# Changelog

## 2026-05-08 14:55 CEST — feat(go): M6.6.1 — Pay-button QR popup modal

- Restored the Python `showPayQR` in-page modal UX that was lost in M6.6 (Pay buttons were navigating the tab to the raw `/qr` PNG).
- Replaced `<a href="{{qrHref ...}}">Pay</a>` with `<button data-name|amount|month|raw-month>` on `/adults` and `/juniors`; click is handled by a new `static/js/payment-qr.js` IIFE module that opens `#qrModal` with title, account, amount, message, and the QR image.
- Added `#qrModal` markup to both templates; CSS `display:none` / `.active{display:flex}` rules added (content rules were already present from M6.1). `Esc`, `[close]`, and outside-click all dismiss; coexists with the M6.5 member-detail modal.
- Removed the now-dead `qrHref` / `qrHrefAll` template helpers from `render.go`.
- Markup tests in `html_handler_test.go` assert modal IDs, script tag, `data-bank-account`, and that no bare `href="/qr"` links remain.
- Key files: `go/internal/web/static/js/payment-qr.js`, `go/internal/web/templates/adults.tmpl`, `go/internal/web/templates/juniors.tmpl`, `go/internal/web/render.go`, `go/internal/web/static/css/app.css`.

## 2026-05-08 13:57 CEST — feat(go): M6.6 — /qr, /sync-bank, /flush-cache, /version

- Added `GET /qr`: generates Czech QR Platba PNG from SPD payload (account, amount, message query params); ports Python's `qr_code()` handler exactly including account validation, amount clamping, and `*` stripping.
- Implemented `GET /sync-bank`: runs Fio sync → infer payments → cache flush, captures output into `sync.tmpl` page with success/error banner.
- Implemented `GET /flush-cache` + `POST /flush-cache`: form + action that deletes cache files and shows deleted count.
- Added `GET /version` as a JSON alias of `GET /api/version` (Python parity).
- Added `FlushCache() (int, error)` to `membership.Sources` interface; implemented on `realSources` via `cache.FileCache.Flush()`.
- Introduced `web.ActionHandlers{BankSync}` — closure-based dep injection for sync, constructed in `serverCmd` with fio + sheets clients.
- New dependency: `github.com/skip2/go-qrcode`.
- Key files: `go/internal/web/qr.go`, `go/internal/web/html_handler.go`, `go/internal/web/server.go`, `go/internal/services/membership/loader.go`, `go/internal/web/templates/sync.tmpl`, `go/internal/web/templates/flush_cache.tmpl`.

## 2026-05-08 13:19 CEST — feat(go): M6.5 — member-detail modal JS module

- Added `static/js/member-detail.js`: fetches `/api/adults` or `/api/juniors` once on page load, caches the response, renders a per-member detail modal on `[i]` row click.
- Modal sections: status-per-month table, fee exceptions, other transactions, matched payment history, toggleable raw-payments debug view.
- Keyboard nav: `Esc` closes, `↑`/`↓` walk visible (name-filtered) rows; click outside modal content closes it.
- Added `[i]` info icon and `#memberModal` markup to `adults.tmpl` and `juniors.tmpl`; all CSS was already in place from M6.1.
- Added `TestModalMarkup` assertions to `html_handler_test.go`.

## 2026-05-08 12:48 CEST — feat(go): M6.4 — Go-native /payments page

- Extracted `AssemblePayments(ctx)` from the inlined JSON handler body, following the M6.2/M6.3 `AssembleAdults`/`AssembleJuniors` pattern.
- Added `PaymentsPageData` to `render.go`; wired `HTMLHandler.ServePayments` to call `AssemblePayments` and render the new template.
- Replaced the "Coming in M6.4" placeholder in `payments.tmpl` with the full grouped-by-person ledger: alphabetical `<h2>` member blocks, each with a `txn-table` (Date / Amount / Purpose / Bank Message), newest-first rows, `"Unmatched / Unknown"` bucket.
- Appended ledger CSS classes to `app.css` (`.ledger-container`, `.member-block`, `.txn-table`, `.txn-{date,amount,purpose,message}`, `tr:hover`).
- Added `TestPaymentsPage` markup test. No filters, no JS — matches the Python page.

## 2026-05-08 11:25 CEST — feat(go): M6.3 — Go-native /juniors page

- Extracted `AssembleJuniors(ctx)` from the JSON handler so HTML and JSON share one view-model path (mirrors `AssembleAdults`).
- Added `JuniorsPageData` to `render.go`; wired `HTMLHandler.ServeJuniors` to call `AssembleJuniors` and render the new template.
- Replaced the 4-line "Coming in M6.3" placeholder in `juniors.tmpl` with the full template: member table, name/month-range filters, totals row, Credits + Debts sections, Pay / Pay All links to `/qr`. No Unmatched section (parity with Python).
- J/A attendance breakdown and `"?"` sentinel rendered via `MonthCell.Text` produced by `buildJuniorMemberRow` — no extra template logic.
- `make parity` reports 3/3 routes OK; all Go tests pass.

## 2026-05-08 11:11 CEST — fix: period selector showed only Dec 2025+ on adults

- Restored the `2025-09 → 2025-10` adult merge in `scripts/attendance.py` and `go/internal/services/membership/sources.go` (commented-out by `1257f0d`); the `2025-12 → 2026-01` mapping stays disabled per product decision (Dec and Jan are billed separately for adults).
- Dropped the `defaultFrom = maxMonthIdx − 4` JS auto-default in `templates/adults.html` and `templates/juniors.html` (introduced by `7774301`); the From-selector now starts at the oldest available month so all non-future periods render on first load. Future-month removal is preserved.
- `go/internal/services/membership/sources_test.go`: `TestLoadAdults` / `TestLoadAdults_Fee` now assert that Sep dates land in the merged `2025-10` bucket.
- **Independent of these code changes**: the live adults attendance Google Sheet header had been pruned to start at `02.12.2025` (Sep/Oct/Nov 2025 columns deleted); restoring those columns from Sheets version history is required to actually see those periods on the dashboard.

## 2026-05-08 10:15 CEST — fix(go): adults template — use lifted CSS classes for visual parity

- Use existing `.balance-pos` / `.balance-neg` (drop invented `balance-cell` / `balance-negative`); Pay-All button now lives inside the balance cell with `position: relative` (matches Python; no separate trailing column).
- Credits / Debts / Unmatched sections rewritten from `<ul>` / `<table>` to `<div class="list-container"><div class="list-item">…` / `<div class="unmatched-row">…` so the lifted CSS actually applies.
- Section headings get the descriptive Python text: "Credits (Advance Payments / Surplus)", "Debts (Missing Payments)".
- Source links moved from page bottom to a `<div class="description">` block under the h1, matching Python's "Source: Attendance Sheet | Payments Ledger".
- Total row uses `cell-{{Status}}` plus the small "received / expected" caption span and Python's inline-styled bold/dark background.
- Drop the redundant `class="cell"` wrapper; debts amount turns red via inline style; balance value drops the trailing "CZK".

## 2026-05-08 01:09 CEST — feat(go): M6.2 — adults page (table, filters, Pay buttons)

- `go/internal/web/api/handler.go`: extracted `ServeAdults` body into `AssembleAdults(ctx)` — shared by the JSON API route and the new HTML handler.
- `go/internal/web/render.go`: added `AdultsPageData` view model (`PageData` + `api.AdultsResponse` + `Error`); `tmplFuncs` with `qrHref` / `qrHrefAll` (URL-encode QR Platba params, convert YYYY-MM → MM/YYYY).
- `go/internal/web/html_handler.go`: `HTMLHandler` gains `*api.Handler`; `ServeAdults` loads real reconcile data and renders the full adults page.
- `go/internal/web/templates/adults.tmpl`: full table (per-member rows, per-cell status classes, `data-month-idx`, Pay button hrefs to `/qr`), totals row, credits/debts/unmatched sections, filter controls, sheet links.
- `go/internal/web/static/js/filters.js`: name filter (NFD-normalize) + month-range hide/show by `data-month-idx`; future months hidden by default.

## 2026-05-08 00:44 CEST — feat(go): M6.1 — template skeleton + embed.FS

- `go/internal/web/templates/`: `base.tmpl` (full HTML layout), `partials/nav.tmpl` (three-tier nav with active-link highlighting), `partials/footer.tmpl` (build meta), and stub pages for each route (adults/juniors/payments/sync/flush_cache).
- `go/internal/web/static/css/app.css`: terminal-green-on-black theme extracted once from Python `templates/adults.html` — shared by all Go HTML pages via `<link>`.
- `go/internal/web/assets.go`: `//go:embed templates static` for single-binary deployment.
- `go/internal/web/render.go`: `Renderer` parses a fresh `*template.Template` per page at startup; `Render(w, name, data)` executes the "base" template block.
- `go/internal/web/html_handler.go`: `HTMLHandler` with one method per route (`ServeAdults`, `ServeJuniors`, `ServePayments`, `ServeSync`, `ServeFlushCache`).
- `go/internal/web/server.go`: drops `helloHandler`; `GET /{$}` now redirects to `/adults`; HTML + `/static/` routes registered alongside the existing `/api/*` routes.
- `go/internal/web/html_handler_test.go`: smoke test — each route returns 200 `text/html` with exactly one `class="active"` on the matching nav link.

## 2026-05-08 00:26 CEST — fix(py): parity coercions — amount/message types + junior '?' sticky

- `scripts/match_payments.py`: added `get_float` helper — non-numeric `amount` values (e.g. `"---"` placeholder rows) now coerce to `0.0` matching Go's `parseFloat` behaviour; `message` field now goes through `get_str` so numeric cell values (bank references) are emitted as strings, matching Go's `fmt.Sprint`.
- `scripts/views.py`: junior month cell `"?"` text is now sticky across exception overrides. Previously `reconcile` replaced `expected` with the exception amount before the view builder ran, silently turning `"?"` into `"-"` when the override was 0. Fixed by deriving `is_unknown` from `original_expected == "?"` instead of `expected == "?"`. Also aligned tooltip guard: only show Received/Expected for non-unknown months (or when paid > 0), matching Go's `!md.IsUnknown` condition.

## 2026-05-07 23:51 CEST — feat(py): M5.4 fix #2 — add vs and sync_id to payments tx projection

- `scripts/match_payments.py`: `fetch_sheet_data` now reads `VS` and `Sync ID` columns and includes `vs`/`sync_id` keys in every tx dict. Previously only 9 columns were projected, causing `make parity` to report extra `vs`/`sync_id` fields on every raw payment row emitted by the Go backend. Values flow through `group_payments_by_person` → `_unwrap_view_model_for_api` to `raw_payments` (adults/juniors) and `grouped_payments` (payments) automatically.
- `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.
- `Expected{Value int; Unknown bool}` custom `MarshalJSON` emits integer or `"?"` for junior single-attendance months.
- `schemagen_test.go` golden-tests four JSON Schemas committed to `go/tests/fixtures/api-schema/`. `JSONSchema()` on `Expected` lives in the test file — production binary has no jsonschema dep.
- PR #16.

## 2026-05-07 15:26 CEST — refactor(app): extract view-model builders into scripts/views.py

- Pulled ~350 lines of inline per-row computation out of `adults_view`, `juniors_view`, and `payments` into three pure functions in `scripts/views.py`: `build_adults_view_model`, `build_juniors_view_model`, `build_payments_view_model`.
- Moved `get_month_labels`, `group_payments_by_person`, `adapt_junior_members` from `app.py` to `scripts/views.py`. Route handlers now ~25 lines each.
- Hotfixed missing `import re` that caused 500 on `/qr` after the refactor.
- No behaviour change; all 27 tests pass. Prep for `/api/*` shadow endpoints (M5).

## 2026-05-07 14:13 CEST — feat(go): --print-fio-table + Fio debug logging + date parser fix

- Added `--print-fio-table` flag to `fuj sync --dry-run`: prints an aligned table of every Fio transaction in the window with `STATUS=NEW/DUP`, using `text/tabwriter`. Key files: `go/internal/services/banksync/fio_table.go`, `sync.go`, `cmd/fuj/main.go`.
- Added `LOG_LEVEL=DEBUG` debug logging on the Fio fetch path: client variant selected, full GET URL (token redacted on API path), HTTP status, body bytes, and per-parse drop-reason counters (`raw_rows`, `kept`, `dropped_bad_date`, `dropped_nonpositive_amount`). Key files: `go/internal/io/fio/{client,api,transparent}.go`.
- Fixed `parseCzechDate` to accept `DD.MM.YY` (2-digit year) in addition to the 4-digit variant — Fio's transparent page now serves this format. Key file: `go/internal/io/fio/transparent.go`.
- Added `make go-sync-debug [DAYS=N]` Makefile target (default 30 days).

## 2026-05-07 10:32 CEST — feat(go): --dry-run for fuj sync

- `SyncOpts.DryRun bool` added; when true, `SyncToSheets` prints planned writes (`would write header row`, `would append date=… amount=… sender=…`, `would sort by date`) and returns without calling `WriteHeader`, `AppendValues`, or `SortByDateColumn`.
- `fuj sync --dry-run` flag wired in `cmd/fuj/main.go`; mirrors existing `fuj infer --dry-run` behaviour.
- `TestSyncToSheets_DryRun` added to banksync test suite.

## 2026-05-07 01:03 CEST — feat(go/M4): IO layer behind interfaces

- `go/internal/io/attendance`: CSV-over-public-URL client + `Fake` for both adult and junior tabs.
- `go/internal/io/drive`: thin Drive v3 wrapper for `modifiedTime` reads + `Fake`.
- `go/internal/io/sheets`: Sheets v4 client (`GetValues`, `AppendValues`, `BatchUpdateValues`, `WriteHeader`, `SortByDateColumn`) + `Fake` with call-capture for assertions.
- `go/internal/io/cache`: Drive-modifiedTime-gated `FileCache` with two TTL knobs, atomic writes, and generic `Get[T]`; Python-compatible JSON format; `Flush()` support.
- `go/internal/io/fio`: `Client` interface backed by Fio REST API (`apiClient`) and HTML-scraper (`transparentClient`); `Fake` for tests. Fixtures in `testdata/`.
- `go/internal/services/membership/sources.go`: `NewSources` wires attendance CSV + Sheets + cache into `LoadAdults`, `LoadJuniors`, `LoadTransactions`, `LoadExceptions`. Includes Czech month/merged-month parsing logic.
- `go/internal/services/banksync`: `SyncToSheets` (dedup via SHA-256 Sync ID, optional sort) and `InferPayments` (name-match + `[?]` review prefix, dry-run) — fully tested with fakes.
- `go/cmd/fuj/main.go`: `sync` and `infer` subcommands wired to real clients; `fees` and `reconcile` now use real `NewSources`.
- All packages lint-clean (golangci-lint v1.64.8, gofumpt extra-rules).

## 2026-05-06 23:25 CEST — feat(go/M3): fixture capture + parity test framework

- `scripts/capture_fixtures.py`: dispatcher CLI that calls each ported function with seeded inputs and emits captured output as JSON fixtures.
- `scripts/scrub_fixtures.py`: deterministic PII scrubber (SHA-256 pseudonyms, digit-preserving account/VS hashes, name-sweep in free text).
- `scripts/_fixture_seeds.py`: handcrafted seed registry for all 10 pure functions + 10 reconcile branch-coverage cases.
- 98 fixture files committed under `go/tests/fixtures/pure/<func>/` and `go/tests/fixtures/reconcile/`; all PII-free.
- `go/tests/parity/parityio.go`: shared loader with generic `LoadDir`/`RunAll` helpers and typed `In`/`Out` structs for all 10 functions.
- 11 parity test packages under `//go:build parity`: 10 pure-function tests + bespoke reconcile test with per-cell float tolerance.
- Makefile: `go-parity`, `go-test-all`, `capture-fixtures` targets.
- `go/tests/fixtures/README.md`: refresh workflow, PII audit guide, adding-a-fixture steps.

## 2026-05-06 17:49 CEST — feat(go/M2.11-12): wire fuj fees + fuj reconcile subcommands

- New `go/internal/services/membership` package: `AttendanceLoader`, `TransactionLoader`, `ExceptionLoader` interfaces, a stub (`NewStubSources`) that returns `ErrIOPending`, and `FeesReport` / `ReconcileReport` orchestration functions backed by real `domain/fees` + `domain/reconcile` logic.
- Text formatters `printFeesTable` / `printReconcileReport` port the output of `calculate_fees.py` and `match_payments.py print_report` verbatim.
- `cmd/fuj/main.go`: `fuj fees` and `fuj reconcile` subcommands now dispatch properly; `fuj sync` / `fuj infer` retain the [M4] placeholder.
- Both subcommands exit 1 with a clean `"io layer not yet wired up; lands in milestone M4"` message until real Sheets loaders are injected in M4.
- 13 unit tests covering stubs, all formatter branches (OK/partial/UNPAID/dash cells, credits, debts, unmatched, review annotation), and orchestration wiring via fake loaders.

## 2026-05-06 16:38 CEST — fix: include juniors in payment-inference roster

- `scripts/infer_payments.py`: union adults + junior rosters so junior-only members are visible to the matcher.
- Root cause: `get_members_with_fees()` reads only the adults sheet; junior-only kids like Jáchym Kubík were absent from `member_names`, causing the exact-match short-circuit to never fire and a different adult sharing the first name to win via fuzzy review.
- Two regression tests added to `tests/test_match_members.py`.

## 2026-05-06 16:05 CEST — feat(go/M2.10): port domain/reconcile.Reconcile

- New `go/internal/domain/reconcile` package porting the three-phase payment allocation from `scripts/match_payments.py reconcile()`.
- 12 unit tests covering all Python test cases plus Go-only extras (diacritics tolerance, `[?]` stripping, `other:` purpose, out-of-window credit, inference fallback, unmatched, no-transaction guard).

## 2026-05-06 13:18 CEST — feat(go/M2.7-2.9): port domain/matching package

- New `go/internal/domain/matching` package porting three helpers from `scripts/match_payments.py`.
- `BuildNameVariants` — extracts normalized ASCII search variants from a member name, including nickname (from parens) and separate first/last; filters variants shorter than 3 chars; `variants[0]` is always the full normalized base name.
- `MatchMembers` — finds members in free text with `"auto"` or `"review"` confidence; exact-name short-circuit prevents nickname substrings (e.g. `tov`) from matching inside surnames (e.g. `ottova`).
- `FormatDate` — normalizes Google Sheets date values: handles nil, empty, int/float64 serial-days since 1899-12-30 (supports fractional serials), pre-formatted `YYYY-MM-DD` strings, and garbage input — never errors.
- `InferTransactionDetails` — composes name + month matching over sender/message/user_id; falls back to sender-only member match and date-derived month when text gives no signal.
- 21 table-driven tests; all expected values verified against live Python on 2026-05-06.

## 2026-05-06 12:43 CEST — feat(go/M2.6): port domain/synch.GenerateSyncID

- New `go/internal/domain/synch` package with `GenerateSyncID(Transaction) string` ported from `scripts/sync_fio_to_sheets.py` `generate_sync_id`.
- Byte-stable SHA-256 hash over `date|amount|currency|sender|vs|message|bank_id` (lowercased, UTF-8); `Currency: ""` defaults to `"CZK"` matching the Python missing-key fallback.
- Key subtlety: Python's `str(float)` emits `"500.0"` for whole-valued floats and switches to scientific notation at `|f| >= 1e16` or `|f| < 1e-4` — replicated in `formatAmount` using `'f'`/`'e'` format selection.
- 6 table-driven hash tests + 9 `formatAmount` tests; all expected values verified against live Python on 2026-05-06.

## 2026-05-06 09:38 CEST — feat(go/M2.5): port domain/money.ParseCZK

- New `go/internal/domain/money` package with `ParseCZK(string) (float64, error)` ported from `scripts/infer_payments.py` `parse_czk_amount`.
- Preserves the Czech-locale heuristic: comma → decimal sep; 2+ dots → thousand seps; single dot → decimal (so `"1.500"` → `1.5`).
- Returns `(0, ErrInvalidAmount)` on parse failure; callers wanting Python's silent-zero contract use `v, _ := ParseCZK(s)`.
- 15 table-driven tests plus a silent-zero contract test; all expected values verified against live Python on 2026-05-06.

## 2026-05-06 09:24 CEST — feat(go/M2.3+M2.4): port domain/fees.CalculateFee and CalculateJuniorFee

- New `go/internal/domain/fees` package with adult and junior fee calculators ported from `scripts/attendance.py`.
- `CalculateFee(count, monthKey) int` — `0→0`, `1→200`, `2+→AdultFeeMonthlyRate[month]` (fallback 700 CZK).
- `CalculateJuniorFee(count, monthKey) Expected` — `0→{0}`, `1→{Unknown:true}` (the `"?"` sentinel, now strictly typed), `2+→JuniorFeeMonthlyRate[month]` (fallback 500 CZK).
- 20 table-driven tests, all verified against live Python; `-race` clean; `golangci-lint` clean.

## 2026-05-06 00:07 CEST — feat(go/M2.2): port czech.ParseMonthReferences

- `internal/domain/czech.ParseMonthReferences`: three-pass regex (numeric slash, dot, Czech month names) with range wrap-around and `m≥10 → previousYear` heuristic, byte-equivalent to Python.
- 35 table-driven tests; all expected outputs verified against live Python before locking (addresses risk #4 from the rewrite plan).

## 2026-05-05 23:33 CEST — feat(go/M2.1): port czech.Normalize

- First M2 pure-domain task: `internal/domain/czech.Normalize` (NFKD + Mn-strip + lowercase), byte-equivalent to Python `czech_utils.normalize`.
- Adds `golang.org/x/text v0.36.0` as first external Go dependency.
- 13-case table-driven test, all spot-checked against Python before locking.

## 2026-05-04 23:08 CEST — fix: payment inference exact-match short-circuit

- `match_members()` now short-circuits on whole-word full-name hits; nickname/partial checks only run when no full name is present.
- Replaced bare `in` substring checks with `_word_in()` word-boundary regex throughout, closing the class of bugs where a short nickname (e.g. `tov`) matches inside another member's surname (`ottova`).
- Added `tests/test_match_members.py` (6 cases). Affects `scripts/match_payments.py`.

## 2026-05-04 23:08 CEST — feat: lower adult monthly fee to 700 CZK from April 2026

- `ADULT_FEE_DEFAULT` reduced from 750 → 700 CZK.
- `ADULT_FEE_MONTHLY_RATE` now pins Sep 2025 – Feb 2026 at 750 to preserve historical billing; Mar 2026 stays 350; Apr–May 2026 at 700. Affects `scripts/attendance.py`.

## 2026-05-04 12:02 CEST — Go rewrite M1: skeleton + tooling

- Created `go/` tree with module `fuj-management/go` (Go 1.26).
- `cmd/fuj`: stdlib-flag subcommand dispatcher; `server` and `version` implemented, stubs for M2/M4 commands.
- `internal/config`: env loader mirroring `scripts/config.py` (same env var names and defaults).
- `internal/logging`: slog setup accepting log level from config.
- `internal/web`: `net/http` ServeMux on `:8080`; `middleware/timer.go` logs method/path/status/ms.
- `go/build/Dockerfile`: multi-stage (`golang:1.26` → `alpine:3`) producing a static binary image.
- Makefile: `web` → `web-py` alias; added `web-go`, `go-build`, `go-test`, `go-run`, `go-lint`.
- `.gitea/workflows/build.yaml`: parallel `build-go` job pushing `<tag>-go` image.
- Gate: `make go-build`, `make go-lint`, `make go-test`, `curl :8080` all pass.

## 2026-05-03 20:37 CEST — Fix Balance column to correctly reflect past-month debt

- Balance (and Pay-All) are now computed as `sum(paid − expected)` over past months only, iterating directly over the ledger entries from `reconcile()`.
- Previously the balance used `total_balance` (which includes current/future-month activity and out-of-window credits) plus a one-sided current-month debt adjustment. Current-month *surplus* leaked through, making the balance appear less negative than the actual past-month debt.
- Pay-All is now `max(0, −balance)` so the two values are derived from a single source and can never disagree.
- Affected: `adults_view()` and `juniors_view()` in `app.py`.

## 2026-05-03 19:26 CEST — Fee-aware allocation for multi-month payments

- `reconcile()` no longer splits a multi-month payment evenly. Allocation is now per-member with two phases: greedy (if amount ≥ total expected, each month gets exactly its expected fee and overflow → credit) and proportional (otherwise distribute by each month's expected). Fixes the case where e.g. 1250 CZK covering 3 months with mixed fees (750/350/150) marked two months red.
- Out-of-window months keep the previous even-split-to-credit behavior. Fallback to even split when all matched months have `expected = 0` (prepayment before attendance is recorded).
- Display layer only — no changes to how payments are stored in Google Sheets; `Inferred Amount` still holds the full bank amount.
- Files: [scripts/match_payments.py](scripts/match_payments.py), [tests/test_reconcile_exceptions.py](tests/test_reconcile_exceptions.py) (6 new test cases).