docs: log stats screen Stage A (feature/stats-final-screen)

Append the Stage A entry to project-memory.md, refresh project-map.md
(app.js/stats.js descriptions + optional data layers + branch note), and add
the A-J stage tracker to TODO.md.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.agents/TODO.md

@@ -72,6 +72,27 @@ Use checkboxes to track progress. Items marked **🔴 BLOCKER** prevent release;
 
 ---
 
+## 7. Stats final screen — `feature/stats-final-screen` (post-Cup release)
+
+Full build of `.agents/stats-screen-plan.md` on a feature branch, merged to `master` at the end of
+the Cup. One approval gate before each stage. A–F are buildable from today's data; G/H/I are
+data-blocked (graceful-degradation shell lets the UI land dark until JSON arrives).
+
+### 🟢 OPTIONAL (release feature)
+- [x] ~~Stage 0 — branch `feature/stats-final-screen` off `master`~~
+- [x] ~~Stage A — degradation engine + fault-tolerant `loadData` + sticky scrollspy sub-nav + media fallback~~ (2026-06-16)
+- [ ] Stage B — verdict hero (gated on FINAL finished; aggregate-hero fallback) + goals-by-round chart
+- [ ] Stage C — final ranking 1–48 (phase-reached chain), favorite-row highlight, team record cards
+- [ ] Stage D — auto record-cards + "format-48 debuts" band
+- [ ] Stage E — 104-match results archive (accordion by phase, row → modal)
+- [ ] Stage F — team comparator (diverging bars)
+- [ ] Stage G — Layer 2 cheap data (attendance, `cards`→{y,r} migration, decidedIn, coords) — **SCHEDULE LATE**
+- [ ] Stage H — Layer 3 players (`players.json` + `player-events.json` + `awards.json`)
+- [ ] Stage I — Layer 4 editorial (`curiosities.json` + `all-time-baselines.json`)
+- [ ] Stage J — polish (responsive/a11y audit, perf, Lighthouse, `DATA_VERSION` bump, README/i18n)
+
+---
+
 ## Quick final checklist
 
 ```

.agents/project-map.md

@@ -3,6 +3,8 @@
 Navigation map of the codebase. Use this to find which file owns a concern before reading code.
 
 > **Status 2026-06-12 (all 12 steps + real-data migration done):** everything works with **real World Cup 2026 data** — all views, bracket interactions, simulation, responsive/a11y pass, favorites, time toggle, challenge, share link, `.ics` export. Remaining: keep `results.json` current, fill `thirdPlaceAssignment` after the group stage (~Jun 27), Lighthouse run + GitHub Pages deploy. Spec source of truth: `world-cup-2026-hub-spec-en.md` + `complement-spec-worldcup2026-en.md` (complement **wins on conflict**).
+>
+> **Branch note (2026-06-16):** the full post-Cup Stats screen (`.agents/stats-screen-plan.md`, stages A–J) is being built on **`feature/stats-final-screen`** (merges to `master` at the end of the Cup). **Stage A done** on that branch (degradation engine + fault-tolerant `loadData` + sticky scrollspy sub-nav + flag monogram fallback). `master` keeps the partial Stats tab + daily refreshes. Descriptions below reflect the branch.
 
 ---
 
@@ -51,7 +53,10 @@ worldcup2026/
 │   │   │                                   live data refresh (startResultsPolling: 90s poll of
 │   │   │                                   results.json, no-store + ?t, content signature, pauses
 │   │   │                                   when tab hidden, stops at FINAL; on change also refetches
-│   │   │                                   bracket-config.json; fires `datachange`)
+│   │   │                                   bracket-config.json; fires `datachange`);
+│   │   │                                   loadOptional() = fault-tolerant fetch of the stats screen's
+│   │   │                                   optional data layers (absent → silent empty default);
+│   │   │                                   trackHeaderHeight() keeps the --header-h CSS var live
 │   │   ├── schedule.js                   Match list, filters (incl. occurrence toggle
 │   │   │                                   Played/Upcoming via hybrid matchState), search,
 │   │   │                                   sort, "My Matches"; 60s clock-tick re-render
@@ -63,8 +68,12 @@ worldcup2026/
 │   │   ├── storage.js                    localStorage wrapper — wc2026_* keys, auto-JSON
 │   │   ├── i18n.js                       EN/PT-BR dicts + t(key), lang toggle
 │   │   ├── stats.js                      ★ Stats tab: tournament-to-date aggregates (finished
-│   │   │                                   matches only), hero pulse + overview + goals-by-stage.
-│   │   │                                   PARTIAL (during-cup) — grows into the post-cup plan.
+│   │   │                                   matches only), hero pulse + overview + goals-by-stage +
+│   │   │                                   48-team sortable table. SECTIONS registry (graceful-
+│   │   │                                   degradation gate: section + chip render only if available,
+│   │   │                                   else removed from DOM) + sticky scrollspy sub-nav (anchor
+│   │   │                                   chips, hash-safe) + flagImg monogram fallback. Grows into
+│   │   │                                   the post-cup plan (.agents/stats-screen-plan.md, A–J).
 │   │   └── calendar.js                   .ics export (RFC 5545, CRLF, Blob download)
 │   ├── images/                           Team flag SVGs, stadium placeholders
 │   └── icons/                            PWA app icons (from the header trophy logo): icon.svg
@@ -80,9 +89,13 @@ worldcup2026/
 │   ├── results.json                      { matchId, homeScore, awayScore, penalties?, status } —
 │   │                                       update as the tournament progresses
 │   ├── stadiums.json                     16 real venues: { id, name, city, capacity, image, timezone }
-│   └── bracket-config.json               ★ official R32 structure + thirdPlaceAssignment (all null) —
-│                                           the ONLY file to edit once real 3rd places are known
-│                                           (slot → allowed-groups table in project-memory.md)
+│   ├── bracket-config.json               ★ official R32 structure + thirdPlaceAssignment (all null) —
+│   │                                       the ONLY file to edit once real 3rd places are known
+│   │                                       (slot → allowed-groups table in project-memory.md)
+│   └── (optional, NOT yet created)        stats-screen data layers loaded fault-tolerantly by
+│                                           loadOptional(): players.json, player-events.json,
+│                                           awards.json, keeper-stats.json, curiosities.json,
+│                                           all-time-baselines.json — absent = silent empty default
 │
 ├── README.md                             Setup, GitHub Pages deploy, JSON maintenance guide
 ├── how-update.md                         Real-data migration runbook (mock → real — DONE 2026-06-12)

.agents/project-memory.md

@@ -240,6 +240,19 @@ Static web app showing the FIFA World Cup 2026 (Mexico/USA/Canada, 48 teams) —
 - **Deploy:** os arquivos novos (manifest.json, favicon.ico, assets/icons/) **não** estão no `exclude` do `deploy.yml` → sobem normalmente. HTTPS da Hostinger já satisfaz o requisito de PWA.
 - **Verificado (preview localhost:8126, contexto seguro):** manifest 200 e parseado (name/short/start `.`/scope `./`/display standalone/theme `#081421`); todos os ícones 200 `image/png`; `favicon.ico` 200; `<meta theme-color>` + apple tags presentes; **console limpo**; app intacto (hero FRA×SEN, 4 cards do dashboard, 16 encerradas/88 próximas — sem regressão visual). **Não testável pelo preview:** o prompt de instalação real / "Add to Home Screen" + ícone no SO — confirmar no Chrome/Edge devtools (aba Application) ou num celular após o deploy.
 
+### Stats final screen — branch + Stage A (2026-06-16)
+- **New feature branch `feature/stats-final-screen`** (off `master`) to build the full post-Cup stats screen from `.agents/stats-screen-plan.md` (stages A–J). `master` stays live with the partial Stats tab + daily refreshes; merge `master`→branch periodically; the branch merges back to `master` at the **end of the Cup** (= release). Pure-UI stages **A–F first**; schema-changing data stages (esp. **G**, which migrates `results.json` `cards`→`{y,r}`) deferred to late to avoid conflicting with master's daily `results.json` edits. **Approval gate before each stage.**
+- **Stage A — degradation engine + scaffolding (DONE, branch only):**
+  - **Fault-tolerant `loadData()` (`app.js`):** the 6 core files still **throw** on failure (fatal → `showError`); 6 NEW optional layers (`players`, `player-events`, `awards`, `keeper-stats`, `curiosities`, `all-time-baselines`) load via `loadOptional(name, fallback)` → an **absent/404 file returns the empty default SILENTLY** (graceful degradation §0.2; absence is the normal "layer not arrived yet" state and keeps the console clean for verification), and it **warns only on a present-but-malformed file**. Exposed on `data` as `players/playerEvents/awards/keeperStats/curiosities/allTimeBaselines`. Core + optional fetch concurrently (two `Promise.all`, core awaited first).
+  - **`DATA_VERSION` deliberately NOT bumped in Stage A** — no deployed *data* changed (the optional files don't exist yet), and bumping it on the branch would conflict with master's daily bump on every merge. Bump only when real data files land (Stage G/H). (Supersedes the plan's literal "bump when wiring loadData".)
+  - **Section-gating contract — `SECTIONS` registry in `stats.js`:** each section `{ id, navKey, available(model), body(model) }` renders — and shows its sub-nav chip — **only when `available` holds**; otherwise it is **omitted from the DOM entirely** (no placeholder, no `—`, no "coming soon"), and the nav never points at emptiness (§0.1). Overview/Teams are `available:()=>true`; players/records/comparator/archive are `available:()=>false` (chips absent until later stages flip them + supply `body`).
+  - **Sticky scrollspy sub-nav:** `render()` now emits hero + `<nav.stats-subnav>` (anchor chips) + one `<section.stats-section>` per available section + footer. Chips are `<a href="#stats-{id}">` but their click is **`preventDefault` + `scrollIntoView`** — they **NEVER set `location.hash`** (the tab router listens on `hashchange`; a real `#stats-teams` fragment would route to an unknown tab → bounce to Home — the key gotcha here). Scrollspy is **position-based** (rAF-throttled `scroll` listener reading `getBoundingClientRect`), **not** an IntersectionObserver band: the band left a short final section unlit at the page bottom, so the position approach + an explicit "at page bottom → last section" rule is used (robust on short pages). `setActiveChip` keeps the active chip visible via the nav's own `scrollLeft` (no page jump).
+  - **`--header-h` CSS var** kept live by `trackHeaderHeight()` (`app.js`, `ResizeObserver` on the variable-height sticky header — one row ≥1100px, two bands below). The sub-nav sticks at `top: var(--header-h)` and sections use `scroll-margin-top: calc(var(--header-h) + 3.75rem)`, correct at every breakpoint (verified 137px wide / 98px at 375px).
+  - **Media fallback (§0.3):** `flagImg(team,w,h)` emits the flag `<img>` with `data-monogram="<id>"`; a one-time capture-phase `error` listener (`installImageFallback`) replaces a broken flag with a `<span.flag-fallback>` of the 3-letter code — never a broken-image icon. Existing stats flag usages (leaders, team table) converted to `flagImg`.
+  - **New i18n keys** (EN+PT): `stats.sectionsNav` + `stats.navOverview/navTeams/navPlayers/navRecords/navComparator/navArchive`. **New CSS** in `stats.css`: `.stats-subnav`/`.stats-subnav-chip`, `.stats-section` (scroll-margin + inter-section spacing + first-heading margin reset), `.flag-fallback`. **No `index.html` change** — the sub-nav is JS-rendered into the existing `#stats-root`.
+  - **Verified (preview 8126, branch):** console clean (no errors, no 404 warnings); 6 optional layers = empty defaults, core 48/104/104; sub-nav sticky at `--header-h`, only Overview+Teams chips; scrollspy top→Overview / bottom→Teams; chip click leaves hash `#stats`; EN↔PT relabels chips + sections/table survive; flag fallback → "XYZ" span at 22×15; mobile 375px (2-band header, 2×2 tiles, nav follows 98px header); Home hero+dashboard regression clean.
+  - **Next:** Stage B (verdict hero gated on FINAL finished, falling back to the current aggregate hero; + goals-by-round chart) — awaiting approval. Will consume `getBracketTree().champion` + `resolveBracketTeams('FINAL'|'THIRD-PLACE')` from `bracket.js`.
+
 ### How to update real-world data (scores, schedule)
 Follow `how-refresh-data.md` (project root). In short:
 1. Edit `data/results.json` (scores/status) or `data/matches.json` (schedule, rare).