feat: temp HP, character isNpc, initiative box

Temp HP:
- setTempHp() in shared/turn.js (replaces, no stacking)
- Damage absorbs temp HP first (both 5e + generic rulesets)
- Inline temp HP input on participant card (cyan when active)
- Temp HP field in edit modal
- makeParticipant tempHp field (default 0)
- 8 shared tests

Character isNpc:
- isNpc field on character roster model
- buildCharacterParticipant: type 'npc' when isNpc
- Add form checkbox + edit form checkbox
- NPC badge on character list row
- Writeback preserves isNpc

Initiative box:
- Amber-bordered box around initiative input
- Gold text (amber-300), disabled stays gold
- Stone-950 bg matches page
- Bumped maxHp (stone-200) + tempHp (stone-300/cyan) visibility

README.md

@@ -307,6 +307,26 @@ ttrpg-initiative-tracker/
 * `docs/GLOSSARY.md` — domain terms (turn vs. round, etc.)
 * `TODO.md` — known bugs and backlog
 
+## Prevent Sleep (Wake Lock)
+
+DM and Player views have a Coffee/Moon toggle to keep screen awake during combat.
+
+**Requires secure context** (HTTPS or localhost). The Screen Wake Lock API refuses
+on plain HTTP.
+
+- **Prod (HTTPS):** works automatically on all devices.
+- **Local dev (localhost):** works automatically — localhost is a trusted origin.
+- **LAN IP (phones, plain HTTP):** wake lock fails silently. Two options:
+  1. **Android Chrome flag (dev testing):** `chrome://flags/#unsafely-treat-insecure-origin-as-secure` → add full URL with port, e.g. `http://10.0.0.5:3999`. Enable flag, relaunch.
+  2. **mkcert local CA:** generate trusted cert for LAN IP. Heavier setup.
+
+**iOS Safari:** Wake Lock API broken in standalone PWA mode (iOS 16.4–18.4, WebKit bug 254545). Fixed in 18.4+. Works in browser tab (not installed PWA).
+
+**Troubleshooting:** if toggle shows active but screen still sleeps, check:
+- Battery saver / power save mode (browser refuses)
+- Chrome devtools console for `WakeLockError`
+- Secure context: `window.isSecureContext` must be `true`
+
 ## Contributing
 
 If you want to contribute, send me a message here: [https://discourse.draft13.com/c/ttrpg-initiative-tracker/16](https://discourse.draft13.com/c/ttrpg-initiative-tracker/16), and I can add to this Gitea instance and you can feel free to fork the repository and submit pull requests. For major changes, please pose a topic to the Discourse instance above linked above first to discuss what you would like to change.

TODO.md

@@ -5,20 +5,27 @@ Backlog of bugs + long-term items. Milestones live in REWORK_PLAN.md.
 ## Open
 
 
-fullscreen and dont lock on main app dm view and the no-game-player view
+x fullscreen and dont lock on main app dm view and the no-game-player view ...and doesnt actually prevent lock on android
 
 also better vert tab layout - labelt friendly
 
-needs AC for players dude
+x needs AC for players dude
 
-and quick entry hp
+x and quick entry hp
 
 hp do not carry from encounter to ecnounter!!!
-
+^feature to add back to campaign character after encounter?
+maybe campaign toggle in charc section (choosing each end is DM overload will be missed forgotten done wront)
 
 hp wont go over max and no temp hp support
 
 
+x refresh/reload/code update causes UI to update to top unselected cambpaign have to drill all the way back down to active encounter....every time. siemtmes?
+
+
+I wonder...if a charcter-list-character should have a isNPC option vailble to them - for longer lived
+ npcs.....
+
 
 
 

docs/DEVELOPMENT.md

@@ -63,6 +63,14 @@ git config core.hooksPath .githooks   # enable pre-push test gate
 
 Idempotent: if port busy, leaves existing proc as-is.
 
+**LAN access (phones):** frontend binds 0.0.0.0, LAN IP auto-detected.
+Other devices hit `http://<lan-ip>:3999`.
+
+**Wake Lock (Prevent Sleep) on LAN IP:** requires secure context.
+Plain HTTP on LAN IP = wake lock silently fails. Android Chrome flag workaround:
+`chrome://flags/#unsafely-treat-insecure-origin-as-secure` → add
+`http://<lan-ip>:3999` (with port), enable, relaunch. See README for full details.
+
 Smoke check:
 ```bash
 curl http://127.0.0.1:4001/health   # -> {"ok":true}

scripts/dev-start.sh

@@ -27,11 +27,15 @@ fi
 
 # frontend: server storage, :3999
 if ! lsof -ti :3999 >/dev/null 2>&1; then
-  echo "starting frontend :3999..."
+  # detect LAN ip so other devices (phones) can reach backend
+  LAN_IP=$(ipconfig getifaddr en0 2>/dev/null || ipconfig getifaddr en1 2>/dev/null || echo 127.0.0.1)
+  echo "starting frontend :3999 (lan ip: $LAN_IP)..."
   NODE_ENV=development REACT_APP_DEV_TOOLS=1 \
   REACT_APP_STORAGE=server \
-  REACT_APP_BACKEND_URL=http://127.0.0.1:4001 \
-  REACT_APP_BACKEND_REALTIME_URL=ws://127.0.0.1:4001/ws \
+  REACT_APP_BACKEND_URL=http://${LAN_IP}:4001 \
+  REACT_APP_BACKEND_REALTIME_URL=ws://${LAN_IP}:4001/ws \
+  DANGEROUSLY_DISABLE_HOST_CHECK=true \
+  HOST=0.0.0.0 \
   BROWSER=none PORT=3999 \
     nohup npm start > tmp/fe.log 2>&1 &
   echo $! > tmp/fe.pid
@@ -51,5 +55,11 @@ done
 echo ""
 echo "backend  : http://127.0.0.1:4001   (curl http://127.0.0.1:4001/health)"
 echo "frontend : http://127.0.0.1:3999   (admin /  player /display)"
+echo "lan url  : http://${LAN_IP}:3999   (phones/other devices on network)"
 echo "logs     : tmp/server.log tmp/fe.log"
 echo "stop     : ./scripts/dev-stop.sh"
+echo ""
+echo "NOTE: Prevent Sleep (wake lock) requires secure context (HTTPS/localhost)."
+echo "  LAN IP (http) won't work unless Android Chrome flag set:"
+echo "  chrome://flags/#unsafely-treat-insecure-origin-as-secure"
+echo "  Add: http://${LAN_IP}:3999 (include port)"

shared/tests/turn.ac.test.js

@@ -0,0 +1,35 @@
+// AC field on participant + builders.
+const shared = require('@ttrpg/shared');
+const { makeParticipant, buildMonsterParticipant, buildCharacterParticipant, rollHpFormula } = shared;
+
+describe('AC field', () => {
+  test('makeParticipant accepts ac', () => {
+    const p = makeParticipant({ name: 'Orc', type: 'monster', initiative: 10, maxHp: 15, currentHp: 15, ac: 13 });
+    expect(p.ac).toBe(13);
+  });
+
+  test('makeParticipant ac defaults null', () => {
+    const p = makeParticipant({ name: 'Orc', type: 'monster', initiative: 10, maxHp: 15, currentHp: 15 });
+    expect(p.ac).toBeNull();
+  });
+
+  test('buildMonsterParticipant accepts ac', () => {
+    const { participant } = buildMonsterParticipant({ name: 'Goblin', maxHp: 7, initMod: 2, ac: 15 });
+    expect(participant.ac).toBe(15);
+  });
+
+  test('buildMonsterParticipant ac defaults null', () => {
+    const { participant } = buildMonsterParticipant({ name: 'Goblin', maxHp: 7 });
+    expect(participant.ac).toBeNull();
+  });
+
+  test('buildCharacterParticipant accepts character ac', () => {
+    const { participant } = buildCharacterParticipant({ id: 'c1', name: 'Fighter', defaultMaxHp: 30, defaultInitMod: 2, defaultAc: 18 });
+    expect(participant.ac).toBe(18);
+  });
+
+  test('buildCharacterParticipant ac defaults null when unset', () => {
+    const { participant } = buildCharacterParticipant({ id: 'c1', name: 'Fighter', defaultMaxHp: 30 });
+    expect(participant.ac).toBeNull();
+  });
+});

shared/tests/turn.temphp.test.js

@@ -0,0 +1,102 @@
+// Temp HP: damage hits temp first, then regular.
+// setTempHp replaces (no stacking). Healing regular HP ignores temp.
+const shared = require('@ttrpg/shared');
+const { makeParticipant, applyHpChange, setTempHp, addParticipant } = shared;
+const { mockCtx } = require('./_helpers');
+
+function setupEnc() {
+  const { ctx } = mockCtx();
+  return {
+    enc: { id: 'enc1', name: 'TempEnc', participants: [], isStarted: false, isPaused: false, round: 0 },
+    ctx,
+  };
+}
+
+describe('temp HP', () => {
+  test('setTempHp sets tempHp on participant', async () => {
+    const { enc, ctx } = setupEnc();
+    const p = makeParticipant({
+      name: 'Hero', type: 'character', initiative: 10, maxHp: 20, currentHp: 20,
+    });
+    let e = await addParticipant(enc, p, ctx);
+    e = await setTempHp(e, p.id, 5, ctx);
+    expect(e.participants[0].tempHp).toBe(5);
+  });
+
+  test('setTempHp replaces existing temp (no stacking)', async () => {
+    const { enc, ctx } = setupEnc();
+    const p = makeParticipant({
+      name: 'Hero', type: 'character', initiative: 10, maxHp: 20, currentHp: 20,
+    });
+    let e = await addParticipant(enc, p, ctx);
+    e = await setTempHp(e, p.id, 5, ctx);
+    e = await setTempHp(e, p.id, 3, ctx);
+    expect(e.participants[0].tempHp).toBe(3);
+  });
+
+  test('setTempHp to 0 clears temp', async () => {
+    const { enc, ctx } = setupEnc();
+    const p = makeParticipant({
+      name: 'Hero', type: 'character', initiative: 10, maxHp: 20, currentHp: 20,
+    });
+    let e = await addParticipant(enc, p, ctx);
+    e = await setTempHp(e, p.id, 5, ctx);
+    e = await setTempHp(e, p.id, 0, ctx);
+    expect(e.participants[0].tempHp).toBe(0);
+  });
+
+  test('damage: temp absorbs before regular HP', async () => {
+    const { enc, ctx } = setupEnc();
+    const p = makeParticipant({
+      name: 'Hero', type: 'character', initiative: 10, maxHp: 20, currentHp: 20,
+    });
+    let e = await addParticipant(enc, p, ctx);
+    e = await setTempHp(e, p.id, 5, ctx);
+    e = await applyHpChange(e, p.id, 'damage', 8, ctx);
+    expect(e.participants[0].tempHp).toBe(0);
+    expect(e.participants[0].currentHp).toBe(17);
+  });
+
+  test('damage less than temp: only temp reduced', async () => {
+    const { enc, ctx } = setupEnc();
+    const p = makeParticipant({
+      name: 'Hero', type: 'character', initiative: 10, maxHp: 20, currentHp: 20,
+    });
+    let e = await addParticipant(enc, p, ctx);
+    e = await setTempHp(e, p.id, 10, ctx);
+    e = await applyHpChange(e, p.id, 'damage', 4, ctx);
+    expect(e.participants[0].tempHp).toBe(6);
+    expect(e.participants[0].currentHp).toBe(20);
+  });
+
+  test('heal: does not affect temp HP', async () => {
+    const { enc, ctx } = setupEnc();
+    const p = makeParticipant({
+      name: 'Hero', type: 'character', initiative: 10, maxHp: 20, currentHp: 10,
+    });
+    let e = await addParticipant(enc, p, ctx);
+    e = await setTempHp(e, p.id, 5, ctx);
+    e = await applyHpChange(e, p.id, 'heal', 8, ctx);
+    expect(e.participants[0].tempHp).toBe(5);
+    expect(e.participants[0].currentHp).toBe(18);
+  });
+
+  test('damage exactly equals temp: temp gone, regular intact', async () => {
+    const { enc, ctx } = setupEnc();
+    const p = makeParticipant({
+      name: 'Hero', type: 'character', initiative: 10, maxHp: 20, currentHp: 20,
+    });
+    let e = await addParticipant(enc, p, ctx);
+    e = await setTempHp(e, p.id, 5, ctx);
+    e = await applyHpChange(e, p.id, 'damage', 5, ctx);
+    expect(e.participants[0].tempHp).toBe(0);
+    expect(e.participants[0].currentHp).toBe(20);
+  });
+
+  test('makeParticipant: tempHp defaults to 0', async () => {
+    const p = makeParticipant({
+      name: 'Hero', type: 'character', initiative: 10, maxHp: 20, currentHp: 20,
+    });
+    expect(p.tempHp).toBe(0);
+  });
+});

shared/tests/turn.writeback.test.js

@@ -0,0 +1,157 @@
+// Character writeback on endEncounter: sync maxHp/ac to campaign players.
+const shared = require('@ttrpg/shared');
+const { endEncounter } = shared;
+
+function makeMockStorage() {
+  const docs = new Map();
+  const writes = [];
+  return {
+    getDoc: jest.fn(async (p) => docs.get(p) || null),
+    setDoc: jest.fn(async (p, d) => { docs.set(p, d); }),
+    updateDoc: jest.fn(async (p, patch) => {
+      writes.push({ path: p, patch });
+      const cur = docs.get(p) || {};
+      docs.set(p, { ...cur, ...patch });
+    }),
+    addDoc: jest.fn(async (p, data) => {
+      writes.push({ path: p, patch: data });
+      docs.set(p, data);
+    }),
+    deleteDoc: jest.fn(async () => {}),
+    getCollection: jest.fn(async () => []),
+    _docs: docs,
+    _writes: writes,
+  };
+}
+
+function makeEncounter(overrides = {}) {
+  return {
+    id: 'enc1',
+    name: 'Test',
+    campaignId: 'camp1',
+    isStarted: true,
+    isPaused: false,
+    currentTurnParticipantId: 'p1',
+    round: 3,
+    turnOrderIds: ['p1', 'p2'],
+    participants: [
+      { id: 'p1', name: 'Fighter', type: 'character', originalCharacterId: 'char1', initiative: 15, maxHp: 28, currentHp: 20, ac: 18 },
+      { id: 'p2', name: 'Goblin', type: 'monster', originalCharacterId: null, initiative: 12, maxHp: 7, currentHp: 7, ac: 13 },
+      { id: 'p3', name: 'Cleric', type: 'character', originalCharacterId: 'char2', initiative: 10, maxHp: 22, currentHp: 22, ac: 16 },
+    ],
+    ...overrides,
+  };
+}
+
+describe('character writeback on endEncounter', () => {
+  test('no writeback when syncCharacters false/missing', async () => {
+    const storage = makeMockStorage();
+    storage._docs.set('campaigns/camp1', {
+      id: 'camp1', name: 'Camp', players: [
+        { id: 'char1', name: 'Fighter', defaultMaxHp: 30, defaultAc: 17 },
+      ],
+    });
+    const enc = makeEncounter();
+    const ctx = {
+      storage,
+      encounterPath: 'campaigns/camp1/encounters/enc1',
+      logPath: 'logs/log1',
+      logCollection: 'logs',
+      displayPath: 'activeDisplay/status',
+    };
+    await endEncounter(enc, ctx);
+    // no campaign write
+    expect(storage._writes.find(w => w.path === 'campaigns/camp1')).toBeUndefined();
+  });
+
+  test('writeback updates char maxHp + ac + currentHp when syncCharacters true', async () => {
+    const storage = makeMockStorage();
+    const players = [
+      { id: 'char1', name: 'Fighter', defaultMaxHp: 30, defaultAc: 17, defaultCurrentHp: 30 },
+      { id: 'char2', name: 'Cleric', defaultMaxHp: 20, defaultAc: 14, defaultCurrentHp: 20 },
+    ];
+    storage._docs.set('campaigns/camp1', { id: 'camp1', name: 'Camp', players, syncCharacters: true });
+    const enc = makeEncounter();
+    const ctx = {
+      storage,
+      encounterPath: 'campaigns/camp1/encounters/enc1',
+      logPath: 'logs/log1',
+      logCollection: 'logs',
+      displayPath: 'activeDisplay/status',
+    };
+    await endEncounter(enc, ctx);
+    const campWrite = storage._writes.find(w => w.path === 'campaigns/camp1');
+    expect(campWrite).toBeDefined();
+    const updated = campWrite.patch.players;
+    const fighter = updated.find(p => p.id === 'char1');
+    expect(fighter.defaultMaxHp).toBe(28);
+    expect(fighter.defaultAc).toBe(18);
+    expect(fighter.defaultCurrentHp).toBe(20);
+    const cleric = updated.find(p => p.id === 'char2');
+    expect(cleric.defaultMaxHp).toBe(22);
+    expect(cleric.defaultAc).toBe(16);
+    expect(cleric.defaultCurrentHp).toBe(22);
+  });
+
+  test('writeback skips monsters (no originalCharacterId)', async () => {
+    const storage = makeMockStorage();
+    const players = [{ id: 'char1', name: 'Fighter', defaultMaxHp: 30, defaultAc: 17 }];
+    storage._docs.set('campaigns/camp1', { id: 'camp1', name: 'Camp', players, syncCharacters: true });
+    const enc = makeEncounter();
+    const ctx = {
+      storage,
+      encounterPath: 'campaigns/camp1/encounters/enc1',
+      logPath: 'logs/log1',
+      logCollection: 'logs',
+      displayPath: 'activeDisplay/status',
+    };
+    await endEncounter(enc, ctx);
+    const campWrite = storage._writes.find(w => w.path === 'campaigns/camp1');
+    // players array still 1 entry, goblin not added
+    expect(campWrite.patch.players.length).toBe(1);
+  });
+
+  test('undo payload includes old char values for restore', async () => {
+    const storage = makeMockStorage();
+    const players = [
+      { id: 'char1', name: 'Fighter', defaultMaxHp: 30, defaultAc: 17, defaultCurrentHp: 30 },
+      { id: 'char2', name: 'Cleric', defaultMaxHp: 20, defaultAc: 14, defaultCurrentHp: 20 },
+    ];
+    storage._docs.set('campaigns/camp1', { id: 'camp1', name: 'Camp', players, syncCharacters: true });
+    storage._docs.set('logs/log1', null);
+    const enc = makeEncounter();
+    const ctx = {
+      storage,
+      encounterPath: 'campaigns/camp1/encounters/enc1',
+      logPath: 'logs/log1',
+      logCollection: 'logs',
+      displayPath: 'activeDisplay/status',
+    };
+    await endEncounter(enc, ctx);
+    const logWrite = storage._writes.find(w => w.path === 'logs/log1');
+    expect(logWrite).toBeDefined();
+    const log = logWrite.patch;
+    expect(log.undo.characterWriteback).toBeDefined();
+    expect(log.undo.characterWriteback).toHaveLength(2);
+    const fighterOld = log.undo.characterWriteback.find(c => c.id === 'char1');
+    expect(fighterOld.defaultMaxHp).toBe(30);
+    expect(fighterOld.defaultAc).toBe(17);
+    expect(fighterOld.defaultCurrentHp).toBe(30);
+  });
+
+  test('writeback no-op if character missing from campaign', async () => {
+    const storage = makeMockStorage();
+    storage._docs.set('campaigns/camp1', { id: 'camp1', name: 'Camp', players: [], syncCharacters: true });
+    const enc = makeEncounter();
+    const ctx = {
+      storage,
+      encounterPath: 'campaigns/camp1/encounters/enc1',
+      logPath: 'logs/log1',
+      logCollection: 'logs',
+      displayPath: 'activeDisplay/status',
+    };
+    await endEncounter(enc, ctx);
+    // no writeback (no matching chars = no change)
+    expect(storage._writes.find(w => w.path === 'campaigns/camp1')).toBeUndefined();
+  });
+});

shared/turn.js

@@ -361,6 +361,8 @@ function makeParticipant(opts) {
     deathSaveSuccesses: opts.deathSaveSuccesses || 0,
     deathSaveFailures: opts.deathSaveFailures || 0,
     hpFormula: opts.hpFormula || null,
+    ac: opts.ac !== undefined ? opts.ac : null,
+    tempHp: opts.tempHp !== undefined ? opts.tempHp : 0,
   };
 }
 
@@ -369,20 +371,22 @@ function buildCharacterParticipant(character) {
   const modifier = character.defaultInitMod || 0;
   const finalInitiative = initiativeRoll + modifier;
   const maxHp = character.defaultMaxHp || DEFAULT_MAX_HP;
+  const currentHp = character.defaultCurrentHp != null ? character.defaultCurrentHp : maxHp;
   return {
     participant: makeParticipant({
       name: character.name,
-      type: 'character',
+      type: character.isNpc ? 'npc' : 'character',
       originalCharacterId: character.id,
       initiative: finalInitiative,
       maxHp,
-      currentHp: maxHp,
+      currentHp,
+      ac: character.defaultAc !== undefined ? character.defaultAc : null,
     }),
     roll: { roll: initiativeRoll, mod: modifier, total: finalInitiative },
   };
 }
 
-function buildMonsterParticipant({ name, maxHp, initMod, asNpc, hpFormula }) {
+function buildMonsterParticipant({ name, maxHp, initMod, asNpc, hpFormula, ac }) {
   const initiativeRoll = rollD20();
   const modifier = initMod !== undefined ? initMod : MONSTER_DEFAULT_INIT_MOD;
   const finalInitiative = initiativeRoll + modifier;
@@ -406,6 +410,7 @@ function buildMonsterParticipant({ name, maxHp, initMod, asNpc, hpFormula }) {
       maxHp: hp,
       currentHp: hp,
       hpFormula: hpFormula || null,
+      ac: ac !== undefined ? ac : null,
     }),
     roll: { roll: initiativeRoll, mod: modifier, total: finalInitiative, hpRoll },
   };
@@ -619,6 +624,25 @@ async function toggleParticipantActive(encounter, participantId, ctx) {
   return commit(encounter, patch, log, ctx);
 }
 
+async function setTempHp(encounter, participantId, tempHp, ctx) {
+  const participant = (encounter.participants || []).find(p => p.id === participantId);
+  if (!participant) throw new Error('Participant not found.');
+  const value = Math.max(0, tempHp || 0);
+  const oldValues = { tempHp: participant.tempHp || 0 };
+  const updatedParticipants = (encounter.participants || []).map(p =>
+    p.id === participantId ? { ...p, tempHp: value } : p
+  );
+  const log = {
+    type: 'set_temp_hp',
+    participantId,
+    participantName: participant.name,
+    message: `${participant.name} temp HP set to ${value}`,
+    delta: { tempHp: value, oldTempHp: oldValues.tempHp },
+    undo: { oldValues, newValues: { tempHp: value } },
+  };
+  return commit(encounter, { participants: updatedParticipants }, log, ctx);
+}
+
 async function applyHpChange(encounter, participantId, changeType, amount, optionsOrCtx, maybeCtx) {
   const ctx = maybeCtx || optionsOrCtx;
   const options = maybeCtx ? (optionsOrCtx || {}) : {};
@@ -633,6 +657,7 @@ async function applyHpChange(encounter, participantId, changeType, amount, optio
 
   const oldValues = {
     currentHp: participant.currentHp,
+    tempHp: participant.tempHp || 0,
     status: participant.status || (participant.currentHp === 0 ? 'dying' : 'conscious'),
     deathSaveSuccesses: participant.deathSaveSuccesses || 0,
     deathSaveFailures: participant.deathSaveFailures || 0,
@@ -644,6 +669,7 @@ async function applyHpChange(encounter, participantId, changeType, amount, optio
   let message = '';
   let logDelta = { amount, from: participant.currentHp };
   const status = oldValues.status;
+  const currentTemp = participant.tempHp || 0;
 
   // GENERIC ruleset: no death saves, negative HP allowed, down status at <=0.
   // Monster death = dead + inactive. No unconscious auto-condition.
@@ -652,6 +678,33 @@ async function applyHpChange(encounter, participantId, changeType, amount, optio
   }
 
   if (changeType === 'damage') {
+    // Temp HP absorbs damage first.
+    let remainingDmg = amount;
+    let tempAfter = currentTemp;
+    if (tempAfter > 0) {
+      const absorbed = Math.min(tempAfter, remainingDmg);
+      tempAfter -= absorbed;
+      remainingDmg -= absorbed;
+      updates.tempHp = tempAfter;
+    }
+    // If fully absorbed by temp, no regular HP change.
+    if (remainingDmg === 0 && participant.currentHp > 0) {
+      const updatedParticipants0 = (encounter.participants || []).map(p =>
+        p.id === participantId ? { ...p, tempHp: tempAfter } : p
+      );
+      const log0 = {
+        type: 'hp_change',
+        participantId,
+        participantName: participant.name,
+        message: `${participant.name} took ${amount} damage (absorbed by temp HP, ${tempAfter} temp remaining)`,
+        delta: { amount, from: participant.currentHp, to: participant.currentHp, tempHp: tempAfter },
+        undo: { oldValues, newValues: { ...oldValues, tempHp: tempAfter } },
+      };
+      return commit(encounter, { participants: updatedParticipants0 }, log0, ctx);
+    }
+    amount = remainingDmg;
+    const tempBefore = currentTemp;
+    const tempFinal = updates.tempHp !== undefined ? updates.tempHp : tempBefore;
     if (participant.currentHp === 0) {
       if (status === 'dead') {
         if (participant.type === 'monster' && participant.isActive !== false) {
@@ -683,23 +736,23 @@ async function applyHpChange(encounter, participantId, changeType, amount, optio
       const add = options.isCriticalHit ? 2 : 1;
       const failures = (status === 'stable' ? 0 : (participant.deathSaveFailures || 0)) + add;
       if (failures >= 3) {
-        updates = { currentHp: 0, status: 'dead', deathSaveSuccesses: 0, deathSaveFailures: 0, ...(participant.type === 'monster' ? { isActive: false } : {}) };
+        updates = { currentHp: 0, status: 'dead', deathSaveSuccesses: 0, deathSaveFailures: 0, tempHp: tempFinal, ...(participant.type === 'monster' ? { isActive: false } : {}) };
       } else {
-        updates = { currentHp: 0, status: 'dying', deathSaveSuccesses: 0, deathSaveFailures: failures };
+        updates = { currentHp: 0, status: 'dying', deathSaveSuccesses: 0, deathSaveFailures: failures, tempHp: tempFinal };
       }
       message = `${participant.name} took ${amount} damage while ${status === 'stable' ? 'stable' : 'dying'}`;
       logDelta = { ...logDelta, to: 0, status: updates.status, deathSaveFailures: updates.deathSaveFailures };
     } else if (amount >= participant.currentHp + participant.maxHp) {
-      updates = { currentHp: 0, status: 'dead', deathSaveSuccesses: 0, deathSaveFailures: 0, ...(participant.type === 'monster' ? { isActive: false } : {}) };
+      updates = { currentHp: 0, status: 'dead', deathSaveSuccesses: 0, deathSaveFailures: 0, tempHp: tempFinal, ...(participant.type === 'monster' ? { isActive: false } : {}) };
       message = `Massive damage! ${participant.name} instantly killed`;
       logDelta = { ...logDelta, to: 0, status: 'dead', massive: true };
     } else {
       const newHp = Math.max(0, participant.currentHp - amount);
       if (newHp === 0) {
         const zeroStatus = participant.type === 'monster' ? 'dead' : 'dying';
-        updates = { currentHp: 0, status: zeroStatus, deathSaveSuccesses: 0, deathSaveFailures: 0, ...(zeroStatus === 'dead' ? { isActive: false } : {}) };
+        updates = { currentHp: 0, status: zeroStatus, deathSaveSuccesses: 0, deathSaveFailures: 0, tempHp: tempFinal, ...(zeroStatus === 'dead' ? { isActive: false } : {}) };
       } else {
-        updates = { currentHp: newHp, status: 'conscious' };
+        updates = { currentHp: newHp, status: 'conscious', tempHp: tempFinal };
       }
       message = `${participant.name} took ${amount} damage (${participant.currentHp} → ${newHp} HP)`;
       logDelta = { ...logDelta, to: newHp, status: updates.status };
@@ -743,8 +796,31 @@ async function applyHpChange(encounter, participantId, changeType, amount, optio
 async function applyHpChangeGeneric(encounter, participant, changeType, amount, oldValues, ctx) {
   const participantId = participant.id;
   let updates, message, logDelta = { amount, from: participant.currentHp };
+  const currentTemp = participant.tempHp || 0;
 
   if (changeType === 'damage') {
+    // Temp HP absorbs damage first.
+    let remainingDmg = amount;
+    let tempAfter = currentTemp;
+    if (tempAfter > 0) {
+      const absorbed = Math.min(tempAfter, remainingDmg);
+      tempAfter -= absorbed;
+      remainingDmg -= absorbed;
+    }
+    if (remainingDmg === 0) {
+      const updatedParticipants0 = (encounter.participants || []).map(p =>
+        p.id === participantId ? { ...p, tempHp: tempAfter } : p
+      );
+      const log0 = {
+        type: 'hp_change', participantId, participantName: participant.name,
+        message: `${participant.name} took ${amount} damage (absorbed by temp HP, ${tempAfter} temp remaining)`,
+        delta: { amount, from: participant.currentHp, to: participant.currentHp, tempHp: tempAfter },
+        undo: { oldValues, newValues: { ...oldValues, tempHp: tempAfter } },
+      };
+      return commit(encounter, { participants: updatedParticipants0 }, log0, ctx);
+    }
+    amount = remainingDmg;
+    const tempFinal = tempAfter;
     if (oldValues.status === 'dead') {
       if (participant.type === 'monster' && participant.isActive !== false) {
         const updatedParticipants = (encounter.participants || []).map(p =>
@@ -768,11 +844,11 @@ async function applyHpChangeGeneric(encounter, participant, changeType, amount,
     const newHp = participant.currentHp - amount;
     const isMonster = participant.type === 'monster';
     if (newHp <= 0 && isMonster) {
-      updates = { currentHp: newHp, status: 'dead', isActive: false };
+      updates = { currentHp: newHp, status: 'dead', isActive: false, tempHp: tempFinal };
     } else if (newHp <= 0) {
-      updates = { currentHp: newHp, status: 'down' };
+      updates = { currentHp: newHp, status: 'down', tempHp: tempFinal };
     } else {
-      updates = { currentHp: newHp, status: 'conscious' };
+      updates = { currentHp: newHp, status: 'conscious', tempHp: tempFinal };
     }
     message = `${participant.name} took ${amount} damage (${participant.currentHp} → ${newHp} HP)`;
     logDelta = { ...logDelta, to: newHp, status: updates.status };
@@ -1051,6 +1127,38 @@ async function endEncounter(encounter, ctx) {
     delta: {},
     undo: { isStarted: encounter.isStarted ?? false, isPaused: encounter.isPaused ?? false, round: encounter.round ?? 0, currentTurnParticipantId: encounter.currentTurnParticipantId ?? null, turnOrderIds: [...(encounter.turnOrderIds || [])], endedAt: encounter.endedAt ?? null },
   };
+
+  // Character writeback: sync maxHp/ac/currentHp to campaign players if enabled.
+  const wbCampaignId = encounter.campaignId || ctx.campaignId;
+  if ((wbCampaignId || ctx.campaign) && ctx.storage) {
+    let campaign;
+    try {
+      campaign = ctx.campaign || await ctx.storage.getDoc(`campaigns/${wbCampaignId}`);
+    } catch { campaign = null; }
+    if (campaign && campaign.syncCharacters && Array.isArray(campaign.players)) {
+      const charParticipants = (encounter.participants || []).filter(p => p.originalCharacterId);
+      const oldValues = [];
+      let changed = false;
+      const updatedPlayers = campaign.players.map(player => {
+        const cp = charParticipants.find(p => p.originalCharacterId === player.id);
+        if (!cp) return player;
+        const oldMaxHp = player.defaultMaxHp;
+        const oldAc = player.defaultAc;
+        const oldCurrentHp = player.defaultCurrentHp;
+        oldValues.push({ id: player.id, defaultMaxHp: oldMaxHp, defaultAc: oldAc, defaultCurrentHp: oldCurrentHp });
+        const newPlayer = { ...player };
+        if (cp.maxHp != null && cp.maxHp !== oldMaxHp) { newPlayer.defaultMaxHp = cp.maxHp; changed = true; }
+        if (cp.ac != null && cp.ac !== oldAc) { newPlayer.defaultAc = cp.ac; changed = true; }
+        if (cp.currentHp != null && cp.currentHp !== oldCurrentHp) { newPlayer.defaultCurrentHp = cp.currentHp; changed = true; }
+        return newPlayer;
+      });
+      if (changed) {
+        await ctx.storage.updateDoc(`campaigns/${wbCampaignId}`, { players: updatedPlayers });
+        log.undo.characterWriteback = oldValues;
+      }
+    }
+  }
+
   return commit(encounter, patch, log, ctx);
 }
 
@@ -1079,7 +1187,7 @@ module.exports = {
   makeParticipant, buildCharacterParticipant, buildMonsterParticipant,
   startEncounter, nextTurn, togglePause,
   addParticipant, addParticipants, updateParticipant, removeParticipant,
-  toggleParticipantActive, applyHpChange, deathSave, stabilizeParticipant, reviveParticipant, markDead, toggleCondition,
+  toggleParticipantActive, applyHpChange, setTempHp, deathSave, stabilizeParticipant, reviveParticipant, markDead, toggleCondition,
   reorderParticipants, endEncounter,
   activateDisplay, clearDisplay, toggleHidePlayerHp,
 };

src/tests/App.characterization.test.js

@@ -62,7 +62,7 @@ describe('Campaign -> Firebase', () => {
 
     // CharacterManager form
     fireEvent.change(screen.getByPlaceholderText('Character name'), { target: { value: 'Brog' } });
-    fireEvent.change(screen.getByLabelText(/Default HP/i), { target: { value: '25' } });
+    fireEvent.change(screen.getByLabelText(/^HP$/i), { target: { value: '25' } });
     fireEvent.change(screen.getByLabelText(/Init Mod/i), { target: { value: '3' } });
     fireEvent.click(screen.getByRole('button', { name: /Add Character/i }));
 

src/tests/DisplayGuard.test.js

@@ -0,0 +1,94 @@
+// Display guard: starting encounter does NOT steal display from another live encounter.
+// Ending encounter does NOT clear display if different encounter showing.
+
+import React from 'react';
+import { screen, fireEvent, waitFor } from '@testing-library/react';
+import '@testing-library/jest-dom';
+import { getCalls, MOCK_DB } from '../__mocks__/firebase/_mock-db';
+import { setupReady, addMonsterViaUI, startCombatViaUI } from './testHelpers';
+
+const DISPLAY_PATH = 'artifacts/ttrpg-initiative-tracker-default/public/data/activeDisplay/status';
+
+function findCallActiveDisplay(fn) {
+  return getCalls().filter(c => c.fn === fn && c.path.includes('activeDisplay/status'));
+}
+
+describe('Display guard', () => {
+  test('startEncounter: claims display when slot empty', async () => {
+    await setupReady('GuardCamp1', 'GuardEnc1');
+    await addMonsterViaUI('Goblin', 10, 5);
+    await startCombatViaUI();
+    const adCalls = findCallActiveDisplay('setDoc');
+    const last = adCalls[adCalls.length - 1];
+    expect(last).toBeTruthy();
+    expect(last.data.activeEncounterId).toBeTruthy();
+  });
+
+  test('startEncounter: does NOT steal display from another live encounter', async () => {
+    // Pre-seed display as busy with a DIFFERENT encounter
+    MOCK_DB.set(DISPLAY_PATH, {
+      activeCampaignId: 'other-camp',
+      activeEncounterId: 'other-enc',
+    });
+
+    await setupReady('GuardCamp2', 'GuardEnc2');
+    await addMonsterViaUI('Orc', 15, 8);
+    await startCombatViaUI();
+
+    // Combat started on encounter doc
+    const encCalls = getCalls().filter(c => c.fn === 'updateDoc' && c.path.includes('/encounters/'));
+    expect(encCalls.some(c => c.data.isStarted === true)).toBe(true);
+
+    // But display setDoc should NOT have been called to claim this encounter
+    const adClaims = findCallActiveDisplay('setDoc').filter(
+      c => c.data && c.data.activeEncounterId && c.data.activeEncounterId !== 'other-enc'
+    );
+    expect(adClaims).toHaveLength(0);
+  });
+
+  test('endEncounter: clears display when ending the displayed encounter', async () => {
+    await setupReady('GuardCamp3', 'GuardEnc3');
+    await addMonsterViaUI('Wolf', 8, 3);
+    await startCombatViaUI();
+
+    fireEvent.click(screen.getByRole('button', { name: /End Combat/i }));
+    fireEvent.click(await screen.findByRole('button', { name: /Confirm/i }));
+
+    await waitFor(() => {
+      const adCalls = findCallActiveDisplay('setDoc');
+      const last = adCalls[adCalls.length - 1];
+      return last && last.data && last.data.activeCampaignId === null;
+    });
+    const adCalls = findCallActiveDisplay('setDoc');
+    const last = adCalls[adCalls.length - 1];
+    expect(last.data).toMatchObject({ activeCampaignId: null, activeEncounterId: null });
+  });
+
+  test('endEncounter: does NOT clear display when different encounter is live', async () => {
+    await setupReady('GuardCamp4', 'GuardEnc4');
+    await addMonsterViaUI('Bat', 4, 2);
+    await startCombatViaUI();
+
+    // Now hijack display to a different encounter (simulating eyeball toggle elsewhere)
+    MOCK_DB.set(DISPLAY_PATH, {
+      activeCampaignId: 'different-camp',
+      activeEncounterId: 'different-enc',
+    });
+
+    fireEvent.click(screen.getByRole('button', { name: /End Combat/i }));
+    fireEvent.click(await screen.findByRole('button', { name: /Confirm/i }));
+
+    // Wait for encounter to end
+    await waitFor(() => {
+      const encCalls = getCalls().filter(c => c.fn === 'updateDoc' && c.path.includes('/encounters/'));
+      const last = encCalls[encCalls.length - 1];
+      return last && last.data.isStarted === false;
+    });
+
+    // Display should NOT have been cleared
+    const clearCalls = findCallActiveDisplay('setDoc').filter(
+      c => c.data && c.data.activeCampaignId === null
+    );
+    expect(clearCalls).toHaveLength(0);
+  });
+});

src/tests/InitiativeReslot.test.js

@@ -26,7 +26,7 @@ describe('FEAT-3 reslot: inline init change reorders list', () => {
     const addOne = async (name, hp, mod, init) => {
       fireEvent.change(form.getByPlaceholderText('e.g., Dire Wolf'), { target: { value: name } });
       fireEvent.change(form.getByLabelText(/Init Mod/i), { target: { value: String(mod) } });
-      fireEvent.change(form.getByLabelText(/Max HP/i), { target: { value: String(hp) } });
+      fireEvent.change(document.getElementById('monsterMaxHp'), { target: { value: String(hp) } });
       fireEvent.change(form.getByPlaceholderText('auto'), { target: { value: String(init) } });
       fireEvent.click(form.getByRole('button', { name: /Add to Encounter/i }));
       await waitFor(() => {

src/tests/LocalStorageScoping.test.js

@@ -0,0 +1,39 @@
+// localStorage scoping: selectedEncounter + scrollY keyed per campaign.
+// Two tabs on different campaigns don't fight over selection/scroll.
+
+import React from 'react';
+import { screen, fireEvent, waitFor } from '@testing-library/react';
+import '@testing-library/jest-dom';
+import { setupReady, addMonsterViaUI } from './testHelpers';
+
+describe('localStorage campaign scoping', () => {
+  test('selectedEncounter key is scoped (not bare)', async () => {
+    await setupReady('ScopeCamp1', 'ScopeEnc1');
+    // bare key should not exist
+    expect(localStorage.getItem('ttrpg.selectedEncounter')).toBeNull();
+    // scoped key with suffix should exist
+    const scoped = Object.keys(localStorage).find(
+      k => k.startsWith('ttrpg.selectedEncounter.') && k !== 'ttrpg.selectedEncounter'
+    );
+    expect(scoped).toBeTruthy();
+    expect(localStorage.getItem(scoped)).toBeTruthy();
+  });
+
+  test('scrollY key is scoped (not bare)', async () => {
+    await setupReady('ScopeCamp2', 'ScopeEnc2');
+    await addMonsterViaUI('Goblin', 10, 5);
+    expect(localStorage.getItem('ttrpg.scrollY')).toBeNull();
+    const scoped = Object.keys(localStorage).find(
+      k => k.startsWith('ttrpg.scrollY.') && k !== 'ttrpg.scrollY'
+    );
+    // key may not exist until save fires — trigger by checking bare is null
+    // and at least scoped format is used if any scrollY key present
+    const scrollKeys = Object.keys(localStorage).filter(k => k.startsWith('ttrpg.scrollY'));
+    scrollKeys.forEach(k => expect(k).not.toBe('ttrpg.scrollY'));
+  });
+
+  test('global keys still exist (campaign selection, wake lock)', async () => {
+    await setupReady('ScopeCamp3', 'ScopeEnc3');
+    expect(localStorage.getItem('ttrpg.selectedCampaign')).toBeTruthy();
+  });
+});

src/tests/Logs.characterization.test.js

@@ -20,7 +20,7 @@ async function addCharacterToEncounter(name = 'Hero', hp = 10) {
   await selectCampaignByName(`DS-${name}`);
 
   fireEvent.change(screen.getByPlaceholderText('Character name'), { target: { value: name } });
-  fireEvent.change(screen.getByLabelText(/Default HP/i), { target: { value: String(hp) } });
+  fireEvent.change(screen.getByLabelText(/^HP$/i), { target: { value: String(hp) } });
   fireEvent.click(screen.getByRole('button', { name: /Add Character/i }));
   await waitFor(() => findCalls('updateDoc', '/campaigns/').find(c => c.data.players?.length === 1));
   const charId = findCalls('updateDoc', '/campaigns/').find(c => c.data.players?.length === 1).data.players[0].id;

src/tests/ReslotAllPaths.test.js

@@ -16,7 +16,7 @@ function lastParticipantsUpdate() {
 async function addOne(form, name, hp, mod, init) {
   fireEvent.change(form.getByPlaceholderText('e.g., Dire Wolf'), { target: { value: name } });
   fireEvent.change(form.getByLabelText(/Init Mod/i), { target: { value: String(mod) } });
-  fireEvent.change(form.getByLabelText(/Max HP/i), { target: { value: String(hp) } });
+  fireEvent.change(document.getElementById('monsterMaxHp'), { target: { value: String(hp) } });
   fireEvent.change(form.getByPlaceholderText('auto'), { target: { value: String(init) } });
   fireEvent.click(form.getByRole('button', { name: /Add to Encounter/i }));
   await waitFor(() => {

src/tests/testHelpers.js

@@ -74,7 +74,7 @@ export async function addMonsterViaUI(name = 'Goblin', maxHp = 7, initMod = 2) {
   const form = within(getParticipantForm());
   fireEvent.change(form.getByPlaceholderText('e.g., Dire Wolf'), { target: { value: name } });
   fireEvent.change(form.getByLabelText(/Init Mod/i), { target: { value: String(initMod) } });
-  fireEvent.change(form.getByLabelText(/Max HP/i), { target: { value: String(maxHp) } });
+  fireEvent.change(document.getElementById('monsterMaxHp'), { target: { value: String(maxHp) } });
   fireEvent.click(form.getByRole('button', { name: /Add to Encounter/i }));
   const { getCalls } = require('../__mocks__/firebase/_mock-db');
   await waitFor(() => {