chore: CHANGELOG and progress tracker for M5.1

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

CHANGELOG.md

@@ -1,5 +1,19 @@
 # Changelog
 
+## 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`.

app.py

@@ -21,8 +21,14 @@ from config import (
     ATTENDANCE_SHEET_ID, PAYMENTS_SHEET_ID, JUNIOR_SHEET_GID,
     BANK_ACCOUNT, CREDENTIALS_PATH,
 )
-from attendance import get_members_with_fees, get_junior_members_with_fees, ADULT_MERGED_MONTHS, JUNIOR_MERGED_MONTHS
+from attendance import get_members_with_fees, get_junior_members_with_fees
-from match_payments import reconcile, fetch_sheet_data, fetch_exceptions, normalize, canonical_member_key
+from match_payments import reconcile, fetch_sheet_data, fetch_exceptions
+from views import (
+    build_adults_view_model,
+    build_juniors_view_model,
+    build_payments_view_model,
+    adapt_junior_members,
+)
 from cache_utils import get_sheet_modified_time, read_cache, write_cache, _LAST_CHECKED, flush_cache
 from sync_fio_to_sheets import sync_to_sheets
 from infer_payments import infer_payments
@@ -38,44 +44,6 @@ def get_cached_data(cache_key, sheet_id, fetch_func, *args, serialize=None, dese
         write_cache(cache_key, mod_time, serialize(data) if serialize else data)
     return data
 
-def get_month_labels(sorted_months, merged_months):
-    labels = {}
-    for m in sorted_months:
-        dt = datetime.strptime(m, "%Y-%m")
-        # Find which months were merged into m (e.g. 2026-01 is merged into 2026-02)
-        merged_in = sorted([k for k, v in merged_months.items() if v == m])
-        if merged_in:
-            all_dts = [datetime.strptime(x, "%Y-%m") for x in sorted(merged_in + [m])]
-            years = {d.year for d in all_dts}
-            if len(years) > 1:
-                parts = [d.strftime("%b %Y") for d in all_dts]
-                labels[m] = "+".join(parts)
-            else:
-                parts = [d.strftime("%b") for d in all_dts]
-                labels[m] = f"{'+'.join(parts)} {dt.strftime('%Y')}"
-        else:
-            labels[m] = dt.strftime("%b %Y")
-    return labels
-
-def group_payments_by_person(transactions, member_names=None):
-    canonical_by_key = (
-        {canonical_member_key(n): n for n in member_names} if member_names else {}
-    )
-    grouped = {}
-    for tx in transactions:
-        person = str(tx.get("person", "")).strip()
-        if not person:
-            continue
-        for p in person.split(","):
-            p = re.sub(r"\[\?\]\s*", "", p).strip()
-            if not p:
-                continue
-            key = canonical_by_key.get(canonical_member_key(p), p)
-            grouped.setdefault(key, []).append(tx)
-    for rows in grouped.values():
-        rows.sort(key=lambda t: str(t.get("date", "")), reverse=True)
-    return grouped
-
 def warmup_cache():
     """Pre-fetch all cached data so first request is fast."""
     logger = logging.getLogger(__name__)
@@ -200,155 +168,20 @@ def adults_view():
     result = reconcile(members, sorted_months, transactions, exceptions)
     record_step("reconcile")
 
-    month_labels = get_month_labels(sorted_months, ADULT_MERGED_MONTHS)
+    vm = build_adults_view_model(
-    adult_names = sorted([name for name, tier, _ in members if tier == "A"])
+        members, sorted_months, result, transactions,
-    current_month = datetime.now().strftime("%Y-%m")
+        datetime.now().strftime("%Y-%m"),
-
-    monthly_totals = {m: {"expected": 0, "paid": 0} for m in sorted_months}
-    formatted_results = []
-    for name in adult_names:
-        data = result["members"][name]
-        row = {"name": name, "months": [], "balance": data["total_balance"], "unpaid_periods": "", "raw_unpaid_periods": ""}
-        unpaid_months = []
-        raw_unpaid_months = []
-        for m in sorted_months:
-            mdata = data["months"].get(m, {"expected": 0, "original_expected": 0, "attendance_count": 0, "paid": 0, "exception": None})
-            expected = mdata.get("expected", 0)
-            original_expected = mdata.get("original_expected", 0)
-            count = mdata.get("attendance_count", 0)
-            paid = int(mdata.get("paid", 0))
-            exception_info = mdata.get("exception", None)
-
-            monthly_totals[m]["expected"] += expected
-            monthly_totals[m]["paid"] += paid
-
-            override_amount = exception_info["amount"] if exception_info else None
-
-            if override_amount is not None and override_amount != original_expected:
-                is_overridden = True
-                fee_display = f"{override_amount} ({original_expected}) CZK ({count})" if count > 0 else f"{override_amount} ({original_expected}) CZK"
-            else:
-                is_overridden = False
-                fee_display = f"{expected} CZK ({count})" if count > 0 else f"{expected} CZK"
-
-            status = "empty"
-            cell_text = "-"
-            amount_to_pay = 0
-
-            if expected > 0:
-                amount_to_pay = max(0, expected - paid)
-                if paid >= expected:
-                    status = "ok"
-                    cell_text = f"{paid}/{fee_display}"
-                elif paid > 0:
-                    status = "partial"
-                    cell_text = f"{paid}/{fee_display}"
-                    if m < current_month:
-                        unpaid_months.append(month_labels[m])
-                        raw_unpaid_months.append(datetime.strptime(m, "%Y-%m").strftime("%m/%Y"))
-                else:
-                    status = "unpaid"
-                    cell_text = f"0/{fee_display}"
-                    if m < current_month:
-                        unpaid_months.append(month_labels[m])
-                        raw_unpaid_months.append(datetime.strptime(m, "%Y-%m").strftime("%m/%Y"))
-            elif paid > 0:
-                status = "surplus"
-                cell_text = f"PAID {paid}"
-            else:
-                cell_text = "-"
-                amount_to_pay = 0
-
-            if expected > 0 or paid > 0:
-                tooltip = f"Received: {paid}, Expected: {expected}"
-            else:
-                tooltip = ""
-
-            row["months"].append({
-                "text": cell_text,
-                "overridden": is_overridden,
-                "status": status,
-                "amount": amount_to_pay,
-                "month": month_labels[m],
-                "raw_month": m,
-                "tooltip": tooltip
-            })
-
-        # Balance = sum of (paid - expected) for past months only; current/future months ignored.
-        settled_balance = 0
-        for m, mdata in data["months"].items():
-            if m >= current_month:
-                continue
-            exp = mdata.get("expected", 0)
-            if isinstance(exp, int):
-                settled_balance += int(mdata.get("paid", 0)) - exp
-
-        payable_amount = max(0, -settled_balance)
-        row["unpaid_periods"] = ", ".join(unpaid_months)
-        row["raw_unpaid_periods"] = "+".join(raw_unpaid_months)
-        row["balance"] = settled_balance
-        row["payable_amount"] = payable_amount
-        formatted_results.append(row)
-
-    formatted_totals = []
-    for m in sorted_months:
-        t = monthly_totals[m]
-        status = "empty"
-        if t["expected"] > 0 or t["paid"] > 0:
-            if t["paid"] == t["expected"]:
-                status = "ok"
-            elif t["paid"] < t["expected"]:
-                status = "unpaid"
-            else:
-                status = "surplus"
-
-        formatted_totals.append({
-            "text": f"{t['paid']} / {t['expected']} CZK",
-            "status": status
-        })
-
-    def settled_balance(name):
-        data = result["members"][name]
-        total = 0
-        for m, mdata in data["months"].items():
-            if m >= current_month:
-                continue
-            exp = mdata.get("expected", 0)
-            if isinstance(exp, int):
-                total += int(mdata.get("paid", 0)) - exp
-        return total
-
-    credits = sorted([{"name": n, "amount": settled_balance(n)} for n in adult_names if settled_balance(n) > 0], key=lambda x: x["name"])
-    debts = sorted([{"name": n, "amount": abs(settled_balance(n))} for n in adult_names if settled_balance(n) < 0], key=lambda x: x["name"])
-    unmatched = result["unmatched"]
-    import json
-    
-    raw_payments_by_person = group_payments_by_person(transactions, [name for name, _, _ in members])
-    record_step("process_data")
-
-    return render_template(
-        "adults.html",
-        months=[month_labels[m] for m in sorted_months],
-        raw_months=sorted_months,
-        results=formatted_results,
-        totals=formatted_totals,
-        member_data=json.dumps(result["members"]),
-        month_labels_json=json.dumps(month_labels),
-        raw_payments_json=json.dumps(raw_payments_by_person),
-        credits=credits,
-        debts=debts,
-        unmatched=unmatched,
         attendance_url=attendance_url,
         payments_url=payments_url,
         bank_account=BANK_ACCOUNT,
-        current_month=current_month
     )
+    record_step("process_data")
+    return render_template("adults.html", **vm)
 
 @app.route("/juniors")
 def juniors_view():
     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"
-    
     credentials_path = CREDENTIALS_PATH
 
     junior_members_data = get_cached_data("attendance_juniors", ATTENDANCE_SHEET_ID, get_junior_members_with_fees)
@@ -367,188 +200,19 @@ def juniors_view():
     )
     record_step("fetch_exceptions")
 
-    # Adapt junior tuple format (name, tier, {month: (fee, total_count, adult_count, junior_count)}) 
+    adapted_members = adapt_junior_members(junior_members)
-    # to what match_payments expects: (name, tier, {month: (expected_fee, attendance_count)})
-    adapted_members = []
-    for name, tier, fees_dict in junior_members:
-        adapted_fees = {}
-        for m, fee_data in fees_dict.items():
-            if len(fee_data) == 4:
-                fee, total_count, _, _ = fee_data
-                adapted_fees[m] = (fee, total_count)
-            else:
-                fee, count = fee_data
-                adapted_fees[m] = (fee, count)
-        adapted_members.append((name, tier, adapted_fees))
-
     result = reconcile(adapted_members, sorted_months, transactions, exceptions)
     record_step("reconcile")
 
-    # Format month labels
+    vm = build_juniors_view_model(
-    month_labels = get_month_labels(sorted_months, JUNIOR_MERGED_MONTHS)
+        junior_members, adapted_members, sorted_months, result, transactions,
-    junior_names = sorted([name for name, tier, _ in adapted_members])
+        datetime.now().strftime("%Y-%m"),
-    junior_members_dict = {name: fees_dict for name, _, fees_dict in junior_members}
-    current_month = datetime.now().strftime("%Y-%m")
-
-    monthly_totals = {m: {"expected": 0, "paid": 0} for m in sorted_months}
-    formatted_results = []
-    for name in junior_names:
-        data = result["members"][name]
-        row = {"name": name, "months": [], "balance": data["total_balance"], "unpaid_periods": "", "raw_unpaid_periods": ""}
-        unpaid_months = []
-        raw_unpaid_months = []
-        for m in sorted_months:
-            mdata = data["months"].get(m, {"expected": 0, "original_expected": 0, "attendance_count": 0, "paid": 0, "exception": None})
-            expected = mdata.get("expected", 0)
-            original_expected = mdata.get("original_expected", 0)
-            count = mdata.get("attendance_count", 0)
-            paid = int(mdata.get("paid", 0))
-            exception_info = mdata.get("exception", None)
-
-            if expected != "?" and isinstance(expected, int):
-                monthly_totals[m]["expected"] += expected
-            monthly_totals[m]["paid"] += paid
-
-            orig_fee_data = junior_members_dict.get(name, {}).get(m)
-            adult_count = 0
-            junior_count = 0
-            if orig_fee_data and len(orig_fee_data) == 4:
-                _, _, adult_count, junior_count = orig_fee_data
-
-            breakdown = ""
-            if adult_count > 0 and junior_count > 0:
-                breakdown = f":{junior_count}J,{adult_count}A"
-            elif junior_count > 0:
-                breakdown = f":{junior_count}J"
-            elif adult_count > 0:
-                breakdown = f":{adult_count}A"
-
-            count_str = f" ({count}{breakdown})" if count > 0 else ""
-
-            override_amount = exception_info["amount"] if exception_info else None
-
-            if override_amount is not None and override_amount != original_expected:
-                is_overridden = True
-                fee_display = f"{override_amount} ({original_expected}) CZK{count_str}"
-            else:
-                is_overridden = False
-                fee_display = f"{expected} CZK{count_str}"
-
-            status = "empty"
-            cell_text = "-"
-            amount_to_pay = 0
-
-            if expected == "?" or (isinstance(expected, int) and expected > 0):
-                if expected == "?":
-                    status = "empty"
-                    cell_text = f"?{count_str}"
-                elif paid >= expected:
-                    status = "ok"
-                    cell_text = f"{paid}/{fee_display}"
-                elif paid > 0:
-                    status = "partial"
-                    cell_text = f"{paid}/{fee_display}"
-                    amount_to_pay = expected - paid
-                    if m < current_month:
-                        unpaid_months.append(month_labels[m])
-                        raw_unpaid_months.append(datetime.strptime(m, "%Y-%m").strftime("%m/%Y"))
-                else:
-                    status = "unpaid"
-                    cell_text = f"0/{fee_display}"
-                    amount_to_pay = expected
-                    if m < current_month:
-                        unpaid_months.append(month_labels[m])
-                        raw_unpaid_months.append(datetime.strptime(m, "%Y-%m").strftime("%m/%Y"))
-            elif paid > 0:
-                status = "surplus"
-                cell_text = f"PAID {paid}"
-
-            if (isinstance(expected, int) and expected > 0) or paid > 0:
-                tooltip = f"Received: {paid}, Expected: {expected}"
-            else:
-                tooltip = ""
-
-            row["months"].append({
-                "text": cell_text,
-                "overridden": is_overridden,
-                "status": status,
-                "amount": amount_to_pay,
-                "month": month_labels[m],
-                "raw_month": m,
-                "tooltip": tooltip
-            })
-
-        # Balance = sum of (paid - expected) for past months only; current/future months ignored.
-        settled_balance = 0
-        for m, mdata in data["months"].items():
-            if m >= current_month:
-                continue
-            exp = mdata.get("expected", 0)
-            if isinstance(exp, int):
-                settled_balance += int(mdata.get("paid", 0)) - exp
-
-        payable_amount = max(0, -settled_balance)
-        row["unpaid_periods"] = ", ".join(unpaid_months)
-        row["raw_unpaid_periods"] = "+".join(raw_unpaid_months)
-        row["balance"] = settled_balance
-        row["payable_amount"] = payable_amount
-        formatted_results.append(row)
-
-    formatted_totals = []
-    for m in sorted_months:
-        t = monthly_totals[m]
-        status = "empty"
-        if t["expected"] > 0 or t["paid"] > 0:
-            if t["paid"] == t["expected"]:
-                status = "ok"
-            elif t["paid"] < t["expected"]:
-                status = "unpaid"
-            else:
-                status = "surplus"
-
-        formatted_totals.append({
-            "text": f"{t['paid']} / {t['expected']} CZK",
-            "status": status
-        })
-
-    # Format credits and debts
-    def junior_settled_balance(name):
-        data = result["members"][name]
-        total = 0
-        for m, mdata in data["months"].items():
-            if m >= current_month:
-                continue
-            exp = mdata.get("expected", 0)
-            if isinstance(exp, int):
-                total += int(mdata.get("paid", 0)) - exp
-        return total
-
-    junior_all_names = [name for name, _, _ in adapted_members]
-    credits = sorted([{"name": n, "amount": junior_settled_balance(n)} for n in junior_all_names if junior_settled_balance(n) > 0], key=lambda x: x["name"])
-    debts = sorted([{"name": n, "amount": abs(junior_settled_balance(n))} for n in junior_all_names if junior_settled_balance(n) < 0], key=lambda x: x["name"])
-    unmatched = result["unmatched"]
-    raw_payments_by_person = group_payments_by_person(transactions, [name for name, _, _ in adapted_members])
-    import json
-
-    record_step("process_data")
-
-    return render_template(
-        "juniors.html",
-        months=[month_labels[m] for m in sorted_months],
-        raw_months=sorted_months,
-        results=formatted_results,
-        totals=formatted_totals,
-        member_data=json.dumps(result["members"]),
-        month_labels_json=json.dumps(month_labels),
-        raw_payments_json=json.dumps(raw_payments_by_person),
-        credits=credits,
-        debts=debts,
-        unmatched=unmatched,
         attendance_url=attendance_url,
         payments_url=payments_url,
         bank_account=BANK_ACCOUNT,
-        current_month=current_month
     )
+    record_step("process_data")
+    return render_template("juniors.html", **vm)
 
 @app.route("/payments")
 def payments():
@@ -567,23 +231,13 @@ def payments():
     if juniors_data:
         member_names.extend(name for name, _, _ in juniors_data[0])
 
-    grouped = group_payments_by_person(transactions, member_names)
+    vm = build_payments_view_model(
-    # payments page also groups unmatched rows under a fallback key
+        transactions, member_names,
-    for tx in transactions:
-        if not str(tx.get("person", "")).strip():
-            grouped.setdefault("Unmatched / Unknown", []).append(tx)
-    for rows in grouped.values():
-        rows.sort(key=lambda t: str(t.get("date", "")), reverse=True)
-    sorted_people = sorted(grouped.keys())
-
-    record_step("process_data")
-    return render_template(
-        "payments.html",
-        grouped_payments=grouped,
-        sorted_people=sorted_people,
         attendance_url=attendance_url,
-        payments_url=payments_url
+        payments_url=payments_url,
     )
+    record_step("process_data")
+    return render_template("payments.html", **vm)
 
 @app.route("/qr")
 def qr_code():

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

@@ -97,7 +97,7 @@ 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.
 
-- [ ] **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/`
+- [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
 - [ ] **M5.3** Add Python `/api/X` shadow endpoints in [app.py](app.py): `jsonify(view_model_dict)` — no transformation
 - [ ] **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

docs/plans/2026-05-07-1431-m5-json-api-parity.md

@@ -0,0 +1,185 @@
+# Python view-model cleanup (M5 prep — Python side only)
+
+Scoped-down precursor to M5 of the Go rewrite. See:
+- [2026-05-03-2349-go-backend-rewrite.md](2026-05-03-2349-go-backend-rewrite.md)
+- [2026-05-03-2349-go-backend-rewrite-progress.md](2026-05-03-2349-go-backend-rewrite-progress.md)
+
+## Context
+
+The Python app is still production. Before adding `/api/X` shadow
+routes, JSON DTOs, parity tooling, and Go handlers, get the Python
+side into a clean shape. Today the `/adults` and `/juniors` routes
+each carry 150–200 lines of inline view-model construction inside
+the Flask handler:
+
+- [adults_view](app.py#L179) — 167 LOC, computes per-row
+  status/cell_text/balance/credits/debts inline.
+- [juniors_view](app.py#L347) — 205 LOC, same plus `"?"` sentinel
+  branching and `:NJ,MA` breakdown.
+- [payments](app.py#L553) — 35 LOC, lighter but still mixes IO and
+  grouping.
+
+Pulling that into pure builder functions:
+- shrinks `app.py` and makes each route handler do only what a route
+  handler should (IO + cache + step timing + render);
+- gives us **already-tested** pure functions that future M5 work can
+  call from a `/api/X` shadow endpoint with one line of `jsonify(...)`;
+- has zero behavioural change (existing tests in
+  [test_app.py](tests/test_app.py) act as the regression guard).
+
+This is a Python-only change. No Go work, no JSON contract, no shadow
+routes — those come after.
+
+## Approach
+
+Three pure builder functions in a new `scripts/views.py` module. Each
+takes already-loaded, deserialized inputs (no Flask globals, no IO,
+no cache calls) and returns the exact dict that today's route passes
+to `render_template`.
+
+```python
+def build_adults_view_model(
+    members, sorted_months, transactions, exceptions, current_month,
+    *, attendance_url, payments_url, bank_account,
+) -> dict: ...
+
+def build_juniors_view_model(
+    junior_members, sorted_months, transactions, exceptions, current_month,
+    *, attendance_url, payments_url, bank_account,
+) -> dict: ...
+
+def build_payments_view_model(
+    transactions, member_names,
+    *, attendance_url, payments_url,
+) -> dict: ...
+```
+
+The route handlers shrink to: load data (with `get_cached_data` and
+`record_step` calls staying in `app.py`), call the builder, render.
+
+```python
+@app.route("/adults")
+def adults_view():
+    members, sorted_months = ... # cached loads + record_step calls
+    transactions = ...
+    exceptions = ...
+    result_meta = ...
+    record_step("process_data")
+    vm = build_adults_view_model(
+        members, sorted_months, transactions, exceptions,
+        datetime.now().strftime("%Y-%m"),
+        attendance_url=..., payments_url=..., bank_account=BANK_ACCOUNT,
+    )
+    return render_template("adults.html", **vm)
+```
+
+## Decisions
+
+1. **Pure builders, no Flask state.** No `record_step`, no `g.*`, no
+   `get_cached_data` inside builders. They take plain args, return
+   plain dicts. This is what makes them trivially unit-testable and,
+   later, trivially reusable from `/api/X`.
+2. **Preserve byte-equal behaviour.** The dicts returned must match
+   today's `render_template(...)` kwargs key-for-key, value-for-value
+   — including the existing `json.dumps(member_data)` /
+   `json.dumps(month_labels_json)` / `json.dumps(raw_payments_json)`
+   wrappers. Those wrappers exist for inline JS in templates; the
+   refactor doesn't touch them. (When `/api/X` lands later, that route
+   will produce a sibling dict with the wrappers stripped, but that's
+   future work.)
+3. **`reconcile()` stays inside the route, not the builder.** It
+   crosses the IO/cache boundary in spirit (its inputs come from
+   cache); but it's also pure-domain and called by both adults and
+   juniors. Keep the call site in the route so `record_step("reconcile")`
+   timing isn't lost. Builder takes `result` as an argument.
+4. **Shared helpers stay in `app.py`** for now —
+   [get_month_labels](app.py#L41) and
+   [group_payments_by_person](app.py#L60) are already module-level
+   pure functions, used by routes and now by builders. Either leave
+   them in `app.py` and import into `scripts/views.py`, or move them
+   into `scripts/views.py`. **Choose: move into `scripts/views.py`**
+   — they're view-model concerns, not Flask concerns, and `app.py`
+   should keep shrinking.
+5. **No new test file needed.** Existing
+   [tests/test_app.py](tests/test_app.py) tests
+   `test_adults_route`, `test_juniors_route`, `test_payments_route`
+   exercise the rendered HTML end-to-end. If they pass after the
+   refactor, behaviour is preserved. Adding builder-level unit tests
+   is a *nice-to-have* but not required for this iteration.
+
+## Tasks
+
+### 1. Create `scripts/views.py` with the three builders + shared helpers
+
+- Move `get_month_labels` and `group_payments_by_person` from
+  [app.py:41–77](app.py#L41-L77) into `scripts/views.py`. Update the
+  import in `app.py`.
+- Implement `build_adults_view_model` by extracting
+  [app.py:200–344](app.py#L200-L344) (everything between `result =
+  reconcile(...)` and `return render_template(...)`). Take `result`
+  as a parameter; emit the same dict that's currently passed as
+  `**kwargs` to `render_template`.
+- Implement `build_juniors_view_model` by extracting
+  [app.py:370–550](app.py#L370-L550). Same shape — including the
+  `adapted_members` adapter loop, the junior `?`-sentinel branches,
+  and the `:NJ,MA` breakdown.
+- Implement `build_payments_view_model` by extracting
+  [app.py:570–586](app.py#L570-L586) (the `group_payments_by_person`
+  call + `Unmatched / Unknown` bucket + sort).
+
+### 2. Slim down the route handlers in `app.py`
+
+Each handler keeps:
+- `attendance_url`/`payments_url` URL building
+- `get_cached_data` calls (with `record_step` between)
+- `reconcile(...)` call (adults/juniors) with `record_step("reconcile")`
+- `record_step("process_data")` after the builder call
+- `return render_template("X.html", **view_model)`
+
+Each handler **drops** all the per-row computation, totals
+formatting, credits/debts sorting, `raw_payments_by_person` building,
+and `import json` lines.
+
+Target post-refactor LOC for each route handler: ~25–30 lines
+(currently 167 / 205 / 35).
+
+### 3. Run the existing test suite + manual smoke
+
+```
+make test                # all tests green
+make web-py              # browse /adults /juniors /payments visually
+```
+
+## Critical files
+
+- [app.py](app.py) — routes shrink dramatically; `get_month_labels`
+  and `group_payments_by_person` get moved out.
+- New: `scripts/views.py` — three builders + the two helpers.
+- [tests/test_app.py](tests/test_app.py) — unchanged; serves as the
+  regression guard.
+
+## Verification
+
+1. `make test` — all four `TestWebApp` tests pass unchanged.
+2. `make web-py` and visit `/adults`, `/juniors`, `/payments` — each
+   renders identically to before (same table contents, same totals,
+   same credits/debts, same `?` rendering on juniors).
+3. `git diff app.py` shows substantial deletions (route bodies
+   shrink) and only thin glue calling the new builders.
+4. Optional sanity check: temporarily add `print(repr(view_model))`
+   in the route before `render_template` on `main` and on the branch,
+   diff for one fixture run — should be byte-identical dicts.
+
+## Out of scope (future iterations, not this plan)
+
+- `/api/<route>` shadow endpoints in Flask
+- Go `internal/web/api/` DTOs and JSON Schemas
+- Go `internal/services/membership/views.go` aggregators
+- Go HTTP handlers for `/api/X`
+- `cmd/parity/main.go` and `make parity` target
+- Junior breakdown sidecar work in
+  `go/internal/services/membership/sources.go`
+
+These are the original M5 tasks (M5.1–M5.4 in the progress tracker).
+They become much easier once today's refactor lands, because the
+shadow `/api/X` routes will be one-liners over the new builders.

docs/plans/2026-05-07-1650-go-rewrite-m5-1-api-structs-schemas.md

@@ -0,0 +1,240 @@
+# M5.1 — Hand-author Go API structs + emit JSON Schemas
+
+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) (progress tracker — M5.1 row)
+- [2026-05-07-1431-m5-json-api-parity.md](2026-05-07-1431-m5-json-api-parity.md) (Python view-model extraction prep — already merged as `b562ce3` / `32a16ff` / `59223c0`)
+
+## Context
+
+M4 (IO layer behind interfaces) just landed. M5 is the JSON-parity contract phase — byte-equal JSON between Python and Go for `/api/adults`, `/api/juniors`, `/api/payments`, `/api/version`. Within M5, the work splits four ways:
+
+- **M5.1 — this plan.** Define the wire contract: hand-authored Go structs with explicit `json:` tags matching Python keys, plus committed JSON Schemas generated by `github.com/invopop/jsonschema`. **Schemas only — no handlers, no Python `/api/X` routes, no parity tool.**
+- M5.2 — Implement Go handlers that compose `services/*` results into these structs.
+- M5.3 — Add Python `/api/X` shadow endpoints in [app.py](app.py).
+- M5.4 — `cmd/parity/main.go` + `make parity` target.
+
+The recent Python view-model extraction (`scripts/views.py`) lays the groundwork: every Python builder now returns a plain dict that an `/api/X` shadow can `jsonify` (with one minor unwrap step — see decision #1 below). M5.1 is the matching Go side: types and schemas that pin down the contract before any code writes JSON to a wire.
+
+## Key design decisions
+
+1. **Wire format is nested objects, not strings-of-JSON.** The Python view-model dicts contain three template-only fields that are pre-serialized JSON strings: `member_data`, `month_labels_json`, `raw_payments_json`. Those exist purely to feed inline `<script>` blocks in Jinja templates ([scripts/views.py:227-237](scripts/views.py#L227-L237)). The `/api/X` JSON contract uses the **un-stringified** nested form. Rationale:
+   - The master design doc references `total_balance`, `original_expected`, `attendance_count` as struct fields ([2026-05-03-2349-go-backend-rewrite.md:223-225](docs/plans/2026-05-03-2349-go-backend-rewrite.md#L223-L225)), which are *inside* `member_data` — only meaningful if it's a nested object.
+   - The `Expected` `MarshalJSON` design (emit `42` or `"?"`) ([same doc:233-238](docs/plans/2026-05-03-2349-go-backend-rewrite.md#L233-L238)) only fires inside `member_data`; pointless if that field is a string.
+   - Strings-of-JSON make `invopop/jsonschema` schemas useless for those fields (`{"type": "string"}` describes nothing).
+   - The Python prep plan ([2026-05-07-1431-m5-json-api-parity.md:87-89](docs/plans/2026-05-07-1431-m5-json-api-parity.md#L87-L89)) already anticipates this: "that route will produce a sibling dict with the wrappers stripped".
+
+   This refines (does not contradict) M5.3's "no transformation" wording. M5.3's `/api/X` will be `jsonify(unwrap_json_strings(view_model_dict))` — a 4-line shim, not real transformation logic.
+
+2. **New package: `internal/web/api/`.** The Go side has no `api/` package today — only [internal/web/server.go](go/internal/web/server.go) with one hello route. The api package owns wire types and (in M5.2) handlers. Sub-files per route keep diffs small.
+
+3. **Wire types are separate from `domain/reconcile.Result`.** [domain/reconcile/reconcile.go:88-92](go/internal/domain/reconcile/reconcile.go#L88-L92) defines `Result`, `MemberResult`, `MonthData`, `TxEntry`, etc. — none have `json:` tags. **Don't tag the domain types**: that bleeds wire concerns into pure logic and locks the JSON contract to internal field names. Define wire types in `internal/web/api/` and convert in M5.2's handlers.
+
+4. **`Expected{Value int; Unknown bool}` with custom `MarshalJSON`/`UnmarshalJSON`** for junior `expected` and `original_expected`. Already prescribed by the master design.
+
+5. **Transaction `amount` / `inferred_amount` may be `int` or `""`** (Sheets `UNFORMATTED_VALUE` returns empty string for blank cells per `scripts/match_payments.py` rows 250-260 in the views.py exploration). Use a custom `SheetsNumber` type with `MarshalJSON`/`UnmarshalJSON` that emits `0`/`null` for empty and the number otherwise. Document in code comment with a one-liner. Verify exact behavior by inspecting one or two existing scrubbed reconcile fixtures before coding.
+
+6. **Schema generation lives in `internal/web/api/schemagen_test.go`** with `-update` flag, à la golden tests. Default test run (`go test ./internal/web/api/...`) re-generates schemas in memory and asserts byte-equality vs the committed files in `tests/fixtures/api-schema/`. `go test -update ./internal/web/api/...` rewrites the committed files. Avoids a separate `cmd/gen-api-schema` binary; CI catches drift automatically.
+
+7. **One schema per route**, named to match the Go type:
+   ```
+   go/tests/fixtures/api-schema/adults.schema.json
+   go/tests/fixtures/api-schema/juniors.schema.json
+   go/tests/fixtures/api-schema/payments.schema.json
+   go/tests/fixtures/api-schema/version.schema.json
+   ```
+
+8. **Adults and Juniors are *not* the same type.** Their outer shapes match (same keys), but `MonthCell.Text` semantics differ (juniors render `"?"`, `"?(3)"`, `:NJ,MA` breakdowns) and `member_data` semantics differ (juniors carry `Expected` sentinel). Define `AdultsResponse` and `JuniorsResponse` separately even if they share most field types — clearer schemas and easier to evolve independently. Share scalar types (`Transaction`, `Exception`, `MonthCell`, `TotalCell`) in `types.go`.
+
+9. **Money is integer CZK** ([master design:55-56](docs/plans/2026-05-03-2349-go-backend-rewrite.md#L55-L56)). All amount fields use `int`. The one exception: `member_data[name].months[YYYY-MM].paid` is a `float64` in the Python output (proportional allocation produces fractional CZK like `33.333333`). Use `float64` only there; document the why in a one-line comment.
+
+## Files to create
+
+```
+go/internal/web/api/
+├── types.go             # SheetsNumber, Expected, Exception, Transaction, MonthCell, TotalCell, MemberRow
+├── adults.go            # AdultsResponse + adults-specific MemberData
+├── juniors.go           # JuniorsResponse + juniors-specific MemberData (with Expected fields)
+├── payments.go          # PaymentsResponse
+├── version.go           # VersionResponse
+└── schemagen_test.go    # generates + golden-asserts schemas
+
+go/tests/fixtures/api-schema/
+├── adults.schema.json
+├── juniors.schema.json
+├── payments.schema.json
+└── version.schema.json
+```
+
+## Struct skeleton (illustrative, not final wording)
+
+```go
+// internal/web/api/types.go
+
+// SheetsNumber wraps a value that may arrive from Google Sheets as either
+// a JSON number or "" (empty string for blank cells). Marshals as 0 when
+// missing; the consumer treats Missing+Value=0 as "no data".
+type SheetsNumber struct {
+    Value   float64
+    Missing bool
+}
+
+// Expected carries a junior's expected fee or the "?" sentinel
+// (single-attendance month requires manual review).
+type Expected struct {
+    Value   int
+    Unknown bool
+}
+
+type Exception struct {
+    Amount int    `json:"amount"`
+    Note   string `json:"note"`
+}
+
+type Transaction struct {
+    Date           string       `json:"date"`
+    Amount         SheetsNumber `json:"amount"`
+    ManualFix      string       `json:"manual_fix"`
+    Person         string       `json:"person"`
+    Purpose        string       `json:"purpose"`
+    InferredAmount SheetsNumber `json:"inferred_amount"`
+    Sender         string       `json:"sender"`
+    Message        string       `json:"message"`
+    BankID         string       `json:"bank_id"`
+}
+
+type MonthCell struct {
+    Text       string `json:"text"`
+    Overridden bool   `json:"overridden"`
+    Status     string `json:"status"` // "empty"|"ok"|"partial"|"unpaid"|"surplus"
+    Amount     int    `json:"amount"`
+    Month      string `json:"month"`      // display label, e.g. "Apr+May 2025"
+    RawMonth   string `json:"raw_month"`  // YYYY-MM
+    Tooltip    string `json:"tooltip"`
+}
+
+type TotalCell struct {
+    Text   string `json:"text"`
+    Status string `json:"status"`
+}
+
+type MemberRow struct {
+    Name              string      `json:"name"`
+    Months            []MonthCell `json:"months"`
+    Balance           int         `json:"balance"`
+    UnpaidPeriods     string      `json:"unpaid_periods"`
+    RawUnpaidPeriods  string      `json:"raw_unpaid_periods"`
+    PayableAmount     int         `json:"payable_amount"`
+}
+
+type Credit struct {
+    Name   string `json:"name"`
+    Amount int    `json:"amount"`
+}
+```
+
+```go
+// internal/web/api/adults.go
+type AdultsMonthData struct {
+    Status      string             `json:"status"`
+    Expected    int                `json:"expected"`
+    Paid        float64            `json:"paid"` // float — proportional allocator can produce 33.333…
+    Exception   *Exception         `json:"exception"`
+    AmountToPay int                `json:"amount_to_pay"`
+    // ... transactions, others, etc — match exact keys from result["members"][name]["months"][YYYY-MM]
+}
+
+type AdultsMemberData struct {
+    TotalBalance int                          `json:"total_balance"`
+    Months       map[string]AdultsMonthData   `json:"months"` // YYYY-MM key
+    Transactions []Transaction                `json:"transactions"`
+}
+
+type AdultsResponse struct {
+    Months          []string                    `json:"months"`
+    RawMonths       []string                    `json:"raw_months"`
+    Results         []MemberRow                 `json:"results"`
+    Totals          []TotalCell                 `json:"totals"`
+    MemberData      map[string]AdultsMemberData `json:"member_data"`
+    MonthLabels     map[string]string           `json:"month_labels"`     // was month_labels_json (string)
+    RawPayments     map[string][]Transaction    `json:"raw_payments"`     // was raw_payments_json (string)
+    Credits         []Credit                    `json:"credits"`
+    Debts           []Credit                    `json:"debts"`
+    Unmatched       []Transaction               `json:"unmatched"`
+    AttendanceURL   string                      `json:"attendance_url"`
+    PaymentsURL     string                      `json:"payments_url"`
+    BankAccount     string                      `json:"bank_account"`
+    CurrentMonth    string                      `json:"current_month"`
+}
+```
+
+`JuniorsResponse` mirrors `AdultsResponse` but the inner `MonthData` carries `Expected` and `OriginalExpected` (both `Expected` type), and adds the `:NJ,MA` breakdown fields produced by [scripts/views.py:290-298](scripts/views.py#L290-L298).
+
+`PaymentsResponse`:
+
+```go
+type PaymentsResponse struct {
+    GroupedPayments map[string][]Transaction `json:"grouped_payments"`
+    SortedPeople    []string                 `json:"sorted_people"`
+    AttendanceURL   string                   `json:"attendance_url"`
+    PaymentsURL     string                   `json:"payments_url"`
+}
+```
+
+`VersionResponse` mirrors Python's `BUILD_META` ([app.py:67](app.py#L67)):
+
+```go
+type VersionResponse struct {
+    Tag       string `json:"tag"`
+    Commit    string `json:"commit"`
+    BuildDate string `json:"build_date"`
+}
+```
+
+Exact fields inside the per-month `MonthData`/`MemberData` will be finalized by inspecting **one** scrubbed `member_data` JSON dump from a current `/adults` and `/juniors` call (see Verification step 1) — names and types have to be identical.
+
+## Reusable existing code
+
+- `domain/reconcile.Result` ([go/internal/domain/reconcile/reconcile.go:88](go/internal/domain/reconcile/reconcile.go#L88)) — source data for adults/juniors. M5.2 maps it to wire types; M5.1 only needs to know the field set.
+- `web.BuildInfo` ([go/internal/web/server.go:11-15](go/internal/web/server.go#L11-L15)) — already wired through `cmd/fuj/main.go:79`. The `VersionResponse` type is a thin renaming of this with json tags. Decide in M5.2 whether to *also* tag `BuildInfo` directly (it's not really domain) or keep `VersionResponse` separate. M5.1 just defines the wire struct.
+- `scripts/views.py` builders — the spec for every key/type. Treat as authoritative.
+
+## Tasks
+
+1. **Add `github.com/invopop/jsonschema` dependency.** `cd go && go get github.com/invopop/jsonschema && go mod tidy`. Single commit.
+2. **Capture one fresh `member_data` dump for adults and juniors** to pin down inner-dict field names and types precisely (especially `paid` precision, `transactions[]` shape, `others[]` if present). Run `make web-py` on a known-good cache, hit `/adults` and `/juniors`, dump `view_model["member_data"]` to a scratch file (gitignored), and inspect. **Do not commit raw dumps** — PII rule. This is for shape inspection only.
+3. **Author `internal/web/api/types.go`** with `SheetsNumber`, `Expected`, `Exception`, `Transaction`, `MonthCell`, `TotalCell`, `MemberRow`, `Credit`. Implement `MarshalJSON`/`UnmarshalJSON` for `SheetsNumber` and `Expected`. Use struct tags `json:"snake_case_key"` matching Python exactly.
+4. **Author `internal/web/api/adults.go`** with `AdultsMonthData`, `AdultsMemberData`, `AdultsResponse`. Cross-check every key against the dump from step 2.
+5. **Author `internal/web/api/juniors.go`** similarly, with `Expected` fields and the J/A breakdown.
+6. **Author `internal/web/api/payments.go` and `version.go`** (small).
+7. **Author `internal/web/api/schemagen_test.go`** that:
+   - Imports `github.com/invopop/jsonschema`.
+   - Defines a `schemaCases` slice: `{name: "adults", typ: AdultsResponse{}, ...}` etc.
+   - For each case, generates a schema, marshals indented JSON, compares against committed file at `../../tests/fixtures/api-schema/<name>.schema.json`.
+   - Honors a `-update` flag (`flag.Bool`) that rewrites the committed file instead of asserting.
+   - One `t.Run(case.name, ...)` per route for clear failure output.
+8. **Run with `-update` once to populate** `tests/fixtures/api-schema/*.schema.json`. Eyeball each schema: required fields list, oneOf for `Expected`, additionalProperties on map types. Commit.
+9. **Lint + test:** `cd go && go vet ./... && make go-test && make go-lint`. Fix any issues. (Expect zero — this is read-only data structures.)
+10. **CHANGELOG entry** + tick `M5.1` in [docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md:100](docs/plans/2026-05-03-2349-go-backend-rewrite-progress.md#L100) with the merge SHA.
+11. **Branch + MR per CLAUDE.md workflow:** branch `feat/go-m5-1-api-structs`, push with `-u`, open MR via `tea pr create`. Do not merge from CLI.
+
+## Verification
+
+1. `cd go && go test ./internal/web/api/...` — **schemas regenerate identically** to committed files.
+2. `cd go && go test ./internal/web/api/... -update` then `git diff go/tests/fixtures/api-schema/` — diff is empty (idempotent generation).
+3. `cd go && make go-lint` — clean.
+4. `cd go && go vet ./...` — clean.
+5. Manual schema inspection: open `adults.schema.json`, confirm:
+   - Top-level `required` list contains every Python key.
+   - `member_data` is `additionalProperties: { ... AdultsMemberData ... }` (a map keyed by name).
+   - `expected` and `original_expected` (juniors only) are `oneOf: [{type: integer}, {const: "?"}]`.
+   - `amount` and `inferred_amount` on `Transaction` accept number or empty/null.
+6. **No production code paths exercised yet** — handlers come in M5.2. Compile-time success + schema golden-test = M5.1 done.
+
+## Out of scope (later M5 tasks)
+
+- Wiring Go HTTP handlers for `/api/X` (M5.2).
+- Adding Python `/api/X` shadow endpoints (M5.3) — including the `unwrap_json_strings(view_model)` shim noted in design decision #1.
+- `cmd/parity/main.go` and `make parity` target (M5.4).
+- Tagging `domain/reconcile.Result` with `json:` tags — explicitly avoided.
+- Refactoring the strings-of-JSON fields out of the Python view-model — they stay in `views.py` for the template path, the `/api/X` shadow unwraps them.

go/go.mod

@@ -3,6 +3,7 @@ module fuj-management/go
 go 1.26.1
 
 require (
+	github.com/invopop/jsonschema v0.14.0
 	golang.org/x/net v0.53.0
 	golang.org/x/text v0.36.0
 	google.golang.org/api v0.278.0
@@ -12,6 +13,8 @@ require (
 	cloud.google.com/go/auth v0.20.0 // indirect
 	cloud.google.com/go/auth/oauth2adapt v0.2.8 // indirect
 	cloud.google.com/go/compute/metadata v0.9.0 // indirect
+	github.com/bahlo/generic-list-go v0.2.0 // indirect
+	github.com/buger/jsonparser v1.1.2 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
 	github.com/go-logr/logr v1.4.3 // indirect
@@ -20,11 +23,13 @@ require (
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.15 // indirect
 	github.com/googleapis/gax-go/v2 v2.22.0 // indirect
+	github.com/pb33f/ordered-map/v2 v2.3.1 // indirect
 	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.67.0 // indirect
 	go.opentelemetry.io/otel v1.43.0 // indirect
 	go.opentelemetry.io/otel/metric v1.43.0 // indirect
 	go.opentelemetry.io/otel/trace v1.43.0 // indirect
+	go.yaml.in/yaml/v4 v4.0.0-rc.2 // indirect
 	golang.org/x/crypto v0.50.0 // indirect
 	golang.org/x/oauth2 v0.36.0 // indirect
 	golang.org/x/sys v0.43.0 // indirect

go/go.sum

@@ -4,6 +4,10 @@ cloud.google.com/go/auth/oauth2adapt v0.2.8 h1:keo8NaayQZ6wimpNSmW5OPc283g65QNIi
 cloud.google.com/go/auth/oauth2adapt v0.2.8/go.mod h1:XQ9y31RkqZCcwJWNSx2Xvric3RrU88hAYYbjDWYDL+c=
 cloud.google.com/go/compute/metadata v0.9.0 h1:pDUj4QMoPejqq20dK0Pg2N4yG9zIkYGdBtwLoEkH9Zs=
 cloud.google.com/go/compute/metadata v0.9.0/go.mod h1:E0bWwX5wTnLPedCKqk3pJmVgCBSM6qQI1yTBdEb3C10=
+github.com/bahlo/generic-list-go v0.2.0 h1:5sz/EEAK+ls5wF+NeqDpk5+iNdMDXrh3z3nPnH1Wvgk=
+github.com/bahlo/generic-list-go v0.2.0/go.mod h1:2KvAjgMlE5NNynlg/5iLrrCCZ2+5xWbdbCW3pNTGyYg=
+github.com/buger/jsonparser v1.1.2 h1:frqHqw7otoVbk5M8LlE/L7HTnIq2v9RX6EJ48i9AxJk=
+github.com/buger/jsonparser v1.1.2/go.mod h1:6RYKKt7H4d4+iWqouImQ9R2FZql3VbhNgx27UK13J/0=
 github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
 github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
@@ -27,6 +31,10 @@ github.com/googleapis/enterprise-certificate-proxy v0.3.15 h1:xolVQTEXusUcAA5Ugt
 github.com/googleapis/enterprise-certificate-proxy v0.3.15/go.mod h1:vqVt9yG9480NtzREnTlmGSBmFrA+bzb0yl0TxoBQXOg=
 github.com/googleapis/gax-go/v2 v2.22.0 h1:PjIWBpgGIVKGoCXuiCoP64altEJCj3/Ei+kSU5vlZD4=
 github.com/googleapis/gax-go/v2 v2.22.0/go.mod h1:irWBbALSr0Sk3qlqb9SyJ1h68WjgeFuiOzI4Rqw5+aY=
+github.com/invopop/jsonschema v0.14.0 h1:MHQqLhvpNUZfw+hM3AZDYK7jxO8FZoQeQM77g8iyZjg=
+github.com/invopop/jsonschema v0.14.0/go.mod h1:ygm6C2EaVNMBDPpaPlnOA2pFAxBnxGjFlMZABxm9n2I=
+github.com/pb33f/ordered-map/v2 v2.3.1 h1:5319HDO0aw4DA4gzi+zv4FXU9UlSs3xGZ40wcP1nBjY=
+github.com/pb33f/ordered-map/v2 v2.3.1/go.mod h1:qxFQgd0PkVUtOMCkTapqotNgzRhMPL7VvaHKbd1HnmQ=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
@@ -45,6 +53,8 @@ go.opentelemetry.io/otel/sdk/metric v1.43.0 h1:S88dyqXjJkuBNLeMcVPRFXpRw2fuwdvfC
 go.opentelemetry.io/otel/sdk/metric v1.43.0/go.mod h1:C/RJtwSEJ5hzTiUz5pXF1kILHStzb9zFlIEe85bhj6A=
 go.opentelemetry.io/otel/trace v1.43.0 h1:BkNrHpup+4k4w+ZZ86CZoHHEkohws8AY+WTX09nk+3A=
 go.opentelemetry.io/otel/trace v1.43.0/go.mod h1:/QJhyVBUUswCphDVxq+8mld+AvhXZLhe+8WVFxiFff0=
+go.yaml.in/yaml/v4 v4.0.0-rc.2 h1:/FrI8D64VSr4HtGIlUtlFMGsm7H7pWTbj6vOLVZcA6s=
+go.yaml.in/yaml/v4 v4.0.0-rc.2/go.mod h1:aZqd9kCMsGL7AuUv/m/PvWLdg5sjJsZ4oHDEnfPPfY0=
 golang.org/x/crypto v0.50.0 h1:zO47/JPrL6vsNkINmLoo/PH1gcxpls50DNogFvB5ZGI=
 golang.org/x/crypto v0.50.0/go.mod h1:3muZ7vA7PBCE6xgPX7nkzzjiUq87kRItoJQM1Yo8S+Q=
 golang.org/x/net v0.53.0 h1:d+qAbo5L0orcWAr0a9JweQpjXF19LMXJE8Ey7hwOdUA=

go/internal/web/api/adults.go

@@ -0,0 +1,42 @@
+package api
+
+// AdultsMonthData is the reconciled ledger for one adult member in one month.
+// Keys match Python's result["members"][name]["months"][YYYY-MM].
+type AdultsMonthData struct {
+	Expected         int             `json:"expected"`
+	OriginalExpected int             `json:"original_expected"`
+	AttendanceCount  int             `json:"attendance_count"`
+	Exception        *ExceptionData  `json:"exception"`
+	Paid             float64         `json:"paid"` // float: proportional allocator may produce fractional CZK
+	Transactions     []MemberTxEntry `json:"transactions"`
+}
+
+// AdultsMemberData is the reconciled ledger for one adult member.
+// Keys match Python's result["members"][name].
+type AdultsMemberData struct {
+	Tier              string                     `json:"tier"`
+	Months            map[string]AdultsMonthData `json:"months"` // YYYY-MM → month data
+	OtherTransactions []MemberOtherEntry         `json:"other_transactions"`
+	TotalBalance      int                        `json:"total_balance"`
+}
+
+// AdultsResponse is the JSON contract for GET /api/adults.
+// MemberData, MonthLabels, and RawPayments correspond to the Python view-model
+// fields member_data, month_labels_json, and raw_payments_json respectively,
+// but as nested objects rather than pre-serialised JSON strings.
+type AdultsResponse struct {
+	Months        []string                    `json:"months"`     // display labels
+	RawMonths     []string                    `json:"raw_months"` // "YYYY-MM"
+	Results       []MemberRow                 `json:"results"`
+	Totals        []TotalCell                 `json:"totals"`
+	MemberData    map[string]AdultsMemberData `json:"member_data"`  // name → ledger
+	MonthLabels   map[string]string           `json:"month_labels"` // YYYY-MM → display label
+	RawPayments   map[string][]RawTransaction `json:"raw_payments"` // name → raw sheet rows
+	Credits       []Credit                    `json:"credits"`
+	Debts         []Credit                    `json:"debts"`
+	Unmatched     []RawTransaction            `json:"unmatched"`
+	AttendanceURL string                      `json:"attendance_url"`
+	PaymentsURL   string                      `json:"payments_url"`
+	BankAccount   string                      `json:"bank_account"`
+	CurrentMonth  string                      `json:"current_month"`
+}

go/internal/web/api/juniors.go

@@ -0,0 +1,41 @@
+package api
+
+// JuniorsMonthData is the reconciled ledger for one junior member in one month.
+// expected and original_expected may be the "?" sentinel (single-attendance month
+// requiring manual review); they are carried via the Expected type.
+type JuniorsMonthData struct {
+	Expected         Expected        `json:"expected"`
+	OriginalExpected Expected        `json:"original_expected"`
+	AttendanceCount  int             `json:"attendance_count"`
+	Exception        *ExceptionData  `json:"exception"`
+	Paid             float64         `json:"paid"`
+	Transactions     []MemberTxEntry `json:"transactions"`
+}
+
+// JuniorsMemberData is the reconciled ledger for one junior member.
+type JuniorsMemberData struct {
+	Tier              string                      `json:"tier"`
+	Months            map[string]JuniorsMonthData `json:"months"`
+	OtherTransactions []MemberOtherEntry          `json:"other_transactions"`
+	TotalBalance      int                         `json:"total_balance"`
+}
+
+// JuniorsResponse is the JSON contract for GET /api/juniors.
+// Same outer shape as AdultsResponse; differs in that member_data carries
+// Expected (int or "?") for expected/original_expected fields.
+type JuniorsResponse struct {
+	Months        []string                     `json:"months"`
+	RawMonths     []string                     `json:"raw_months"`
+	Results       []MemberRow                  `json:"results"`
+	Totals        []TotalCell                  `json:"totals"`
+	MemberData    map[string]JuniorsMemberData `json:"member_data"`
+	MonthLabels   map[string]string            `json:"month_labels"`
+	RawPayments   map[string][]RawTransaction  `json:"raw_payments"`
+	Credits       []Credit                     `json:"credits"`
+	Debts         []Credit                     `json:"debts"`
+	Unmatched     []RawTransaction             `json:"unmatched"`
+	AttendanceURL string                       `json:"attendance_url"`
+	PaymentsURL   string                       `json:"payments_url"`
+	BankAccount   string                       `json:"bank_account"`
+	CurrentMonth  string                       `json:"current_month"`
+}

go/internal/web/api/payments.go

@@ -0,0 +1,9 @@
+package api
+
+// PaymentsResponse is the JSON contract for GET /api/payments.
+type PaymentsResponse struct {
+	GroupedPayments map[string][]RawTransaction `json:"grouped_payments"` // person name → rows
+	SortedPeople    []string                    `json:"sorted_people"`
+	AttendanceURL   string                      `json:"attendance_url"`
+	PaymentsURL     string                      `json:"payments_url"`
+}

go/internal/web/api/schemagen_test.go

@@ -0,0 +1,81 @@
+package api
+
+// schemagen_test.go generates and golden-compares JSON Schema files for every
+// /api/X response type.
+//
+// Normal run (CI): go test ./internal/web/api/... — asserts schemas match committed files.
+// Regenerate:      go test -run TestGenerateSchemas -update ./internal/web/api/...
+
+import (
+	"encoding/json"
+	"flag"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/invopop/jsonschema"
+)
+
+var updateFlag = flag.Bool("update", false, "overwrite api-schema fixture files with freshly generated schemas")
+
+// JSONSchema makes Expected self-describing for the reflector at test time.
+// The method is in a test file and is not compiled into production binaries.
+// It emits oneOf [integer, "?"] to match the custom MarshalJSON behaviour.
+func (Expected) JSONSchema() *jsonschema.Schema {
+	return &jsonschema.Schema{
+		OneOf: []*jsonschema.Schema{
+			{Type: "integer"},
+			{Enum: []any{"?"}},
+		},
+	}
+}
+
+func TestGenerateSchemas(t *testing.T) {
+	r := &jsonschema.Reflector{
+		AllowAdditionalProperties: false,
+	}
+
+	cases := []struct {
+		name string
+		val  any
+	}{
+		{"adults", &AdultsResponse{}},
+		{"juniors", &JuniorsResponse{}},
+		{"payments", &PaymentsResponse{}},
+		{"version", &VersionResponse{}},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			schema := r.Reflect(tc.val)
+
+			got, err := json.MarshalIndent(schema, "", "  ")
+			if err != nil {
+				t.Fatalf("marshal schema: %v", err)
+			}
+			got = append(got, '\n')
+
+			// Path: go/internal/web/api/ → ../../.. → go/ → tests/fixtures/api-schema/
+			path := filepath.Join("..", "..", "..", "tests", "fixtures", "api-schema", tc.name+".schema.json")
+
+			if *updateFlag {
+				if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+					t.Fatalf("mkdir: %v", err)
+				}
+				if err := os.WriteFile(path, got, 0o644); err != nil {
+					t.Fatalf("write schema: %v", err)
+				}
+				t.Logf("wrote %s", path)
+				return
+			}
+
+			want, err := os.ReadFile(path)
+			if err != nil {
+				t.Fatalf("read fixture %s: %v (re-run with -update to generate)", path, err)
+			}
+			if string(got) != string(want) {
+				t.Errorf("schema mismatch for %s; re-run with -update to regenerate", tc.name)
+			}
+		})
+	}
+}

go/internal/web/api/types.go

@@ -0,0 +1,122 @@
+// Package api defines wire types for the JSON API contract (/api/...).
+// These structs have explicit json: tags matching the Python view-model dict
+// keys so that M5 parity tests can do byte-equal comparison between backends.
+//
+// The three Python template-only JSON-string fields (member_data,
+// month_labels_json, raw_payments_json) are represented here as nested objects;
+// the Python /api/X shadow endpoint strips the json.dumps wrappers before
+// serialising.
+package api
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+// Expected holds a junior fee expectation: either a concrete integer or the
+// "?" sentinel (single-attendance month requiring manual review).
+// MarshalJSON emits the integer or the JSON string "?".
+type Expected struct {
+	Value   int
+	Unknown bool
+}
+
+func (e Expected) MarshalJSON() ([]byte, error) {
+	if e.Unknown {
+		return []byte(`"?"`), nil
+	}
+	return json.Marshal(e.Value)
+}
+
+func (e *Expected) UnmarshalJSON(data []byte) error {
+	if len(data) > 0 && data[0] == '"' {
+		var s string
+		if err := json.Unmarshal(data, &s); err != nil {
+			return err
+		}
+		if s == "?" {
+			e.Unknown = true
+			return nil
+		}
+		return fmt.Errorf("api.Expected: unexpected string %q", s)
+	}
+	e.Unknown = false
+	return json.Unmarshal(data, &e.Value)
+}
+
+// ExceptionData is a manual fee override for one member in one month.
+type ExceptionData struct {
+	Amount int    `json:"amount"`
+	Note   string `json:"note"`
+}
+
+// MemberTxEntry is one payment allocation to a member+month, as stored in
+// member_data.months[YYYY-MM].transactions.
+type MemberTxEntry struct {
+	Amount     float64 `json:"amount"`
+	Date       string  `json:"date"`
+	Sender     string  `json:"sender"`
+	Message    string  `json:"message"`
+	Confidence string  `json:"confidence"`
+}
+
+// MemberOtherEntry is an "other:…" purpose payment allocated to a member.
+type MemberOtherEntry struct {
+	Amount     float64 `json:"amount"`
+	Date       string  `json:"date"`
+	Sender     string  `json:"sender"`
+	Message    string  `json:"message"`
+	Purpose    string  `json:"purpose"`
+	Confidence string  `json:"confidence"`
+}
+
+// RawTransaction is a full payments-sheet row.
+// Used for unmatched transactions and raw_payments groupings.
+// Columns match the sheet layout: Date|Amount|manual fix|Person|Purpose|
+// Inferred Amount|Sender|VS|Message|Bank ID|Sync ID.
+type RawTransaction struct {
+	Date           string  `json:"date"`
+	Amount         float64 `json:"amount"`
+	ManualFix      string  `json:"manual_fix"`
+	Person         string  `json:"person"`
+	Purpose        string  `json:"purpose"`
+	InferredAmount float64 `json:"inferred_amount"`
+	Sender         string  `json:"sender"`
+	VS             string  `json:"vs"`
+	Message        string  `json:"message"`
+	BankID         string  `json:"bank_id"`
+	SyncID         string  `json:"sync_id"`
+}
+
+// MonthCell is one cell in a member's month column on the dashboard.
+type MonthCell struct {
+	Text       string `json:"text"`
+	Overridden bool   `json:"overridden"`
+	Status     string `json:"status"` // "empty"|"ok"|"partial"|"unpaid"|"surplus"
+	Amount     int    `json:"amount"`
+	Month      string `json:"month"`     // display label, e.g. "Apr+May 2025"
+	RawMonth   string `json:"raw_month"` // "YYYY-MM"
+	Tooltip    string `json:"tooltip"`
+}
+
+// TotalCell is one cell in the monthly totals row.
+type TotalCell struct {
+	Text   string `json:"text"`
+	Status string `json:"status"`
+}
+
+// MemberRow is one member's summary row in the dashboard results table.
+type MemberRow struct {
+	Name             string      `json:"name"`
+	Months           []MonthCell `json:"months"`
+	Balance          int         `json:"balance"`
+	UnpaidPeriods    string      `json:"unpaid_periods"`
+	RawUnpaidPeriods string      `json:"raw_unpaid_periods"`
+	PayableAmount    int         `json:"payable_amount"`
+}
+
+// Credit is one entry in the credits or debts lists.
+type Credit struct {
+	Name   string `json:"name"`
+	Amount int    `json:"amount"`
+}

go/internal/web/api/version.go

@@ -0,0 +1,9 @@
+package api
+
+// VersionResponse is the JSON contract for GET /api/version.
+// Keys match Python's BUILD_META dict (see app.py).
+type VersionResponse struct {
+	Tag       string `json:"tag"`
+	Commit    string `json:"commit"`
+	BuildDate string `json:"build_date"`
+}

go/tests/fixtures/api-schema/adults.schema.json

@@ -0,0 +1,399 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$ref": "#/$defs/AdultsResponse",
+  "$defs": {
+    "AdultsMemberData": {
+      "properties": {
+        "tier": {
+          "type": "string"
+        },
+        "months": {
+          "additionalProperties": {
+            "$ref": "#/$defs/AdultsMonthData"
+          },
+          "type": "object"
+        },
+        "other_transactions": {
+          "items": {
+            "$ref": "#/$defs/MemberOtherEntry"
+          },
+          "type": "array"
+        },
+        "total_balance": {
+          "type": "integer"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "tier",
+        "months",
+        "other_transactions",
+        "total_balance"
+      ]
+    },
+    "AdultsMonthData": {
+      "properties": {
+        "expected": {
+          "type": "integer"
+        },
+        "original_expected": {
+          "type": "integer"
+        },
+        "attendance_count": {
+          "type": "integer"
+        },
+        "exception": {
+          "$ref": "#/$defs/ExceptionData"
+        },
+        "paid": {
+          "type": "number"
+        },
+        "transactions": {
+          "items": {
+            "$ref": "#/$defs/MemberTxEntry"
+          },
+          "type": "array"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "expected",
+        "original_expected",
+        "attendance_count",
+        "exception",
+        "paid",
+        "transactions"
+      ]
+    },
+    "AdultsResponse": {
+      "properties": {
+        "months": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
+        "raw_months": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
+        "results": {
+          "items": {
+            "$ref": "#/$defs/MemberRow"
+          },
+          "type": "array"
+        },
+        "totals": {
+          "items": {
+            "$ref": "#/$defs/TotalCell"
+          },
+          "type": "array"
+        },
+        "member_data": {
+          "additionalProperties": {
+            "$ref": "#/$defs/AdultsMemberData"
+          },
+          "type": "object"
+        },
+        "month_labels": {
+          "additionalProperties": {
+            "type": "string"
+          },
+          "type": "object"
+        },
+        "raw_payments": {
+          "additionalProperties": {
+            "items": {
+              "$ref": "#/$defs/RawTransaction"
+            },
+            "type": "array"
+          },
+          "type": "object"
+        },
+        "credits": {
+          "items": {
+            "$ref": "#/$defs/Credit"
+          },
+          "type": "array"
+        },
+        "debts": {
+          "items": {
+            "$ref": "#/$defs/Credit"
+          },
+          "type": "array"
+        },
+        "unmatched": {
+          "items": {
+            "$ref": "#/$defs/RawTransaction"
+          },
+          "type": "array"
+        },
+        "attendance_url": {
+          "type": "string"
+        },
+        "payments_url": {
+          "type": "string"
+        },
+        "bank_account": {
+          "type": "string"
+        },
+        "current_month": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "months",
+        "raw_months",
+        "results",
+        "totals",
+        "member_data",
+        "month_labels",
+        "raw_payments",
+        "credits",
+        "debts",
+        "unmatched",
+        "attendance_url",
+        "payments_url",
+        "bank_account",
+        "current_month"
+      ]
+    },
+    "Credit": {
+      "properties": {
+        "name": {
+          "type": "string"
+        },
+        "amount": {
+          "type": "integer"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "name",
+        "amount"
+      ]
+    },
+    "ExceptionData": {
+      "properties": {
+        "amount": {
+          "type": "integer"
+        },
+        "note": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "amount",
+        "note"
+      ]
+    },
+    "MemberOtherEntry": {
+      "properties": {
+        "amount": {
+          "type": "number"
+        },
+        "date": {
+          "type": "string"
+        },
+        "sender": {
+          "type": "string"
+        },
+        "message": {
+          "type": "string"
+        },
+        "purpose": {
+          "type": "string"
+        },
+        "confidence": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "amount",
+        "date",
+        "sender",
+        "message",
+        "purpose",
+        "confidence"
+      ]
+    },
+    "MemberRow": {
+      "properties": {
+        "name": {
+          "type": "string"
+        },
+        "months": {
+          "items": {
+            "$ref": "#/$defs/MonthCell"
+          },
+          "type": "array"
+        },
+        "balance": {
+          "type": "integer"
+        },
+        "unpaid_periods": {
+          "type": "string"
+        },
+        "raw_unpaid_periods": {
+          "type": "string"
+        },
+        "payable_amount": {
+          "type": "integer"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "name",
+        "months",
+        "balance",
+        "unpaid_periods",
+        "raw_unpaid_periods",
+        "payable_amount"
+      ]
+    },
+    "MemberTxEntry": {
+      "properties": {
+        "amount": {
+          "type": "number"
+        },
+        "date": {
+          "type": "string"
+        },
+        "sender": {
+          "type": "string"
+        },
+        "message": {
+          "type": "string"
+        },
+        "confidence": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "amount",
+        "date",
+        "sender",
+        "message",
+        "confidence"
+      ]
+    },
+    "MonthCell": {
+      "properties": {
+        "text": {
+          "type": "string"
+        },
+        "overridden": {
+          "type": "boolean"
+        },
+        "status": {
+          "type": "string"
+        },
+        "amount": {
+          "type": "integer"
+        },
+        "month": {
+          "type": "string"
+        },
+        "raw_month": {
+          "type": "string"
+        },
+        "tooltip": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "text",
+        "overridden",
+        "status",
+        "amount",
+        "month",
+        "raw_month",
+        "tooltip"
+      ]
+    },
+    "RawTransaction": {
+      "properties": {
+        "date": {
+          "type": "string"
+        },
+        "amount": {
+          "type": "number"
+        },
+        "manual_fix": {
+          "type": "string"
+        },
+        "person": {
+          "type": "string"
+        },
+        "purpose": {
+          "type": "string"
+        },
+        "inferred_amount": {
+          "type": "number"
+        },
+        "sender": {
+          "type": "string"
+        },
+        "vs": {
+          "type": "string"
+        },
+        "message": {
+          "type": "string"
+        },
+        "bank_id": {
+          "type": "string"
+        },
+        "sync_id": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "date",
+        "amount",
+        "manual_fix",
+        "person",
+        "purpose",
+        "inferred_amount",
+        "sender",
+        "vs",
+        "message",
+        "bank_id",
+        "sync_id"
+      ]
+    },
+    "TotalCell": {
+      "properties": {
+        "text": {
+          "type": "string"
+        },
+        "status": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "text",
+        "status"
+      ]
+    }
+  }
+}

go/tests/fixtures/api-schema/juniors.schema.json

@@ -0,0 +1,411 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$ref": "#/$defs/JuniorsResponse",
+  "$defs": {
+    "Credit": {
+      "properties": {
+        "name": {
+          "type": "string"
+        },
+        "amount": {
+          "type": "integer"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "name",
+        "amount"
+      ]
+    },
+    "ExceptionData": {
+      "properties": {
+        "amount": {
+          "type": "integer"
+        },
+        "note": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "amount",
+        "note"
+      ]
+    },
+    "Expected": {
+      "oneOf": [
+        {
+          "type": "integer"
+        },
+        {
+          "enum": [
+            "?"
+          ]
+        }
+      ]
+    },
+    "JuniorsMemberData": {
+      "properties": {
+        "tier": {
+          "type": "string"
+        },
+        "months": {
+          "additionalProperties": {
+            "$ref": "#/$defs/JuniorsMonthData"
+          },
+          "type": "object"
+        },
+        "other_transactions": {
+          "items": {
+            "$ref": "#/$defs/MemberOtherEntry"
+          },
+          "type": "array"
+        },
+        "total_balance": {
+          "type": "integer"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "tier",
+        "months",
+        "other_transactions",
+        "total_balance"
+      ]
+    },
+    "JuniorsMonthData": {
+      "properties": {
+        "expected": {
+          "$ref": "#/$defs/Expected"
+        },
+        "original_expected": {
+          "$ref": "#/$defs/Expected"
+        },
+        "attendance_count": {
+          "type": "integer"
+        },
+        "exception": {
+          "$ref": "#/$defs/ExceptionData"
+        },
+        "paid": {
+          "type": "number"
+        },
+        "transactions": {
+          "items": {
+            "$ref": "#/$defs/MemberTxEntry"
+          },
+          "type": "array"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "expected",
+        "original_expected",
+        "attendance_count",
+        "exception",
+        "paid",
+        "transactions"
+      ]
+    },
+    "JuniorsResponse": {
+      "properties": {
+        "months": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
+        "raw_months": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
+        "results": {
+          "items": {
+            "$ref": "#/$defs/MemberRow"
+          },
+          "type": "array"
+        },
+        "totals": {
+          "items": {
+            "$ref": "#/$defs/TotalCell"
+          },
+          "type": "array"
+        },
+        "member_data": {
+          "additionalProperties": {
+            "$ref": "#/$defs/JuniorsMemberData"
+          },
+          "type": "object"
+        },
+        "month_labels": {
+          "additionalProperties": {
+            "type": "string"
+          },
+          "type": "object"
+        },
+        "raw_payments": {
+          "additionalProperties": {
+            "items": {
+              "$ref": "#/$defs/RawTransaction"
+            },
+            "type": "array"
+          },
+          "type": "object"
+        },
+        "credits": {
+          "items": {
+            "$ref": "#/$defs/Credit"
+          },
+          "type": "array"
+        },
+        "debts": {
+          "items": {
+            "$ref": "#/$defs/Credit"
+          },
+          "type": "array"
+        },
+        "unmatched": {
+          "items": {
+            "$ref": "#/$defs/RawTransaction"
+          },
+          "type": "array"
+        },
+        "attendance_url": {
+          "type": "string"
+        },
+        "payments_url": {
+          "type": "string"
+        },
+        "bank_account": {
+          "type": "string"
+        },
+        "current_month": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "months",
+        "raw_months",
+        "results",
+        "totals",
+        "member_data",
+        "month_labels",
+        "raw_payments",
+        "credits",
+        "debts",
+        "unmatched",
+        "attendance_url",
+        "payments_url",
+        "bank_account",
+        "current_month"
+      ]
+    },
+    "MemberOtherEntry": {
+      "properties": {
+        "amount": {
+          "type": "number"
+        },
+        "date": {
+          "type": "string"
+        },
+        "sender": {
+          "type": "string"
+        },
+        "message": {
+          "type": "string"
+        },
+        "purpose": {
+          "type": "string"
+        },
+        "confidence": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "amount",
+        "date",
+        "sender",
+        "message",
+        "purpose",
+        "confidence"
+      ]
+    },
+    "MemberRow": {
+      "properties": {
+        "name": {
+          "type": "string"
+        },
+        "months": {
+          "items": {
+            "$ref": "#/$defs/MonthCell"
+          },
+          "type": "array"
+        },
+        "balance": {
+          "type": "integer"
+        },
+        "unpaid_periods": {
+          "type": "string"
+        },
+        "raw_unpaid_periods": {
+          "type": "string"
+        },
+        "payable_amount": {
+          "type": "integer"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "name",
+        "months",
+        "balance",
+        "unpaid_periods",
+        "raw_unpaid_periods",
+        "payable_amount"
+      ]
+    },
+    "MemberTxEntry": {
+      "properties": {
+        "amount": {
+          "type": "number"
+        },
+        "date": {
+          "type": "string"
+        },
+        "sender": {
+          "type": "string"
+        },
+        "message": {
+          "type": "string"
+        },
+        "confidence": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "amount",
+        "date",
+        "sender",
+        "message",
+        "confidence"
+      ]
+    },
+    "MonthCell": {
+      "properties": {
+        "text": {
+          "type": "string"
+        },
+        "overridden": {
+          "type": "boolean"
+        },
+        "status": {
+          "type": "string"
+        },
+        "amount": {
+          "type": "integer"
+        },
+        "month": {
+          "type": "string"
+        },
+        "raw_month": {
+          "type": "string"
+        },
+        "tooltip": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "text",
+        "overridden",
+        "status",
+        "amount",
+        "month",
+        "raw_month",
+        "tooltip"
+      ]
+    },
+    "RawTransaction": {
+      "properties": {
+        "date": {
+          "type": "string"
+        },
+        "amount": {
+          "type": "number"
+        },
+        "manual_fix": {
+          "type": "string"
+        },
+        "person": {
+          "type": "string"
+        },
+        "purpose": {
+          "type": "string"
+        },
+        "inferred_amount": {
+          "type": "number"
+        },
+        "sender": {
+          "type": "string"
+        },
+        "vs": {
+          "type": "string"
+        },
+        "message": {
+          "type": "string"
+        },
+        "bank_id": {
+          "type": "string"
+        },
+        "sync_id": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "date",
+        "amount",
+        "manual_fix",
+        "person",
+        "purpose",
+        "inferred_amount",
+        "sender",
+        "vs",
+        "message",
+        "bank_id",
+        "sync_id"
+      ]
+    },
+    "TotalCell": {
+      "properties": {
+        "text": {
+          "type": "string"
+        },
+        "status": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "text",
+        "status"
+      ]
+    }
+  }
+}

go/tests/fixtures/api-schema/payments.schema.json

@@ -0,0 +1,91 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$ref": "#/$defs/PaymentsResponse",
+  "$defs": {
+    "PaymentsResponse": {
+      "properties": {
+        "grouped_payments": {
+          "additionalProperties": {
+            "items": {
+              "$ref": "#/$defs/RawTransaction"
+            },
+            "type": "array"
+          },
+          "type": "object"
+        },
+        "sorted_people": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
+        "attendance_url": {
+          "type": "string"
+        },
+        "payments_url": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "grouped_payments",
+        "sorted_people",
+        "attendance_url",
+        "payments_url"
+      ]
+    },
+    "RawTransaction": {
+      "properties": {
+        "date": {
+          "type": "string"
+        },
+        "amount": {
+          "type": "number"
+        },
+        "manual_fix": {
+          "type": "string"
+        },
+        "person": {
+          "type": "string"
+        },
+        "purpose": {
+          "type": "string"
+        },
+        "inferred_amount": {
+          "type": "number"
+        },
+        "sender": {
+          "type": "string"
+        },
+        "vs": {
+          "type": "string"
+        },
+        "message": {
+          "type": "string"
+        },
+        "bank_id": {
+          "type": "string"
+        },
+        "sync_id": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "date",
+        "amount",
+        "manual_fix",
+        "person",
+        "purpose",
+        "inferred_amount",
+        "sender",
+        "vs",
+        "message",
+        "bank_id",
+        "sync_id"
+      ]
+    }
+  }
+}

go/tests/fixtures/api-schema/version.schema.json

@@ -0,0 +1,26 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$ref": "#/$defs/VersionResponse",
+  "$defs": {
+    "VersionResponse": {
+      "properties": {
+        "tag": {
+          "type": "string"
+        },
+        "commit": {
+          "type": "string"
+        },
+        "build_date": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "type": "object",
+      "required": [
+        "tag",
+        "commit",
+        "build_date"
+      ]
+    }
+  }
+}

scripts/views.py

@@ -0,0 +1,445 @@
+import json
+import re
+from datetime import datetime
+
+from attendance import ADULT_MERGED_MONTHS, JUNIOR_MERGED_MONTHS
+from match_payments import canonical_member_key
+
+
+def get_month_labels(sorted_months, merged_months):
+    labels = {}
+    for m in sorted_months:
+        dt = datetime.strptime(m, "%Y-%m")
+        merged_in = sorted([k for k, v in merged_months.items() if v == m])
+        if merged_in:
+            all_dts = [datetime.strptime(x, "%Y-%m") for x in sorted(merged_in + [m])]
+            years = {d.year for d in all_dts}
+            if len(years) > 1:
+                parts = [d.strftime("%b %Y") for d in all_dts]
+                labels[m] = "+".join(parts)
+            else:
+                parts = [d.strftime("%b") for d in all_dts]
+                labels[m] = f"{'+'.join(parts)} {dt.strftime('%Y')}"
+        else:
+            labels[m] = dt.strftime("%b %Y")
+    return labels
+
+
+def group_payments_by_person(transactions, member_names=None):
+    canonical_by_key = (
+        {canonical_member_key(n): n for n in member_names} if member_names else {}
+    )
+    grouped = {}
+    for tx in transactions:
+        person = str(tx.get("person", "")).strip()
+        if not person:
+            continue
+        for p in person.split(","):
+            p = re.sub(r"\[\?\]\s*", "", p).strip()
+            if not p:
+                continue
+            key = canonical_by_key.get(canonical_member_key(p), p)
+            grouped.setdefault(key, []).append(tx)
+    for rows in grouped.values():
+        rows.sort(key=lambda t: str(t.get("date", "")), reverse=True)
+    return grouped
+
+
+def adapt_junior_members(junior_members):
+    """Convert 4-tuple junior fee data to (fee, total_count) for reconcile."""
+    adapted = []
+    for name, tier, fees_dict in junior_members:
+        adapted_fees = {}
+        for m, fee_data in fees_dict.items():
+            if len(fee_data) == 4:
+                fee, total_count, _, _ = fee_data
+                adapted_fees[m] = (fee, total_count)
+            else:
+                fee, count = fee_data
+                adapted_fees[m] = (fee, count)
+        adapted.append((name, tier, adapted_fees))
+    return adapted
+
+
+def build_adults_view_model(
+    members,
+    sorted_months,
+    result,
+    transactions,
+    current_month,
+    *,
+    attendance_url,
+    payments_url,
+    bank_account,
+):
+    month_labels = get_month_labels(sorted_months, ADULT_MERGED_MONTHS)
+    adult_names = sorted([name for name, tier, _ in members if tier == "A"])
+
+    monthly_totals = {m: {"expected": 0, "paid": 0} for m in sorted_months}
+    formatted_results = []
+    for name in adult_names:
+        data = result["members"][name]
+        row = {
+            "name": name,
+            "months": [],
+            "balance": data["total_balance"],
+            "unpaid_periods": "",
+            "raw_unpaid_periods": "",
+        }
+        unpaid_months = []
+        raw_unpaid_months = []
+        for m in sorted_months:
+            mdata = data["months"].get(m, {
+                "expected": 0, "original_expected": 0,
+                "attendance_count": 0, "paid": 0, "exception": None,
+            })
+            expected = mdata.get("expected", 0)
+            original_expected = mdata.get("original_expected", 0)
+            count = mdata.get("attendance_count", 0)
+            paid = int(mdata.get("paid", 0))
+            exception_info = mdata.get("exception", None)
+
+            monthly_totals[m]["expected"] += expected
+            monthly_totals[m]["paid"] += paid
+
+            override_amount = exception_info["amount"] if exception_info else None
+
+            if override_amount is not None and override_amount != original_expected:
+                is_overridden = True
+                fee_display = (
+                    f"{override_amount} ({original_expected}) CZK ({count})"
+                    if count > 0
+                    else f"{override_amount} ({original_expected}) CZK"
+                )
+            else:
+                is_overridden = False
+                fee_display = (
+                    f"{expected} CZK ({count})" if count > 0 else f"{expected} CZK"
+                )
+
+            status = "empty"
+            cell_text = "-"
+            amount_to_pay = 0
+
+            if expected > 0:
+                amount_to_pay = max(0, expected - paid)
+                if paid >= expected:
+                    status = "ok"
+                    cell_text = f"{paid}/{fee_display}"
+                elif paid > 0:
+                    status = "partial"
+                    cell_text = f"{paid}/{fee_display}"
+                    if m < current_month:
+                        unpaid_months.append(month_labels[m])
+                        raw_unpaid_months.append(
+                            datetime.strptime(m, "%Y-%m").strftime("%m/%Y")
+                        )
+                else:
+                    status = "unpaid"
+                    cell_text = f"0/{fee_display}"
+                    if m < current_month:
+                        unpaid_months.append(month_labels[m])
+                        raw_unpaid_months.append(
+                            datetime.strptime(m, "%Y-%m").strftime("%m/%Y")
+                        )
+            elif paid > 0:
+                status = "surplus"
+                cell_text = f"PAID {paid}"
+            else:
+                cell_text = "-"
+                amount_to_pay = 0
+
+            if expected > 0 or paid > 0:
+                tooltip = f"Received: {paid}, Expected: {expected}"
+            else:
+                tooltip = ""
+
+            row["months"].append({
+                "text": cell_text,
+                "overridden": is_overridden,
+                "status": status,
+                "amount": amount_to_pay,
+                "month": month_labels[m],
+                "raw_month": m,
+                "tooltip": tooltip,
+            })
+
+        settled_balance = 0
+        for m, mdata in data["months"].items():
+            if m >= current_month:
+                continue
+            exp = mdata.get("expected", 0)
+            if isinstance(exp, int):
+                settled_balance += int(mdata.get("paid", 0)) - exp
+
+        payable_amount = max(0, -settled_balance)
+        row["unpaid_periods"] = ", ".join(unpaid_months)
+        row["raw_unpaid_periods"] = "+".join(raw_unpaid_months)
+        row["balance"] = settled_balance
+        row["payable_amount"] = payable_amount
+        formatted_results.append(row)
+
+    formatted_totals = []
+    for m in sorted_months:
+        t = monthly_totals[m]
+        status = "empty"
+        if t["expected"] > 0 or t["paid"] > 0:
+            if t["paid"] == t["expected"]:
+                status = "ok"
+            elif t["paid"] < t["expected"]:
+                status = "unpaid"
+            else:
+                status = "surplus"
+        formatted_totals.append({
+            "text": f"{t['paid']} / {t['expected']} CZK",
+            "status": status,
+        })
+
+    def _settled_balance(name):
+        data = result["members"][name]
+        total = 0
+        for m, mdata in data["months"].items():
+            if m >= current_month:
+                continue
+            exp = mdata.get("expected", 0)
+            if isinstance(exp, int):
+                total += int(mdata.get("paid", 0)) - exp
+        return total
+
+    credits = sorted(
+        [{"name": n, "amount": _settled_balance(n)} for n in adult_names if _settled_balance(n) > 0],
+        key=lambda x: x["name"],
+    )
+    debts = sorted(
+        [{"name": n, "amount": abs(_settled_balance(n))} for n in adult_names if _settled_balance(n) < 0],
+        key=lambda x: x["name"],
+    )
+
+    raw_payments_by_person = group_payments_by_person(
+        transactions, [name for name, _, _ in members]
+    )
+
+    return dict(
+        months=[month_labels[m] for m in sorted_months],
+        raw_months=sorted_months,
+        results=formatted_results,
+        totals=formatted_totals,
+        member_data=json.dumps(result["members"]),
+        month_labels_json=json.dumps(month_labels),
+        raw_payments_json=json.dumps(raw_payments_by_person),
+        credits=credits,
+        debts=debts,
+        unmatched=result["unmatched"],
+        attendance_url=attendance_url,
+        payments_url=payments_url,
+        bank_account=bank_account,
+        current_month=current_month,
+    )
+
+
+def build_juniors_view_model(
+    junior_members,
+    adapted_members,
+    sorted_months,
+    result,
+    transactions,
+    current_month,
+    *,
+    attendance_url,
+    payments_url,
+    bank_account,
+):
+    month_labels = get_month_labels(sorted_months, JUNIOR_MERGED_MONTHS)
+    junior_names = sorted([name for name, tier, _ in adapted_members])
+    junior_members_dict = {name: fees_dict for name, _, fees_dict in junior_members}
+
+    monthly_totals = {m: {"expected": 0, "paid": 0} for m in sorted_months}
+    formatted_results = []
+    for name in junior_names:
+        data = result["members"][name]
+        row = {
+            "name": name,
+            "months": [],
+            "balance": data["total_balance"],
+            "unpaid_periods": "",
+            "raw_unpaid_periods": "",
+        }
+        unpaid_months = []
+        raw_unpaid_months = []
+        for m in sorted_months:
+            mdata = data["months"].get(m, {
+                "expected": 0, "original_expected": 0,
+                "attendance_count": 0, "paid": 0, "exception": None,
+            })
+            expected = mdata.get("expected", 0)
+            original_expected = mdata.get("original_expected", 0)
+            count = mdata.get("attendance_count", 0)
+            paid = int(mdata.get("paid", 0))
+            exception_info = mdata.get("exception", None)
+
+            if expected != "?" and isinstance(expected, int):
+                monthly_totals[m]["expected"] += expected
+            monthly_totals[m]["paid"] += paid
+
+            orig_fee_data = junior_members_dict.get(name, {}).get(m)
+            adult_count = 0
+            junior_count = 0
+            if orig_fee_data and len(orig_fee_data) == 4:
+                _, _, adult_count, junior_count = orig_fee_data
+
+            breakdown = ""
+            if adult_count > 0 and junior_count > 0:
+                breakdown = f":{junior_count}J,{adult_count}A"
+            elif junior_count > 0:
+                breakdown = f":{junior_count}J"
+            elif adult_count > 0:
+                breakdown = f":{adult_count}A"
+
+            count_str = f" ({count}{breakdown})" if count > 0 else ""
+
+            override_amount = exception_info["amount"] if exception_info else None
+
+            if override_amount is not None and override_amount != original_expected:
+                is_overridden = True
+                fee_display = f"{override_amount} ({original_expected}) CZK{count_str}"
+            else:
+                is_overridden = False
+                fee_display = f"{expected} CZK{count_str}"
+
+            status = "empty"
+            cell_text = "-"
+            amount_to_pay = 0
+
+            if expected == "?" or (isinstance(expected, int) and expected > 0):
+                if expected == "?":
+                    status = "empty"
+                    cell_text = f"?{count_str}"
+                elif paid >= expected:
+                    status = "ok"
+                    cell_text = f"{paid}/{fee_display}"
+                elif paid > 0:
+                    status = "partial"
+                    cell_text = f"{paid}/{fee_display}"
+                    amount_to_pay = expected - paid
+                    if m < current_month:
+                        unpaid_months.append(month_labels[m])
+                        raw_unpaid_months.append(
+                            datetime.strptime(m, "%Y-%m").strftime("%m/%Y")
+                        )
+                else:
+                    status = "unpaid"
+                    cell_text = f"0/{fee_display}"
+                    amount_to_pay = expected
+                    if m < current_month:
+                        unpaid_months.append(month_labels[m])
+                        raw_unpaid_months.append(
+                            datetime.strptime(m, "%Y-%m").strftime("%m/%Y")
+                        )
+            elif paid > 0:
+                status = "surplus"
+                cell_text = f"PAID {paid}"
+
+            if (isinstance(expected, int) and expected > 0) or paid > 0:
+                tooltip = f"Received: {paid}, Expected: {expected}"
+            else:
+                tooltip = ""
+
+            row["months"].append({
+                "text": cell_text,
+                "overridden": is_overridden,
+                "status": status,
+                "amount": amount_to_pay,
+                "month": month_labels[m],
+                "raw_month": m,
+                "tooltip": tooltip,
+            })
+
+        settled_balance = 0
+        for m, mdata in data["months"].items():
+            if m >= current_month:
+                continue
+            exp = mdata.get("expected", 0)
+            if isinstance(exp, int):
+                settled_balance += int(mdata.get("paid", 0)) - exp
+
+        payable_amount = max(0, -settled_balance)
+        row["unpaid_periods"] = ", ".join(unpaid_months)
+        row["raw_unpaid_periods"] = "+".join(raw_unpaid_months)
+        row["balance"] = settled_balance
+        row["payable_amount"] = payable_amount
+        formatted_results.append(row)
+
+    formatted_totals = []
+    for m in sorted_months:
+        t = monthly_totals[m]
+        status = "empty"
+        if t["expected"] > 0 or t["paid"] > 0:
+            if t["paid"] == t["expected"]:
+                status = "ok"
+            elif t["paid"] < t["expected"]:
+                status = "unpaid"
+            else:
+                status = "surplus"
+        formatted_totals.append({
+            "text": f"{t['paid']} / {t['expected']} CZK",
+            "status": status,
+        })
+
+    junior_all_names = [name for name, _, _ in adapted_members]
+
+    def _junior_settled_balance(name):
+        data = result["members"][name]
+        total = 0
+        for m, mdata in data["months"].items():
+            if m >= current_month:
+                continue
+            exp = mdata.get("expected", 0)
+            if isinstance(exp, int):
+                total += int(mdata.get("paid", 0)) - exp
+        return total
+
+    credits = sorted(
+        [{"name": n, "amount": _junior_settled_balance(n)} for n in junior_all_names if _junior_settled_balance(n) > 0],
+        key=lambda x: x["name"],
+    )
+    debts = sorted(
+        [{"name": n, "amount": abs(_junior_settled_balance(n))} for n in junior_all_names if _junior_settled_balance(n) < 0],
+        key=lambda x: x["name"],
+    )
+
+    raw_payments_by_person = group_payments_by_person(
+        transactions, [name for name, _, _ in adapted_members]
+    )
+
+    return dict(
+        months=[month_labels[m] for m in sorted_months],
+        raw_months=sorted_months,
+        results=formatted_results,
+        totals=formatted_totals,
+        member_data=json.dumps(result["members"]),
+        month_labels_json=json.dumps(month_labels),
+        raw_payments_json=json.dumps(raw_payments_by_person),
+        credits=credits,
+        debts=debts,
+        unmatched=result["unmatched"],
+        attendance_url=attendance_url,
+        payments_url=payments_url,
+        bank_account=bank_account,
+        current_month=current_month,
+    )
+
+
+def build_payments_view_model(transactions, member_names, *, attendance_url, payments_url):
+    grouped = group_payments_by_person(transactions, member_names)
+    for tx in transactions:
+        if not str(tx.get("person", "")).strip():
+            grouped.setdefault("Unmatched / Unknown", []).append(tx)
+    for rows in grouped.values():
+        rows.sort(key=lambda t: str(t.get("date", "")), reverse=True)
+    sorted_people = sorted(grouped.keys())
+    return dict(
+        grouped_payments=grouped,
+        sorted_people=sorted_people,
+        attendance_url=attendance_url,
+        payments_url=payments_url,
+    )