance-neg{{else if gt $row.Balance 0}}balance-pos{{end}}" style="position: relative;">
+        {{$row.Balance}}
+        {{if gt $row.PayableAmount 0}}
+        <button type="button" class="pay-btn" data-name="{{$row.Name}}" data-amount="{{$row.PayableAmount}}" data-month="{{$row.UnpaidPeriods}}" data-raw-month="{{$row.RawUnpaidPeriods}}" data-pay-all="1">Pay All</button>
+        {{end}}
+      </td>
+    </tr>
+    {{end}}
+    <tr class="totals-row" style="font-weight: bold; background-color: #111; border-top: 2px solid #333;">
+      <td style="text-align: left; padding: 6px 8px;">TOTAL</td>
+      {{range $i, $t := .Data.Totals}}
+      <td data-month-idx="{{$i}}" data-raw-month="{{index $.Data.RawMonths $i}}" class="{{if eq $t.Status "ok"}}cell-ok{{else if eq $t.Status "unpaid"}}cell-unpaid{{else if eq $t.Status "surplus"}}cell-overridden{{end}}" style="padding-top: 4px; padding-bottom: 4px;">
+        <span style="font-size: 0.6em; font-weight: normal; color: #666; text-transform: lowercase; display: block; margin-bottom: 2px;">received / expected</span>
+        {{$t.Text}}
+      </td>
+      {{end}}
+      <td></td>
+    </tr>
+  </tbody>
+</table>
+</div>
+{{else}}
+<div class="description">No members found.</div>
+{{end}}
+
+{{if .Data.Credits}}
+<h2>Credits (Advance Payments / Surplus)</h2>
+<div class="list-container">
+  {{range .Data.Credits}}
+  <div class="list-item">
+    <span class="list-item-name">{{.Name}}</span>
+    <span class="list-item-val">{{.Amount}} CZK</span>
+  </div>
+  {{end}}
+</div>
+{{end}}
+
+{{if .Data.Debts}}
+<h2>Debts (Missing Payments)</h2>
+<div class="list-container">
+  {{range .Data.Debts}}
+  <div class="list-item">
+    <span class="list-item-name">{{.Name}}</span>
+    <span class="list-item-val" style="color: #ff3333;">{{.Amount}} CZK</span>
+  </div>
+  {{end}}
+</div>
+{{end}}
+
+{{end}}
+
+<div id="memberModal" onclick="if(event.target===this)this.classList.remove('active')">
+  <div class="modal-content">
+    <div class="modal-header">
+      <div class="modal-title" id="modalMemberName">Member Name</div>
+      <div class="close-btn" onclick="document.getElementById('memberModal').classList.remove('active')">[close]</div>
+    </div>
+
+    <div class="modal-section">
+      <div class="modal-section-title">Status Summary</div>
+      <div id="modalTier" style="margin-bottom: 10px; color: #888;">Tier: -</div>
+      <table class="modal-table">
+        <thead><tr>
+          <th>Month</th>
+          <th style="text-align: center;">Att.</th>
+          <th style="text-align: center;">Expected</th>
+          <th style="text-align: center;">Paid</th>
+          <th style="text-align: right;">Status</th>
+        </tr></thead>
+        <tbody id="modalStatusBody"></tbody>
+      </table>
+    </div>
+
+    <div class="modal-section" id="modalExceptionSection" style="display: none;">
+      <div class="modal-section-title">Fee Exceptions</div>
+      <div id="modalExceptionList" class="tx-list"></div>
+    </div>
+
+    <div class="modal-section" id="modalOtherSection" style="display: none;">
+      <div class="modal-section-title">Other Transactions</div>
+      <div id="modalOtherList" class="tx-list"></div>
+    </div>
+
+    <div class="modal-section">
+      <div class="modal-section-title">Payment History</div>
+      <div id="modalTxList" class="tx-list"></div>
+    </div>
+
+    <div class="modal-section">
+      <div class="modal-section-title">
+        Raw Payments
+        <a href="#" id="rawPaymentsToggle" class="raw-toggle">[show]</a>
+      </div>
+      <div id="modalRawList" class="tx-list" style="display: none;"></div>
+    </div>
+  </div>
+</div>
+
+<div id="qrModal" onclick="if(event.target===this)this.classList.remove('active')">
+  <div class="modal-content">
+    <div class="modal-header">
+      <div class="modal-title" id="qrTitle">Payment for —</div>
+      <div class="close-btn" onclick="document.getElementById('qrModal').classList.remove('active')">[close]</div>
+    </div>
+    <div class="qr-image">
+      <img id="qrImg" src="" alt="Payment QR Code">
+    </div>
+    <div class="qr-details">
+      <div>Account: <span id="qrAccount"></span></div>
+      <div>Amount: <span id="qrAmount"></span> CZK</div>
+      <div>Message: <span id="qrMessage"></span></div>
+    </div>
+  </div>
+</div>
+
+<script src="/static/js/filters.js" defer></script>
+<script src="/static/js/member-detail.js" defer></script>
+<script src="/static/js/payment-qr.js" defer></script>
+{{end}}

go/internal/web/templates/partials/footer.tmpl

@@ -0,0 +1,3 @@
+{{define "footer"}}
+<div class="footer">{{.Build.Version}}@{{.Build.Commit}} | built {{.Build.BuildDate}}</div>
+{{end}}

go/internal/web/templates/partials/nav.tmpl

@@ -0,0 +1,17 @@
+{{define "nav"}}
+<div class="nav">
+    <div>
+        <a href="/adults"{{if eq .Active "adults"}} class="active"{{end}}>[Adults]</a>
+        <a href="/juniors"{{if eq .Active "juniors"}} class="active"{{end}}>[Juniors]</a>
+    </div>
+    <div class="nav-archived">
+        <span style="color: #666; margin-right: 5px;">Archived:</span>
+        <a href="/payments"{{if eq .Active "payments"}} class="active"{{end}}>[Payments Ledger]</a>
+    </div>
+    <div class="nav-archived">
+        <span style="color: #666; margin-right: 5px;">Tools:</span>
+        <a href="/sync-bank"{{if eq .Active "sync"}} class="active"{{end}}>[Sync Bank Data]</a>
+        <a href="/flush-cache"{{if eq .Active "flush"}} class="active"{{end}}>[Flush Cache]</a>
+    </div>
+</div>
+{{end}}

go/internal/web/templates/payments.tmpl

@@ -0,0 +1,38 @@
+{{define "title"}}Payments Ledger{{end}}
+{{define "content"}}
+<h1>Payments Ledger</h1>
+<p class="description">
+    All bank transactions from the
+    <a href="{{.Data.PaymentsURL}}" target="_blank">payments sheet</a>,
+    grouped by member. Names are matched against the
+    <a href="{{.Data.AttendanceURL}}" target="_blank">attendance sheet</a>.
+</p>
+{{if .Error}}<p class="error">{{.Error}}</p>{{end}}
+<div class="ledger-container">
+{{range $person := .Data.SortedPeople}}
+    <div class="member-block">
+        <h2>{{$person}}</h2>
+        <table class="txn-table">
+            <thead>
+                <tr>
+                    <th class="txn-date">Date</th>
+                    <th class="txn-amount">Amount</th>
+                    <th class="txn-purpose">Purpose</th>
+                    <th class="txn-message">Bank Message</th>
+                </tr>
+            </thead>
+            <tbody>
+            {{range $tx := index $.Data.GroupedPayments $person}}
+                <tr>
+                    <td class="txn-date">{{$tx.Date}}</td>
+                    <td class="txn-amount">{{printf "%.0f" $tx.Amount}} CZK</td>
+                    <td class="txn-purpose">{{$tx.Purpose}}</td>
+                    <td class="txn-message">{{$tx.Message}}</td>
+                </tr>
+            {{end}}
+            </tbody>
+        </table>
+    </div>
+{{end}}
+</div>
+{{end}}

go/internal/web/templates/sync.tmpl

@@ -0,0 +1,15 @@
+{{define "title"}}Sync Bank Data{{end}}
+{{define "content"}}
+<h1>Sync Bank Data</h1>
+{{if .Output}}
+  {{if .Success}}
+    <p class="status-ok">Sync completed successfully.</p>
+  {{else}}
+    <p class="status-error">Sync failed — see log below.</p>
+  {{end}}
+  <pre class="sync-log{{if not .Success}} sync-log--error{{end}}">{{.Output}}</pre>
+{{else}}
+  <p class="description">Fetches Fio transactions for the current year, infers payment details, and flushes the cache.</p>
+{{end}}
+<p><a href="/sync-bank" class="btn">{{if .Output}}Run Again{{else}}Run Sync{{end}}</a></p>
+{{end}}

go/tests/fixtures/reconcile/03_proportional_remainder.json

@@ -1,7 +1,7 @@
 {
   "case": "03_proportional_remainder",
   "func": "scripts.match_payments.reconcile",
-  "captured_at": "2026-05-06",
+  "captured_at": "2026-05-11",
   "input": {
     "members": [
       {
@@ -54,10 +54,10 @@
             "original_expected": 750,
             "attendance_count": 3,
             "exception": null,
-            "paid": 324.3243243243243,
+            "paid": 750.0,
             "transactions": [
               {
-                "amount": 324.3243243243243,
+                "amount": 750.0,
                 "date": "2026-03-10",
                 "sender": "Member_d035d9f9",
                 "message": "",
@@ -70,10 +70,10 @@
             "original_expected": 750,
             "attendance_count": 2,
             "exception": null,
-            "paid": 324.3243243243243,
+            "paid": 50.0,
             "transactions": [
               {
-                "amount": 324.3243243243243,
+                "amount": 50.0,
                 "date": "2026-03-10",
                 "sender": "Member_d035d9f9",
                 "message": "",
@@ -86,25 +86,17 @@
             "original_expected": 350,
             "attendance_count": 2,
             "exception": null,
-            "paid": 151.35135135135135,
+            "paid": 0,
-            "transactions": [
+            "transactions": []
-              {
-                "amount": 151.35135135135135,
-                "date": "2026-03-10",
-                "sender": "Member_d035d9f9",
-                "message": "",
-                "confidence": "auto"
-              }
-            ]
           }
         },
         "other_transactions": [],
-        "total_balance": -1051
+        "total_balance": -1050
       }
     },
     "unmatched": [],
     "credits": {
-      "Member_d035d9f9": -1051
+      "Member_d035d9f9": -1050
     }
   }
 }

go/tests/fixtures/reconcile/09_multiperson_multimonth.json

@@ -1,7 +1,7 @@
 {
   "case": "09_multiperson_multimonth",
   "func": "scripts.match_payments.reconcile",
-  "captured_at": "2026-05-06",
+  "captured_at": "2026-05-11",
   "input": {
     "members": [
       {
@@ -63,10 +63,10 @@
             "original_expected": 750,
             "attendance_count": 3,
             "exception": null,
-            "paid": 500.0,
+            "paid": 750.0,
             "transactions": [
               {
-                "amount": 500.0,
+                "amount": 750.0,
                 "date": "2026-02-15",
                 "sender": "Member_d035d9f9",
                 "message": "",
@@ -79,10 +79,10 @@
             "original_expected": 750,
             "attendance_count": 2,
             "exception": null,
-            "paid": 500.0,
+            "paid": 250.0,
             "transactions": [
               {
-                "amount": 500.0,
+                "amount": 250.0,
                 "date": "2026-02-15",
                 "sender": "Member_d035d9f9",
                 "message": "",
@@ -102,10 +102,10 @@
             "original_expected": 750,
             "attendance_count": 2,
             "exception": null,
-            "paid": 681.8181818181819,
+            "paid": 750.0,
             "transactions": [
               {
-                "amount": 681.8181818181819,
+                "amount": 750.0,
                 "date": "2026-02-15",
                 "sender": "Member_d035d9f9",
                 "message": "",
@@ -118,10 +118,10 @@
             "original_expected": 350,
             "attendance_count": 2,
             "exception": null,
-            "paid": 318.18181818181813,
+            "paid": 250.0,
             "transactions": [
               {
-                "amount": 318.18181818181813,
+                "amount": 250.0,
                 "date": "2026-02-15",
                 "sender": "Member_d035d9f9",
                 "message": "",
@@ -131,13 +131,13 @@
           }
         },
         "other_transactions": [],
-        "total_balance": -101
+        "total_balance": -100
       }
     },
     "unmatched": [],
     "credits": {
       "Member_d035d9f9": -500,
-      "Member_f4a93e46": -101
+      "Member_f4a93e46": -100
     }
   }
 }

scripts/attendance.py

@@ -30,8 +30,7 @@ JUNIOR_MONTHLY_RATE = {
     "2026-03": 250   # reduced fee for March 2026
 }
 ADULT_MERGED_MONTHS = {
-    #"2025-12": "2026-01",   # keys are merged into values
+    "2025-09": "2025-10",   # keys are merged into values
-    #"2025-09": "2025-10"
 }
 
 JUNIOR_MERGED_MONTHS = {

scripts/fio_utils.py

@@ -4,6 +4,7 @@
 import json
 import os
 import re
+import sys
 import urllib.request
 from datetime import datetime
 from html.parser import HTMLParser
@@ -89,9 +90,11 @@ def parse_czech_amount(s: str) -> float | None:
 
 
 def parse_czech_date(s: str) -> str | None:
-    """Parse 'DD.MM.YYYY' to 'YYYY-MM-DD'."""
+    """Parse a Czech date to 'YYYY-MM-DD'. Accepts 4-digit and 2-digit years
+    with dot or slash separators; Fio's transparent page mixes 'DD.MM.YYYY'
+    and 'DD.MM.YY' in the same response."""
     s = s.strip()
-    for fmt in ("%d.%m.%Y", "%d/%m/%Y"):
+    for fmt in ("%d.%m.%Y", "%d/%m/%Y", "%d.%m.%y", "%d/%m/%y"):
         try:
             return datetime.strptime(s, fmt).strftime("%Y-%m-%d")
         except ValueError:
@@ -146,6 +149,7 @@ def fetch_transactions_transparent(
             "bank_id": "", # HTML scraping doesn't give stable ID
         })
 
+    print(f"fio: transparent fetched {len(rows)} raw rows, {len(transactions)} transaction(s) after filtering", file=sys.stderr)
     return transactions
 
 
@@ -169,7 +173,8 @@ def fetch_transactions_api(
 
     transactions = []
     tx_list = data.get("accountStatement", {}).get("transactionList", {})
-    for tx in (tx_list.get("transaction") or []):
+    raw_list = tx_list.get("transaction") or []
+    for tx in raw_list:
         # Each field is {"value": ..., "name": ..., "id": ...} or null
         def val(col_id):
             col = tx.get(f"column{col_id}")
@@ -197,6 +202,7 @@ def fetch_transactions_api(
             "currency": str(val(14) or "CZK"), # column14 = Currency
         })
 
+    print(f"fio: api fetched {len(raw_list)} raw transaction(s), {len(transactions)} after filtering", file=sys.stderr)
     return transactions
 
 
@@ -204,8 +210,14 @@ def fetch_transactions(date_from: str, date_to: str) -> list[dict]:
     """Fetch transactions, using API if token available, else transparent page."""
     token = os.environ.get("FIO_API_TOKEN", "").strip()
     if token:
+        print(f"fio: using authenticated API, window {date_from}..{date_to}", file=sys.stderr)
         return fetch_transactions_api(token, date_from, date_to)
 
+    print(
+        f"fio: using transparent page (FIO_API_TOKEN unset — expect publishing lag), "
+        f"window {date_from}..{date_to}, account=2800359168",
+        file=sys.stderr,
+    )
     # Convert YYYY-MM-DD to DD.MM.YYYY for the transparent page URL
     from_dt = datetime.strptime(date_from, "%Y-%m-%d")
     to_dt = datetime.strptime(date_to, "%Y-%m-%d")

scripts/match_payments.py

@@ -468,26 +468,19 @@ def reconcile(
 
             total_expected = sum(e for _, e in in_window)
 
-            if total_expected > 0 and in_window_share >= total_expected:
+            if total_expected > 0:
-                # Greedy phase: payment covers all in-window fees; overflow → credit.
+                # Fill-first: iterate in_window in matched_months order (chronological by
-                credits[member_name] = credits.get(member_name, 0) + int(in_window_share - total_expected)
+                # convention from infer_payments.py), allocating min(remaining, deficit) to
-                for m, exp in in_window:
+                # each month. Deficit is net of what prior transactions already paid, so a
-                    alloc = float(exp)
+                # second payment on the same months correctly fills only what remains due.
-                    ledger[member_name][m]["paid"] += alloc
+                # Any surplus after all deficits are covered goes to the credit bucket.
-                    ledger[member_name][m]["transactions"].append({
-                        "amount": alloc,
-                        "date": tx["date"],
-                        "sender": tx["sender"],
-                        "message": tx["message"],
-                        "confidence": confidence,
-                    })
-            elif total_expected > 0:
-                # Proportional phase: distribute in_window_share by each month's expected fee.
-                # Last month absorbs any float remainder so the sum equals in_window_share exactly.
                 remaining = in_window_share
-                for i, (m, exp) in enumerate(in_window):
+                for m, exp in in_window:
-                    alloc = remaining if i == len(in_window) - 1 else in_window_share * exp / total_expected
+                    paid_so_far = ledger[member_name][m]["paid"]
-                    remaining -= alloc
+                    deficit = max(0.0, float(exp) - paid_so_far)
+                    alloc = min(remaining, deficit)
+                    if alloc <= 0:
+                        continue
                     ledger[member_name][m]["paid"] += alloc
                     ledger[member_name][m]["transactions"].append({
                         "amount": alloc,
@@ -496,6 +489,9 @@ def reconcile(
                         "message": tx["message"],
                         "confidence": confidence,
                     })
+                    remaining -= alloc
+                if remaining > 0:
+                    credits[member_name] = credits.get(member_name, 0) + int(remaining)
             else:
                 # Fallback: no expected fees (prepayment before attendance recorded); even split.
                 per_month = in_window_share / len(in_window)

scripts/sync_fio_to_sheets.py

@@ -77,6 +77,35 @@ def generate_sync_id(tx: dict) -> str:
     return hashlib.sha256(raw_str.encode("utf-8")).hexdigest()
 
 
+def _trunc(s: str, n: int = 40) -> str:
+    s = str(s)
+    return s if len(s) <= n else s[: n - 1] + "…"
+
+
+def _print_fio_table(transactions: list[dict], statuses: list[str]) -> None:
+    headers = ["DATE", "AMOUNT", "SENDER", "VS", "MESSAGE", "BANKID", "STATUS"]
+    rows = [
+        [
+            str(tx.get("date", "")),
+            f"{float(tx.get('amount', 0)):.2f}",
+            str(tx.get("sender", "")),
+            str(tx.get("vs", "")),
+            _trunc(str(tx.get("message", ""))),
+            str(tx.get("bank_id", "")),
+            status,
+        ]
+        for tx, status in zip(transactions, statuses)
+    ]
+    widths = [
+        max(len(headers[i]), max((len(r[i]) for r in rows), default=0))
+        for i in range(len(headers))
+    ]
+    sep = "  "
+    print(sep.join(h.ljust(w) for h, w in zip(headers, widths)))
+    for row in rows:
+        print(sep.join(cell.ljust(w) for cell, w in zip(row, widths)))
+
+
 def sort_sheet_by_date(service, spreadsheet_id):
     """Sort the sheet by the Date column (Column B)."""
     # Get the sheet ID (gid) of the first sheet
@@ -104,12 +133,21 @@ def sort_sheet_by_date(service, spreadsheet_id):
     print("Sheet sorted by date.")
 
 
-def sync_to_sheets(spreadsheet_id: str, credentials_path: str, days: int = None, date_from_str: str = None, date_to_str: str = None, sort_by_date: bool = False):
+def sync_to_sheets(
+    spreadsheet_id: str,
+    credentials_path: str,
+    days: int = None,
+    date_from_str: str = None,
+    date_to_str: str = None,
+    sort_by_date: bool = False,
+    dry_run: bool = False,
+    print_fio_table: bool = False,
+):
     print(f"Connecting to Google Sheets using {credentials_path}...")
     service = get_sheets_service(credentials_path)
     sheet = service.spreadsheets()
 
-    # 1. Fetch existing IDs from Column G (last column in A-G range)
+    # 1. Read existing sync IDs from Column K
     print(f"Reading existing sync IDs from sheet...")
     try:
         result = sheet.values().get(
@@ -117,19 +155,22 @@ def sync_to_sheets(spreadsheet_id: str, credentials_path: str, days: int = None,
             range="A1:K" # Include header and all columns to check Sync ID
         ).execute()
         values = result.get("values", [])
-        
+
         # Check and insert labels if missing
         if not values or values[0] != COLUMN_LABELS:
-            print("Inserting column labels...")
+            if dry_run:
-            sheet.values().update(
+                print("Dry run: would write header row")
-                spreadsheetId=spreadsheet_id,
+            else:
-                range="A1",
+                print("Inserting column labels...")
-                valueInputOption="USER_ENTERED",
+                sheet.values().update(
-                body={"values": [COLUMN_LABELS]}
+                    spreadsheetId=spreadsheet_id,
-            ).execute()
+                    range="A1",
+                    valueInputOption="USER_ENTERED",
+                    body={"values": [COLUMN_LABELS]}
+                ).execute()
             existing_ids = set()
         else:
-            # Sync ID is now the last column (index 10)
+            # Sync ID is the last column (index 10)
             existing_ids = {row[10] for row in values[1:] if len(row) > 10}
     except Exception as e:
         print(f"Error reading sheet (maybe empty?): {e}")
@@ -150,8 +191,12 @@ def sync_to_sheets(spreadsheet_id: str, credentials_path: str, days: int = None,
     transactions = fetch_transactions(df_str, dt_str)
     print(f"Found {len(transactions)} transactions.")
 
-    # 3. Filter for new transactions
+    if dry_run:
+        print(f"Dry run: window {df_str} to {dt_str}, fetched {len(transactions)} transaction(s) from Fio")
+
+    # 3. Determine NEW/DUP for each transaction
     new_rows = []
+    tx_statuses = []
     for tx in transactions:
         sync_id = generate_sync_id(tx)
         if sync_id not in existing_ids:
@@ -169,24 +214,48 @@ def sync_to_sheets(spreadsheet_id: str, credentials_path: str, days: int = None,
                 tx.get("bank_id", ""),
                 sync_id,
             ])
+            tx_statuses.append("NEW")
+        else:
+            tx_statuses.append("DUP")
+
+    # 4. Print table (before early-return so all transactions are shown including DUPs)
+    if print_fio_table and transactions:
+        _print_fio_table(transactions, tx_statuses)
 
     if not new_rows:
-        print("No new transactions to sync.")
+        if dry_run:
+            print("Dry run: would sync 0 new transaction(s).")
+        else:
+            print("No new transactions to sync.")
         return
 
-    # 4. Append to sheet
+    # 5. Append to sheet or print dry-run would-write lines
-    print(f"Appending {len(new_rows)} new transactions to the sheet...")
+    if dry_run:
-    body = {"values": new_rows}
+        for tx, status in zip(transactions, tx_statuses):
-    sheet.values().append(
+            if status == "NEW":
-        spreadsheetId=spreadsheet_id,
+                print(
-        range="A2", # Appends to the end of the sheet
+                    f"Dry run: would append"
-        valueInputOption="USER_ENTERED",
+                    f" date={tx.get('date', '')}"
-        body=body
+                    f" amount={tx.get('amount', '')}"
-    ).execute()
+                    f" sender={tx.get('sender', '')}"
-    print("Sync completed successfully.")
+                    f" vs={tx.get('vs', '')}"
-
+                    f" message={tx.get('message', '')}"
-    if sort_by_date:
+                )
-        sort_sheet_by_date(service, spreadsheet_id)
+        if sort_by_date:
+            print("Dry run: would sort by date")
+        print(f"Dry run: would sync {len(new_rows)} new transaction(s).")
+    else:
+        print(f"Appending {len(new_rows)} new transactions to the sheet...")
+        body = {"values": new_rows}
+        sheet.values().append(
+            spreadsheetId=spreadsheet_id,
+            range="A2", # Appends to the end of the sheet
+            valueInputOption="USER_ENTERED",
+            body=body
+        ).execute()
+        print("Sync completed successfully.")
+        if sort_by_date:
+            sort_sheet_by_date(service, spreadsheet_id)
 
 
 def main():
@@ -197,16 +266,20 @@ def main():
     parser.add_argument("--from", dest="date_from", help="Start date YYYY-MM-DD")
     parser.add_argument("--to", dest="date_to", help="End date YYYY-MM-DD")
     parser.add_argument("--sort-by-date", action="store_true", help="Sort the sheet by date after sync")
+    parser.add_argument("--dry-run", action="store_true", help="Fetch and dedup without writing to the sheet")
+    parser.add_argument("--print-fio-table", action="store_true", help="Print aligned table of all fetched transactions with NEW/DUP status (use with --dry-run)")
     args = parser.parse_args()
 
     try:
         sync_to_sheets(
-            spreadsheet_id=args.sheet_id, 
+            spreadsheet_id=args.sheet_id,
             credentials_path=args.credentials,
             days=args.days,
             date_from_str=args.date_from,
             date_to_str=args.date_to,
-            sort_by_date=args.sort_by_date
+            sort_by_date=args.sort_by_date,
+            dry_run=args.dry_run,
+            print_fio_table=args.print_fio_table,
         )
     except Exception as e:
         print(f"Sync failed: {e}")

templates/adults.html

@@ -1044,8 +1044,6 @@
                 }
             });
 
-            var defaultFrom = Math.max(0, maxMonthIdx - 4);
-            fromSelect.value = defaultFrom;
             toSelect.value = maxMonthIdx;
             applyMonthFilter();
         })();

templates/juniors.html

@@ -1025,8 +1025,6 @@
                 }
             });
 
-            var defaultFrom = Math.max(0, maxMonthIdx - 4);
-            fromSelect.value = defaultFrom;
             toSelect.value = maxMonthIdx;
             applyMonthFilter();
         })();

tests/test_reconcile_exceptions.py

@@ -93,8 +93,8 @@ class TestMultiMonthAllocation(unittest.TestCase):
         self.assertEqual(int(months['2026-02']['paid']), 750)
         self.assertEqual(result['credits'].get('Alice', 0), 500)
 
-    def test_proportional_underpayment(self):
+    def test_underpayment_fills_earliest_first(self):
-        """Payment < total expected → proportional split; sum of paid == payment amount."""
+        """Payment < total expected → fill earliest months first, spill remainder to later."""
         members = [('Alice', 'A', {'2026-02': (750, 3), '2026-03': (350, 3), '2026-04': (750, 3)})]
         sorted_months = ['2026-02', '2026-03', '2026-04']
         amount = 1250
@@ -103,18 +103,28 @@ class TestMultiMonthAllocation(unittest.TestCase):
         result = reconcile(members, sorted_months, [tx])
         months = result['members']['Alice']['months']
 
-        paid_02 = months['2026-02']['paid']
+        # 02 filled first (750), then 03 (350), then remainder 150 to 04
-        paid_03 = months['2026-03']['paid']
+        self.assertAlmostEqual(months['2026-02']['paid'], 750, places=2)
-        paid_04 = months['2026-04']['paid']
+        self.assertAlmostEqual(months['2026-03']['paid'], 350, places=2)
+        self.assertAlmostEqual(months['2026-04']['paid'], 150, places=2)
+        # No CZK lost
+        self.assertAlmostEqual(
+            months['2026-02']['paid'] + months['2026-03']['paid'] + months['2026-04']['paid'],
+            amount, places=2,
+        )
 
-        # All months should be partial (underpaid)
+    def test_fill_first_across_two_transactions(self):
-        self.assertLess(paid_02, 750)
+        """Prior txn fills 02 partially; later txn finishes 02 then spills to 03."""
-        self.assertLess(paid_03, 350)
+        members = [('Matyáš', 'A', {'2026-02': (500, 2), '2026-03': (250, 1)})]
-        self.assertLess(paid_04, 750)
+        sorted_months = ['2026-02', '2026-03']
-        # Sum must equal the original payment (no CZK lost)
+        tx1 = _tx('Matyáš', '2026-02', 200)
-        self.assertAlmostEqual(paid_02 + paid_03 + paid_04, amount, places=2)
+        tx2 = _tx('Matyáš', '2026-02, 2026-03', 550)
-        # 02 and 04 have equal expected → equal allocation
+
-        self.assertAlmostEqual(paid_02, paid_04, places=2)
+        result = reconcile(members, sorted_months, [tx1, tx2])
+        months = result['members']['Matyáš']['months']
+
+        self.assertAlmostEqual(months['2026-02']['paid'], 500, places=2)
+        self.assertAlmostEqual(months['2026-03']['paid'], 250, places=2)
 
     def test_single_month_unchanged(self):
         """Single-month payment: full amount goes to that month (regression guard)."""