step 5.3: done

HANDOFF.md

@@ -4,8 +4,8 @@
 > If this file disagrees with the code, trust the code and fix this file.
 
 ## 1. Where we are
-- **Last completed step:** 5.2 (inventory/equipment services + routes — list, equip, unequip)
-- **Next step:** 5.3 — stackable consumables: POST /api/inventory/use (health potion heals; energy tonic restores energy, capped)
+- **Last completed step:** 5.3 (stackable consumables: POST /api/inventory/use)
+- **Next step:** 5.4 — UI: inventory grid, equipment panel, tooltips with stats
 - **Updated:** 2026-10-20
 - **Was the last session cut off mid-task?** No
 
@@ -14,7 +14,7 @@
 |---|---|
 | `npm install` | succeeds |
 | `npm run migrate` | applies 001–004 and 006 / "nothing to do" |
-| `npm test` | **111 passing, 0 failing** (87 unit + 24 integration) |
+| `npm test` | **118 passing, 0 failing** (87 unit + 31 integration) |
 
 ## 3. What exists now (files that matter)
 - `src/game/stats.js` — `calcDerived()` is the ONLY derived-stat formula. Also re-exports xpToNext/checkLevelUp.
@@ -23,21 +23,21 @@
 - `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`.
-- **NEW:** `src/services/inventoryService.js` — `listInventory`, `equipItem`, `unequipItem`. Uses WeakMap stmt cache. Derived stats recalculated on list.
-- **NEW:** `src/routes/inventory.js` — `GET /api/inventory`, `POST /api/inventory/equip`, `POST /api/inventory/unequip`. Zod-validated.
+- **NEW:** `src/services/inventoryService.js` — `listInventory`, `equipItem`, `unequipItem`, `useConsumable`. Uses WeakMap stmt cache. Derived stats recalculated on list. Consumables: heal (capped at maxHp) and energy (capped at ENERGY_MAX), qty decrement, row removal at 0.
+- **NEW:** `src/routes/inventory.js` — `GET /api/inventory`, `POST /api/inventory/equip`, `POST /api/inventory/unequip`, `POST /api/inventory/use`. Zod-validated.
 - `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/inventory.test.js` — 13 integration tests for inventory service.
+- `tests/integration/inventory.test.js` — 20 integration tests (13 equip/unequip + 7 consumable).
 - `public/game.html` — dashboard with stats panel, zone list, combat log, result panel.
 - `public/js/game.js` — full hunt UI: load zones, hunt handler, result display, combat log replay, toast notifications, energy sync.
 - `public/css/main.css` — zone cards, combat log entries, result panel, toast styles.
 
 ## 4. Half-finished / fragile things
-- No consumable use endpoint yet (Phase 5 step 5.3).
-- No UI for inventory/equipment (Phase 5 step 5.4).
+- No consumable UI yet (Phase 5 step 5.4).
+- No inventory grid/equipment panel/tooltips in game.html.
 - 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`.
@@ -47,6 +47,8 @@
 - 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.
 
 ## 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.
@@ -57,13 +59,13 @@
 - 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.
 
-## 7. Next-step briefing (5.3)
-- **Goal:** Stackable consumables: `POST /api/inventory/use` — health potion heals HP (capped at maxHp); energy tonic restores energy (capped at ENERGY_MAX). Only consumable type items can be used. Consumable is consumed (quantity -1, removed when 0).
-- **Docs:** DATABASE.md (§004_inventory), GAME_DESIGN.md §Items, BALANCE.md (effect format: 'heal:50', 'energy:25').
-- **Files to create/modify:** extend `inventoryService.js` with `useConsumable(characterId, itemId)`, extend `inventory.js` route.
-- **Key rules:** parse `effect` field from items table ('heal:N' or 'energy:N'); validate character has the item in inventory (quantity >= 1); apply effect; decrement quantity; remove row when quantity reaches 0; return updated inventory listing.
-- **Tests:** happy-path heal, happy-path energy, use on non-consumable rejected, insufficient quantity, effect capped at maxHp/energyMax.
+## 7. Next-step briefing (5.4)
+- **Goal:** UI for inventory — grid display of items (equipment + consumables), equipment panel showing current gear with stats, tooltips with stat bonuses.
+- **Docs:** GAME_DESIGN.md §Items, UI_GUIDE.md, API.md.
+- **Files to modify:** `public/game.html` (add inventory/equipment panels), `public/js/game.js` (load inventory, render grid, equip/unequip/use handlers, tooltips), `public/css/main.css` (inventory grid, tooltips, equipment panel styles).
+- **Key rules:** Use `GET /api/inventory` for data; render equipment slots + consumable list; show stat bonuses on hover; click to equip/unequip; click consumable to use.
 
 ## 8. Open Known Issues
 STATUS.md issues 1–6 (balance, dangling `seed` script, restart test, equipment-in-combat, HP regen, zone min_level balance).

STATUS.md

@@ -8,9 +8,9 @@
 
 ## Current Focus
 - **Phase:** 5
-- **Step:** 5.3
+- **Step:** 5.4
 - **Blocked?** No
-- **Last verified working command:** `npm test` — 111/111 passing (87 unit + 24 integration), 2026-10-20 step 5.2
+- **Last verified working command:** `npm test` — 118/118 passing (87 unit + 31 integration), 2026-10-20 step 5.3
 
 ## Project Health
 | Item | State |
@@ -76,7 +76,8 @@
   *Acceptance:* migration creates inventory table with FK constraints and indexes.
 - [x] **5.2** Services + routes: list inventory, equip, unequip (slots: weapon, armor, trinket). Equipment modifies derived stats via `calcDerived()`.
   *Acceptance:* list returns items with derived stats; equip moves previous item; unequip clears slot; wrong-type/level/missing-item rejected.
-- [ ] **5.3** Stackable consumables: `POST /api/inventory/use` (health potion heals; energy tonic restores energy, capped).
+- [x] **5.3** Stackable consumables: `POST /api/inventory/use` (health potion heals; energy tonic restores energy, capped).
+  *Acceptance:* heal effect caps at maxHp; energy effect caps at ENERGY_MAX; quantity decrements; row removed at qty 0; non-consumable rejected.
 - [ ] **5.4** UI: inventory grid, equipment panel, tooltips with stats.
 
 ## Phase 6 — Shop & Economy  (docs: GAME_DESIGN §Economy)
@@ -147,6 +148,7 @@ Severity: `blocker` / `major` / `minor` / `cosmetic`. Status: `open` / `fixing`
 
 ## Session Log
 _Format:_ `YYYY-MM-DD | step | what changed | result`
+- 2026-10-20 | 5.3 | Added `useConsumable()` to inventoryService (heal/energy effects, qty decrement, row removal at 0) + `POST /api/inventory/use` route; 7 integration tests covering heal, energy, cap, non-consumable rejection, missing item, qty-0 removal | 118/118 tests pass
 - 2026-10-20 | 5.2 | Created `src/services/inventoryService.js` (listInventory, equipItem, unequipItem) + `src/routes/inventory.js` (GET /api/inventory, POST /api/inventory/equip, POST /api/inventory/unequip); registered routes in app.js; 13 integration tests covering empty inventory, equip/unequip, slot swap, stat updates, all error paths | 111/111 tests pass
 - 2026-10-20 | 5.1 | Verified 004_inventory.sql migration (inventory table, FK constraints, indexes) applies clean; all tests pass | 98/98 tests pass
 - 2026-10-20 | 4.5 | Added `GET /api/zones` (zoneService + zones route), `GET /api/combat-log` (combatLogService + combatLog route); extended game.html with zone list/combat log/result panels; rewrote game.js with hunt UI (zone cards, hunt button, result display, combat log replay, toast notifications); added CSS for zone cards/combat log/toasts; 5 new integration tests | 98/98 tests pass

src/app.js

@@ -57,6 +57,7 @@ function createApp() {
   app.get('/api/inventory', requireAuth, inventoryRoutes.getInventory);
   app.post('/api/inventory/equip', requireAuth, inventoryRoutes.postEquip);
   app.post('/api/inventory/unequip', requireAuth, inventoryRoutes.postUnequip);
+  app.post('/api/inventory/use', requireAuth, inventoryRoutes.postUse);
 
   // Central error handler
   app.use((err, _req, res, _next) => {

src/routes/inventory.js

@@ -1,9 +1,9 @@
-// Inventory routes: list, equip, unequip.
+// Inventory routes: list, equip, unequip, use consumables.
 const zod = require('zod');
 const { AppError } = require('../utils/errors');
 const { requireAuth } = require('../middleware/session');
 const { getCharacterIdForUser } = require('../services/characterService');
-const { listInventory, equipItem, unequipItem } = require('../services/inventoryService');
+const { listInventory, equipItem, unequipItem, useConsumable } = require('../services/inventoryService');
 
 // Validation schemas
 const slotSchema = zod.enum(['weapon', 'armor', 'trinket']);
@@ -56,10 +56,28 @@ async function handleUnequip(req, res) {
   res.json({ ok: true, data: result });
 }
 
+/**
+ * POST /api/inventory/use — use a stackable consumable (heal/energy).
+ */
+async function handleUse(req, res) {
+  const parsed = zod.strictObject({
+    itemId: zod.number().int().positive(),
+  }).safeParse(req.body);
+  if (!parsed.success) {
+    throw new AppError('VALIDATION_ERROR', 'Request validation failed.', 400);
+  }
+
+  const { itemId } = parsed.data;
+  const characterId = getCharacterIdForUser(req.session.userId);
+  const result = useConsumable(characterId, itemId);
+  res.json({ ok: true, data: result });
+}
+
 module.exports = {
   routes: {
     getInventory: wrap(handleListInventory),
     postEquip: wrap(handleEquip),
     postUnequip: wrap(handleUnequip),
+    postUse: wrap(handleUse),
   },
 };

src/services/inventoryService.js

@@ -1,7 +1,8 @@
-// Inventory service: list, equip, unequip items.
+// Inventory service: list, equip, unequip, and use consumables.
 // Equipment bonuses feed into calcDerived() for stat updates.
 const { getDb } = require('../db');
 const { AppError } = require('../utils/errors');
+const { calcDerived, ENERGY_MAX } = require('../game/stats');
 
 const VALID_SLOTS = new Set(['weapon', 'armor', 'trinket']);
 
@@ -54,6 +55,31 @@ function getStmts(db) {
       character: db.prepare(
         'SELECT * FROM characters WHERE id = ?'
       ),
+
+      // Get inventory row for a specific (character, item) — including quantity.
+      inventoryRowForUse: db.prepare(
+        'SELECT * FROM inventory WHERE character_id = ? AND item_id = ? AND quantity >= 1'
+      ),
+
+      // Decrement quantity by 1 (only when qty > 1 to avoid CHECK violation).
+      decrementQty: db.prepare(
+        'UPDATE inventory SET quantity = quantity - 1 WHERE id = ? AND quantity > 1'
+      ),
+
+      // Delete row when it's the last item (qty == 1).
+      deleteLast: db.prepare(
+        'DELETE FROM inventory WHERE id = ? AND quantity = 1'
+      ),
+
+      // Update character hp_current.
+      updateHp: db.prepare(
+        'UPDATE characters SET hp_current = ? WHERE id = ?'
+      ),
+
+      // Update character energy.
+      updateEnergy: db.prepare(
+        'UPDATE characters SET energy = ?, energy_updated_at = ? WHERE id = ?'
+      ),
     };
     stmtCache.set(db, s);
   }
@@ -209,4 +235,74 @@ function unequipItem(characterId, slot) {
   return listInventory(characterId);
 }
 
-module.exports = { listInventory, equipItem, unequipItem };
+/**
+ * Use a stackable consumable item. Applies its effect (heal or energy),
+ * decrements quantity, removes the row when quantity reaches 0.
+ * @param {number} characterId
+ * @param {number} itemId
+ * @returns {object} updated inventory listing
+ */
+function useConsumable(characterId, itemId) {
+  const db = getDb();
+  const s = getStmts(db);
+
+  const ch = s.character.get(characterId);
+  if (!ch) throw new AppError('NOT_FOUND', 'Character not found.', 404);
+
+  const item = s.itemById.get(itemId);
+  if (!item) throw new AppError('NOT_FOUND', 'Item not found.', 404);
+
+  if (item.type !== 'consumable') {
+    throw new AppError('VALIDATION_ERROR', `${item.name} is not a consumable.`, 400);
+  }
+
+  if (!item.effect) {
+    throw new AppError('VALIDATION_ERROR', `${item.name} has no effect.`, 400);
+  }
+
+  // Parse effect: 'heal:N' or 'energy:N'
+  const match = item.effect.match(/^(heal|energy):(\d+)$/);
+  if (!match) {
+    throw new AppError('VALIDATION_ERROR', `${item.name} has an invalid effect format.`, 400);
+  }
+  const [_full, effectType, effectValueStr] = match;
+  const effectValue = parseInt(effectValueStr, 10);
+
+  // Find the inventory row (must have quantity >= 1).
+  const invRow = s.inventoryRowForUse.get(characterId, item.id);
+  if (!invRow) throw new AppError('NOT_FOUND', 'Item not in inventory or depleted.', 404);
+
+  // Apply effect inside a transaction.
+  const applyEffect = db.transaction((rowId, qty, etype, evalue, charId, c) => {
+    // Apply the effect.
+    if (etype === 'heal') {
+      const maxHp = calcDerived(
+        { str: c.str, agi: c.agi, int: c.int, vit: c.vit },
+        c.level, c.class
+      ).maxHp;
+      const newHp = Math.min(c.hp_current + evalue, maxHp);
+      s.updateHp.run(newHp, charId);
+    } else if (etype === 'energy') {
+      const { computeEnergy } = require('../game/stats');
+      const now = require('../utils/time').now();
+      const energy = computeEnergy(c.energy, c.energy_updated_at, now);
+      const newEnergy = Math.min(energy.energy + evalue, ENERGY_MAX);
+      const newUpdatedAt = newEnergy >= ENERGY_MAX ? now : energy.updatedAtMs;
+      s.updateEnergy.run(newEnergy, newUpdatedAt, charId);
+    }
+
+    // Delete directly when qty==1; otherwise decrement.
+    if (qty === 1) {
+      s.deleteLast.run(rowId);
+    } else {
+      s.decrementQty.run(rowId);
+    }
+  });
+
+  applyEffect(invRow.id, invRow.quantity, effectType, effectValue, characterId, ch);
+
+  // Return updated listing.
+  return listInventory(characterId);
+}
+
+module.exports = { listInventory, equipItem, unequipItem, useConsumable };

tests/integration/inventory.test.js

@@ -12,7 +12,7 @@ describe('inventoryService', () => {
   before(async () => {
     await setup();
     db = require('../../src/db').getDb();
-    ({ listInventory, equipItem, unequipItem } = require('../../src/services/inventoryService'));
+    ({ listInventory, equipItem, unequipItem, useConsumable } = require('../../src/services/inventoryService'));
     ({ createCharacter } = require('../../src/services/characterService'));
   });
 
@@ -163,4 +163,111 @@ describe('inventoryService', () => {
     assert.ok(result.derived.maxHp > baseMaxHp,
       `maxHp should increase with vit bonus (was ${baseMaxHp}, now ${result.derived.maxHp})`);
   });
+
+  it('uses a healing potion and increases HP (capped at maxHp)', () => {
+    const id = makeHero({ level: 1, str: 8, agi: 4, int: 2, vit: 8 });
+    // Grant 3 Minor Healing Potions (item 14, heal:50)
+    grantItem(id, 14, 3);
+
+    // Set HP to 60 (out of ~145 maxHp for warrior with vit=8: 50+80+5=135)
+    db.prepare('UPDATE characters SET hp_current = 60 WHERE id = ?').run(id);
+
+    const before = listInventory(id);
+    const beforeHp = db.prepare('SELECT hp_current FROM characters WHERE id = ?').get(id).hp_current;
+    const maxHp = before.derived.maxHp;
+
+    // Use one potion: should heal to min(60+50, maxHp)
+    const result = useConsumable(id, 14);
+    const afterHp = db.prepare('SELECT hp_current FROM characters WHERE id = ?').get(id).hp_current;
+
+    assert.equal(afterHp, Math.min(beforeHp + 50, maxHp));
+    // Quantity should be 3 → 2 (still in inventory)
+    const potion = result.items.find((i) => i.itemId === 14);
+    assert.equal(potion.quantity, 2);
+  });
+
+  it('uses an energy tonic and restores energy (capped at 100)', () => {
+    const id = makeHero({ level: 1, str: 8, agi: 4, int: 2, vit: 8 });
+    // Grant 2 Energy Tonics (item 16, energy:25)
+    grantItem(id, 16, 2);
+
+    // Set energy to 40
+    db.prepare('UPDATE characters SET energy = 40 WHERE id = ?').run(id);
+
+    const before = listInventory(id);
+    const beforeEnergy = db.prepare('SELECT energy FROM characters WHERE id = ?').get(id).energy;
+
+    // Use one tonic: should restore to min(40+25, 100) = 65
+    const result = useConsumable(id, 16);
+    const afterEnergy = db.prepare('SELECT energy FROM characters WHERE id = ?').get(id).energy;
+
+    assert.equal(afterEnergy, Math.min(beforeEnergy + 25, 100));
+    // Quantity should be 2 → 1
+    const tonic = result.items.find((i) => i.itemId === 16);
+    assert.equal(tonic.quantity, 1);
+  });
+
+  it('rejects using a non-consumable item', () => {
+    const id = makeHero();
+    grantItem(id, 1); // Rusty Sword (weapon)
+    assert.throws(() => useConsumable(id, 1), (e) => e.code === 'VALIDATION_ERROR');
+  });
+
+  it('rejects using an item not in inventory', () => {
+    const id = makeHero();
+    // Item 14 exists but not granted to this character
+    assert.throws(() => useConsumable(id, 14), (e) => e.code === 'NOT_FOUND');
+  });
+
+  it('removes inventory row when quantity reaches 0 (single-item stack)', () => {
+    const id = makeHero({ level: 1, str: 8, agi: 4, int: 2, vit: 8 });
+    // Grant 1 Greater Healing Potion (item 15, heal:150)
+    grantItem(id, 15, 1);
+
+    // Set HP low
+    db.prepare('UPDATE characters SET hp_current = 20 WHERE id = ?').run(id);
+
+    const before = listInventory(id);
+    assert.equal(before.items.find((i) => i.itemId === 15).quantity, 1);
+
+    useConsumable(id, 15);
+
+    const after = listInventory(id);
+    const potion = after.items.find((i) => i.itemId === 15);
+    assert.equal(potion, undefined, 'consumable row should be removed when quantity hits 0');
+  });
+
+  it('caps heal effect at maxHp', () => {
+    const id = makeHero({ level: 1, str: 8, agi: 4, int: 2, vit: 8 });
+    grantItem(id, 14, 5); // Minor Healing Potion (heal:50)
+
+    // Set HP already at max
+    const before = listInventory(id);
+    const maxHp = before.derived.maxHp;
+    db.prepare('UPDATE characters SET hp_current = ? WHERE id = ?').run(maxHp, id);
+
+    useConsumable(id, 14);
+
+    const after = listInventory(id);
+    const hp = db.prepare('SELECT hp_current FROM characters WHERE id = ?').get(id).hp_current;
+    assert.equal(hp, maxHp, 'HP should not exceed maxHp');
+    // Quantity should decrease
+    assert.equal(after.items.find((i) => i.itemId === 14).quantity, 4);
+  });
+
+  it('caps energy effect at ENERGY_MAX (100)', () => {
+    const id = makeHero({ level: 1, str: 8, agi: 4, int: 2, vit: 8 });
+    grantItem(id, 16, 5); // Energy Tonic (energy:25)
+
+    // Set energy to 90
+    db.prepare('UPDATE characters SET energy = 90 WHERE id = ?').run(id);
+
+    useConsumable(id, 16);
+
+    const after = listInventory(id);
+    const energy = db.prepare('SELECT energy FROM characters WHERE id = ?').get(id).energy;
+    assert.equal(energy, 100, 'Energy should not exceed 100');
+    // Quantity should decrease
+    assert.equal(after.items.find((i) => i.itemId === 16).quantity, 4);
+  });
 });