# HANDOFF.md — Session Handoff (OVERWRITE at the end of every phase or when context is getting long)

> **Read order for a new session:** `NOTES.md` → `STATUS.md` → this file → then work.
> If this file disagrees with the code, trust the code and fix this file.

## 1. Where we are
- **Last completed step:** 6.2 (Shop UI: `shop.html` + `shop.js` with buy/sell tabs, level-gated stock display, material sell list) — TICKED in STATUS.md
- **Next step:** 6.3 — Additional tests: buy with insufficient gold (already covered in shop.test.js), sell equipped item (must be rejected), concurrent double-buy safety (transaction)
- **Updated:** 2026-10-21
- **Was the last session cut off mid-task?** No

## 2. Verified state (run these first)
| Command | Expected |
|---|---|
| `npm install` | succeeds |
| `npm run migrate` | applies 001–004 and 006 / "nothing to do" |
| `npm test` | **137 passing, 0 failing** (85 unit + 52 integration) |

## 3. What exists now (files that matter)
- `src/game/stats.js` — `calcDerived()` is the ONLY derived-stat formula. Also re-exports xpToNext/checkLevelUp.
- `src/game/combat.js` — `resolveCombat(hero, monster, rng)`; both sides attack each round, faster first.
- `src/services/huntService.js` — `hunt(characterId, zoneId, {rng, now})`; ONE transaction; test-injectable.
- `src/services/zoneService.js` — `listZones(characterLevel)` → zones with `unlocked` flag.
- `src/services/combatLogService.js` — `getCombatLog(characterId, limit)` → recent fights.
- `src/services/characterService.js` — `createCharacter`, `getCharacterProfile`, `getCharacterIdForUser`.
- `src/services/inventoryService.js` — `listInventory`, `equipItem`, `unequipItem`, `useConsumable`. Uses WeakMap stmt cache.
- `src/services/shopService.js` — `getStock`, `buyItem`, `sellItem`. Uses WeakMap stmt cache. Sell value = 40% of buy_price (materials use rarity default).
- `src/routes/shop.js` — `GET /api/shop`, `POST /api/shop/buy`, `POST /api/shop/sell`.
- `src/routes/inventory.js` — `GET /api/inventory`, `POST /api/inventory/equip`, `POST /api/inventory/unequip`, `POST /api/inventory/use`.
- `src/utils/time.js` — `now()/setNow()/resetNow()`; never call `Date.now()` in services.
- `src/routes/zones.js` — `GET /api/zones`.
- `src/routes/combatLog.js` — `GET /api/combat-log`.
- `src/db/migrations/003_content.sql` — also SEEDS zones/monsters/items/loot (INSERT OR IGNORE).
- `src/db/migrations/004_inventory.sql` — inventory table, FK constraints, partial unique index for equipped slots.
- `tests/integration/shop.test.js` — 14 integration tests (stock listing, level gating, buy, sell, error paths, round-trip spread).
- `tests/integration/shop-page.test.js` — 5 integration tests (stock listing, levelOk, sell pricing, buy/sell round-trip).
- `tests/integration/inventory.test.js` — 20 integration tests (13 equip/unequip + 7 consumable).
- `public/shop.html` — dedicated shop page with buy/sell tabs.
- `public/js/shop.js` — shop page JS: render stock, render materials, buy/sell handlers, tab switching, auth guard.
- `public/game.html` — dashboard with stats panel, tabbed action panel (Hunt/Inventory), equipment panel, inventory grid.
- `public/js/game.js` — full hunt UI + inventory UI.
- `public/css/main.css` — zone cards, combat log, result panel, toast styles, tabs, equipment panel, inventory grid, tooltips, rarity colors.

## 4. Half-finished / fragile things
- No shop link in game.html top-bar navigation (users must navigate manually to /shop.html).
- No expedition UI yet (Phase 7).
- No leaderboard UI yet (Phase 8).
- HP never regenerates naturally; only level-up restores it.
- No restart-persistence test for sessions.
- `npm run seed` script in package.json points to nonexistent `scripts/seed.js`.
- Equipment bonuses not yet passed into combat (Issue #5 in STATUS.md).
- Step 6.3 needs: sell equipped item rejection test, concurrent double-buy safety test.

## 5. Decisions & deviations from the docs
- D-004..D-007 in `docs/DECISIONS.md` (combat rounds, equipment counted once, session store, clock).
- Zod query param parsing uses `zod.coerce.number()` because Express query params are strings.
- Inventory response uses `itemId` (item.id) and `inventoryId` (inventory row id) to avoid confusion.
- Consumable effect parsing: regex `^(heal|energy):(\d+)$` on items.effect field.
- Qty decrement avoids CHECK constraint violation: delete directly when qty==1, decrement when qty>1.
- UI uses emoji icons (⚔️🛡️💍🧪📦) for item types per UI_GUIDE recommendation.
- Rarity colors match UI_GUIDE spec (common #b8b0a3, uncommon #5fb36b, rare #4a8fe0, epic #a45ee0, legendary #f2a23a).
- **D-008:** Shop materials with buy_price=0 sell at `floor(default_rate * character_level / item_min_level)` where default_rate is common=2, uncommon=4, rare=8, epic=16, legendary=32 (min 1).

## 6. Gotchas learned
- `npm test` must be `node --test` with NO path/glob; files must be named `*.test.js`. A shell glob once skipped 17 tests.
- better-sqlite3-session-store ignores `clear:false`; that's why the timer is unref'd.
- Statement caches are per-DB-handle (WeakMap) in huntService; copy that pattern for new services.
- Verify test COUNT, not just "all passing".
- Node.js `fetch` doesn't persist cookies across calls — extract `Set-Cookie` header and pass manually in integration tests.
- Express query params are strings, not numbers — use `zod.coerce.number()` for numeric query params.
- SQL `SELECT id` from inventory returns the auto-increment row id; rename with `AS inventory_id` when you also need `item_id`.
- `itemInSlot` query must alias `id AS inventory_id` so `existing.inventory_id` works in unequip logic.
- Transaction callback args must match the call order exactly — passing `qty` as the second arg when the callback expects `etype` silently misapplies the effect.
- Error responses from route-level `AppError`s do NOT include `data` field — only `{ ok: false, error: { code, message } }`.

## 7. Next-step briefing (6.3)
- **Goal:** Additional shop tests — buy with insufficient gold (already covered in shop.test.js), sell equipped item (must be rejected), concurrent double-buy safety (transaction).
- **Docs:** GAME_DESIGN.md §Economy, API.md.
- **Files to modify:** `tests/integration/shop.test.js` or `tests/integration/shop-page.test.js`.
- **Key rules:** Sell equipped item → should reject (item is in slot, still in inventory but equipped). Concurrent double-buy → two requests for same item simultaneously, only one should succeed if gold is insufficient for both.

## 8. Open Known Issues
STATUS.md issues 1–6 (balance, dangling `seed` script, restart test, equipment-in-combat, HP regen, zone min_level balance).