From 36142de6c518cc4d1cd84a773986ce3266e90223 Mon Sep 17 00:00:00 2001
From: tiennm99 <tiennm99@outlook.com>
Date: Tue, 28 Apr 2026 10:03:54 +0700
Subject: [PATCH] chore(plans): add todo-backlog implementation plan

9-phase plan covering the highest-leverage items from `plans/todo.md`
plus tech-debt and UX polish. YAGNI cuts: GhostBoardPreview (rule of
three not met), upstream-blocked override removals, parking-lot
features. Phase 1 (auto-tick test) marked completed.
---
 .../phase-01-auto-tick-test.md                |  92 +++++++++++++
 .../phase-02-ci-inline-script-guard.md        |  96 +++++++++++++
 .../phase-03-mode-picker-glyphs.md            |  68 +++++++++
 .../phase-04-settings-modal-sticky.md         |  80 +++++++++++
 .../phase-05-cho-row-indicator.md             | 130 ++++++++++++++++++
 .../phase-06-confetti-polish.md               |  99 +++++++++++++
 .../phase-07-strict-csp-hashed.md             | 128 +++++++++++++++++
 .../phase-08-audio-cache-lru.md               |  85 ++++++++++++
 .../phase-09-pwa-verify-install.md            |  92 +++++++++++++
 .../plan.md                                   |  49 +++++++
 10 files changed, 919 insertions(+)
 create mode 100644 web/plans/260428-0927-implement-todo-backlog/phase-01-auto-tick-test.md
 create mode 100644 web/plans/260428-0927-implement-todo-backlog/phase-02-ci-inline-script-guard.md
 create mode 100644 web/plans/260428-0927-implement-todo-backlog/phase-03-mode-picker-glyphs.md
 create mode 100644 web/plans/260428-0927-implement-todo-backlog/phase-04-settings-modal-sticky.md
 create mode 100644 web/plans/260428-0927-implement-todo-backlog/phase-05-cho-row-indicator.md
 create mode 100644 web/plans/260428-0927-implement-todo-backlog/phase-06-confetti-polish.md
 create mode 100644 web/plans/260428-0927-implement-todo-backlog/phase-07-strict-csp-hashed.md
 create mode 100644 web/plans/260428-0927-implement-todo-backlog/phase-08-audio-cache-lru.md
 create mode 100644 web/plans/260428-0927-implement-todo-backlog/phase-09-pwa-verify-install.md
 create mode 100644 web/plans/260428-0927-implement-todo-backlog/plan.md

diff --git a/web/plans/260428-0927-implement-todo-backlog/phase-01-auto-tick-test.md b/web/plans/260428-0927-implement-todo-backlog/phase-01-auto-tick-test.md
new file mode 100644
index 0000000..f55d90e
--- /dev/null
+++ b/web/plans/260428-0927-implement-todo-backlog/phase-01-auto-tick-test.md
@@ -0,0 +1,92 @@
+---
+name: Auto-tick integration test
+phase: 1
+status: completed
+priority: high
+effort: 1-2h
+completed: 2026-04-28
+---
+
+# Phase 1 — Auto-tick integration test
+
+## Context
+- TODO entry: highest-leverage item ("dedup-by-`at` fix already caught a P0")
+- `src/lib/PlayerBoard.svelte:157-171` (auto-tick effect, dedup guard)
+- `src/lib/call-bus.svelte.js` (bus driver — already tested)
+- `src/lib/game-logic.js` — `findUncrossedCell` (pure helper)
+- Existing test infra: vitest + happy-dom, **no** `@testing-library/svelte`
+
+## Decision
+Don't add `@testing-library/svelte` just for one component. Extract the
+auto-tick body into a pure helper in `game-logic.js`, test that. The
+effect in `PlayerBoard.svelte` becomes a thin wrapper that calls the
+helper and applies the result.
+
+## Files
+- Create: `src/lib/auto-tick.js`
+- Create: `src/lib/auto-tick.test.js`
+- Modify: `src/lib/PlayerBoard.svelte` — replace effect body with helper call
+
+## Helper API
+
+```js
+/**
+ * @param {object} args
+ * @param {number[][]} args.grid
+ * @param {boolean[][]} args.crossed
+ * @param {{num: number, at: number} | null} args.lastDraw
+ * @param {number} args.lastHandledAt
+ * @param {"player" | "master" | "both"} args.mode
+ * @returns {{ crossed: boolean[][], lastHandledAt: number, changed: boolean }}
+ */
+export function processAutoTick({ grid, crossed, lastDraw, lastHandledAt, mode }) {
+  if (!lastDraw) return { crossed, lastHandledAt, changed: false };
+  if (lastDraw.at === lastHandledAt) return { crossed, lastHandledAt, changed: false };
+  const next = { lastHandledAt: lastDraw.at };
+  if (mode !== "both") return { crossed, ...next, changed: false };
+  if (!grid || crossed.length === 0) return { crossed, ...next, changed: false };
+  const target = findUncrossedCell(grid, crossed, lastDraw.num);
+  if (!target) return { crossed, ...next, changed: false };
+  const updated = crossed.map((row, ri) =>
+    ri === target.row ? row.map((v, ci) => (ci === target.col ? true : v)) : row
+  );
+  return { crossed: updated, ...next, changed: true };
+}
+```
+
+## Test cases (5)
+1. NEW draw, mode=both, number on board → cell crossed, `changed: true`
+2. Same `at` re-fire → no mutation, `changed: false`, `lastHandledAt` unchanged
+3. Manual untick after auto-tick, then SAME number with NEW `at` → re-crosses
+4. mode=player → no mutation regardless of draw
+5. Number not on board → no mutation, `lastHandledAt` advances (we still consume the event)
+
+## Steps
+1. Create `auto-tick.js` with `processAutoTick` (above). Import `findUncrossedCell`.
+2. Create `auto-tick.test.js` — mirror style of `call-bus.test.js`.
+3. Refactor `PlayerBoard.svelte:157-171` effect:
+   ```js
+   $effect(() => {
+     const drawn = bus.lastDrawn;
+     const result = processAutoTick({
+       grid, crossed, lastDraw: drawn,
+       lastHandledAt: lastHandledDrawAt,
+       mode: settings.mode,
+     });
+     lastHandledDrawAt = result.lastHandledAt;
+     if (result.changed) crossed = result.crossed;
+   });
+   ```
+4. `npm test` — all green.
+5. Manual smoke: open app in mode=both, draw a number from master panel, confirm player cell crosses.
+
+## Success
+- 5 unit cases pass.
+- `npm test` green (no regression in existing tests).
+- Manual smoke confirms behavior unchanged.
+
+## Risks
+- The effect tracks `bus.lastDrawn` reactively — extracting body into a
+  helper means the effect still needs to *read* `bus.lastDrawn` for
+  reactivity. The wrapper above does that correctly (read inside the
+  `$effect` body before passing to helper).
diff --git a/web/plans/260428-0927-implement-todo-backlog/phase-02-ci-inline-script-guard.md b/web/plans/260428-0927-implement-todo-backlog/phase-02-ci-inline-script-guard.md
new file mode 100644
index 0000000..41a6ad2
--- /dev/null
+++ b/web/plans/260428-0927-implement-todo-backlog/phase-02-ci-inline-script-guard.md
@@ -0,0 +1,96 @@
+---
+name: CI inline-script guard
+phase: 2
+status: todo
+priority: high
+effort: 30m
+---
+
+# Phase 2 — CI inline-script guard
+
+## Context
+- TODO: SvelteKit emits one inline bootstrap script. CSP relaxed to
+  `'unsafe-inline'` to accommodate. If a future SvelteKit upgrade adds
+  another inline block, we want CI to fail loudly.
+- `static/_headers:2` — current CSP includes `script-src 'self' 'unsafe-inline'`.
+- No CI build job today (Cloudflare Pages builds on its own; only
+  `.github/workflows/deploy-github-pages.yml` is a redirect-only job).
+
+## Decision
+Add an `npm run verify:build` script that:
+1. Counts `<script>` tags in `build/index.html`
+2. Fails if count > 1 (current expected: 1 inline bootstrap)
+3. Wires into `npm run build` as a sanity post-step (or kept manual via
+   `package.json` scripts so dev builds aren't slowed).
+
+Then add a minimal GH Actions job that runs `npm ci && npm run build &&
+npm run verify:build`.
+
+## Files
+- Create: `scripts/verify-build-inline-scripts.mjs`
+- Create: `.github/workflows/verify-build.yml`
+- Modify: `package.json` — add `"verify:build"` script
+
+## Script (`scripts/verify-build-inline-scripts.mjs`)
+
+```js
+#!/usr/bin/env node
+import { readFileSync } from "node:fs";
+
+const EXPECTED_INLINE = 1;
+const html = readFileSync("build/index.html", "utf8");
+const inline = (html.match(/<script(?![^>]*\bsrc=)[^>]*>/g) || []).length;
+
+if (inline > EXPECTED_INLINE) {
+  console.error(
+    `verify-build: found ${inline} inline <script> tags in build/index.html (expected ${EXPECTED_INLINE}).\n` +
+    `If this is intentional, update EXPECTED_INLINE in scripts/verify-build-inline-scripts.mjs ` +
+    `AND add the SHA-256 hash(es) to static/_headers script-src.`
+  );
+  process.exit(1);
+}
+console.log(`verify-build: ${inline} inline <script> tag(s) — OK.`);
+```
+
+## Workflow (`.github/workflows/verify-build.yml`)
+
+```yaml
+name: Verify build
+
+on:
+  pull_request:
+    branches: [main]
+  push:
+    branches: [main]
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: npm
+      - run: npm ci
+      - run: npm test
+      - run: npm run build
+      - run: npm run verify:build
+```
+
+## Steps
+1. Write `scripts/verify-build-inline-scripts.mjs` (executable not required, run via node).
+2. Add `"verify:build": "node scripts/verify-build-inline-scripts.mjs"` to `package.json`.
+3. Build locally and run — confirm passes with `EXPECTED_INLINE = 1`.
+4. Tweak EXPECTED to 0 temporarily, confirm script fails. Reset to 1.
+5. Add `.github/workflows/verify-build.yml`.
+6. Push, observe green action.
+
+## Success
+- `npm run verify:build` exits 0 on current build.
+- Tampering EXPECTED to 0 causes exit 1 (proves guard works).
+- GH Actions runs on push/PR to main.
+
+## Edge cases
+- Module scripts (`<script type="module" src="...">` with src) excluded by `(?![^>]*\bsrc=)` — only inline counted.
+- Whitespace before `>` handled by `[^>]*`.
diff --git a/web/plans/260428-0927-implement-todo-backlog/phase-03-mode-picker-glyphs.md b/web/plans/260428-0927-implement-todo-backlog/phase-03-mode-picker-glyphs.md
new file mode 100644
index 0000000..01e1819
--- /dev/null
+++ b/web/plans/260428-0927-implement-todo-backlog/phase-03-mode-picker-glyphs.md
@@ -0,0 +1,68 @@
+---
+name: Mode picker glyph redesign
+phase: 3
+status: todo
+priority: medium
+effort: 45m
+---
+
+# Phase 3 — Mode picker glyph redesign
+
+## Context
+- `src/lib/SettingsButton.svelte:259-278` — three SVG glyphs for
+  player / master / both modes.
+- TODO complaint: "Both" two-stacked-rectangles reads as "windows", not
+  the intended "player + master" combination. Player rect is clear,
+  megaphone is abstract but acceptable.
+
+## Decision
+Two paths considered, picking **Path B**:
+- ❌ Path A: redesign the "Both" glyph to be more obvious. Risk: any
+  abstract glyph in a 24×20 box has the same readability ceiling.
+- ✅ Path B: keep glyphs as visual anchors, add an icon-pair for "Both"
+  (mini-grid + mini-megaphone composed), and the existing button text
+  label below the glyph already says "Cả hai" — that text is the real
+  affordance. Tighten the SVG.
+
+## Files
+- Modify: `src/lib/SettingsButton.svelte:269-275` — replace "both" SVG only
+
+## New "Both" glyph
+
+Instead of two stacked rectangles, show a small grid (player) AND a
+small megaphone shape side-by-side:
+
+```html
+{:else}
+  <svg viewBox="0 0 28 16" class="w-7 h-5" fill="none" stroke="currentColor" stroke-width="1.5" aria-hidden="true">
+    <!-- Player grid (left) -->
+    <rect x="1" y="2" width="11" height="12" rx="1" />
+    <path d="M1 6h11M1 10h11M5 2v12M9 2v12" />
+    <!-- Megaphone (right) -->
+    <path d="M16 6l9-3v10l-9-3z" stroke-linejoin="round" />
+    <path d="M16 6v4" />
+  </svg>
+{/if}
+```
+
+Outcome: glyph reads as "grid + megaphone" — concrete representation of
+the two roles being combined. Same 1.5px stroke as siblings, fits in
+existing button height.
+
+## Steps
+1. Replace the `{:else}` SVG block (lines 270-274 region).
+2. Visual check: open settings modal, all three buttons aligned, glyphs
+   feel proportional.
+3. Dark mode: confirm `currentColor` strokes contrast properly in both themes.
+4. iPhone SE width (375px) — buttons stay in `grid-cols-3` row without
+   wrapping.
+
+## Success
+- "Both" glyph visually combines a grid + megaphone.
+- All three buttons align (same row, equal heights).
+- Touch targets unchanged (button padding intact).
+
+## Out of scope
+- Adding labels under glyphs — buttons already render `{label}` from
+  `MODES`. The TODO author proposed "tiny role labels under each glyph"
+  but the existing label already serves that role.
diff --git a/web/plans/260428-0927-implement-todo-backlog/phase-04-settings-modal-sticky.md b/web/plans/260428-0927-implement-todo-backlog/phase-04-settings-modal-sticky.md
new file mode 100644
index 0000000..04b6ed3
--- /dev/null
+++ b/web/plans/260428-0927-implement-todo-backlog/phase-04-settings-modal-sticky.md
@@ -0,0 +1,80 @@
+---
+name: Settings modal sticky on small screens
+phase: 4
+status: todo
+priority: medium
+effort: 30m
+---
+
+# Phase 4 — Settings modal sticky header/footer
+
+## Context
+- `src/lib/SettingsButton.svelte:166-459` — modal panel.
+- Wrapper: `max-h-[90vh] overflow-y-auto` (line 167).
+- TODO: on iPhone SE (375×667) the `<h2 id="settings-title">` and the
+  bottom action row scroll out of view, so user has to scroll back to
+  reach "Xong" / "Đặt lại".
+
+## Decision
+Make the title (`<h2>` block lines 169-177 — title + subtitle) and the
+action row (lines 436-457) sticky inside the scrollable panel. Use
+`position: sticky` rather than restructuring into a flex layout because
+the existing `overflow-y-auto` container already creates a scrolling
+context.
+
+## Files
+- Modify: `src/lib/SettingsButton.svelte`
+
+## Changes
+
+```html
+<!-- Outer panel (line 166-167) — same -->
+<div
+  class="relative mx-4 max-w-sm sm:max-w-md w-full max-h-[90vh] overflow-y-auto rounded-3xl bg-white dark:bg-slate-800 shadow-2xl animate-pop-in"
+>
+  <!-- Sticky header — replace lines 169-177 -->
+  <div class="sticky top-0 z-10 bg-white dark:bg-slate-800 px-6 pt-6 pb-3 -mx-px rounded-t-3xl">
+    <h2 id="settings-title" class="text-2xl font-bold text-slate-800 dark:text-slate-100 mb-1">
+      Cài đặt
+    </h2>
+    <p class="text-sm text-slate-500 dark:text-slate-400">
+      Tuỳ chỉnh giao diện bảng lô tô
+    </p>
+  </div>
+
+  <!-- Body wrapper — wraps existing fieldsets -->
+  <div class="px-6">
+    {/* existing fieldsets here, unchanged */}
+  </div>
+
+  <!-- Sticky footer — replace lines 436-457 -->
+  <div class="sticky bottom-0 z-10 bg-white dark:bg-slate-800 px-6 py-4 border-t border-slate-200 dark:border-slate-700 flex justify-between gap-2 rounded-b-3xl">
+    <!-- existing buttons unchanged -->
+  </div>
+</div>
+```
+
+Note: panel `p-6` is removed and replaced with per-section padding so
+sticky regions can render edge-to-edge backgrounds.
+
+## Steps
+1. Move panel padding: drop `p-6` from outer; add `px-6 pt-6 pb-3` to
+   sticky header, `px-6` wrapper around fieldsets, `px-6 py-4` on footer.
+2. Apply `sticky top-0` / `sticky bottom-0` with matching bg + z-10.
+3. Add `border-t` divider on footer for visual separation when content
+   is behind it.
+4. Test scroll on iPhone SE viewport (Chrome DevTools 375×667) —
+   verify h2 stays pinned at top, button row pinned at bottom.
+5. Test desktop — modal still pops in cleanly, no double-rounding.
+
+## Success
+- iPhone SE: title visible while scrolling middle of modal; close
+  button reachable without scrolling.
+- Desktop: visual unchanged or improved (subtle border above footer).
+- Dark mode: sticky bg matches panel bg (no color seam).
+
+## Risks
+- `animate-pop-in` may conflict with `position: sticky` during the open
+  animation. Mitigation: sticky elements compute fine inside an
+  animated parent; if jitter shows up, scope the animation to a child
+  div instead of the panel.
diff --git a/web/plans/260428-0927-implement-todo-backlog/phase-05-cho-row-indicator.md b/web/plans/260428-0927-implement-todo-backlog/phase-05-cho-row-indicator.md
new file mode 100644
index 0000000..04ee225
--- /dev/null
+++ b/web/plans/260428-0927-implement-todo-backlog/phase-05-cho-row-indicator.md
@@ -0,0 +1,130 @@
+---
+name: Per-row "Chờ" indicator
+phase: 5
+status: todo
+priority: medium
+effort: 1h
+---
+
+# Phase 5 — Per-row "Chờ" visual indicator
+
+## Context
+- `src/lib/PlayerBoard.svelte` — current "Chờ" notification is a
+  toast-only signal (`showToast` in the waiting-row $effect at lines
+  120-130). When the toast dismisses (5s), no persistent visual cue.
+- TODO: subtle ring/glow on the `section-label` band when a Chờ row
+  exists in that section, so user retains awareness without re-reading
+  the toast.
+- 9 rows split into 3 sections (`SECTIONS = [0, 3, 6]`). Section labels
+  rendered at `PlayerBoard.svelte:266`.
+
+## Decision
+Track waiting state reactively per row, derive per-section flag, apply
+a Tailwind ring + soft pulse to that section's `section-label` band.
+
+Already have `notifiedWaitingRows` (a plain Set, not reactive). Need a
+reactive mirror. Cheapest: derive from `grid` + `crossed` directly.
+
+## Files
+- Modify: `src/lib/PlayerBoard.svelte`
+
+## Approach
+
+### 1. Derive waiting flag per row
+Reuse `getWaitingNumber` from `game-logic.js`:
+
+```js
+const waitingRows = $derived(
+  grid && crossed.length
+    ? grid.map((_, r) => getWaitingNumber(grid, crossed, r) !== null && !celebratedRows.has(r))
+    : []
+);
+```
+
+⚠ `celebratedRows` is a Set (not reactive). For the derived flag to
+update when a row completes, switch `celebratedRows` to `$state(new Set())`
+or a derived `completedRows` array. Simpler: just derive from
+`isRowComplete` directly:
+
+```js
+const waitingRows = $derived(
+  grid && crossed.length
+    ? grid.map((_, r) =>
+        !isRowComplete(grid, crossed, r) &&
+        getWaitingNumber(grid, crossed, r) !== null
+      )
+    : []
+);
+```
+
+### 2. Per-section flag
+```js
+const sectionHasWaiting = $derived(
+  SECTIONS.map((startRow) =>
+    waitingRows.slice(startRow, startRow + 3).some(Boolean)
+  )
+);
+```
+
+### 3. Apply visual to section label
+At line 266:
+```html
+<div
+  class="section-label {sectionHasWaiting[sectionIdx] ? 'section-label-waiting' : ''}"
+>
+  {SECTION_LABELS[sectionIdx]}
+</div>
+```
+
+### 4. CSS
+Add to `src/app.css` (where `section-label` is already defined):
+
+```css
+.section-label-waiting {
+  box-shadow: inset 0 0 0 2px rgb(245 158 11 / 0.6);
+  animation: section-pulse 2.4s ease-in-out infinite;
+}
+
+@keyframes section-pulse {
+  0%, 100% { box-shadow: inset 0 0 0 2px rgb(245 158 11 / 0.45); }
+  50%      { box-shadow: inset 0 0 0 2px rgb(245 158 11 / 0.85); }
+}
+
+@media (prefers-reduced-motion: reduce) {
+  .section-label-waiting { animation: none; }
+}
+```
+
+Amber-500 chosen to match the existing toast color (`bg-amber-500/95`
+at PlayerBoard.svelte:336). Reduces context-switching; user already
+associates amber with "Chờ".
+
+## Steps
+1. Verify `section-label` is defined in `src/app.css` (grep first).
+2. Add `.section-label-waiting` + `@keyframes` to `src/app.css`.
+3. Add the two `$derived` blocks to `PlayerBoard.svelte` script.
+4. Add conditional class on the `section-label` div.
+5. Test: tick 8/9 cells in row 1 (section 0). Section 0 label glows.
+   Tick the 9th cell. Glow stops, "Kinh!" fires.
+6. Test: untick a cell to break the Chờ. Glow stops.
+7. Test reduced-motion: animation off, ring still present.
+
+## Success
+- Section label band has visible ring when any of its 3 rows is in Chờ.
+- Glow stops on row complete or Chờ broken.
+- Ring color matches amber toast.
+- Reduced-motion users see static ring (no pulse).
+
+## Risks
+- Computing `getWaitingNumber` 9× per render is fine (called per cell
+  click only; <1ms).
+- `isRowComplete` already memoized via `rowCompleteness` derived —
+  consider reusing it for the `!isRowComplete` half of the check:
+
+  ```js
+  const waitingRows = $derived(
+    grid && crossed.length
+      ? grid.map((_, r) => !rowCompleteness[r] && getWaitingNumber(grid, crossed, r) !== null)
+      : []
+  );
+  ```
diff --git a/web/plans/260428-0927-implement-todo-backlog/phase-06-confetti-polish.md b/web/plans/260428-0927-implement-todo-backlog/phase-06-confetti-polish.md
new file mode 100644
index 0000000..2442c56
--- /dev/null
+++ b/web/plans/260428-0927-implement-todo-backlog/phase-06-confetti-polish.md
@@ -0,0 +1,99 @@
+---
+name: Confetti polish
+phase: 6
+status: todo
+priority: low
+effort: 30m
+---
+
+# Phase 6 — Confetti polish
+
+## Context
+- `src/lib/PlayerBoard.svelte:34-35` — confetti emoji set + count.
+- `:113` — `celebrationTier = celebratedRows.size >= 3 ? 2 : 1`.
+- `:381-390` — confetti rendering loop.
+- TODO: tier-2 threshold 3+ rare on 9-row card; emoji pool too small.
+
+## Decision
+
+### 1. Threshold: 2nd bingo OR (1st bingo + active Chờ)
+Lower threshold so tier-2 fires more often without devaluing it.
+"Active Chờ" means at least one OTHER row is one cell away.
+
+```js
+// Before:
+celebrationTier = celebratedRows.size >= 3 ? 2 : 1;
+
+// After:
+const hasActiveCho = grid.some((_, r) =>
+  !celebratedRows.has(r) && getWaitingNumber(grid, crossed, r) !== null
+);
+celebrationTier =
+  celebratedRows.size >= 2 || (celebratedRows.size >= 1 && hasActiveCho)
+    ? 2
+    : 1;
+```
+
+### 2. Emoji variety
+Add festive Vietnamese-flavored 🥢 🎋 🏮 to the existing 🎊 ✨ 🎉 🥳.
+7 emojis. 12 confetti pieces — `i % 7` distributes.
+
+```js
+const CONFETTI_EMOJI = ["🎊", "✨", "🎉", "🥳", "🥢", "🎋", "🏮"];
+```
+
+### 3. Random size 1.5–2.5rem
+The existing `.confetti` CSS sets a fixed `font-size`. Override via
+inline style with a stable random per piece:
+
+```svelte
+{#each CONFETTI as i (i)}
+  <span
+    class="confetti"
+    style:--x="{(i * 8.3 + (i % 3) * 11) % 100}%"
+    style:--delay="{(i * 37) % 400}ms"
+    style:--rot="{(i * 67) % 360}deg"
+    style:--size="{1.5 + ((i * 13) % 11) / 10}rem"
+  >
+    {CONFETTI_EMOJI[i % CONFETTI_EMOJI.length]}
+  </span>
+{/each}
+```
+
+CSS — read the var:
+
+```css
+.confetti { font-size: var(--size, 2rem); /* …existing… */ }
+```
+
+`(i * 13) % 11 / 10` → values in {0.0, 0.3, 0.6, 0.9, 0.2, 0.5, ...} → 1.5–2.4rem.
+
+## Files
+- Modify: `src/lib/PlayerBoard.svelte`
+- Modify: `src/app.css` (confetti `font-size` rule)
+
+## Steps
+1. `grep -n "\.confetti" src/app.css` — confirm rule location.
+2. Replace `CONFETTI_EMOJI` array.
+3. Update `celebrationTier` assignment around line 113. Need to import
+   `getWaitingNumber` (already imported).
+4. Add `--size` inline style + read var in CSS.
+5. Manual test:
+   - Tick row 1 fully → tier 1 (no confetti). ✓
+   - Tick row 2 fully → tier 2 (confetti). ✓ (was 3+ before)
+   - Reset, tick most of row 1, get one Chờ on row 2, complete row 1
+     → tier 2 confetti immediately on first bingo.
+6. Visual check: confetti reads as varied sizes, lantern + chopsticks
+   visible alongside party emojis.
+
+## Success
+- Tier-2 confetti triggers on 2nd bingo (or 1st bingo + active Chờ).
+- Emoji set includes 🥢 🎋 🏮.
+- Sizes vary 1.5–2.4rem.
+- No regression on tier-1 silent celebration.
+
+## Out of scope
+- Adjusting confetti animation (drift speed, rotation curve).
+- Reduced-motion gating — already handled by parent component or app.
+  Confirm in test if `prefers-reduced-motion: reduce` skips the animation
+  path; if not, that's a separate issue.
diff --git a/web/plans/260428-0927-implement-todo-backlog/phase-07-strict-csp-hashed.md b/web/plans/260428-0927-implement-todo-backlog/phase-07-strict-csp-hashed.md
new file mode 100644
index 0000000..ea7cb0e
--- /dev/null
+++ b/web/plans/260428-0927-implement-todo-backlog/phase-07-strict-csp-hashed.md
@@ -0,0 +1,128 @@
+---
+name: Strict CSP via hashed inline script
+phase: 7
+status: todo
+priority: medium
+effort: 1.5h
+---
+
+# Phase 7 — Strict CSP via hashed inline script
+
+## Context
+- `static/_headers:2` — current CSP: `script-src 'self' 'unsafe-inline'`.
+- The `'unsafe-inline'` is a relaxation to admit SvelteKit's bootstrap
+  inline `<script>` block in built `index.html`.
+- Goal: replace `'unsafe-inline'` with `'sha256-…'` hash of the actual
+  inline. Brittle — hash changes per build — so build pipeline must
+  regenerate the hash and rewrite `_headers` on every build.
+
+## Approach
+
+### Option A — vite plugin (preferred)
+A Vite plugin `closeBundle` hook reads `build/index.html`, extracts
+inline scripts, computes SHA-256 of each, and rewrites `build/_headers`
+with the hashes injected into `script-src`.
+
+### Option B — postbuild npm script
+Same logic but as `scripts/inject-csp-hashes.mjs` invoked via
+`"build": "vite build && node scripts/inject-csp-hashes.mjs"`.
+
+**Pick Option B** — keeps `vite.config.js` simpler and the script is
+isolated. `_headers` lives in `static/` and is copied to `build/_headers`
+by the static adapter, so we rewrite the *built* copy.
+
+## Files
+- Create: `scripts/inject-csp-hashes.mjs`
+- Modify: `package.json` — change `"build"` and `"build:gh"` to chain
+- Modify: `static/_headers` — change marker for replacement
+- Verify: `Phase 2 verify-build` script still passes (still 1 inline,
+  just now hashed not unsafe-inline)
+
+## Script (`scripts/inject-csp-hashes.mjs`)
+
+```js
+#!/usr/bin/env node
+import { readFileSync, writeFileSync } from "node:fs";
+import { createHash } from "node:crypto";
+
+const HEADERS = "build/_headers";
+const HTML = "build/index.html";
+
+const html = readFileSync(HTML, "utf8");
+const inlineScripts = [...html.matchAll(/<script(?![^>]*\bsrc=)[^>]*>([\s\S]*?)<\/script>/g)];
+
+if (inlineScripts.length === 0) {
+  console.log("inject-csp-hashes: no inline scripts found, leaving CSP as-is.");
+  process.exit(0);
+}
+
+const hashes = inlineScripts.map((m) => {
+  const body = m[1];
+  const h = createHash("sha256").update(body, "utf8").digest("base64");
+  return `'sha256-${h}'`;
+});
+
+let headers = readFileSync(HEADERS, "utf8");
+const before = `script-src 'self' 'unsafe-inline'`;
+const after = `script-src 'self' ${hashes.join(" ")}`;
+
+if (!headers.includes(before)) {
+  console.error(`inject-csp-hashes: marker not found in ${HEADERS}.\nLooking for: ${before}`);
+  process.exit(1);
+}
+
+headers = headers.replace(before, after);
+writeFileSync(HEADERS, headers, "utf8");
+console.log(`inject-csp-hashes: injected ${hashes.length} hash(es) into ${HEADERS}.`);
+```
+
+## Package.json
+
+```json
+"scripts": {
+  "build": "vite build && node scripts/inject-csp-hashes.mjs",
+  "build:gh": "BUILD_PROFILE=gh vite build && node scripts/inject-csp-hashes.mjs"
+}
+```
+
+## Steps
+1. Confirm static adapter copies `static/_headers` → `build/_headers`
+   (it does — same as `static/_redirects`).
+2. Write the script.
+3. `npm run build` — confirm `build/_headers` now has
+   `script-src 'self' 'sha256-…'` (no `'unsafe-inline'`).
+4. Local serve `build/` (e.g. `npx serve build`) → verify SW registers,
+   no CSP errors in DevTools console.
+5. Wire `verify:build` (Phase 2) to also assert `'unsafe-inline'`
+   absent from `build/_headers` script-src — extend that script:
+
+   ```js
+   const headers = readFileSync("build/_headers", "utf8");
+   if (/script-src[^;]*'unsafe-inline'/.test(headers)) {
+     console.error("verify-build: script-src still contains 'unsafe-inline'");
+     process.exit(1);
+   }
+   ```
+
+## Success
+- `build/_headers` contains hashed `script-src` instead of `'unsafe-inline'`.
+- App still loads, SW registers, no CSP violations in browser console.
+- `verify:build` from Phase 2 enforces no-unsafe-inline going forward.
+
+## Risks
+- Each build rewrites the hash → `_headers` shipped to Cloudflare changes
+  on every deploy. That's fine; `_headers` is treated as build artifact.
+- If SvelteKit upgrades and adds another inline script, the regex
+  catches it automatically (multi-hash). Phase 2's `EXPECTED_INLINE`
+  may need bumping.
+- `style-src 'unsafe-inline'` stays — Svelte's `style:` directives are
+  attribute-level, no nonce/hash escape. Documented in
+  `plans/reports/security-260427-2047-pass2-full.md`.
+
+## Edge cases
+- Whitespace inside `<script>` — `.update(body, "utf8")` digests the
+  exact bytes; minor formatting changes shift the hash. Keep
+  vite/svelte versions pinned.
+- If a future SvelteKit release injects script via `<script src=…>`
+  only, `inlineScripts.length === 0` → no rewrite needed; CSP stays
+  `script-src 'self'`. The early `process.exit(0)` handles that.
diff --git a/web/plans/260428-0927-implement-todo-backlog/phase-08-audio-cache-lru.md b/web/plans/260428-0927-implement-todo-backlog/phase-08-audio-cache-lru.md
new file mode 100644
index 0000000..850351e
--- /dev/null
+++ b/web/plans/260428-0927-implement-todo-backlog/phase-08-audio-cache-lru.md
@@ -0,0 +1,85 @@
+---
+name: Audio cache LRU rule
+phase: 8
+status: todo
+priority: low
+effort: 30m
+---
+
+# Phase 8 — Audio cache LRU rule
+
+## Context
+- `vite.config.js:55-69` — workbox runtime cache `loto-audio`:
+  - `maxEntries: 400`
+  - `maxAgeSeconds: 60 * 60 * 24 * 30` (30 days, age-based)
+- TODO: prefer "drop voices not used in 30 days" (LRU on access) over
+  pure age-on-cache.
+
+## Decision
+Workbox's `expiration.maxAgeSeconds` is age-on-cache, not LRU. Workbox
+ships **no built-in true LRU** plugin — but `purgeOnQuotaError: true`
+plus `matchOptions.ignoreSearch` and `cacheName` is what we have.
+
+Pragmatic options:
+- **A)** Lower `maxAgeSeconds` to 7 days, accept some re-fetches.
+- **B)** Set `purgeOnQuotaError: true`, leave 30d, ride out quota
+  pressure when storage hits caps.
+- **C)** Custom workbox plugin that re-touches the cache entry on each
+  match (workaround for missing LRU).
+
+**Pick A + B** combined. Voices < 200KB each; 30d → 7d won't hurt
+offline UX meaningfully (only matters for voices NEVER played in 30d,
+which means user has ignored that voice — they can refetch on next
+play). Add `purgeOnQuotaError: true` as a belt-and-suspenders.
+
+Skip C — TODO says "only matters at voices > 10" and we have 2.
+Workbox plugin scope is unjustified now.
+
+## Files
+- Modify: `vite.config.js:55-69`
+
+## Changes
+
+```js
+runtimeCaching: [
+  {
+    urlPattern: /\/audio\/.*\.mp3$/,
+    handler: "CacheFirst",
+    options: {
+      cacheName: "loto-audio",
+      expiration: {
+        maxEntries: 400,
+        // 7 days — clip stays cached as long as it gets played at least
+        // once a week. If a voice is unused for 7d, it falls out and
+        // re-fetches on next play. Low impact: each clip <200KB.
+        maxAgeSeconds: 60 * 60 * 24 * 7,
+        purgeOnQuotaError: true,
+      },
+      cacheableResponse: { statuses: [200] },
+    },
+  },
+],
+```
+
+## Steps
+1. Edit `vite.config.js`.
+2. Update the comment in the block above the `additionalManifestEntries`
+   line if it still says "30d" or implies long retention.
+3. `npm run build` — confirm SW generates without errors.
+4. Hard-refresh in DevTools → Application → Cache Storage → `loto-audio`.
+   Trigger a play; entry appears with current timestamp.
+5. Bump device clock 8 days, refresh, verify entry is purged on next
+   workbox housekeeping (or simulate via `caches.delete('loto-audio')`).
+
+## Success
+- `maxAgeSeconds` = 7 days.
+- `purgeOnQuotaError: true`.
+- Build passes.
+- Default voice still precached (unchanged).
+
+## Risks
+- Users who only play once a month will see a re-fetch. Acceptable —
+  audio is small and same-origin.
+- 7d × 184 default-voice precache entries: precache survives via
+  `additionalManifestEntries` (separate flow), not the runtime cache,
+  so 7d doesn't affect the default voice.
diff --git a/web/plans/260428-0927-implement-todo-backlog/phase-09-pwa-verify-install.md b/web/plans/260428-0927-implement-todo-backlog/phase-09-pwa-verify-install.md
new file mode 100644
index 0000000..c53b88b
--- /dev/null
+++ b/web/plans/260428-0927-implement-todo-backlog/phase-09-pwa-verify-install.md
@@ -0,0 +1,92 @@
+---
+name: PWA install verification
+phase: 9
+status: todo
+priority: medium
+effort: 1h (manual)
+---
+
+# Phase 9 — PWA install verification checklist
+
+## Context
+- TODO: Lighthouse PWA = 100/100 + manual install on Android Chrome
+  and iOS Safari. Splash + theme color flow.
+- `BUILD_PROFILE=gh` deploy under `/loto/` base — confirm SW + manifest
+  paths still resolve.
+- Manifest: `static/manifest.webmanifest` (existing, hand-written).
+- This phase is **verification, not code**. Output is a checklist
+  filled in after running checks.
+
+## Pre-flight
+1. Phases 1-8 merged (or at least nothing breaking).
+2. Production deploy on Cloudflare Pages and a `BUILD_PROFILE=gh`
+   build for GitHub Pages comparison.
+
+## Checklist
+
+### Lighthouse (Cloudflare Pages — root base)
+- [ ] Open `https://loto.miti99.com/` in incognito Chrome.
+- [ ] DevTools → Lighthouse → PWA + Performance + Best Practices + a11y → Analyze.
+- [ ] Score PWA = 100. If not, capture failures here:
+  - …
+- [ ] No CSP violations in console (Phase 7 strict CSP active).
+- [ ] No mixed-content warnings.
+
+### Lighthouse (GitHub Pages — `/loto/` base)
+- [ ] Open `https://tiennm99.github.io/loto/` in incognito.
+- [ ] Same scoring run.
+- [ ] Confirm SW URL resolves: `/loto/sw.js` (not `/sw.js`).
+- [ ] Confirm manifest URL: `/loto/manifest.webmanifest`.
+- [ ] Manifest icons load from `/loto/icons/...`.
+
+### Android Chrome (physical device or emulator)
+- [ ] Visit production URL.
+- [ ] "Add to Home Screen" prompt offered (auto or via menu).
+- [ ] Install. Launch from home screen.
+- [ ] Splash screen renders with theme color (`#1565c0` light /
+      `#0a0f1f` dark) — match `app.html:9-10`.
+- [ ] Status bar uses theme color.
+- [ ] App opens in standalone mode (no Chrome chrome).
+- [ ] Airplane mode → reload from home screen → app shell + default
+      voice clips work offline.
+- [ ] Maskable icon: long-press app icon, ensure shape mask doesn't
+      crop the centered glyph (TODO mentions 70% safe-zone — verify
+      in Chrome DevTools "Show maskable preview" too).
+
+### iOS Safari
+- [ ] Visit production URL.
+- [ ] Share → Add to Home Screen.
+- [ ] Icon uses `apple-touch-icon` (`/icons/icon-192.png`) — round-ish
+      glyph, no white bars.
+- [ ] Launch. iOS uses `apple-mobile-web-app-status-bar-style` =
+      `black-translucent` — content goes under status bar, fonts legible.
+- [ ] Standalone display (no Safari toolbar).
+- [ ] Airplane mode → app shell loads, default voice clips play.
+
+### CSP + headers (production)
+- [ ] `curl -I https://loto.miti99.com/` shows `Content-Security-Policy`,
+      `X-Content-Type-Options: nosniff`, `Referrer-Policy`,
+      `Permissions-Policy`, `X-Frame-Options: DENY`.
+- [ ] CSP `script-src` no longer contains `'unsafe-inline'` (post-Phase 7).
+
+## Failures → Action
+If any check fails, file a follow-up issue (or extend `plans/todo.md`).
+Common gotchas:
+- **Manifest paths break under `/loto/` base** → check `vite.config.js`
+  PWA `manifest: false` + `app.html` uses `%sveltekit.assets%` (it does).
+- **iOS install flow shows wrong icon** → ensure `icons/icon-192.png`
+  exists and is 192×192 actual size, not just declared.
+- **Splash flicker dark→light** → `theme-color` media queries in
+  `app.html:9-10` must match the active scheme on first paint; SvelteKit
+  emits these statically so should be fine.
+
+## Success
+- PWA score 100 on both deploys.
+- Install succeeds on Android + iOS.
+- Offline-capable shell + default voice.
+- No CSP/headers regressions.
+
+## Out of scope
+- Maskable icon redesign at 65%/70% safe-zone — separate phase if mask
+  crops too tight (TODO entry).
+- iOS PWA push notifications, share targets, etc. — not requested.
diff --git a/web/plans/260428-0927-implement-todo-backlog/plan.md b/web/plans/260428-0927-implement-todo-backlog/plan.md
new file mode 100644
index 0000000..e0a69f5
--- /dev/null
+++ b/web/plans/260428-0927-implement-todo-backlog/plan.md
@@ -0,0 +1,49 @@
+---
+name: Implement TODO backlog
+status: in-progress
+created: 2026-04-28
+priority: medium
+blockedBy: []
+blocks: []
+---
+
+# Implement TODO backlog
+
+Source: `plans/todo.md` (commit `00fbc97`). Brutal cuts applied per
+YAGNI — parking-lot features and upstream-blocked items skipped.
+9 implementation phases + 1 verification checklist.
+
+## Phases
+
+| # | Phase | File |
+|---|-------|------|
+| 1 | Auto-tick integration test ✅ | `phase-01-auto-tick-test.md` |
+| 2 | CI inline-script guard | `phase-02-ci-inline-script-guard.md` |
+| 3 | Mode picker glyph redesign | `phase-03-mode-picker-glyphs.md` |
+| 4 | Settings modal sticky on small screens | `phase-04-settings-modal-sticky.md` |
+| 5 | Per-row "Chờ" indicator | `phase-05-cho-row-indicator.md` |
+| 6 | Confetti polish (threshold + variety) | `phase-06-confetti-polish.md` |
+| 7 | Strict CSP via hashed inline script | `phase-07-strict-csp-hashed.md` |
+| 8 | Audio cache LRU rule | `phase-08-audio-cache-lru.md` |
+| 9 | PWA install verification checklist | `phase-09-pwa-verify-install.md` |
+
+## Cuts (YAGNI)
+
+- GhostBoardPreview extraction — rule-of-three not met
+- Drop `cookie`/`serialize-javascript` overrides — blocked on upstream
+- Maskable icon 70% safe-zone — manual DevTools, no code
+- Voice precache for >2 voices — explicit YAGNI in TODO
+- Parking-lot features — multi-card, undo, spacebar, i18n, SW toast
+
+## Dependencies
+
+- Phase 1 first — test safety net for everything else
+- Phase 2 before Phase 7 — CI guard catches CSP regressions
+- Phase 9 last — runs after everything ships
+
+## References
+
+- `plans/todo.md` (source list)
+- `plans/archive/260427-1930-ui-polish-and-pwa-v2/` (prior PWA + CSP work)
+- `plans/reports/security-260427-2047-pass2-full.md` (CSP findings)
+- `plans/reports/code-reviewer-260427-2047-pass2-full.md` (test gaps)