feat(py): M5.4 fix #2 — add vs and sync_id to payments tx projection

Python's fetch_sheet_data read 9 sheet columns but skipped VS and
Sync ID, causing make parity to report extra fields on every raw
payment row emitted by the Go backend. Both columns are already on
the sheet; add idx_vs / idx_sync_id lookups and the matching keys
to the tx dict so the Python /api/* wire shape matches Go's
RawTransaction.

Update /api/* test fixtures to include vs/sync_id keys for realism.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -1,8 +1,25 @@
 # Changelog
 
+## 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/version`, `/api/adults`, `/api/juniors`, `/api/payments` from both Python (:5001) and Go (:8080) backends, scrubs an allowlist (`render_time.total`, `build_meta`), 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.
+- `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/2026-05-03-2349-go-backend-rewrite-progress.md

@@ -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.

go/cmd/parity/main.go

@@ -14,13 +14,17 @@ import (
 	"github.com/google/go-cmp/cmp/cmpopts"
 )
 
-var allRoutes = []string{"/api/version", "/api/adults", "/api/juniors", "/api/payments"}
+// /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.
-// These fields are expected to differ between backends (e.g. build tags, timing)
-// or may appear on one side only. Today both are absent from the JSON — this is
-// forward-compatible insurance for if either is added later.
-var defaultAllowlist = []string{"render_time.total", "build_meta"}
+// 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")

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/services/membership/sources.go

@@ -142,7 +142,13 @@ 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
@@ -394,9 +400,19 @@ 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 = ""

go/internal/services/membership/sources_test.go

@@ -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()

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]
@@ -255,8 +257,10 @@ def fetch_sheet_data(spreadsheet_id: str, credentials_path: str) -> list[dict]:
             "purpose": get_val(idx_purpose),
             "inferred_amount": get_val(idx_inferred_amount),
             "sender": get_val(idx_sender),
+            "vs": get_val(idx_vs),
             "message": get_val(idx_message),
             "bank_id": get_val(idx_bank_id),
+            "sync_id": get_val(idx_sync_id),
         }
         transactions.append(tx)
     

tests/test_app.py

@@ -129,6 +129,7 @@ class TestWebApp(unittest.TestCase):
             '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)
@@ -155,6 +156,7 @@ class TestWebApp(unittest.TestCase):
         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)
@@ -172,6 +174,7 @@ class TestWebApp(unittest.TestCase):
         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)