fix: restore Sep+Oct adult merge and stop auto-truncating period selector

Two regressions made older periods invisible on the adults dashboard:

- 1257f0d (Mar 9) commented out ADULT_MERGED_MONTHS, removing the
  Sep+Oct 2025 merged label. Restored only the 2025-09 → 2025-10
  mapping (Dec and Jan are billed separately for adults; the
  Dec → Jan mapping stays disabled per product decision). Mirrored
  on the Go side. Test fixtures in sources_test.go now assert Sep
  dates land in merged 2025-10 instead of 2025-09.

- 7774301 (Apr 9) added a JS onload default that set the From
  selector to maxMonthIdx − 4 and immediately filtered the table,
  hiding everything older than 5 months on first load. Dropped that
  default in templates/adults.html and templates/juniors.html so
  the From-selector starts at the oldest available month. Future
  months are still removed from the dropdowns and hidden in the
  table — only the past-month truncation is gone.

Note: the live adults attendance sheet had also been pruned to
start at 02.12.2025; restoring Sep/Oct/Nov 2025 columns from
Sheets version history is required to actually see those periods.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CHANGELOG.md

@@ -1,5 +1,89 @@
 # Changelog
 
+## 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.
+- `tests/test_app.py`: updated `/api/*` mock fixtures to include `vs`/`sync_id` keys for realism.
+- **Cache note**: after deploying, hit `POST /flush-cache` once so the in-process cache is cleared and the next request picks up the new column lookups.
+
+## 2026-05-07 23:37 CEST — fix(go): accept single-digit day/month in attendance date headers
+
+- `go/internal/services/membership/sources.go`: `parseDates` now uses Go time formats `2.1.2006` and `1/2/2006` (single-digit reference forms, which accept both padded and unpadded inputs) instead of `02.01.2006` and `01/02/2006`. The Czech attendance sheet headers contain dates like `1.6.2026`, `23.3.2026`, `6.4.2026` — Go silently dropped those columns under the strict zero-padded format, while Python's `strptime("%d.%m.%Y")` accepted them. Effect was a missing `2026-06` month entirely on `/api/juniors` plus undercounted attendance for any month with single-digit columns; both surfaced as diffs in `make parity`.
+- `sources_test.go::TestParseDates_SingleDigitDayMonth` added as a regression guard covering both Czech and US format flavours with and without leading zeros.
+
+## 2026-05-07 23:17 CEST — fix(go): pass raw value to FormatDate so numeric serial-day dates format
+
+- `go/internal/services/membership/sources.go`: transaction-row parser now passes `row[idxDate]` directly to `matching.FormatDate` (via a new `getRaw` helper) instead of stringifying first via `getVal`. The Sheets API returns numeric serial-day values as `float64` for date-formatted cells; pre-stringifying them defeated `FormatDate`'s `case float64:` dispatch, causing all numeric dates to leak through as `"46147"` style strings instead of `"2026-05-05"`.
+- Surfaced by `make parity` (M5.4): every `transactions[].date` field on `/api/adults` and `/api/juniors` differed between Python and Go.
+- `sources_test.go::TestLoadTransactions` extended with a numeric-serial-day row covering the regression.
+
+## 2026-05-07 23:05 CEST — fix(go): default CacheDir to `tmp/go` to avoid Python collision
+
+- `go/internal/config/config.go`: `CacheDir` default changed from `tmp` to `tmp/go`. Override via `CACHE_DIR` env var still works.
+- Why: both backends used `tmp/<key>_cache.json` with the same keys (`attendance_regular`, `attendance_juniors`, `payments_transactions`, `exceptions_dict`) but different shapes — Python caches post-processed view-model tuples, Go caches raw rows. Whichever wrote last poisoned the cache; running both in parallel produced `ValueError: too many values to unpack (expected 2, got 68)` on Python's `/adults` after the Go server populated `attendance_regular_cache.json` with raw CSV rows.
+- After upgrading: stop the Go server, hit `/flush-cache` on the Python side once (rewrites `tmp/*.json` with correct shapes), then restart `make web-go` — it will use `tmp/go/` going forward. Required for the M5.4 `make parity` workflow which assumes both backends run side-by-side.
+
+## 2026-05-07 22:55 CEST — feat(go): M5.4 — parity diff binary + `make parity`
+
+- `go/cmd/parity/main.go`: new standalone binary that GETs `/api/adults`, `/api/juniors`, `/api/payments` from both Python (:5001) and Go (:8080) backends, scrubs an allowlist (`render_time.total`), and prints `cmp.Diff` for any remaining differences. Exits 0 on full match, 1 on diffs, 2 on fetch/parse errors — CI-friendly for M7.2. `/api/version` is excluded by design (returns binary identity — tag/commit/build_date — which differs between independently built backends); still accessible via `make parity ARGS="-route /api/version"`.
+- `go/cmd/parity/scrub_test.go`: 4 unit tests covering top-level delete, nested delete, missing path, and non-map parent.
+- `go/go.mod`: `github.com/google/go-cmp` promoted to direct dependency.
+- `Makefile`: `parity` target added (`.PHONY`, help, `cd go && go run ./cmd/parity`).
+- `docs/plans/2026-05-07-2254-m5-4-parity-binary.md`: plan archived.
+
+## 2026-05-07 22:37 CEST — feat(py): M5.3 — Python /api/* shadow endpoints
+
+- `app.py`: four new JSON routes (`/api/version`, `/api/adults`, `/api/juniors`, `/api/payments`) mirroring the Go `/api/*` handlers; `_unwrap_view_model_for_api()` helper expands pre-serialised JSON strings and renames `month_labels_json` → `month_labels`, `raw_payments_json` → `raw_payments` to match Go wire contract.
+- `tests/test_app.py`: four new smoke tests asserting top-level key sets and that unwrapped fields are objects (not strings).
+
+## 2026-05-07 20:13 CEST — feat(go): M5.2 — HTTP handlers for /api/adults, /api/juniors, /api/payments, /api/version
+
+- `web/api/handler.go`: `Handler` struct + `ServeAdults`, `ServeJuniors`, `ServePayments`, `ServeVersion` using `membership.Sources`.
+- `web/api/build_{adults,juniors,payments,common}.go`: ports of `scripts/views.py` view-model builders; `buildJuniorMemberRow` handles `"?"` sentinel, `:NJ,MA` breakdown, unknown-month skip.
+- Extended `reconcile.FeeData`/`MonthData` with `IsUnknown`, `JuniorAttendance`, `AdultAttendance`; `Transaction` with `ManualFix`, `VS`, `BankID`, `SyncID`.
+- `sources.go` exports `AdultMergedMonths`/`JuniorMergedMonths`; parses new FeeData and transaction columns.
+- `web/server.go` + `cmd/fuj/main.go` wired to register `/api/*` routes.
+- PR #17.
+
 ## 2026-05-07 17:37 CEST — feat(go): M5.1 — /api/* wire types + JSON Schemas
 
 - New `go/internal/web/api/` package: `AdultsResponse`, `JuniorsResponse`, `PaymentsResponse`, `VersionResponse` with explicit `json:` tags matching Python view-model keys.

Makefile

@@ -1,4 +1,4 @@
-.PHONY: help fees match web web-py web-debug web-go go-build go-test go-test-all go-parity go-run go-sync-debug go-lint capture-fixtures image run sync sync-2026 test test-v docs
+.PHONY: help fees match web web-py web-debug web-go go-build go-test go-test-all go-parity go-run go-sync-debug go-lint capture-fixtures parity image run sync sync-2026 test test-v docs
 
 export PYTHONPATH := scripts:$(PYTHONPATH)
 VENV := .venv
@@ -29,6 +29,7 @@ help:
 	@echo "  make go-lint     - Run golangci-lint on Go code"
 	@echo "  make go-sync-debug [DAYS=N] - Dry-run Go sync with Fio debug logs and txn table (default DAYS=30)"
 	@echo "  make capture-fixtures - Regenerate parity fixture corpus from live Python"
+	@echo "  make parity      - Diff /api/* between web-py (:5001) and web-go (:8080); both must be running"
 	@echo "  make image       - Build Python OCI container image"
 	@echo "  make run         - Run the built Python Docker image locally"
 	@echo "  make sync        - Sync Fio transactions to Google Sheets"
@@ -102,6 +103,9 @@ go-lint:
 web-go: go-build
 	./$(GO_BIN) server
 
+parity:
+	cd $(GO_SRC) && go run ./cmd/parity $(ARGS)
+
 image:
 	docker build -t fuj-management:latest \
 		--build-arg GIT_TAG=$$(git describe --tags --always 2>/dev/null || echo "untagged") \

app.py

@@ -7,7 +7,7 @@ import os
 import io
 import qrcode
 import logging
-from flask import Flask, render_template, g, send_file, request
+from flask import Flask, render_template, g, send_file, request, jsonify
 
 # Configure logging, allowing override via LOG_LEVEL environment variable
 log_level = os.environ.get("LOG_LEVEL", "INFO").upper()
@@ -68,6 +68,16 @@ BUILD_META = _json.loads(_meta_path.read_text()) if _meta_path.exists() else {
     "tag": "dev", "commit": "local", "build_date": ""
 }
 
+
+def _unwrap_view_model_for_api(vm: dict) -> dict:
+    """Expand pre-stringified JSON fields and rename to match Go API contract."""
+    out = dict(vm)
+    out["member_data"] = _json.loads(out.pop("member_data"))
+    out["month_labels"] = _json.loads(out.pop("month_labels_json"))
+    out["raw_payments"] = _json.loads(out.pop("raw_payments_json"))
+    return out
+
+
 warmup_cache()
 
 @app.before_request
@@ -144,6 +154,75 @@ def sync_bank():
 def version():
     return BUILD_META
 
+@app.route("/api/version")
+def api_version():
+    return jsonify(BUILD_META)
+
+@app.route("/api/adults")
+def api_adults():
+    attendance_url = f"https://docs.google.com/spreadsheets/d/{ATTENDANCE_SHEET_ID}/edit"
+    payments_url = f"https://docs.google.com/spreadsheets/d/{PAYMENTS_SHEET_ID}/edit"
+    members_data = get_cached_data("attendance_regular", ATTENDANCE_SHEET_ID, get_members_with_fees)
+    if not members_data:
+        return jsonify({"error": "no data"}), 503
+    members, sorted_months = members_data
+    transactions = get_cached_data("payments_transactions", PAYMENTS_SHEET_ID, fetch_sheet_data, PAYMENTS_SHEET_ID, CREDENTIALS_PATH)
+    exceptions = get_cached_data(
+        "exceptions_dict", PAYMENTS_SHEET_ID, fetch_exceptions,
+        PAYMENTS_SHEET_ID, CREDENTIALS_PATH,
+        serialize=lambda d: [[list(k), v] for k, v in d.items()],
+        deserialize=lambda c: {tuple(k): v for k, v in c},
+    )
+    result = reconcile(members, sorted_months, transactions, exceptions)
+    vm = build_adults_view_model(
+        members, sorted_months, result, transactions,
+        datetime.now().strftime("%Y-%m"),
+        attendance_url=attendance_url, payments_url=payments_url, bank_account=BANK_ACCOUNT,
+    )
+    return jsonify(_unwrap_view_model_for_api(vm))
+
+@app.route("/api/juniors")
+def api_juniors():
+    attendance_url = f"https://docs.google.com/spreadsheets/d/{ATTENDANCE_SHEET_ID}/edit#gid={JUNIOR_SHEET_GID}"
+    payments_url = f"https://docs.google.com/spreadsheets/d/{PAYMENTS_SHEET_ID}/edit"
+    junior_members_data = get_cached_data("attendance_juniors", ATTENDANCE_SHEET_ID, get_junior_members_with_fees)
+    if not junior_members_data:
+        return jsonify({"error": "no data"}), 503
+    junior_members, sorted_months = junior_members_data
+    transactions = get_cached_data("payments_transactions", PAYMENTS_SHEET_ID, fetch_sheet_data, PAYMENTS_SHEET_ID, CREDENTIALS_PATH)
+    exceptions = get_cached_data(
+        "exceptions_dict", PAYMENTS_SHEET_ID, fetch_exceptions,
+        PAYMENTS_SHEET_ID, CREDENTIALS_PATH,
+        serialize=lambda d: [[list(k), v] for k, v in d.items()],
+        deserialize=lambda c: {tuple(k): v for k, v in c},
+    )
+    adapted_members = adapt_junior_members(junior_members)
+    result = reconcile(adapted_members, sorted_months, transactions, exceptions)
+    vm = build_juniors_view_model(
+        junior_members, adapted_members, sorted_months, result, transactions,
+        datetime.now().strftime("%Y-%m"),
+        attendance_url=attendance_url, payments_url=payments_url, bank_account=BANK_ACCOUNT,
+    )
+    return jsonify(_unwrap_view_model_for_api(vm))
+
+@app.route("/api/payments")
+def api_payments():
+    attendance_url = f"https://docs.google.com/spreadsheets/d/{ATTENDANCE_SHEET_ID}/edit"
+    payments_url = f"https://docs.google.com/spreadsheets/d/{PAYMENTS_SHEET_ID}/edit"
+    transactions = get_cached_data("payments_transactions", PAYMENTS_SHEET_ID, fetch_sheet_data, PAYMENTS_SHEET_ID, CREDENTIALS_PATH)
+    adults_data = get_cached_data("attendance_regular", ATTENDANCE_SHEET_ID, get_members_with_fees)
+    juniors_data = get_cached_data("attendance_juniors", ATTENDANCE_SHEET_ID, get_junior_members_with_fees)
+    member_names = []
+    if adults_data:
+        member_names.extend(name for name, _, _ in adults_data[0])
+    if juniors_data:
+        member_names.extend(name for name, _, _ in juniors_data[0])
+    vm = build_payments_view_model(
+        transactions, member_names,
+        attendance_url=attendance_url, payments_url=payments_url,
+    )
+    return jsonify(vm)
+
 @app.route("/adults")
 def adults_view():
     attendance_url = f"https://docs.google.com/spreadsheets/d/{ATTENDANCE_SHEET_ID}/edit"

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:** M4 — IO layer behind interfaces ✅
+**Current milestone:** M6 — Go-native HTML frontend
 **Started:** 2026-05-04
-**Last updated:** 2026-05-07
+**Last updated:** 2026-05-08 (M6.2 merged)
 
 ## How to use
 
@@ -98,9 +98,9 @@ Goal: every external IO (Sheets, Drive, Fio, file cache) accessed through a narr
 Goal: byte-equal JSON between Python and Go for every route. This is the parity contract.
 
 - [x] **M5.1** Hand-author Go structs for `/api/adults`, `/api/juniors`, `/api/payments`, `/api/version` with explicit `json:` tags matching Python keys; emit JSON Schemas via `github.com/invopop/jsonschema` to `tests/fixtures/api-schema/` — `f253e3f`
-- [ ] **M5.2** Implement Go handlers for `/api/*` routes composing `services/*` results into the JSON structs
+- [x] **M5.2** Implement Go handlers for `/api/*` routes composing `services/*` results into the JSON structs — `7d48e8f`
-- [ ] **M5.3** Add Python `/api/X` shadow endpoints in [app.py](app.py): `jsonify(view_model_dict)` — no transformation
+- [x] **M5.3** Add Python `/api/X` shadow endpoints in [app.py](app.py): `jsonify(view_model_dict)` — no transformation — `40e4a9e`
-- [ ] **M5.4** Build `cmd/parity/main.go`: hits both backends' `/api/X`, normalizes allowlist (`render_time.total`, `build_meta`), prints `cmp.Diff`. Add `make parity` target
+- [x] **M5.4** Build `cmd/parity/main.go`: hits both backends' `/api/X`, normalizes allowlist (`render_time.total`, `build_meta`), prints `cmp.Diff`. Add `make parity` target
 
 **Gate:** For each route, `make parity` reports zero non-allowlisted diffs across the M3 fixture corpus.
 
@@ -110,8 +110,8 @@ 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
 - [ ] **M6.4** `/payments` page: grouped-by-person ledger view
 - [ ] **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, ↑/↓)
@@ -154,6 +154,7 @@ Goal: Go is the one true backend.
 
 (Add entries as you go. Format: `YYYY-MM-DD — short note`.)
 
+- 2026-05-07 — `/api/version` excluded from parity diff by design. Each binary's tag/commit/build_date is identity, not a data contract — diffing it would always flag a diff between independently built backends. Route remains reachable via `make parity ARGS="-route /api/version"` for manual inspection.
 - 2026-05-04 — Plan approved. Versioning policy: latest stable for Go and all libs at the time M1 starts. Frontends explicitly allowed to diverge between Python and Go; only the JSON API contract is parity-locked. No reverse proxy — both backends run on different ports via `make web-py` / `make web-go`.
 - 2026-05-07 — M4 complete. Chose fakes-only unit tests (no live integration tests) and CSV-via-public-URL for attendance (no Sheets API auth required for read-only). golangci-lint gofumpt extra-rules differ slightly from standalone gofumpt; used `golangci-lint run --fix --enable-only gofumpt` to auto-resolve formatting.
 - 2026-05-04 — M1 complete. Dockerfile base changed from `distroless/static:nonroot` → `alpine:3` for debuggability (can tighten later). CLI dispatcher uses stdlib `flag`; module path `fuj-management/go`. golangci-lint v1 embedded gofumpt merges all imports into one group (no stdlib/local split) — accepted as the project style.

docs/plans/2026-05-07-2114-go-rewrite-m5-3-python-api-shadow.md

@@ -0,0 +1,113 @@
+# M5.3 — Python `/api/X` shadow endpoints
+
+Companion to:
+- [2026-05-03-2349-go-backend-rewrite.md](2026-05-03-2349-go-backend-rewrite.md) (master design)
+- [2026-05-03-2349-go-backend-rewrite-progress.md](2026-05-03-2349-go-backend-rewrite-progress.md) (M5.3 row)
+- [2026-05-07-1431-m5-json-api-parity.md](2026-05-07-1431-m5-json-api-parity.md) (Python view-model extraction prep)
+- [2026-05-07-1650-go-rewrite-m5-1-api-structs-schemas.md](2026-05-07-1650-go-rewrite-m5-1-api-structs-schemas.md) (Go wire types)
+
+## Context
+
+M5.1 (Go wire types + JSON Schemas) and M5.2 (Go HTTP handlers for `/api/adults` `/api/juniors` `/api/payments` `/api/version`) have merged. M5.3 mirrors the same four endpoints on the Python Flask side so M5.4's `cmd/parity` tool can hit both backends and diff the JSON. After M5.3, every byte the Go side emits has a Python counterpart to compare against.
+
+The Python view-model builders ([scripts/views.py](scripts/views.py)) already produce dicts very close to the wire shape — except three template-only fields (`member_data`, `month_labels_json`, `raw_payments_json`) are pre-`json.dumps`'d for inline `<script>` blocks. M5.1's plan called this out explicitly: M5.3's `/api/X` is `jsonify(unwrap_json_strings(view_model_dict))` — a 4-line shim, not real transformation logic.
+
+## Approach
+
+Add four shadow routes to [app.py](app.py) and one private unwrap helper. Builders and templates are untouched.
+
+### Decisions
+
+1. **Unwrap shim lives in `app.py`**, not `scripts/views.py`. It's 4 lines, only the API routes use it, and it's parity-only scaffolding that M8 will delete. Keeping `views.py` free of HTTP-layer concerns means cleaner deletion later.
+2. **No data-loading helper extraction.** Each shadow route duplicates ~8 lines of cache loads from its sibling HTML route. A helper would have to thread `attendance_url` / `payments_url` / `bank_account` and the adults-vs-juniors-vs-payments branching back out — net negative for code that M8 will erase wholesale.
+3. **Drop `record_step` calls in API routes.** `record_step` only feeds `inject_render_time` (a Jinja `context_processor`); JSON responses don't go through templates, so timing breakdown has no consumer.
+4. **`/api/version` is a one-liner.** `BUILD_META` already has the keys (`tag`, `commit`, `build_date`) Go emits. Just `jsonify(BUILD_META)`. Existing `/version` route stays as-is — the new endpoint sits alongside.
+5. **Tests assert key sets and unwrap, not values.** Hard-code `EXPECTED_ADULTS_KEYS` etc. as module constants in [tests/test_app.py](tests/test_app.py). Catches drift in unit tests rather than waiting for M5.4 parity diffs. Type-check the unwrapped fields (`isinstance(member_data, dict)` etc.) to prove the shim ran.
+
+### The shim
+
+```python
+def _unwrap_view_model_for_api(vm: dict) -> dict:
+    out = dict(vm)
+    out["member_data"] = _json.loads(out.pop("member_data"))
+    out["month_labels"] = _json.loads(out.pop("month_labels_json"))
+    out["raw_payments"] = _json.loads(out.pop("raw_payments_json"))
+    return out
+```
+
+Note the **rename**: `month_labels_json` → `month_labels`, `raw_payments_json` → `raw_payments` (matches Go contract per [adults.go](go/internal/web/api/adults.go) JSON tags).
+
+### Route skeleton (`/api/adults`)
+
+```python
+@app.route("/api/adults")
+def api_adults():
+    attendance_url = f"https://docs.google.com/spreadsheets/d/{ATTENDANCE_SHEET_ID}/edit"
+    payments_url = f"https://docs.google.com/spreadsheets/d/{PAYMENTS_SHEET_ID}/edit"
+    members_data = get_cached_data("attendance_regular", ATTENDANCE_SHEET_ID, get_members_with_fees)
+    if not members_data:
+        return jsonify({"error": "no data"}), 503
+    members, sorted_months = members_data
+    transactions = get_cached_data("payments_transactions", PAYMENTS_SHEET_ID, fetch_sheet_data, PAYMENTS_SHEET_ID, CREDENTIALS_PATH)
+    exceptions = get_cached_data(
+        "exceptions_dict", PAYMENTS_SHEET_ID, fetch_exceptions,
+        PAYMENTS_SHEET_ID, CREDENTIALS_PATH,
+        serialize=lambda d: [[list(k), v] for k, v in d.items()],
+        deserialize=lambda c: {tuple(k): v for k, v in c},
+    )
+    result = reconcile(members, sorted_months, transactions, exceptions)
+    vm = build_adults_view_model(
+        members, sorted_months, result, transactions,
+        datetime.now().strftime("%Y-%m"),
+        attendance_url=attendance_url, payments_url=payments_url, bank_account=BANK_ACCOUNT,
+    )
+    return jsonify(_unwrap_view_model_for_api(vm))
+```
+
+`/api/juniors` mirrors with `adapt_junior_members` + `JUNIOR_SHEET_GID` + `build_juniors_view_model`. `/api/payments` skips the unwrap (its builder has no JSON-string fields): `return jsonify(vm)`. `/api/version`: `return jsonify(BUILD_META)`.
+
+## Files to modify
+
+- [app.py](app.py)
+  - L10: add `jsonify` to `from flask import ...`.
+  - Add `_unwrap_view_model_for_api` near [BUILD_META](app.py#L67) (it already imports `json as _json`).
+  - Add four routes: `/api/version`, `/api/adults`, `/api/juniors`, `/api/payments`. Place them after [`/version`](app.py#L143) for grouping.
+- [tests/test_app.py](tests/test_app.py)
+  - Add `EXPECTED_ADULTS_KEYS`, `EXPECTED_JUNIORS_KEYS`, `EXPECTED_PAYMENTS_KEYS`, `EXPECTED_VERSION_KEYS` module constants (sourced from [adults.go](go/internal/web/api/adults.go) / [juniors.go](go/internal/web/api/juniors.go) / [payments.go](go/internal/web/api/payments.go) / [version.go](go/internal/web/api/version.go) JSON tags).
+  - Four new test functions: `test_api_adults`, `test_api_juniors`, `test_api_payments`, `test_api_version`. Reuse the existing `_bypass_cache` patcher and the `fetch_sheet_data` / `fetch_exceptions` / `get_members_with_fees` / `get_junior_members_with_fees` mocks already in the file.
+  - Each adults/juniors test asserts: `200`, `response.is_json`, `set(json.keys()) == EXPECTED_*_KEYS`, `isinstance(json["member_data"], dict)`, `isinstance(json["month_labels"], dict)`, `isinstance(json["raw_payments"], dict)`.
+- [CHANGELOG.md](CHANGELOG.md): post-merge entry per CLAUDE.md format.
+- [docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md:102](docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md#L102): tick M5.3 with merge SHA.
+
+## Reusable existing code
+
+- [`build_adults_view_model`](scripts/views.py#L64), [`build_juniors_view_model`](scripts/views.py#L240), [`build_payments_view_model`](scripts/views.py#L432) — call as-is, no changes.
+- [`reconcile`](scripts/match_payments.py) and [`adapt_junior_members`](scripts/views.py#L48) — same.
+- [`get_cached_data`](app.py#L36), [`fetch_sheet_data`](scripts/match_payments.py), [`fetch_exceptions`](scripts/match_payments.py), [`get_members_with_fees`](scripts/attendance.py), [`get_junior_members_with_fees`](scripts/attendance.py) — same call sites as the HTML routes.
+- [`BUILD_META`](app.py#L67) — already shaped to match Go's `VersionResponse`.
+
+## Verification
+
+1. `make test` — all existing tests still pass; four new `test_api_*` tests pass.
+2. `python -c "import app"` — catches the missing `jsonify` import.
+3. `make web-py`, then:
+   - `curl -s localhost:5001/api/version | jq .` → `{tag, commit, build_date}`.
+   - `curl -s localhost:5001/api/adults | jq 'keys'` → 14 keys, no `_json` suffix anywhere.
+   - `curl -s localhost:5001/api/adults | jq '.member_data | type, .month_labels | type, .raw_payments | type'` → all `"object"` (proves unwrap).
+   - Same checks on `/api/juniors` and `/api/payments`.
+4. Visit `/adults`, `/juniors`, `/payments` in browser — HTML still renders identically (regression check on builders).
+5. **Optional pre-M5.4 peek:** `make web-go` on :8080 + `make web-py` on :5001, then `diff <(curl -s :5001/api/adults | jq -S .) <(curl -s :8080/api/adults | jq -S .)`. Expect non-zero diff (raw transaction key shape, see below) — that is fine; M5.4 surfaces and resolves these.
+
+## Out of scope (M5.4 will surface and resolve)
+
+These are known parity friction points; **don't fix in M5.3** — the whole point of M5.4 is to enumerate them:
+
+- **`raw_payments[name][i]` row shape**: Python emits raw Google Sheets row dicts with column-header keys (e.g. `"VS"`, `"Sync ID"`); Go's `RawTransaction` uses snake_case (`vs`, `sync_id`). Keys and types will diverge.
+- **`unmatched[]`**: same divergence (same raw row dicts).
+- **`null` vs missing keys**: Python omits keys never set; Go zero-value structs may emit `null`/`""` depending on `omitempty`.
+- **`Decimal` / float precision** in `grouped_payments` amounts.
+- **Field insertion order**: `jsonify` preserves insertion order (Python 3.7+); Go marshals struct fields in declaration order. Likely fine, parity tool will tell.
+
+## Branch + MR
+
+Per CLAUDE.md: branch `feat/go-m5-3-python-api-shadow`, push with `-u`, open MR via `tea pr create --title ... --description ... --base main --head feat/go-m5-3-python-api-shadow`. Do not merge from CLI.

docs/plans/2026-05-07-2254-m5-4-parity-binary.md

@@ -0,0 +1,152 @@
+# M5.4 — Parity diff binary (`cmd/parity`) + `make parity`
+
+## Context
+
+Per [docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md:103](docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md#L103), M5.4 is the next milestone in the Go rewrite. M5.1–M5.3 already landed:
+
+- M5.1: hand-authored Go response structs at [go/internal/web/api/](go/internal/web/api/) + JSON Schemas in [go/tests/fixtures/api-schema/](go/tests/fixtures/api-schema/).
+- M5.2: Go `/api/version|adults|juniors|payments` handlers in [go/internal/web/api/handler.go](go/internal/web/api/handler.go).
+- M5.3: Python shadow endpoints in [app.py:157-224](app.py#L157-L224) using `_unwrap_view_model_for_api` for the same JSON shape.
+
+What's missing: a tool that proves the two backends actually agree on the wire. The M5 gate says "byte-equal JSON between Python and Go for every route." Without a diffing tool, drift between the two implementations slips in silently and we can't gate further milestones (M6 frontend, M7 watch period) on parity.
+
+This task delivers the **parity contract enforcer**: a Go binary that fetches `/api/*` from both backends, scrubs an allowlist of expected diffs, and prints `cmp.Diff` for everything else. Both backends read the same live Google Sheets — that shared state is what makes parity meaningful, no scenario fixtures needed.
+
+## Scope
+
+In scope:
+- New binary `go/cmd/parity/main.go` plus a small support package for the allowlist scrubber.
+- A unit test for the scrubber.
+- New `make parity` target.
+- `go-cmp` promoted to a direct dependency.
+
+Out of scope (explicitly):
+- CI integration / nightly job — that's M7.2.
+- Fixture-driven offline parity — pure-fn parity already runs via `make go-parity` (M3).
+- Hooking `make parity` into `make go-test-all` — leave it manual since it requires two live servers.
+
+## Approach
+
+### 1. New binary: `go/cmd/parity/main.go`
+
+Standalone binary (mirrors task spec — not a subcommand of `fuj`). Stdlib `flag`, no third-party CLI lib.
+
+**Flags:**
+- `-py` — Python base URL, default `http://localhost:5001`
+- `-go` — Go base URL, default `http://localhost:8080`
+- `-route` — optional single route to diff (e.g. `/api/adults`); empty means iterate all four
+- `-timeout` — per-request timeout, default `30s` (sheet fetches are slow on cold cache)
+
+**Routes**, hard-coded:
+```go
+var routes = []string{"/api/version", "/api/adults", "/api/juniors", "/api/payments"}
+```
+All `GET`, no query params (verified in [app.py:157-224](app.py#L157-L224) and [go/internal/web/api/handler.go:27-68](go/internal/web/api/handler.go#L27-L68)).
+
+**Per route, the binary:**
+1. `GET py+route` and `GET go+route` (sequential — keep it simple; total wall time ~1–2s on warm cache).
+2. Verify both return HTTP 200; on non-200, print body and mark route as ERROR.
+3. Decode each body into `map[string]any` (NOT into `api.AdultsResponse` — using the typed struct would silently drop unknown Python-side keys, defeating the diff. Map gives `cmp.Diff` clean dotted-path field names for free.).
+4. Run `scrub(m, allowlist)` on both decoded maps.
+5. `diff := cmp.Diff(pyMap, goMap, cmpopts.EquateEmpty())`.
+6. If `diff != ""`, print `=== /api/X ===` header followed by the diff; track for exit code.
+
+**Exit codes:**
+- `0` — all routes match (or the only diffs were under the allowlist).
+- `1` — at least one route had a non-allowlisted diff.
+- `2` — at least one route failed to fetch / parse (HTTP error, timeout, non-JSON body).
+
+This makes the binary CI-friendly when M7.2 lands.
+
+**Output**: human-readable to stdout — header per route, then "OK" or the diff. Final summary line: `parity: 4/4 routes match` or `parity: 2/4 match, 1 diff, 1 error`.
+
+### 2. Allowlist scrubber
+
+Live in same package (`main`). Keep it tiny — no need for a separate sub-package.
+
+```go
+var defaultAllowlist = []string{"render_time.total", "build_meta"}
+
+// scrub walks m and deletes any key whose dotted path matches an allowlist entry.
+// "render_time.total" deletes m["render_time"]["total"] only (preserves render_time.breakdown).
+// "build_meta" (no dot) deletes m["build_meta"] entirely.
+func scrub(m map[string]any, paths []string) { ... }
+```
+
+Today these fields **don't appear in the JSON** — they're Jinja template-only ([app.py:91-110](app.py#L91-L110)) and the Go side only logs render time via [go/internal/web/middleware/timer.go](go/internal/web/middleware/timer.go). So today the scrub is a no-op. The implementation is forward-compatible insurance: if someone later adds either field to a JSON response on one side only, the parity binary already tolerates it.
+
+The implementation note in [go/internal/web/middleware/timer.go](go/internal/web/middleware/timer.go) ("the elapsed value maps to render_time.total in the M5 JSON allowlist") confirms this is the intended design.
+
+### 3. Unit test
+
+Add `go/cmd/parity/scrub_test.go` with a couple of cases:
+- Scrubbing top-level key (`build_meta`) — key removed; siblings untouched.
+- Scrubbing nested key (`render_time.total`) — only `total` removed; `breakdown` preserved.
+- Path that doesn't exist — no-op, no error.
+- Map without the parent key — no-op (don't panic).
+
+Runs as part of normal `make go-test` (no `-tags` needed).
+
+### 4. Makefile target
+
+Add to [Makefile](Makefile):
+
+```make
+parity:
+	cd $(GO_SRC) && go run ./cmd/parity $(ARGS)
+```
+
+Add `parity` to the `.PHONY` line at [Makefile:1](Makefile#L1) and a `help` entry like:
+
+```
+@echo "  make parity      - Diff /api/* between web-py (:5001) and web-go (:8080); both must be running"
+```
+
+Don't depend on `go-build` — `go run` compiles ad-hoc, and parity is interactive enough that the slight rebuild cost doesn't matter.
+
+### 5. Dependency
+
+`github.com/google/go-cmp v0.7.0` is already a transitive dep ([go/go.sum:24-25](go/go.sum#L24-L25)) but not in `go.mod`'s `require` block. After adding the import, run `go mod tidy` inside `go/` to promote it to direct. No new external deps.
+
+## Files to add / modify
+
+**Add:**
+- [go/cmd/parity/main.go](go/cmd/parity/main.go) — flags, route loop, fetch+scrub+diff, exit codes
+- [go/cmd/parity/scrub_test.go](go/cmd/parity/scrub_test.go) — unit tests for the scrubber
+
+**Modify:**
+- [Makefile](Makefile) — `.PHONY`, help block, `parity` target
+- [go/go.mod](go/go.mod) — promote `go-cmp` to direct (via `go mod tidy`)
+- [go/go.sum](go/go.sum) — likely unchanged (already pinned)
+- [docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md](docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md) — tick M5.4, add commit SHA
+- [CHANGELOG.md](CHANGELOG.md) — entry per project convention
+
+**Per [CLAUDE.md](CLAUDE.md) plans convention:** copy this plan to `docs/plans/2026-05-07-HHMM-m5-4-parity-binary.md` (timestamp via `date "+%Y-%m-%d-%H%M"`) before opening the MR, since plan files are committed for posterity.
+
+## Existing utilities to reuse
+
+- `cmp.Diff` + `cmpopts.EquateEmpty()` from `github.com/google/go-cmp/cmp` (already in go.sum).
+- Stdlib `net/http`, `encoding/json`, `flag` — sufficient; no need to pull a CLI framework.
+- No existing scrubber to reuse — the one in [scripts/scrub_fixtures.py](scripts/scrub_fixtures.py) operates on the *capture* path and renames PII; the parity scrubber is a different concern (path-based deletion of expected diffs).
+
+## Verification
+
+Manual smoke test (the binary is meant to be run against live servers):
+
+1. **Sanity / build:** `cd go && go build ./cmd/parity && go test ./cmd/parity/...` — compiles + scrubber unit test passes.
+2. **Both backends up:**
+   - Terminal A: `make web-py`
+   - Terminal B: `make web-go`
+   - Terminal C: `make parity`
+   Expected: `parity: 4/4 routes match`, exit 0.
+3. **Negative test:** add a literal extra field to one Go handler temporarily (e.g. `"diagnostic": "test"` in `VersionResponse`), rebuild, re-run `make parity`. Expected: non-zero exit, diff shown for `/api/version`. Revert.
+4. **Allowlist test:** in a unit test (or by manually constructing a payload with `render_time.total` injected), confirm the scrubber removes it before the diff stage.
+5. **CHANGELOG** entry added; progress tracker ticked with the merge commit SHA.
+
+Per [CLAUDE.md](CLAUDE.md) branching policy: this is a feature, so work happens on `feat/go-m5-4-parity-binary`, push with `-u`, open MR with `tea pr create --base main --head feat/go-m5-4-parity-binary`. User merges in Gitea.
+
+## Notes & risks
+
+- **Cache-warmth dependency:** Both backends cache aggressively. A cold-cache fetch on Python can take 30s+ — hence the configurable timeout. If parity is run immediately after `flush-cache`, expect the first run to be slow.
+- **Order-sensitive lists:** `cmp.Diff` on `map[string]any` treats slices as ordered. If either backend ever returns members/transactions in a different order, the diff will flag it — that's a real parity bug, not a false positive, so this is correct behavior. If we hit ordering instability later, fix the source, don't add `cmpopts.SortSlices`.
+- **Float formatting:** Both sides go through `encoding/json` (Go) and `jsonify` (Python `json.dumps`). Floats in totals/balances may format differently (`123` vs `123.0`). If this surfaces, the Go side already uses typed structs with `int` where appropriate — investigate at the source rather than allowlisting.

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).

go/cmd/fuj/main.go

@@ -73,10 +73,18 @@ func serverCmd(args []string) {
 		cfg.ServerAddr = *addr
 	}
 
+	ctx := context.Background()
 	logger := logging.New(cfg.LogLevel)
+
+	sources, err := membership.NewSources(ctx, cfg)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "fuj server: init sources: %v\n", err)
+		os.Exit(1)
+	}
+
 	build := web.BuildInfo{Version: version, Commit: commit, BuildDate: buildDate}
 
-	if err := web.Run(logger, cfg.ServerAddr, build); err != nil {
+	if err := web.Run(logger, cfg.ServerAddr, build, sources, cfg); err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
 	}

go/cmd/parity/main.go

@@ -0,0 +1,133 @@
+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
+)
+
+// /api/version is intentionally excluded — it returns each binary's own build
+// identity (tag/commit/build_date), which differs by design between independently
+// built backends. Pass -route /api/version to inspect it manually.
+var allRoutes = []string{"/api/adults", "/api/juniors", "/api/payments"}
+
+// defaultAllowlist holds dotted key paths to strip before diffing.
+// render_time.total is forward-compatible insurance: today it lives in the Jinja
+// template context only (app.py inject_render_time) and is logged via
+// middleware/timer.go on the Go side, so it isn't in any JSON response. If either
+// side ever surfaces it under a render_time envelope, the scrubber handles it.
+var defaultAllowlist = []string{"render_time.total"}
+
+func main() {
+	pyURL := flag.String("py", "http://localhost:5001", "Python backend base URL")
+	goURL := flag.String("go", "http://localhost:8080", "Go backend base URL")
+	route := flag.String("route", "", "single route to diff, e.g. /api/adults (default: all)")
+	timeout := flag.Duration("timeout", 30*time.Second, "per-request HTTP timeout")
+	flag.Parse()
+
+	client := &http.Client{Timeout: *timeout}
+
+	targets := allRoutes
+	if *route != "" {
+		targets = []string{*route}
+	}
+
+	matched, diffs, errs := 0, 0, 0
+
+	for _, r := range targets {
+		pyMap, err1 := fetch(client, *pyURL+r)
+		goMap, err2 := fetch(client, *goURL+r)
+
+		if err1 != nil || err2 != nil {
+			fmt.Printf("=== %s ===\n", r)
+			if err1 != nil {
+				fmt.Printf("ERROR (py): %v\n", err1)
+			}
+			if err2 != nil {
+				fmt.Printf("ERROR (go): %v\n", err2)
+			}
+			fmt.Println()
+			errs++
+			continue
+		}
+
+		scrub(pyMap, defaultAllowlist)
+		scrub(goMap, defaultAllowlist)
+
+		diff := cmp.Diff(pyMap, goMap, cmpopts.EquateEmpty())
+		if diff == "" {
+			fmt.Printf("=== %s ===\nOK\n\n", r)
+			matched++
+		} else {
+			fmt.Printf("=== %s ===\n%s\n", r, diff)
+			diffs++
+		}
+	}
+
+	total := len(targets)
+	fmt.Printf("parity: %d/%d routes match", matched, total)
+	if diffs > 0 {
+		fmt.Printf(", %d diff", diffs)
+		if diffs > 1 {
+			fmt.Print("s")
+		}
+	}
+	if errs > 0 {
+		fmt.Printf(", %d error", errs)
+		if errs > 1 {
+			fmt.Print("s")
+		}
+	}
+	fmt.Println()
+
+	if errs > 0 {
+		os.Exit(2)
+	}
+	if diffs > 0 {
+		os.Exit(1)
+	}
+}
+
+func fetch(client *http.Client, url string) (map[string]any, error) {
+	resp, err := client.Get(url) //nolint:noctx
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("read body: %w", err)
+	}
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("HTTP %d: %s", resp.StatusCode, strings.TrimSpace(string(body)))
+	}
+	var m map[string]any
+	if err := json.Unmarshal(body, &m); err != nil {
+		return nil, fmt.Errorf("decode JSON: %w", err)
+	}
+	return m, nil
+}
+
+// scrub removes keys from m whose dotted paths appear in paths.
+// A bare segment (no dot) deletes a top-level key.
+// A two-segment path "parent.child" deletes child from m["parent"] if it is a map.
+func scrub(m map[string]any, paths []string) {
+	for _, path := range paths {
+		parts := strings.SplitN(path, ".", 2)
+		if len(parts) == 1 {
+			delete(m, parts[0])
+		} else {
+			if child, ok := m[parts[0]].(map[string]any); ok {
+				delete(child, parts[1])
+			}
+		}
+	}
+}

go/cmd/parity/scrub_test.go

@@ -0,0 +1,57 @@
+package main
+
+import "testing"
+
+func TestScrubTopLevel(t *testing.T) {
+	m := map[string]any{
+		"build_meta": map[string]any{"tag": "v1"},
+		"other":      "keep",
+	}
+	scrub(m, []string{"build_meta"})
+	if _, ok := m["build_meta"]; ok {
+		t.Error("expected build_meta to be removed")
+	}
+	if m["other"] != "keep" {
+		t.Error("expected other to be preserved")
+	}
+}
+
+func TestScrubNested(t *testing.T) {
+	m := map[string]any{
+		"render_time": map[string]any{
+			"total":     "0.123",
+			"breakdown": "fetch:0.1s",
+		},
+		"other": "keep",
+	}
+	scrub(m, []string{"render_time.total"})
+	rt, ok := m["render_time"].(map[string]any)
+	if !ok {
+		t.Fatal("render_time should still be present")
+	}
+	if _, ok := rt["total"]; ok {
+		t.Error("expected render_time.total to be removed")
+	}
+	if rt["breakdown"] != "fetch:0.1s" {
+		t.Error("expected render_time.breakdown to be preserved")
+	}
+	if m["other"] != "keep" {
+		t.Error("expected other to be preserved")
+	}
+}
+
+func TestScrubMissingPath(t *testing.T) {
+	m := map[string]any{"foo": "bar"}
+	scrub(m, []string{"nonexistent", "render_time.total"})
+	if m["foo"] != "bar" {
+		t.Error("expected foo to be preserved")
+	}
+}
+
+func TestScrubNestedParentNotMap(t *testing.T) {
+	m := map[string]any{"render_time": "not-a-map"}
+	scrub(m, []string{"render_time.total"})
+	if m["render_time"] != "not-a-map" {
+		t.Error("expected render_time to be unchanged when it is not a map")
+	}
+}

go/go.mod

@@ -3,6 +3,7 @@ module fuj-management/go
 go 1.26.1
 
 require (
+	github.com/google/go-cmp v0.7.0
 	github.com/invopop/jsonschema v0.14.0
 	golang.org/x/net v0.53.0
 	golang.org/x/text v0.36.0

go/internal/config/config.go

@@ -50,7 +50,7 @@ func Load() Config {
 	return Config{
 		CredentialsPath:  env("CREDENTIALS_PATH", ".secret/fuj-management-bot-credentials.json"),
 		BankAccount:      env("BANK_ACCOUNT", "CZ8520100000002800359168"),
-		CacheDir:         env("CACHE_DIR", "tmp"),
+		CacheDir:         env("CACHE_DIR", "tmp/go"),
 		CacheTTL:         envDuration("CACHE_TTL_SECONDS", 300),
 		CacheAPICheckTTL: envDuration("CACHE_API_CHECK_TTL_SECONDS", 300),
 		DriveTimeout:     envDuration("DRIVE_TIMEOUT_SECONDS", 10),

go/internal/domain/reconcile/reconcile.go

@@ -20,10 +20,13 @@ type Exception struct {
 	Note   string
 }
 
-// FeeData holds the expected fee and attendance count for one member in one month.
+// FeeData holds the expected fee and attendance data for one member in one month.
 type FeeData struct {
-	Expected   int
+	Expected         int
-	Attendance int
+	IsUnknown        bool // true when junior has exactly 1 session (manual review; Python sentinel "?")
+	Attendance       int
+	JuniorAttendance int // junior-tab sessions; used for the :NJ,MA breakdown in the juniors view
+	AdultAttendance  int // adult-tab sessions for J-tier members; used for the :NJ,MA breakdown
 }
 
 // Member is one row from the attendance sheet.
@@ -39,11 +42,15 @@ type Member struct {
 type Transaction struct {
 	Date           string
 	Amount         float64
+	ManualFix      string   // "manual fix" column; non-empty disables re-inference
 	Person         string   // comma-separated canonical names (empty → use inference)
 	Purpose        string   // comma-separated "YYYY-MM" or "other:…" (empty → use inference)
 	InferredAmount *float64 // nil → fall back to Amount
 	Sender         string
+	VS             string // Variabilní symbol (Czech variable payment symbol)
 	Message        string
+	BankID         string
+	SyncID         string
 	UserID         string
 }
 
@@ -69,8 +76,11 @@ type OtherEntry struct {
 // MonthData is the ledger state for one member in one month.
 type MonthData struct {
 	Expected         int
+	IsUnknown        bool // mirrors FeeData.IsUnknown; not overridden by exceptions
 	OriginalExpected int
 	AttendanceCount  int
+	JuniorAttendance int // junior-tab sessions; for :NJ,MA breakdown in juniors view
+	AdultAttendance  int // adult-tab sessions; for :NJ,MA breakdown
 	Exception        *Exception
 	Paid             float64
 	Transactions     []TxEntry
@@ -173,8 +183,11 @@ func Reconcile(
 
 			ledger[name][m] = MonthData{
 				Expected:         expected,
+				IsUnknown:        fd.IsUnknown,
 				OriginalExpected: originalExpected,
 				AttendanceCount:  attendanceCount,
+				JuniorAttendance: fd.JuniorAttendance,
+				AdultAttendance:  fd.AdultAttendance,
 				Exception:        exInfo,
 				Paid:             0,
 				Transactions:     []TxEntry{},

go/internal/domain/reconcile/reconcile_test.go

@@ -29,7 +29,7 @@ func tx(person, purpose string, amount float64) Transaction {
 
 func TestReconcileExceptionOverride(t *testing.T) {
 	t.Parallel()
-	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {750, 4}}}}
+	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 4}}}}
 	exceptions := map[ExceptionKey]Exception{
 		{Name: "alice", Period: "2026-01"}: {Amount: 400, Note: "Test exception"},
 	}
@@ -54,7 +54,7 @@ func TestReconcileExceptionOverride(t *testing.T) {
 
 func TestReconcileFallbackToAttendance(t *testing.T) {
 	t.Parallel()
-	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {750, 4}}}}
+	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 4}}}}
 
 	result := Reconcile(members, []string{"2026-01"}, nil, nil, defaultYear)
 
@@ -68,9 +68,9 @@ func TestReconcileGreedyExactMatch(t *testing.T) {
 	members := []Member{{
 		Name: "Alice", Tier: "A",
 		Fees: map[string]FeeData{
-			"2026-02": {750, 3},
+			"2026-02": {Expected: 750, Attendance: 3},
-			"2026-03": {350, 3},
+			"2026-03": {Expected: 350, Attendance: 3},
-			"2026-04": {150, 2},
+			"2026-04": {Expected: 150, Attendance: 2},
 		},
 	}}
 	sortedMonths := []string{"2026-02", "2026-03", "2026-04"}
@@ -93,7 +93,7 @@ func TestReconcileGreedyOverpaymentGoesToCredit(t *testing.T) {
 	t.Parallel()
 	members := []Member{{
 		Name: "Alice", Tier: "A",
-		Fees: map[string]FeeData{"2026-01": {750, 3}, "2026-02": {750, 3}},
+		Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}, "2026-02": {Expected: 750, Attendance: 3}},
 	}}
 	sortedMonths := []string{"2026-01", "2026-02"}
 
@@ -115,7 +115,7 @@ func TestReconcileProportionalUnderpayment(t *testing.T) {
 	t.Parallel()
 	members := []Member{{
 		Name: "Alice", Tier: "A",
-		Fees: map[string]FeeData{"2026-02": {750, 3}, "2026-03": {350, 3}, "2026-04": {750, 3}},
+		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
@@ -146,7 +146,7 @@ func TestReconcileProportionalUnderpayment(t *testing.T) {
 
 func TestReconcileSingleMonthUnchanged(t *testing.T) {
 	t.Parallel()
-	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {750, 3}}}}
+	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}}}}
 
 	result := Reconcile(members, []string{"2026-01"}, []Transaction{tx("Alice", "2026-01", 750)}, nil, defaultYear)
 
@@ -158,8 +158,8 @@ func TestReconcileSingleMonthUnchanged(t *testing.T) {
 func TestReconcileTwoMembersMultiMonth(t *testing.T) {
 	t.Parallel()
 	members := []Member{
-		{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {750, 3}, "2026-02": {350, 3}}},
+		{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}, "2026-02": {Expected: 350, Attendance: 3}}},
-		{Name: "Bob", Tier: "A", Fees: map[string]FeeData{"2026-01": {750, 3}, "2026-02": {350, 3}}},
+		{Name: "Bob", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}, "2026-02": {Expected: 350, Attendance: 3}}},
 	}
 	sortedMonths := []string{"2026-01", "2026-02"}
 
@@ -180,7 +180,7 @@ func TestReconcileEvenSplitFallbackWhenNoExpected(t *testing.T) {
 	t.Parallel()
 	members := []Member{{
 		Name: "Alice", Tier: "A",
-		Fees: map[string]FeeData{"2026-01": {0, 0}, "2026-02": {0, 0}},
+		Fees: map[string]FeeData{"2026-01": {Expected: 0, Attendance: 0}, "2026-02": {Expected: 0, Attendance: 0}},
 	}}
 	sortedMonths := []string{"2026-01", "2026-02"}
 
@@ -197,7 +197,7 @@ func TestReconcileEvenSplitFallbackWhenNoExpected(t *testing.T) {
 
 func TestReconcileDiacriticsTolerantPersonMatching(t *testing.T) {
 	t.Parallel()
-	members := []Member{{Name: "Mária Maco", Tier: "A", Fees: map[string]FeeData{"2026-04": {750, 4}}}}
+	members := []Member{{Name: "Mária Maco", Tier: "A", Fees: map[string]FeeData{"2026-04": {Expected: 750, Attendance: 4}}}}
 	txFn := func(person string) Transaction {
 		return Transaction{
 			Date: "2026-04-15", Amount: 750, Person: person, Purpose: "2026-04",
@@ -232,7 +232,7 @@ func TestReconcileDiacriticsTolerantPersonMatching(t *testing.T) {
 
 func TestReconcileTrulyUnknownPersonIsUnmatched(t *testing.T) {
 	t.Parallel()
-	members := []Member{{Name: "Mária Maco", Tier: "A", Fees: map[string]FeeData{"2026-04": {750, 4}}}}
+	members := []Member{{Name: "Mária Maco", Tier: "A", Fees: map[string]FeeData{"2026-04": {Expected: 750, Attendance: 4}}}}
 	txs := []Transaction{{
 		Date: "2026-04-15", Amount: 750,
 		Person: "Někdo Neznámý", Purpose: "2026-04",
@@ -252,7 +252,7 @@ func TestReconcileTrulyUnknownPersonIsUnmatched(t *testing.T) {
 // [Go] Test that [?] markers are stripped from the Person field before lookup.
 func TestReconcileQuestionMarkMarkerStripped(t *testing.T) {
 	t.Parallel()
-	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {750, 3}}}}
+	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}}}}
 	txs := []Transaction{{
 		Date: "2026-01-01", Amount: 750,
 		Person: "[?] Alice", Purpose: "2026-01",
@@ -269,7 +269,7 @@ func TestReconcileQuestionMarkMarkerStripped(t *testing.T) {
 // [Go] Purpose "other:shirt" puts payment in OtherTransactions, not in month ledger.
 func TestReconcileOtherPurpose(t *testing.T) {
 	t.Parallel()
-	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {750, 3}}}}
+	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}}}}
 	txs := []Transaction{{
 		Date: "2026-01-01", Amount: 300,
 		Person: "Alice", Purpose: "other:shirt",
@@ -297,7 +297,7 @@ func TestReconcileOtherPurpose(t *testing.T) {
 func TestReconcileOutOfWindowGoesToCredit(t *testing.T) {
 	t.Parallel()
 	// Window shows only 2026-01. Transaction references 2026-01 (in) and 2026-02 (out).
-	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {600, 3}}}}
+	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 600, Attendance: 3}}}}
 	txs := []Transaction{{
 		Date: "2026-01-01", Amount: 1200,
 		Person: "Alice", Purpose: "2026-01, 2026-02",
@@ -322,7 +322,7 @@ func TestReconcileOutOfWindowGoesToCredit(t *testing.T) {
 // [Go] No person/purpose → inference fallback resolves sender name and date month.
 func TestReconcileInferenceFallback(t *testing.T) {
 	t.Parallel()
-	members := []Member{{Name: "Tomáš Němeček", Tier: "A", Fees: map[string]FeeData{"2026-04": {750, 3}}}}
+	members := []Member{{Name: "Tomáš Němeček", Tier: "A", Fees: map[string]FeeData{"2026-04": {Expected: 750, Attendance: 3}}}}
 	txs := []Transaction{{
 		Date: "2026-04-15", Amount: 750,
 		// Person and Purpose are empty → inference path
@@ -340,7 +340,7 @@ func TestReconcileInferenceFallback(t *testing.T) {
 // [Go] Transaction with no match at all ends up in Unmatched; ledger unchanged.
 func TestReconcileNoMatchGoesToUnmatched(t *testing.T) {
 	t.Parallel()
-	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {750, 3}}}}
+	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}}}}
 	txs := []Transaction{{
 		Date: "2026-01-01", Amount: 500,
 		// empty person+purpose and sender name not matching any member
@@ -360,7 +360,7 @@ func TestReconcileNoMatchGoesToUnmatched(t *testing.T) {
 // [Go] Empty transaction list leaves every month at paid=0 and balance=–expected.
 func TestReconcileNoTransactionsAllUnpaid(t *testing.T) {
 	t.Parallel()
-	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {750, 3}}}}
+	members := []Member{{Name: "Alice", Tier: "A", Fees: map[string]FeeData{"2026-01": {Expected: 750, Attendance: 3}}}}
 
 	result := Reconcile(members, []string{"2026-01"}, nil, nil, defaultYear)
 

go/internal/io/fio/fio_test.go

@@ -98,8 +98,8 @@ func TestParseCzechDate(t *testing.T) {
 		{"7.5.2026", "2026-05-07"},  // non-padded — real Fio transparent page format
 		{"3.12.2025", "2025-12-03"}, // non-padded single-digit day, double-digit month
 		{"07.05.26", "2026-05-07"},  // padded 2-digit year — current Fio transparent page format
-		{"7.5.26", "2026-05-07"},   // non-padded 2-digit year
+		{"7.5.26", "2026-05-07"},    // non-padded 2-digit year
-		{"07/05/26", "2026-05-07"}, // slash variant
+		{"07/05/26", "2026-05-07"},  // slash variant
 		{"", ""},
 		{"invalid", ""},
 	}

go/internal/services/banksync/fio_table.go

@@ -2,10 +2,9 @@ package banksync
 
 import (
 	"fmt"
+	"fuj-management/go/internal/io/fio"
 	"io"
 	"text/tabwriter"
-
-	"fuj-management/go/internal/io/fio"
 )
 
 func printFioTable(w io.Writer, txns []fio.Transaction, syncIDs []string, existing map[string]bool) {

go/internal/services/membership/sources.go

@@ -25,12 +25,14 @@ const (
 	firstDateCol = 3
 )
 
-// adultMergedMonths mirrors ADULT_MERGED_MONTHS in scripts/attendance.py.
+// 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.
+// JuniorMergedMonths mirrors JUNIOR_MERGED_MONTHS in scripts/attendance.py.
-var juniorMergedMonths = map[string]string{
+var JuniorMergedMonths = map[string]string{
 	"2025-12": "2026-01",
 	"2025-09": "2025-10",
 }
@@ -142,7 +144,13 @@ func parseDates(header []string) []struct {
 		}
 		var dt time.Time
 		var err error
-		for _, fmt_ := range []string{"02.01.2006", "01/02/2006"} {
+		// Use the unpadded reference forms ("2.1" and "1/2"): Go's time.Parse
+		// accepts both single-digit and zero-padded inputs against them, so
+		// "1.6.2026", "01.06.2026", "23.3.2026" all parse. Czech sheet authors
+		// drop the leading zero on dates ≤ 9 — Python's strptime is lenient
+		// the same way; the previous "02.01.2006" form silently dropped those
+		// columns and undercounted attendance.
+		for _, fmt_ := range []string{"2.1.2006", "1/2/2006"} {
 			dt, err = time.Parse(fmt_, raw)
 			if err == nil {
 				break
@@ -195,7 +203,7 @@ func parseAdultRows(rows [][]string) ([]reconcile.Member, []string, error) {
 		return nil, nil, nil
 	}
 	dates := parseDates(rows[0])
-	months := groupByMonth(dates, adultMergedMonths)
+	months := groupByMonth(dates, AdultMergedMonths)
 	sortedMonths := sortedKeys(months)
 
 	var members []reconcile.Member
@@ -243,8 +251,8 @@ func parseJuniorRows(adultRows, juniorRows [][]string) ([]reconcile.Member, []st
 
 	mainDates := parseDates(adultRows[0])
 	juniorDates := parseDates(juniorRows[0])
-	mainMonths := groupByMonth(mainDates, juniorMergedMonths)
+	mainMonths := groupByMonth(mainDates, JuniorMergedMonths)
-	jrMonths := groupByMonth(juniorDates, juniorMergedMonths)
+	jrMonths := groupByMonth(juniorDates, JuniorMergedMonths)
 
 	allMonths := make(map[string]bool)
 	for m := range mainMonths {
@@ -337,7 +345,13 @@ func parseJuniorRows(adultRows, juniorRows [][]string) ([]reconcile.Member, []st
 			if !exp.Unknown {
 				fee = exp.Value
 			}
-			feeMap[m] = reconcile.FeeData{Expected: fee, Attendance: total}
+			feeMap[m] = reconcile.FeeData{
+				Expected:         fee,
+				IsUnknown:        exp.Unknown,
+				Attendance:       total,
+				JuniorAttendance: c.junior,
+				AdultAttendance:  c.adult,
+			}
 		}
 		members = append(members, reconcile.Member{Name: name, Tier: data.tier, Fees: feeMap})
 	}
@@ -365,11 +379,15 @@ func parseTransactionRows(rows [][]any) ([]reconcile.Transaction, error) {
 	}
 	idxDate := idx("date")
 	idxAmount := idx("amount")
+	idxManualFix := idx("manual fix")
 	idxPerson := idx("person")
 	idxPurpose := idx("purpose")
 	idxInferred := idx("inferred amount")
 	idxSender := idx("sender")
+	idxVS := idx("vs")
 	idxMessage := idx("message")
+	idxBankID := idx("bank id")
+	idxSyncID := idx("sync id")
 
 	for _, label := range []string{"date", "amount", "person", "purpose"} {
 		if idx(label) == -1 {
@@ -384,9 +402,19 @@ func parseTransactionRows(rows [][]any) ([]reconcile.Transaction, error) {
 		return fmt.Sprint(row[i])
 	}
 
+	// getRaw returns row[i] without stringifying — needed for FormatDate to
+	// dispatch on the underlying numeric type (Sheets returns serial-day
+	// numbers as float64). Stringifying first defeats that dispatch.
+	getRaw := func(row []any, i int) any {
+		if i < 0 || i >= len(row) {
+			return nil
+		}
+		return row[i]
+	}
+
 	var txns []reconcile.Transaction
 	for _, row := range rows[1:] {
-		dateStr := matching.FormatDate(getVal(row, idxDate))
+		dateStr := matching.FormatDate(getRaw(row, idxDate))
 		amountRaw := row[idxAmount]
 		if idxAmount < 0 || idxAmount >= len(row) {
 			amountRaw = ""
@@ -403,11 +431,15 @@ func parseTransactionRows(rows [][]any) ([]reconcile.Transaction, error) {
 		txns = append(txns, reconcile.Transaction{
 			Date:           dateStr,
 			Amount:         amount,
+			ManualFix:      getVal(row, idxManualFix),
 			Person:         getVal(row, idxPerson),
 			Purpose:        getVal(row, idxPurpose),
 			InferredAmount: inferredAmount,
 			Sender:         getVal(row, idxSender),
+			VS:             getVal(row, idxVS),
 			Message:        getVal(row, idxMessage),
+			BankID:         getVal(row, idxBankID),
+			SyncID:         getVal(row, idxSyncID),
 		})
 	}
 	return txns, nil

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"])
 	}
@@ -114,12 +114,15 @@ func TestLoadJuniors(t *testing.T) {
 
 func TestLoadTransactions(t *testing.T) {
 	// Sheets fake keyed by "<spreadsheetID>/<range>" — use the real constant.
+	// Row 1 uses a pre-formatted date string; row 2 uses the numeric Sheets
+	// serial-day form (float64) — the API returns either depending on cell
+	// formatting, and FormatDate must handle both.
 	paymentsKey := config.PaymentsSheetID + "/A1:Z"
 	sh := &sheets.Fake{Values: map[string][][]any{
 		paymentsKey: {
 			{"Date", "Amount", "manual fix", "Person", "Purpose", "Inferred Amount", "Sender", "VS", "Message", "Bank ID", "Sync ID"},
 			{"2026-04-01", 700.0, "", "Alice", "2026-04", "", "Alice Bank", "", "fee", "", "abc"},
-			{"2026-05-01", 500.0, "", "", "", "", "Bob Bank", "", "platba", "", "def"},
+			{46147.0, 500.0, "", "", "", "", "Bob Bank", "", "platba", "", "def"}, // 46147 serial-day = 2026-05-05
 		},
 	}}
 	s := buildSources(t, &attendance.Fake{}, sh)
@@ -137,6 +140,12 @@ func TestLoadTransactions(t *testing.T) {
 	if txns[0].Amount != 700 {
 		t.Errorf("txn[0].Amount: want 700, got %v", txns[0].Amount)
 	}
+	if txns[0].Date != "2026-04-01" {
+		t.Errorf("txn[0].Date: want 2026-04-01, got %q", txns[0].Date)
+	}
+	if txns[1].Date != "2026-05-05" {
+		t.Errorf("txn[1].Date (numeric serial-day): want 2026-05-05, got %q", txns[1].Date)
+	}
 }
 
 func TestLoadExceptions(t *testing.T) {
@@ -165,6 +174,28 @@ func TestLoadExceptions(t *testing.T) {
 	}
 }
 
+// TestParseDates_SingleDigitDayMonth covers the regression where Go's strict
+// "02.01.2006" format dropped header cells written without leading zeros
+// (e.g. "1.6.2026", "23.3.2026"), causing attendance undercounts and missing
+// months on the /api/juniors response. Czech sheet authors drop the zero
+// pad freely; Python's strptime tolerates it, so the parsers must match.
+func TestParseDates_SingleDigitDayMonth(t *testing.T) {
+	// Czech form ("DD.MM.YYYY", with leading zeros optional) is the primary
+	// path. The "M/D/YYYY" fallback mirrors Python's %m/%d/%Y secondary
+	// strptime branch — month-first, day-second.
+	header := []string{"Jméno", "Tier", "", "01.06.2026", "1.6.2026", "23.3.2026", "6.4.2026", "01/02/2026", "1/2/2026"}
+	got := parseDates(header)
+	want := []string{"2026-06", "2026-06", "2026-03", "2026-04", "2026-01", "2026-01"}
+	if len(got) != len(want) {
+		t.Fatalf("parseDates: got %d entries, want %d (%v)", len(got), len(want), got)
+	}
+	for i, e := range got {
+		if e.month != want[i] {
+			t.Errorf("parseDates[%d].month = %q, want %q (raw=%q)", i, e.month, want[i], header[e.col])
+		}
+	}
+}
+
 // TTL smoke test: second call within TTL must not call fetch again.
 func TestLoadAdults_CacheHit(t *testing.T) {
 	dir := t.TempDir()

go/internal/web/api/build_adults.go

@@ -0,0 +1,263 @@
+package api
+
+import (
+	"fmt"
+	"fuj-management/go/internal/config"
+	"fuj-management/go/internal/services/membership"
+	"sort"
+	"time"
+
+	domreconcile "fuj-management/go/internal/domain/reconcile"
+)
+
+type monthSums struct{ expected, paid int }
+
+// buildAdultsResponse constructs the AdultsResponse wire type from reconcile output.
+// Mirrors scripts/views.py:build_adults_view_model.
+func buildAdultsResponse(
+	members []domreconcile.Member,
+	sortedMonths []string,
+	result domreconcile.Result,
+	txns []domreconcile.Transaction,
+	cfg config.Config,
+	currentMonth string,
+) AdultsResponse {
+	monthLabels := getMonthLabels(sortedMonths, membership.AdultMergedMonths)
+
+	// Collect tier-A names, sorted.
+	var adultNames []string
+	allNames := make([]string, 0, len(members))
+	for _, m := range members {
+		allNames = append(allNames, m.Name)
+		if m.Tier == "A" {
+			adultNames = append(adultNames, m.Name)
+		}
+	}
+	sort.Strings(adultNames)
+
+	// Per-month aggregate totals (expected and paid integers).
+	monthlyTotals := make(map[string]*monthSums, len(sortedMonths))
+	for _, m := range sortedMonths {
+		monthlyTotals[m] = &monthSums{}
+	}
+
+	var results []MemberRow
+	for _, name := range adultNames {
+		mr := result.Members[name]
+		row, unpaidMonths, rawUnpaidMonths := buildAdultMemberRow(name, mr, sortedMonths, monthLabels, currentMonth, monthlyTotals)
+		row.UnpaidPeriods = joinComma(unpaidMonths)
+		row.RawUnpaidPeriods = joinPlus(rawUnpaidMonths)
+		row.Balance = settledBalance(mr, currentMonth)
+		row.PayableAmount = max(0, -row.Balance)
+		results = append(results, row)
+	}
+
+	// Totals row.
+	totalsCells := make([]TotalCell, len(sortedMonths))
+	for i, m := range sortedMonths {
+		t := monthlyTotals[m] // *monthSums, never nil (initialised above)
+		status := "empty"
+		if t.expected > 0 || t.paid > 0 {
+			switch {
+			case t.paid == t.expected:
+				status = "ok"
+			case t.paid < t.expected:
+				status = "unpaid"
+			default:
+				status = "surplus"
+			}
+		}
+		totalsCells[i] = TotalCell{
+			Text:   fmt.Sprintf("%d / %d CZK", t.paid, t.expected),
+			Status: status,
+		}
+	}
+
+	// Credits and debts (settled balance, past months only).
+	var credits, debts []Credit
+	for _, name := range adultNames {
+		bal := settledBalance(result.Members[name], currentMonth)
+		if bal > 0 {
+			credits = append(credits, Credit{Name: name, Amount: bal})
+		} else if bal < 0 {
+			debts = append(debts, Credit{Name: name, Amount: -bal})
+		}
+	}
+	sort.Slice(credits, func(i, j int) bool { return credits[i].Name < credits[j].Name })
+	sort.Slice(debts, func(i, j int) bool { return debts[i].Name < debts[j].Name })
+
+	// member_data: full reconcile output for all members (not just adults).
+	memberData := make(map[string]AdultsMemberData, len(result.Members))
+	for name, mr := range result.Members {
+		months := make(map[string]AdultsMonthData, len(mr.Months))
+		for m, md := range mr.Months {
+			var exc *ExceptionData
+			if md.Exception != nil {
+				exc = &ExceptionData{Amount: md.Exception.Amount, Note: md.Exception.Note}
+			}
+			txEntries := make([]MemberTxEntry, len(md.Transactions))
+			for i, te := range md.Transactions {
+				txEntries[i] = memberTxFromDomain(te)
+			}
+			months[m] = AdultsMonthData{
+				Expected:         md.Expected,
+				OriginalExpected: md.OriginalExpected,
+				AttendanceCount:  md.AttendanceCount,
+				Exception:        exc,
+				Paid:             md.Paid,
+				Transactions:     txEntries,
+			}
+		}
+		otherTxs := make([]MemberOtherEntry, len(mr.OtherTransactions))
+		for i, oe := range mr.OtherTransactions {
+			otherTxs[i] = memberOtherFromDomain(oe)
+		}
+		memberData[name] = AdultsMemberData{
+			Tier:              mr.Tier,
+			Months:            months,
+			OtherTransactions: otherTxs,
+			TotalBalance:      mr.TotalBalance,
+		}
+	}
+
+	unmatched := make([]RawTransaction, len(result.Unmatched))
+	for i, tx := range result.Unmatched {
+		unmatched[i] = rawTxFromDomain(tx)
+	}
+
+	return AdultsResponse{
+		Months:        labelsForMonths(sortedMonths, monthLabels),
+		RawMonths:     sortedMonths,
+		Results:       ensureSlice(results),
+		Totals:        totalsCells,
+		MemberData:    memberData,
+		MonthLabels:   monthLabels,
+		RawPayments:   groupRawPaymentsByPerson(txns, allNames),
+		Credits:       ensureSlice(credits),
+		Debts:         ensureSlice(debts),
+		Unmatched:     unmatched,
+		AttendanceURL: "https://docs.google.com/spreadsheets/d/" + config.AttendanceSheetID + "/edit",
+		PaymentsURL:   "https://docs.google.com/spreadsheets/d/" + config.PaymentsSheetID + "/edit",
+		BankAccount:   cfg.BankAccount,
+		CurrentMonth:  currentMonth,
+	}
+}
+
+func buildAdultMemberRow(
+	name string,
+	mr domreconcile.MemberResult,
+	sortedMonths []string,
+	monthLabels map[string]string,
+	currentMonth string,
+	monthlyTotals map[string]*monthSums,
+) (row MemberRow, unpaidMonths, rawUnpaidMonths []string) {
+	row = MemberRow{Name: name}
+	for _, m := range sortedMonths {
+		md, ok := mr.Months[m]
+		if !ok {
+			md = domreconcile.MonthData{}
+		}
+		paid := int(md.Paid)
+		expected := md.Expected
+
+		if t := monthlyTotals[m]; t != nil {
+			t.expected += expected
+			t.paid += paid
+		}
+
+		var feeDisplay string
+		var isOverridden bool
+		if md.Exception != nil && md.Exception.Amount != md.OriginalExpected {
+			isOverridden = true
+			if md.AttendanceCount > 0 {
+				feeDisplay = fmt.Sprintf("%d (%d) CZK (%d)", md.Exception.Amount, md.OriginalExpected, md.AttendanceCount)
+			} else {
+				feeDisplay = fmt.Sprintf("%d (%d) CZK", md.Exception.Amount, md.OriginalExpected)
+			}
+		} else {
+			if md.AttendanceCount > 0 {
+				feeDisplay = fmt.Sprintf("%d CZK (%d)", expected, md.AttendanceCount)
+			} else {
+				feeDisplay = fmt.Sprintf("%d CZK", expected)
+			}
+		}
+
+		status := "empty"
+		cellText := "-"
+		amountToPay := 0
+
+		switch {
+		case expected > 0:
+			amountToPay = max(0, expected-paid)
+			switch {
+			case paid >= expected:
+				status = "ok"
+				cellText = fmt.Sprintf("%d/%s", paid, feeDisplay)
+			case paid > 0:
+				status = "partial"
+				cellText = fmt.Sprintf("%d/%s", paid, feeDisplay)
+				if m < currentMonth {
+					unpaidMonths = append(unpaidMonths, monthLabels[m])
+					rawUnpaidMonths = append(rawUnpaidMonths, rawMonthLabel(m))
+				}
+			default:
+				status = "unpaid"
+				cellText = fmt.Sprintf("0/%s", feeDisplay)
+				if m < currentMonth {
+					unpaidMonths = append(unpaidMonths, monthLabels[m])
+					rawUnpaidMonths = append(rawUnpaidMonths, rawMonthLabel(m))
+				}
+			}
+		case paid > 0:
+			status = "surplus"
+			cellText = fmt.Sprintf("PAID %d", paid)
+		}
+
+		tooltip := ""
+		if expected > 0 || paid > 0 {
+			tooltip = fmt.Sprintf("Received: %d, Expected: %d", paid, expected)
+		}
+
+		row.Months = append(row.Months, MonthCell{
+			Text:       cellText,
+			Overridden: isOverridden,
+			Status:     status,
+			Amount:     amountToPay,
+			Month:      monthLabels[m],
+			RawMonth:   m,
+			Tooltip:    tooltip,
+		})
+	}
+	return row, unpaidMonths, rawUnpaidMonths
+}
+
+// rawMonthLabel converts "YYYY-MM" to "MM/YYYY" matching Python's strftime("%m/%Y").
+func rawMonthLabel(m string) string {
+	dt, err := time.Parse("2006-01", m)
+	if err != nil {
+		return m
+	}
+	return dt.Format("01/2006")
+}
+
+func joinComma(parts []string) string {
+	if len(parts) == 0 {
+		return ""
+	}
+	result := parts[0]
+	for _, p := range parts[1:] {
+		result += ", " + p
+	}
+	return result
+}
+
+func joinPlus(parts []string) string {
+	if len(parts) == 0 {
+		return ""
+	}
+	result := parts[0]
+	for _, p := range parts[1:] {
+		result += "+" + p
+	}
+	return result
+}

go/internal/web/api/build_common.go

@@ -0,0 +1,184 @@
+package api
+
+import (
+	"fuj-management/go/internal/domain/czech"
+	"regexp"
+	"sort"
+	"strings"
+	"time"
+
+	domreconcile "fuj-management/go/internal/domain/reconcile"
+)
+
+// getMonthLabels builds display labels for sortedMonths, merging month names
+// (e.g. "Dec+Jan 2026") when mergedMonths maps a source month into this target.
+// Mirrors scripts/views.py:get_month_labels.
+func getMonthLabels(sortedMonths []string, mergedMonths map[string]string) map[string]string {
+	labels := make(map[string]string, len(sortedMonths))
+	for _, m := range sortedMonths {
+		dt, err := time.Parse("2006-01", m)
+		if err != nil {
+			labels[m] = m
+			continue
+		}
+		var mergedIn []string
+		for src, dst := range mergedMonths {
+			if dst == m {
+				mergedIn = append(mergedIn, src)
+			}
+		}
+		sort.Strings(mergedIn)
+		if len(mergedIn) == 0 {
+			labels[m] = dt.Format("Jan 2006")
+			continue
+		}
+		allMonths := append(mergedIn, m) //nolint:gocritic // intentional: mergedIn already owned
+		sort.Strings(allMonths)
+		years := map[int]bool{}
+		for _, x := range allMonths {
+			if d, err2 := time.Parse("2006-01", x); err2 == nil {
+				years[d.Year()] = true
+			}
+		}
+		parts := make([]string, 0, len(allMonths))
+		if len(years) > 1 {
+			for _, x := range allMonths {
+				if d, err2 := time.Parse("2006-01", x); err2 == nil {
+					parts = append(parts, d.Format("Jan 2006"))
+				}
+			}
+			labels[m] = strings.Join(parts, "+")
+		} else {
+			for _, x := range allMonths {
+				if d, err2 := time.Parse("2006-01", x); err2 == nil {
+					parts = append(parts, d.Format("Jan"))
+				}
+			}
+			labels[m] = strings.Join(parts, "+") + " " + dt.Format("2006")
+		}
+	}
+	return labels
+}
+
+// labelsForMonths returns the display labels for sortedMonths in slice order.
+func labelsForMonths(sortedMonths []string, labels map[string]string) []string {
+	out := make([]string, len(sortedMonths))
+	for i, m := range sortedMonths {
+		out[i] = labels[m]
+	}
+	return out
+}
+
+var questionMarkRe = regexp.MustCompile(`\[\?\]\s*`)
+
+// canonicalKey returns a normalized form of a person name used for deduplication.
+// Mirrors scripts/match_payments.py:canonical_member_key.
+func canonicalKey(name string) string {
+	return strings.Join(strings.Fields(czech.Normalize(name)), " ")
+}
+
+// groupRawPaymentsByPerson groups transactions by the "person" column,
+// canonicalizing names against memberNames where possible.
+// Mirrors scripts/views.py:group_payments_by_person (without the
+// "Unmatched / Unknown" bucket that is payments-view-specific).
+func groupRawPaymentsByPerson(txns []domreconcile.Transaction, memberNames []string) map[string][]RawTransaction {
+	canonicalByKey := make(map[string]string, len(memberNames))
+	for _, n := range memberNames {
+		k := canonicalKey(n)
+		if _, exists := canonicalByKey[k]; !exists {
+			canonicalByKey[k] = n
+		}
+	}
+	grouped := make(map[string][]RawTransaction)
+	for _, tx := range txns {
+		person := strings.TrimSpace(tx.Person)
+		if person == "" {
+			continue
+		}
+		for _, p := range strings.Split(person, ",") {
+			p = questionMarkRe.ReplaceAllString(p, "")
+			p = strings.TrimSpace(p)
+			if p == "" {
+				continue
+			}
+			key := p
+			if canonical, ok := canonicalByKey[canonicalKey(p)]; ok {
+				key = canonical
+			}
+			grouped[key] = append(grouped[key], rawTxFromDomain(tx))
+		}
+	}
+	for k := range grouped {
+		sort.Slice(grouped[k], func(i, j int) bool {
+			return grouped[k][i].Date > grouped[k][j].Date
+		})
+	}
+	return grouped
+}
+
+// rawTxFromDomain converts a domain Transaction to the wire RawTransaction.
+func rawTxFromDomain(tx domreconcile.Transaction) RawTransaction {
+	inferredAmount := 0.0
+	if tx.InferredAmount != nil {
+		inferredAmount = *tx.InferredAmount
+	}
+	return RawTransaction{
+		Date:           tx.Date,
+		Amount:         tx.Amount,
+		ManualFix:      tx.ManualFix,
+		Person:         tx.Person,
+		Purpose:        tx.Purpose,
+		InferredAmount: inferredAmount,
+		Sender:         tx.Sender,
+		VS:             tx.VS,
+		Message:        tx.Message,
+		BankID:         tx.BankID,
+		SyncID:         tx.SyncID,
+	}
+}
+
+// memberTxFromDomain converts a domain TxEntry to a wire MemberTxEntry.
+func memberTxFromDomain(te domreconcile.TxEntry) MemberTxEntry {
+	return MemberTxEntry{
+		Amount:     te.Amount,
+		Date:       te.Date,
+		Sender:     te.Sender,
+		Message:    te.Message,
+		Confidence: te.Confidence,
+	}
+}
+
+// memberOtherFromDomain converts a domain OtherEntry to a wire MemberOtherEntry.
+func memberOtherFromDomain(oe domreconcile.OtherEntry) MemberOtherEntry {
+	return MemberOtherEntry{
+		Amount:     oe.Amount,
+		Date:       oe.Date,
+		Sender:     oe.Sender,
+		Message:    oe.Message,
+		Purpose:    oe.Purpose,
+		Confidence: oe.Confidence,
+	}
+}
+
+// settledBalance computes the settled balance: sum of (paid − expected) for months
+// strictly before currentMonth. Months with IsUnknown=true are excluded to match
+// Python's isinstance(exp, int) guard (skips "?" months).
+func settledBalance(mr domreconcile.MemberResult, currentMonth string) int {
+	total := 0
+	for m, md := range mr.Months {
+		if m >= currentMonth || md.IsUnknown {
+			continue
+		}
+		total += int(md.Paid) - md.Expected
+	}
+	return total
+}
+
+// ensureSlice returns s unchanged when non-nil, or an empty (non-nil) slice so
+// json.Marshal emits [] instead of null.
+func ensureSlice[T any](s []T) []T {
+	if s == nil {
+		return []T{}
+	}
+	return s
+}

go/internal/web/api/build_juniors.go

@@ -0,0 +1,276 @@
+package api
+
+import (
+	"fmt"
+	"fuj-management/go/internal/config"
+	"fuj-management/go/internal/services/membership"
+	"sort"
+	"strconv"
+
+	domreconcile "fuj-management/go/internal/domain/reconcile"
+)
+
+// buildJuniorsResponse constructs the JuniorsResponse wire type from reconcile output.
+// Mirrors scripts/views.py:build_juniors_view_model.
+func buildJuniorsResponse(
+	members []domreconcile.Member,
+	sortedMonths []string,
+	result domreconcile.Result,
+	txns []domreconcile.Transaction,
+	cfg config.Config,
+	currentMonth string,
+) JuniorsResponse {
+	monthLabels := getMonthLabels(sortedMonths, membership.JuniorMergedMonths)
+
+	allNames := make([]string, 0, len(members))
+	juniorNames := make([]string, 0, len(members))
+	for _, m := range members {
+		allNames = append(allNames, m.Name)
+		juniorNames = append(juniorNames, m.Name)
+	}
+	sort.Strings(juniorNames)
+
+	monthlyTotals := make(map[string]*monthSums, len(sortedMonths))
+	for _, m := range sortedMonths {
+		monthlyTotals[m] = &monthSums{}
+	}
+
+	var results []MemberRow
+	for _, name := range juniorNames {
+		mr := result.Members[name]
+		row, unpaidMonths, rawUnpaidMonths := buildJuniorMemberRow(name, mr, sortedMonths, monthLabels, currentMonth, monthlyTotals)
+		row.UnpaidPeriods = joinComma(unpaidMonths)
+		row.RawUnpaidPeriods = joinPlus(rawUnpaidMonths)
+		row.Balance = settledBalance(mr, currentMonth)
+		row.PayableAmount = max(0, -row.Balance)
+		results = append(results, row)
+	}
+
+	// Totals row.
+	totalsCells := make([]TotalCell, len(sortedMonths))
+	for i, m := range sortedMonths {
+		t := monthlyTotals[m] // *monthSums, never nil (initialised above)
+		status := "empty"
+		if t.expected > 0 || t.paid > 0 {
+			switch {
+			case t.paid == t.expected:
+				status = "ok"
+			case t.paid < t.expected:
+				status = "unpaid"
+			default:
+				status = "surplus"
+			}
+		}
+		totalsCells[i] = TotalCell{
+			Text:   fmt.Sprintf("%d / %d CZK", t.paid, t.expected),
+			Status: status,
+		}
+	}
+
+	var credits, debts []Credit
+	for _, name := range juniorNames {
+		bal := settledBalance(result.Members[name], currentMonth)
+		if bal > 0 {
+			credits = append(credits, Credit{Name: name, Amount: bal})
+		} else if bal < 0 {
+			debts = append(debts, Credit{Name: name, Amount: -bal})
+		}
+	}
+	sort.Slice(credits, func(i, j int) bool { return credits[i].Name < credits[j].Name })
+	sort.Slice(debts, func(i, j int) bool { return debts[i].Name < debts[j].Name })
+
+	// member_data: full reconcile output for all junior members.
+	memberData := make(map[string]JuniorsMemberData, len(result.Members))
+	for name, mr := range result.Members {
+		months := make(map[string]JuniorsMonthData, len(mr.Months))
+		for m, md := range mr.Months {
+			var exc *ExceptionData
+			if md.Exception != nil {
+				exc = &ExceptionData{Amount: md.Exception.Amount, Note: md.Exception.Note}
+			}
+			txEntries := make([]MemberTxEntry, len(md.Transactions))
+			for i, te := range md.Transactions {
+				txEntries[i] = memberTxFromDomain(te)
+			}
+			months[m] = JuniorsMonthData{
+				Expected:         juniorExpected(md),
+				OriginalExpected: juniorOriginalExpected(md),
+				AttendanceCount:  md.AttendanceCount,
+				Exception:        exc,
+				Paid:             md.Paid,
+				Transactions:     txEntries,
+			}
+		}
+		otherTxs := make([]MemberOtherEntry, len(mr.OtherTransactions))
+		for i, oe := range mr.OtherTransactions {
+			otherTxs[i] = memberOtherFromDomain(oe)
+		}
+		memberData[name] = JuniorsMemberData{
+			Tier:              mr.Tier,
+			Months:            months,
+			OtherTransactions: otherTxs,
+			TotalBalance:      mr.TotalBalance,
+		}
+	}
+
+	unmatched := make([]RawTransaction, len(result.Unmatched))
+	for i, tx := range result.Unmatched {
+		unmatched[i] = rawTxFromDomain(tx)
+	}
+
+	juniorURL := "https://docs.google.com/spreadsheets/d/" + config.AttendanceSheetID +
+		"/edit#gid=" + config.JuniorSheetGID
+
+	return JuniorsResponse{
+		Months:        labelsForMonths(sortedMonths, monthLabels),
+		RawMonths:     sortedMonths,
+		Results:       ensureSlice(results),
+		Totals:        totalsCells,
+		MemberData:    memberData,
+		MonthLabels:   monthLabels,
+		RawPayments:   groupRawPaymentsByPerson(txns, allNames),
+		Credits:       ensureSlice(credits),
+		Debts:         ensureSlice(debts),
+		Unmatched:     unmatched,
+		AttendanceURL: juniorURL,
+		PaymentsURL:   "https://docs.google.com/spreadsheets/d/" + config.PaymentsSheetID + "/edit",
+		BankAccount:   cfg.BankAccount,
+		CurrentMonth:  currentMonth,
+	}
+}
+
+func buildJuniorMemberRow(
+	name string,
+	mr domreconcile.MemberResult,
+	sortedMonths []string,
+	monthLabels map[string]string,
+	currentMonth string,
+	monthlyTotals map[string]*monthSums,
+) (row MemberRow, unpaidMonths, rawUnpaidMonths []string) {
+	row = MemberRow{Name: name}
+	for _, m := range sortedMonths {
+		md, ok := mr.Months[m]
+		if !ok {
+			md = domreconcile.MonthData{}
+		}
+		paid := int(md.Paid)
+
+		// Update monthly totals (skip "?" months for expected).
+		if t := monthlyTotals[m]; t != nil {
+			if !md.IsUnknown {
+				t.expected += md.Expected
+			}
+			t.paid += paid
+		}
+
+		// Attendance breakdown string e.g. ":3J,2A".
+		var breakdown string
+		jc, ac := md.JuniorAttendance, md.AdultAttendance
+		switch {
+		case jc > 0 && ac > 0:
+			breakdown = fmt.Sprintf(":%dJ,%dA", jc, ac)
+		case jc > 0:
+			breakdown = fmt.Sprintf(":%dJ", jc)
+		case ac > 0:
+			breakdown = fmt.Sprintf(":%dA", ac)
+		}
+		countStr := ""
+		if md.AttendanceCount > 0 {
+			countStr = fmt.Sprintf(" (%d%s)", md.AttendanceCount, breakdown)
+		}
+
+		// Fee display string.
+		var feeDisplay string
+		var isOverridden bool
+		if md.Exception != nil {
+			overrideAmount := md.Exception.Amount
+			var origStr string
+			if md.IsUnknown {
+				origStr = "?"
+				isOverridden = true
+			} else {
+				origStr = strconv.Itoa(md.OriginalExpected)
+				isOverridden = overrideAmount != md.OriginalExpected
+			}
+			if isOverridden {
+				feeDisplay = fmt.Sprintf("%d (%s) CZK%s", overrideAmount, origStr, countStr)
+			} else {
+				feeDisplay = fmt.Sprintf("%d CZK%s", md.Expected, countStr)
+			}
+		} else {
+			if md.IsUnknown {
+				feeDisplay = "? CZK" + countStr
+			} else {
+				feeDisplay = fmt.Sprintf("%d CZK%s", md.Expected, countStr)
+			}
+		}
+
+		status := "empty"
+		cellText := "-"
+		amountToPay := 0
+
+		switch {
+		case md.IsUnknown:
+			cellText = "?" + countStr
+		case md.Expected > 0:
+			switch {
+			case paid >= md.Expected:
+				status = "ok"
+				cellText = fmt.Sprintf("%d/%s", paid, feeDisplay)
+			case paid > 0:
+				status = "partial"
+				cellText = fmt.Sprintf("%d/%s", paid, feeDisplay)
+				amountToPay = md.Expected - paid
+				if m < currentMonth {
+					unpaidMonths = append(unpaidMonths, monthLabels[m])
+					rawUnpaidMonths = append(rawUnpaidMonths, rawMonthLabel(m))
+				}
+			default:
+				status = "unpaid"
+				cellText = fmt.Sprintf("0/%s", feeDisplay)
+				amountToPay = md.Expected
+				if m < currentMonth {
+					unpaidMonths = append(unpaidMonths, monthLabels[m])
+					rawUnpaidMonths = append(rawUnpaidMonths, rawMonthLabel(m))
+				}
+			}
+		case paid > 0:
+			status = "surplus"
+			cellText = fmt.Sprintf("PAID %d", paid)
+		}
+
+		tooltip := ""
+		if (!md.IsUnknown && md.Expected > 0) || paid > 0 {
+			tooltip = fmt.Sprintf("Received: %d, Expected: %d", paid, md.Expected)
+		}
+
+		row.Months = append(row.Months, MonthCell{
+			Text:       cellText,
+			Overridden: isOverridden,
+			Status:     status,
+			Amount:     amountToPay,
+			Month:      monthLabels[m],
+			RawMonth:   m,
+			Tooltip:    tooltip,
+		})
+	}
+	return row, unpaidMonths, rawUnpaidMonths
+}
+
+// juniorExpected converts domain MonthData to the Expected wire type.
+// When an exception exists it always produces a concrete int; otherwise
+// the "?" sentinel is used when IsUnknown=true.
+func juniorExpected(md domreconcile.MonthData) Expected {
+	if md.Exception == nil && md.IsUnknown {
+		return Expected{Unknown: true}
+	}
+	return Expected{Value: md.Expected}
+}
+
+// juniorOriginalExpected converts the original (pre-exception) expected fee.
+func juniorOriginalExpected(md domreconcile.MonthData) Expected {
+	if md.IsUnknown {
+		return Expected{Unknown: true}
+	}
+	return Expected{Value: md.OriginalExpected}
+}

go/internal/web/api/build_payments.go

@@ -0,0 +1,44 @@
+package api
+
+import (
+	"fuj-management/go/internal/config"
+	"sort"
+	"strings"
+
+	domreconcile "fuj-management/go/internal/domain/reconcile"
+)
+
+// buildPaymentsResponse constructs the PaymentsResponse wire type.
+// Mirrors scripts/views.py:build_payments_view_model.
+func buildPaymentsResponse(
+	txns []domreconcile.Transaction,
+	memberNames []string,
+) PaymentsResponse {
+	grouped := groupRawPaymentsByPerson(txns, memberNames)
+
+	// Add unmatched/unknown bucket for transactions with no person set.
+	const unknownKey = "Unmatched / Unknown"
+	for _, tx := range txns {
+		if strings.TrimSpace(tx.Person) == "" {
+			grouped[unknownKey] = append(grouped[unknownKey], rawTxFromDomain(tx))
+		}
+	}
+	// Sort the unknown bucket newest-first (others are sorted in groupRawPaymentsByPerson).
+	if rows, ok := grouped[unknownKey]; ok {
+		sort.Slice(rows, func(i, j int) bool { return rows[i].Date > rows[j].Date })
+		grouped[unknownKey] = rows
+	}
+
+	sortedPeople := make([]string, 0, len(grouped))
+	for p := range grouped {
+		sortedPeople = append(sortedPeople, p)
+	}
+	sort.Strings(sortedPeople)
+
+	return PaymentsResponse{
+		GroupedPayments: grouped,
+		SortedPeople:    sortedPeople,
+		AttendanceURL:   "https://docs.google.com/spreadsheets/d/" + config.AttendanceSheetID + "/edit",
+		PaymentsURL:     "https://docs.google.com/spreadsheets/d/" + config.PaymentsSheetID + "/edit",
+	}
+}

go/internal/web/api/handler.go

@@ -0,0 +1,134 @@
+package api
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"fuj-management/go/internal/config"
+	"fuj-management/go/internal/services/membership"
+	"log/slog"
+	"net/http"
+	"time"
+
+	domreconcile "fuj-management/go/internal/domain/reconcile"
+)
+
+// Handler holds the shared dependencies for all /api/* routes.
+type Handler struct {
+	BuildVersion string
+	BuildCommit  string
+	BuildDate    string
+	Sources      membership.Sources
+	Config       config.Config
+	Logger       *slog.Logger
+}
+
+// ServeVersion handles GET /api/version.
+func (h *Handler) ServeVersion(w http.ResponseWriter, r *http.Request) {
+	writeJSON(w, VersionResponse{
+		Tag:       h.BuildVersion,
+		Commit:    h.BuildCommit,
+		BuildDate: h.BuildDate,
+	})
+}
+
+// ServeAdults handles GET /api/adults.
+func (h *Handler) ServeAdults(w http.ResponseWriter, r *http.Request) {
+	resp, err := h.AssembleAdults(r.Context())
+	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())
+	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()
+	members, sortedMonths, txns, exceptions, err := h.loadAll(ctx, false)
+	if err != nil {
+		h.writeError(w, r, err)
+		return
+	}
+	result := domreconcile.Reconcile(members, sortedMonths, txns, exceptions, time.Now().Year())
+	writeJSON(w, buildJuniorsResponse(members, sortedMonths, result, txns, h.Config, time.Now().Format("2006-01")))
+}
+
+// ServePayments handles GET /api/payments.
+func (h *Handler) ServePayments(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	txns, err := h.Sources.LoadTransactions(ctx)
+	if err != nil {
+		h.writeError(w, r, fmt.Errorf("load transactions: %w", err))
+		return
+	}
+	writeJSON(w, buildPaymentsResponse(txns, h.allMemberNames(ctx)))
+}
+
+func (h *Handler) loadAll(ctx context.Context, adults bool) (
+	members []domreconcile.Member,
+	sortedMonths []string,
+	txns []domreconcile.Transaction,
+	exceptions map[domreconcile.ExceptionKey]domreconcile.Exception,
+	err error,
+) {
+	if adults {
+		members, sortedMonths, err = h.Sources.LoadAdults(ctx)
+	} else {
+		members, sortedMonths, err = h.Sources.LoadJuniors(ctx)
+	}
+	if err != nil {
+		err = fmt.Errorf("load members: %w", err)
+		return
+	}
+	txns, err = h.Sources.LoadTransactions(ctx)
+	if err != nil {
+		err = fmt.Errorf("load transactions: %w", err)
+		return
+	}
+	exceptions, err = h.Sources.LoadExceptions(ctx)
+	if err != nil {
+		err = fmt.Errorf("load exceptions: %w", err)
+	}
+	return
+}
+
+func (h *Handler) allMemberNames(ctx context.Context) []string {
+	var names []string
+	if adults, _, err := h.Sources.LoadAdults(ctx); err == nil {
+		for _, m := range adults {
+			names = append(names, m.Name)
+		}
+	}
+	if juniors, _, err := h.Sources.LoadJuniors(ctx); err == nil {
+		for _, m := range juniors {
+			names = append(names, m.Name)
+		}
+	}
+	return names
+}
+
+func (h *Handler) writeError(w http.ResponseWriter, r *http.Request, err error) {
+	if h.Logger != nil {
+		h.Logger.Error("api error", "path", r.URL.Path, "err", err)
+	}
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.WriteHeader(http.StatusInternalServerError)
+	_ = json.NewEncoder(w).Encode(map[string]string{"error": err.Error()})
+}
+
+func writeJSON(w http.ResponseWriter, v any) {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	_ = json.NewEncoder(w).Encode(v)
+}

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/html_handler.go

@@ -0,0 +1,49 @@
+package web
+
+import (
+	"fuj-management/go/internal/web/api"
+	"net/http"
+)
+
+// HTMLHandler serves the Go-native HTML frontend.
+type HTMLHandler struct {
+	renderer   *Renderer
+	build      BuildInfo
+	apiHandler *api.Handler
+}
+
+// NewHTMLHandler constructs an HTMLHandler.
+func NewHTMLHandler(r *Renderer, b BuildInfo, ah *api.Handler) *HTMLHandler {
+	return &HTMLHandler{renderer: r, build: b, apiHandler: ah}
+}
+
+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) {
+	h.renderer.Render(w, "juniors", PageData{Active: "juniors", Build: h.build})
+}
+
+func (h *HTMLHandler) ServePayments(w http.ResponseWriter, r *http.Request) {
+	h.renderer.Render(w, "payments", PageData{Active: "payments", Build: h.build})
+}
+
+func (h *HTMLHandler) ServeSync(w http.ResponseWriter, r *http.Request) {
+	h.renderer.Render(w, "sync", PageData{Active: "sync", Build: h.build})
+}
+
+func (h *HTMLHandler) ServeFlushCache(w http.ResponseWriter, r *http.Request) {
+	h.renderer.Render(w, "flush_cache", PageData{Active: "flush", Build: h.build})
+}

go/internal/web/html_handler_test.go

@@ -0,0 +1,128 @@
+package web_test
+
+import (
+	"context"
+	"fmt"
+	"fuj-management/go/internal/config"
+	"fuj-management/go/internal/domain/reconcile"
+	"fuj-management/go/internal/web"
+	"fuj-management/go/internal/web/api"
+	"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 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))
+
+	cases := []struct {
+		path    string
+		handler http.HandlerFunc
+	}{
+		{"/adults", h.ServeAdults},
+		{"/juniors", h.ServeJuniors},
+		{"/payments", h.ServePayments},
+		{"/sync-bank", h.ServeSync},
+		{"/flush-cache", h.ServeFlushCache},
+	}
+
+	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))
+
+	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<")
+	}
+}

go/internal/web/render.go

@@ -0,0 +1,94 @@
+package web
+
+import (
+	"fmt"
+	"fuj-management/go/internal/web/api"
+	"html/template"
+	"log/slog"
+	"net/http"
+	"net/url"
+	"strconv"
+)
+
+// 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
+}
+
+// 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"}
+
+// qrHref builds the /qr query URL for a single-month Pay button.
+// rawMonth is "YYYY-MM"; it is converted to "MM/YYYY" in the QR message.
+func qrHref(account string, amount int, name, rawMonth string) string {
+	// Convert "YYYY-MM" → "MM/YYYY" to match Python's showPayQR JS.
+	if len(rawMonth) == 7 && rawMonth[4] == '-' {
+		rawMonth = rawMonth[5:] + "/" + rawMonth[:4]
+	}
+	msg := name + ": " + rawMonth
+	return "/qr?" + url.Values{
+		"account": {account},
+		"amount":  {strconv.Itoa(amount)},
+		"message": {msg},
+	}.Encode()
+}
+
+// qrHrefAll builds the /qr query URL for a Pay-All button.
+// rawPeriods is the "+" -joined MM/YYYY string from MemberRow.RawUnpaidPeriods.
+func qrHrefAll(account string, amount int, name, rawPeriods string) string {
+	msg := name + ": " + rawPeriods
+	return "/qr?" + url.Values{
+		"account": {account},
+		"amount":  {strconv.Itoa(amount)},
+		"message": {msg},
+	}.Encode()
+}
+
+var tmplFuncs = template.FuncMap{
+	"qrHref":    qrHref,
+	"qrHrefAll": qrHrefAll,
+}
+
+// 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

@@ -2,7 +2,11 @@ package web
 
 import (
 	"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/fs"
 	"log/slog"
 	"net/http"
 )
@@ -15,18 +19,48 @@ type BuildInfo struct {
 }
 
 // Run registers routes and starts the HTTP server on addr.
-func Run(logger *slog.Logger, addr string, build BuildInfo) error {
+func Run(logger *slog.Logger, addr string, build BuildInfo, sources membership.Sources, cfg config.Config) error {
+	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,
+		Sources:      sources,
+		Config:       cfg,
+		Logger:       logger,
+	}
+	hh := NewHTMLHandler(renderer, build, ah)
+
+	staticSubFS, err := fs.Sub(staticFS, "static")
+	if err != nil {
+		return fmt.Errorf("static subfs: %w", err)
+	}
+
 	mux := http.NewServeMux()
-	mux.HandleFunc("GET /{$}", helloHandler(build))
+
+	// HTML routes
+	mux.HandleFunc("GET /{$}", func(w http.ResponseWriter, r *http.Request) {
+		http.Redirect(w, r, "/adults", http.StatusFound)
+	})
+	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.ServeFlushCache)
+
+	// Static files
+	mux.Handle("/static/", http.StripPrefix("/static/", http.FileServerFS(staticSubFS)))
+
+	// JSON API routes
+	mux.HandleFunc("GET /api/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 +1,478 @@
+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 .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;
+}

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/templates/adults.tmpl

@@ -0,0 +1,141 @@
+{{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}}">
+  <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}}</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)}}
+        <a class="pay-btn" href="{{qrHref $.Data.BankAccount $cell.Amount $row.Name $cell.RawMonth}}">Pay</a>
+        {{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}}
+        <a class="pay-btn" href="{{qrHrefAll $.Data.BankAccount $row.PayableAmount $row.Name $row.RawUnpaidPeriods}}">Pay All</a>
+        {{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}}
+
+<script src="/static/js/filters.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 +1,5 @@
+{{define "title"}}Flush Cache{{end}}
+{{define "content"}}
+<h1>Flush Cache</h1>
+<p class="description">Coming in M6.6</p>
+{{end}}

go/internal/web/templates/juniors.tmpl

@@ -0,0 +1,5 @@
+{{define "title"}}Juniors{{end}}
+{{define "content"}}
+<h1>Juniors Dashboard</h1>
+<p class="description">Coming in M6.3</p>
+{{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 +1,5 @@
+{{define "title"}}Payments Ledger{{end}}
+{{define "content"}}
+<h1>Payments Ledger</h1>
+<p class="description">Coming in M6.4</p>
+{{end}}

go/internal/web/templates/sync.tmpl

@@ -0,0 +1,5 @@
+{{define "title"}}Sync Bank Data{{end}}
+{{define "content"}}
+<h1>Sync Bank Data</h1>
+<p class="description">Coming in M6.6</p>
+{{end}}

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/match_payments.py

@@ -236,6 +236,8 @@ def fetch_sheet_data(spreadsheet_id: str, credentials_path: str) -> list[dict]:
     idx_sender = get_col_index("Sender")
     idx_message = get_col_index("Message")
     idx_bank_id = get_col_index("Bank ID")
+    idx_vs = get_col_index("VS")
+    idx_sync_id = get_col_index("Sync ID")
 
     required = {"Date": idx_date, "Amount": idx_amount, "Person": idx_person, "Purpose": idx_purpose}
     missing = [name for name, idx in required.items() if idx == -1]
@@ -247,16 +249,33 @@ def fetch_sheet_data(spreadsheet_id: str, credentials_path: str) -> list[dict]:
         def get_val(idx):
             return row[idx] if idx != -1 and idx < len(row) else ""
 
+        def get_str(idx):
+            v = get_val(idx)
+            if isinstance(v, float) and v.is_integer():
+                return str(int(v))
+            return str(v)
+
+        def get_float(idx):
+            v = get_val(idx)
+            if isinstance(v, (int, float)):
+                return float(v)
+            try:
+                return float(str(v).strip())
+            except (ValueError, TypeError):
+                return 0.0
+
         tx = {
             "date": format_date(get_val(idx_date)),
-            "amount": get_val(idx_amount),
+            "amount": get_float(idx_amount),
             "manual_fix": get_val(idx_manual),
             "person": get_val(idx_person),
             "purpose": get_val(idx_purpose),
             "inferred_amount": get_val(idx_inferred_amount),
             "sender": get_val(idx_sender),
-            "message": get_val(idx_message),
+            "vs": get_str(idx_vs),
+            "message": get_str(idx_message),
             "bank_id": get_val(idx_bank_id),
+            "sync_id": get_val(idx_sync_id),
         }
         transactions.append(tx)
     

scripts/views.py

@@ -310,8 +310,9 @@ def build_juniors_view_model(
             cell_text = "-"
             amount_to_pay = 0
 
-            if expected == "?" or (isinstance(expected, int) and expected > 0):
+            is_unknown = original_expected == "?"
-                if expected == "?":
+            if is_unknown or (isinstance(expected, int) and expected > 0):
+                if is_unknown:
                     status = "empty"
                     cell_text = f"?{count_str}"
                 elif paid >= expected:
@@ -339,7 +340,7 @@ def build_juniors_view_model(
                 status = "surplus"
                 cell_text = f"PAID {paid}"
 
-            if (isinstance(expected, int) and expected > 0) or paid > 0:
+            if (not is_unknown and isinstance(expected, int) and expected > 0) or paid > 0:
                 tooltip = f"Received: {paid}, Expected: {expected}"
             else:
                 tooltip = ""

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_app.py

@@ -1,7 +1,17 @@
 import unittest
+import json
 from unittest.mock import patch
 from app import app
 
+EXPECTED_ADULTS_KEYS = {
+    "months", "raw_months", "results", "totals", "member_data", "month_labels",
+    "raw_payments", "credits", "debts", "unmatched", "attendance_url",
+    "payments_url", "bank_account", "current_month",
+}
+EXPECTED_JUNIORS_KEYS = EXPECTED_ADULTS_KEYS
+EXPECTED_PAYMENTS_KEYS = {"grouped_payments", "sorted_people", "attendance_url", "payments_url"}
+EXPECTED_VERSION_KEYS = {"tag", "commit", "build_date"}
+
 
 def _bypass_cache(cache_key, sheet_id, fetch_func, *args, serialize=None, deserialize=None, **kwargs):
     """Test helper: call fetch_func directly, bypassing the cache layer."""
@@ -97,5 +107,83 @@ class TestWebApp(unittest.TestCase):
         self.assertIn(b'500/500 CZK', response.data)
         self.assertIn(b'?', response.data)
 
+    def test_api_version(self):
+        """Test /api/version returns BUILD_META keys as JSON."""
+        response = self.client.get('/api/version')
+        self.assertEqual(response.status_code, 200)
+        self.assertTrue(response.is_json)
+        data = json.loads(response.data)
+        self.assertEqual(set(data.keys()), EXPECTED_VERSION_KEYS)
+
+    @patch('app.get_cached_data', side_effect=_bypass_cache)
+    @patch('app.fetch_sheet_data')
+    @patch('app.fetch_exceptions', return_value={})
+    @patch('app.get_members_with_fees')
+    def test_api_adults(self, mock_get_members, mock_exceptions, mock_fetch_sheet, mock_cache):
+        """Test /api/adults returns JSON with correct top-level keys and unwrapped fields."""
+        mock_get_members.return_value = (
+            [('Test Member', 'A', {'2026-01': (750, 4)})],
+            ['2026-01']
+        )
+        mock_fetch_sheet.return_value = [{
+            'date': '2026-01-01', 'amount': 750, 'person': 'Test Member',
+            'purpose': '2026-01', 'message': 'test payment',
+            'sender': 'External Bank User', 'inferred_amount': 750,
+            'vs': '', 'sync_id': 'abc123',
+        }]
+        response = self.client.get('/api/adults')
+        self.assertEqual(response.status_code, 200)
+        self.assertTrue(response.is_json)
+        data = json.loads(response.data)
+        self.assertEqual(set(data.keys()), EXPECTED_ADULTS_KEYS)
+        self.assertIsInstance(data['member_data'], dict)
+        self.assertIsInstance(data['month_labels'], dict)
+        self.assertIsInstance(data['raw_payments'], dict)
+
+    @patch('app.get_cached_data', side_effect=_bypass_cache)
+    @patch('app.fetch_sheet_data')
+    @patch('app.fetch_exceptions', return_value={})
+    @patch('app.get_junior_members_with_fees')
+    def test_api_juniors(self, mock_get_junior_members, mock_exceptions, mock_fetch_sheet, mock_cache):
+        """Test /api/juniors returns JSON with correct top-level keys and unwrapped fields."""
+        mock_get_junior_members.return_value = (
+            [
+                ('Junior One', 'J', {'2026-01': (500, 3, 0, 3)}),
+                ('Junior Two', 'X', {'2026-01': ('?', 1, 0, 1)}),
+            ],
+            ['2026-01']
+        )
+        mock_fetch_sheet.return_value = [{
+            'date': '2026-01-15', 'amount': 500, 'person': 'Junior One',
+            'purpose': '2026-01', 'message': '', 'sender': 'Parent', 'inferred_amount': 500,
+            'vs': '', 'sync_id': 'def456',
+        }]
+        response = self.client.get('/api/juniors')
+        self.assertEqual(response.status_code, 200)
+        self.assertTrue(response.is_json)
+        data = json.loads(response.data)
+        self.assertEqual(set(data.keys()), EXPECTED_JUNIORS_KEYS)
+        self.assertIsInstance(data['member_data'], dict)
+        self.assertIsInstance(data['month_labels'], dict)
+        self.assertIsInstance(data['raw_payments'], dict)
+
+    @patch('app.get_cached_data', side_effect=_bypass_cache)
+    @patch('app.fetch_sheet_data')
+    def test_api_payments(self, mock_fetch_sheet, mock_cache):
+        """Test /api/payments returns JSON with correct top-level keys."""
+        mock_fetch_sheet.return_value = [{
+            'date': '2026-01-01', 'amount': 750, 'person': 'Test Member',
+            'purpose': '2026-01', 'message': 'test', 'sender': 'Someone',
+            'vs': '', 'sync_id': 'ghi789',
+        }]
+        response = self.client.get('/api/payments')
+        self.assertEqual(response.status_code, 200)
+        self.assertTrue(response.is_json)
+        data = json.loads(response.data)
+        self.assertEqual(set(data.keys()), EXPECTED_PAYMENTS_KEYS)
+        self.assertIsInstance(data['grouped_payments'], dict)
+        self.assertIsInstance(data['sorted_people'], list)
+
+
 if __name__ == '__main__':
     unittest.main()