Session 8: Fix broken prestige system - load prestige scripts, fix particles.js parse error, add prestige tab UI

dev-journal.md

@@ -181,3 +181,60 @@
 - Achievement progress tracking in stats panel
 - Consider adding more sound variations or background music
 - Potential new building tiers or prestige milestones
+
+---
+
+### Session 8 - 2026-08-21 (Afternoon)
+**Status:** ✅ Critical Bugfix - Prestige System Now Actually Loads (reported by user)
+
+#### Bug report:
+User reported (with screenshot) that clicking "Collect Stardust" no longer works
+after the prestige feature shipped in Session 5. Console showed:
+`Uncaught ReferenceError: PRESTIGE is not defined` (game.js line 159, in getClickPower)
+
+#### Root cause:
+Session 5 created `js/prestige.js` + `js/prestigeUI.js` and rewired `game.js` to
+call `PRESTIGE`/`PRESTIGE_UPGRADES` in click power, production, and offline
+earnings — but **never added the two script tags to `index.html`**. So:
+1. `PRESTIGE` was undefined → `getClickPower()` threw on every tick (250ms) and
+   every click → clicking did nothing, console flooded with errors.
+2. `Game.init()` calls `PrestigeUI.init()` → crashed the whole init sequence
+   after `UI.init()`, so even the harvest click listener was never attached.
+3. A second latent bug in `js/particles.js`: missing comma between
+   `createAmbientStars()` and `createPrestigeEffect()` (added in Session 5)
+   made the whole file fail to parse → `Particles` undefined → would have
+   broken `harvest()` even after fix #1.
+4. The prestige tab UI (essence display, prestige button, upgrade list) was
+   also never added to `index.html`.
+
+#### Fixes applied:
+- `index.html` - added `<script>` tags for `js/prestige.js` and `js/prestigeUI.js`
+  (before `main.js`), added the ✦ Prestige tab button + tab panel with
+  `prestige-btn`, `prestige-essence-count`, `prestige-multiplier`,
+  `prestige-next-essence`, `prestige-upgrades-list`
+- `js/particles.js` - added missing comma after `createAmbientStars()`
+- `js/ui.js` - `UI.update()` now also calls `PrestigeUI.update()` so the
+  prestige display refreshes every tick
+
+#### Verification:
+Built a headless DOM test harness (`headless-test/test_game.py`, lives OUTSIDE
+the game repo) running all game scripts in a real JS engine (py_mini_racer /
+JavaScriptCore) with DOM stubs. 33/33 checks pass: init, 5 harvest clicks →
+5 stardust, 20 game ticks without errors, full prestige flow (2M stardust →
+1 essence, reset, multiplier), prestige upgrade purchase math, UI rendering,
+firstPrestige achievement, save/load round-trip preserving essence.
+
+#### Files modified:
+- `index.html` - prestige scripts + prestige tab UI
+- `js/particles.js` - missing comma (parse error)
+- `js/ui.js` - PrestigeUI.update() wired into UI.update()
+
+#### Lessons / notes for future sessions:
+- Always check `index.html` script tags when adding new JS files!
+- A headless smoke test exists at /workspace/headless-test/test_game.py —
+  re-run it after any change to js/ to catch ReferenceErrors before pushing.
+  (Requires `pip install py_mini_racer`.)
+
+#### Next goals:
+- Achievement progress tracking in stats panel
+- Consider adding a "next essence at X stardust" progress hint