diff --git a/rulesdocs/refector_rules_and_tracking.md b/rulesdocs/refector_rules_and_tracking.md
index 08f1827b..63d92681 100644
--- a/rulesdocs/refector_rules_and_tracking.md
+++ b/rulesdocs/refector_rules_and_tracking.md
@@ -43,7 +43,7 @@
 ### BIGGEST OFFENDERS
 - [ ] audio forward service
 - [ ] button box service
-- [ ] chat service
+- [x] chat service
 - [x] discord bot service
 - [x] home assistant service
 - [ ] llm commentary service
@@ -60,6 +60,7 @@
 ### COMPLETED SERVICES
 - turn service
 - session service
+- chat service
 
 ### LARGE CHANGES
 - Folderized all files in `server/src/services/` into per-service folders with `index.js` entrypoints and updated internal relative imports for new path depth.
@@ -88,6 +89,7 @@
 - Finished `discordBotService` decomposition by extracting presence rotation/state to `discordBotService/presence.js`, channel/typing transport helpers to `discordBotService/channelIO.js`, command routing and admin command handlers to `discordBotService/commandHandlers.js`, and event-bus/chat-bridge/moderation DM workflows to `discordBotService/integrations.js`; `discordBotService/index.js` is now a thin composition layer.
 - Finished `replayEngineV2` decomposition by extracting environment/path constants to `replayEngineV2/constants.js`, mutable runtime state to `replayEngineV2/state.js`, source discovery/worker arg building to `replayEngineV2/sources.js`, ffmpeg worker lifecycle to `replayEngineV2/workerManager.js`, segment indexing/retention/health snapshot logic to `replayEngineV2/segmentStore.js`, sidebar SVG/video rendering to `replayEngineV2/sidebarRenderer.js`, and replay assembly pipeline to `replayEngineV2/replayBuilder.js`; `replayEngineV2/index.js` is now a thin orchestration layer.
 - Consolidated replay-related single-file services into `replayEngineV2` by moving cooldown state (`cooldown.js`), user-facing replay source validation/defaults (`replaySources.js`), and replay socket hooks (`socketHooks.js`) into the engine folder; removed obsolete standalone services `replayBuildService`, `replayService`, `replaySourceService`, and `replaySocketService` and rewired dependents to import directly from `replayEngineV2`.
+- Finished `chatService` decomposition by extracting runtime constants (`chatService/constants.js`), shared mutable state (`chatService/state.js`), content/moderation helpers (`chatService/contentFilters.js`), payload/context builders (`chatService/contextBuilders.js`), bus/history broadcast pipeline (`chatService/broadcast.js`), rover-side notification helpers (`chatService/notifications.js`), message handlers (`chatService/handlers.js`), and socket/event-bus wiring (`chatService/socketHooks.js`); `chatService/index.js` is now a thin orchestration layer.
 
 ## WebUI frontend
 ### BIGGEST OFFENDERS
diff --git a/server/src/services/chatService/broadcast.js b/server/src/services/chatService/broadcast.js
new file mode 100644
index 00000000..31f0ae43
--- /dev/null
+++ b/server/src/services/chatService/broadcast.js
@@ -0,0 +1,20 @@
+// Chat Broadcast Pipeline
+// Purpose: Publishes chat message and typing payloads to event bus while preserving in-memory history.
+// Scope: Encapsulates chat fan-out side effects and recent-history accessors.
+const { publishEvent } = require('../eventBus');
+const { pushHistory, getRecentMessages } = require('./state');
+
+function broadcastMessage(message) {
+  pushHistory(message);
+  publishEvent({ source: 'chat', type: 'chat:message', payload: message });
+}
+
+function broadcastTyping(payload) {
+  publishEvent({ source: 'chat', type: 'chat:typing', payload });
+}
+
+module.exports = {
+  broadcastMessage,
+  broadcastTyping,
+  getRecentMessages,
+};
diff --git a/server/src/services/chatService/constants.js b/server/src/services/chatService/constants.js
new file mode 100644
index 00000000..359f99fa
--- /dev/null
+++ b/server/src/services/chatService/constants.js
@@ -0,0 +1,26 @@
+// Chat Service Constants
+// Purpose: Defines chat moderation, history, and UX timing constants used across chat modules.
+// Scope: Centralizes immutable runtime tuning values for message and typing behavior.
+const RATE_LIMIT_WINDOW_MS = 8000;
+const RATE_LIMIT_MAX = 5;
+const MAX_HISTORY = 100;
+const PROFANITY_ALLOWLIST = ['fuck', 'ass', 'shit'];
+const DUPLICATE_WINDOW_MS = 15000;
+const TYPING_START_NOTE = 72;
+const TYPING_SEND_NOTE = 79;
+const TYPING_NOTE_DURATION = 8;
+const ACCESS_NOTICE_COOLDOWN_MS = 60000;
+const ACCESS_KEYWORD_RE = /\b(drive|roomba)\b/i;
+
+module.exports = {
+  RATE_LIMIT_WINDOW_MS,
+  RATE_LIMIT_MAX,
+  MAX_HISTORY,
+  PROFANITY_ALLOWLIST,
+  DUPLICATE_WINDOW_MS,
+  TYPING_START_NOTE,
+  TYPING_SEND_NOTE,
+  TYPING_NOTE_DURATION,
+  ACCESS_NOTICE_COOLDOWN_MS,
+  ACCESS_KEYWORD_RE,
+};
diff --git a/server/src/services/chatService/contentFilters.js b/server/src/services/chatService/contentFilters.js
new file mode 100644
index 00000000..9489f401
--- /dev/null
+++ b/server/src/services/chatService/contentFilters.js
@@ -0,0 +1,60 @@
+// Chat Content Filters
+// Purpose: Provides profanity, spam, and text normalization helpers for incoming chat messages.
+// Scope: Contains pure filtering logic and duplicate/keymash detectors.
+const { DataSet, RegExpMatcher, englishDataset, englishRecommendedTransformers } = require('obscenity');
+const { PROFANITY_ALLOWLIST, DUPLICATE_WINDOW_MS } = require('./constants');
+const { lastMessageBySocket } = require('./state');
+
+const normalizedProfanityAllowlist = new Set(
+  PROFANITY_ALLOWLIST
+    .filter((term) => typeof term === 'string')
+    .map((term) => term.trim().toLowerCase())
+    .filter(Boolean),
+);
+
+const profanityDataset = new DataSet()
+  .addAll(englishDataset)
+  .removePhrasesIf((phrase) => normalizedProfanityAllowlist.has(phrase.metadata?.originalWord))
+  .build();
+
+const profanityMatcher = new RegExpMatcher({
+  ...profanityDataset,
+  ...englishRecommendedTransformers,
+  whitelistedTerms: profanityDataset.whitelistedTerms,
+});
+
+function hasProfanity(text) {
+  if (typeof text !== 'string' || !text) return false;
+  return profanityMatcher.hasMatch(text);
+}
+
+function isDuplicate(socketId, text) {
+  const prev = lastMessageBySocket.get(socketId);
+  const now = Date.now();
+  if (!prev) {
+    lastMessageBySocket.set(socketId, { text, ts: now });
+    return false;
+  }
+  lastMessageBySocket.set(socketId, { text, ts: now });
+  return prev.text === text && now - prev.ts <= DUPLICATE_WINDOW_MS;
+}
+
+function isKeymash(text) {
+  if (!text) return false;
+  if (/(.)\1{6,}/.test(text)) return true;
+  if (/^[asdfghjkl;'\-=\[\]\\]{6,}$/i.test(text)) return true;
+  if (/^[qwertyuiop]{6,}$/i.test(text)) return true;
+  return false;
+}
+
+function normalizeUserText(raw) {
+  if (typeof raw !== 'string') return '';
+  return raw.replace(/\\n/g, '\n');
+}
+
+module.exports = {
+  hasProfanity,
+  isDuplicate,
+  isKeymash,
+  normalizeUserText,
+};
diff --git a/server/src/services/chatService/contextBuilders.js b/server/src/services/chatService/contextBuilders.js
new file mode 100644
index 00000000..77d7e437
--- /dev/null
+++ b/server/src/services/chatService/contextBuilders.js
@@ -0,0 +1,156 @@
+// Chat Context Builders
+// Purpose: Builds normalized chat message/typing payloads and rover context snapshots.
+// Scope: Encapsulates chat DTO construction and rover/driver metadata extraction.
+const { v4: uuidv4 } = require('uuid');
+const io = require('../../globals/io');
+const roverManager = require('../roverManager');
+const { getRole } = require('../roleService');
+const { describeAssignment } = require('../assignmentService');
+const { getNickname } = require('../nicknameService');
+
+function resolveRoverId(socketId) {
+  const primary = roverManager.getPrimaryRoverForSocket(socketId);
+  if (primary) return primary;
+  const assignment = describeAssignment(socketId);
+  return assignment?.roverId || null;
+}
+
+function resolveRoverColor(roverId) {
+  if (!roverId) return null;
+  const record = roverManager.rovers.get(String(roverId));
+  return record?.meta?.color || null;
+}
+
+function isPrivateClosedRoverId(roverId) {
+  if (!roverId) return false;
+  return roverManager.canReplayRoverId(roverId) !== true;
+}
+
+function isChargingFromSensors(sensors = {}) {
+  const label = String(sensors?.chargingState?.label || '').toLowerCase();
+  if (label === 'waiting' || label === 'full charging' || label === 'trickle charging') return true;
+  const code = sensors?.chargingState?.code;
+  return code === 2 || code === 3 || code === 4;
+}
+
+function buildRoverCtxSnapshot(roverId) {
+  if (!roverId) return null;
+  const key = String(roverId);
+  const record = roverManager.rovers.get(key);
+  if (!record) return null;
+  const sensors = record?.lastSensor?.decoded || {};
+  const batteryState = record?.batteryState || null;
+  const { getActiveDrivers } = require('../turnService');
+  const activeDrivers = getActiveDrivers();
+  const driverSocketId = activeDrivers[key] || record?.drivers?.values?.().next?.().value || null;
+  const charging = isChargingFromSensors(sensors);
+  const docked = Boolean(sensors?.chargingSources?.homeBase);
+  const wheelsOffGround = Boolean(sensors?.bumpsAndWheelDrops?.wheelDropLeft && sensors?.bumpsAndWheelDrops?.wheelDropRight);
+  const latestDistanceM = Math.round((Math.abs(Number(sensors?.distanceMm) || 0) / 1000) * 10) / 10;
+  const latestTurnDeg = Math.round(Math.abs(Number(sensors?.angleDeg) || 0));
+  const latestBumps = (sensors?.bumpsAndWheelDrops?.bumpLeft ? 0.5 : 0) + (sensors?.bumpsAndWheelDrops?.bumpRight ? 0.5 : 0);
+  const light = sensors?.lightBumper || {};
+  const contactState = docked ? 'clear' : latestBumps >= 0.5 ? 'bumps_recent' : sensors?.wall || light.left || light.frontLeft || light.centerLeft || light.centerRight || light.frontRight || light.right ? 'wall_brush' : 'clear';
+  const hazardState = docked ? 'normal' : sensors?.virtualWall ? 'virtual_wall_seen' : sensors?.cliffLeft || sensors?.cliffFrontLeft || sensors?.cliffFrontRight || sensors?.cliffRight ? 'cliff_alert' : 'normal';
+  const mobilityState = wheelsOffGround ? 'wheels_off_ground' : 'normal';
+  const baseScore = Math.min(100, Math.round(Math.min(45, latestDistanceM * 25) + Math.min(30, latestTurnDeg / 12) + Math.min(25, latestBumps * 12)));
+  const activityScore = Math.max(0, Math.min(100, baseScore + (contactState === 'wall_brush' ? 6 : 0) + (contactState === 'bumps_recent' ? 12 : 0) + (hazardState !== 'normal' ? 8 : 0) + (wheelsOffGround ? -20 : 0)));
+  const activityBand = activityScore >= 75 ? 'intense' : activityScore >= 50 ? 'high' : activityScore >= 25 ? 'medium' : activityScore >= 8 ? 'low' : 'idle';
+  const moving = latestDistanceM > 0.05 || latestTurnDeg > 10;
+  let statusTag = 'idle';
+  if (charging) statusTag = 'charging';
+  else if (docked) statusTag = 'docked';
+  else if (driverSocketId && moving) statusTag = 'driving';
+  else if (driverSocketId) statusTag = 'active-idle';
+
+  return {
+    id: key,
+    status_tag: statusTag,
+    battery_low: Boolean(batteryState?.warnActive || batteryState?.urgentActive),
+    docked,
+    charging,
+    wheels_off_ground: wheelsOffGround,
+    contact_state: contactState,
+    hazard_state: hazardState,
+    mobility_state: mobilityState,
+    activity_score: activityScore,
+    activity_band: activityBand,
+    activity_trend: 'steady',
+    activity_30s: {
+      distance_m: latestDistanceM,
+      turn_deg: latestTurnDeg,
+      bumps: latestBumps,
+    },
+  };
+}
+
+function buildMessage(socket, text, meta = {}) {
+  const roverId = meta.roverId || resolveRoverId(socket?.id);
+  const roverColor = meta.roverColor ?? resolveRoverColor(roverId);
+  return {
+    id: uuidv4(),
+    ts: Date.now(),
+    socketId: socket?.id || null,
+    nickname: meta.nickname || getNickname(socket) || null,
+    role: meta.role || getRole(socket),
+    roverId,
+    roverColor,
+    fromDiscord: Boolean(meta.fromDiscord),
+    discordGuildId: meta.discordGuildId || null,
+    discordGuildName: meta.discordGuildName || null,
+    discordGuildIconUrl: meta.discordGuildIconUrl || null,
+    discordChannelId: meta.discordChannelId || null,
+    discordUserId: meta.discordUserId || null,
+    discordUserName: meta.discordUserName || null,
+    discordUserAvatarUrl: meta.discordUserAvatarUrl || null,
+    roverCtx: meta.roverCtx || null,
+    text,
+    tts: meta.tts || null,
+    system: Boolean(meta.system),
+  };
+}
+
+function buildTypingPayload(socket, meta = {}) {
+  const roverId = meta.roverId || resolveRoverId(socket?.id);
+  const roverColor = meta.roverColor ?? resolveRoverColor(roverId);
+  const socketId = socket?.id || null;
+  const fromDiscord = Boolean(meta.fromDiscord);
+  let typingId = meta.typingId || null;
+  if (!typingId) {
+    if (fromDiscord) {
+      if (meta.discordUserId) typingId = `discord:${meta.discordUserId}`;
+      else if (meta.discordUserName) typingId = `discord:${meta.discordUserName}`;
+      else if (meta.nickname) typingId = `discord:${meta.nickname}`;
+      else typingId = 'discord:unknown';
+    } else if (socketId) typingId = `socket:${socketId}`;
+    else if (meta.nickname) typingId = `socket:${meta.nickname}`;
+    else typingId = 'socket:unknown';
+  }
+  return {
+    id: uuidv4(),
+    ts: Date.now(),
+    typingId,
+    isTyping: Boolean(meta.isTyping),
+    socketId,
+    nickname: meta.nickname || getNickname(socket) || null,
+    role: meta.role || getRole(socket),
+    roverId,
+    roverColor,
+    fromDiscord,
+    discordGuildId: meta.discordGuildId || null,
+    discordGuildName: meta.discordGuildName || null,
+    discordGuildIconUrl: meta.discordGuildIconUrl || null,
+    discordChannelId: meta.discordChannelId || null,
+    discordUserId: meta.discordUserId || null,
+    discordUserName: meta.discordUserName || null,
+    discordUserAvatarUrl: meta.discordUserAvatarUrl || null,
+  };
+}
+
+module.exports = {
+  resolveRoverId,
+  isPrivateClosedRoverId,
+  buildRoverCtxSnapshot,
+  buildMessage,
+  buildTypingPayload,
+};
diff --git a/server/src/services/chatService/handlers.js b/server/src/services/chatService/handlers.js
new file mode 100644
index 00000000..d738633c
--- /dev/null
+++ b/server/src/services/chatService/handlers.js
@@ -0,0 +1,93 @@
+// Chat Message Handlers
+// Purpose: Handles inbound socket/external chat payloads and applies moderation, routing, and side effects.
+// Scope: Owns message validation pipeline and typed outbound message construction.
+const logger = require('../../globals/logger').child('chatService');
+const { getRole } = require('../roleService');
+const { withinRateLimit } = require('./state');
+const { hasProfanity, isKeymash, normalizeUserText } = require('./contentFilters');
+const { buildMessage, buildTypingPayload, resolveRoverId, isPrivateClosedRoverId, buildRoverCtxSnapshot } = require('./contextBuilders');
+const { broadcastMessage, broadcastTyping } = require('./broadcast');
+const { playTypingNote, normalizeTtsOptions, maybeSendAccessNotice, maybeSpeak, TYPING_SEND_NOTE } = require('./notifications');
+
+function createHandlers({ sendSystemMessage }) {
+  function handleIncoming({ text, tts } = {}, socket, cb = () => {}) {
+    const role = getRole(socket);
+    void role;
+    const normalized = normalizeUserText(text);
+    const clean = normalized.trim();
+    if (!clean) return cb({ error: 'Message required' });
+    if (!withinRateLimit(socket.id)) return cb({ error: 'Slow down' });
+    if (clean.length > 400) return cb({ error: 'Message too long' });
+    if (hasProfanity(clean)) return cb({ error: 'Message blocked' });
+
+    const roverId = resolveRoverId(socket?.id);
+    const ttsOptions = normalizeTtsOptions(tts);
+    const message = buildMessage(socket, clean, {
+      fromDiscord: false,
+      roverId,
+      roverCtx: buildRoverCtxSnapshot(roverId),
+      tts: ttsOptions,
+    });
+
+    logger.info('Chat message', { socket: socket.id, roverId: message.roverId });
+    playTypingNote(roverId, TYPING_SEND_NOTE, socket?.id);
+
+    if (isPrivateClosedRoverId(message.roverId)) {
+      const forcedTts = ttsOptions || { speak: true, engine: 'flite' };
+      maybeSpeak(socket, message, forcedTts);
+      cb({ success: true, privateOnly: true });
+      return;
+    }
+
+    broadcastMessage(message);
+    maybeSendAccessNotice(message, sendSystemMessage);
+    maybeSpeak(socket, message, ttsOptions);
+    cb({ success: true });
+  }
+
+  function sendExternalMessage({ text, nickname = 'Discord', role = 'admin', roverId = null, discordGuildId = null, discordGuildName = null, discordGuildIconUrl = null, discordChannelId = null, discordUserId = null, discordUserName = null, discordUserAvatarUrl = null }) {
+    const normalized = normalizeUserText(text);
+    const clean = normalized.trim();
+    if (!clean || clean.length > 400) throw new Error('Message invalid');
+    if (hasProfanity(clean)) throw new Error('Message blocked');
+    if (isKeymash(clean)) throw new Error('Message looks like spam');
+    if (isPrivateClosedRoverId(roverId)) throw new Error('Private rover chat is closed');
+
+    const message = buildMessage(null, clean, {
+      nickname,
+      role,
+      roverId,
+      roverCtx: buildRoverCtxSnapshot(roverId),
+      fromDiscord: true,
+      discordGuildId,
+      discordGuildName,
+      discordGuildIconUrl,
+      discordChannelId,
+      discordUserId,
+      discordUserName,
+      discordUserAvatarUrl,
+    });
+
+    logger.info('External chat message', { roverId, nickname });
+    broadcastMessage(message);
+    maybeSendAccessNotice(message, sendSystemMessage);
+    return message;
+  }
+
+  function sendExternalTyping({ nickname = 'Discord', role = 'user', roverId = null, discordGuildId = null, discordGuildName = null, discordGuildIconUrl = null, discordChannelId = null, discordUserId = null, discordUserName = null, discordUserAvatarUrl = null, isTyping = true }) {
+    if (isPrivateClosedRoverId(roverId)) return null;
+    const payload = buildTypingPayload(null, { nickname, role, roverId, fromDiscord: true, discordGuildId, discordGuildName, discordGuildIconUrl, discordChannelId, discordUserId, discordUserName, discordUserAvatarUrl, isTyping });
+    broadcastTyping(payload);
+    return payload;
+  }
+
+  return {
+    handleIncoming,
+    sendExternalMessage,
+    sendExternalTyping,
+  };
+}
+
+module.exports = {
+  createHandlers,
+};
diff --git a/server/src/services/chatService/index.js b/server/src/services/chatService/index.js
index 3143e5e4..008ac321 100644
--- a/server/src/services/chatService/index.js
+++ b/server/src/services/chatService/index.js
@@ -1,353 +1,12 @@
-// chat Service
-// Purpose: Defines the chat Service module and the helpers/state used by this service unit.
-// Scope: Keeps runtime behavior unchanged while isolating responsibilities into a clear module boundary.
-const { v4: uuidv4 } = require('uuid');
-const { DataSet, RegExpMatcher, englishDataset, englishRecommendedTransformers } = require('obscenity');
-const io = require('../../globals/io');
-const logger = require('../../globals/logger').child('chatService');
-const { publishEvent, subscribe } = require('../eventBus');
-const { getRole } = require('../roleService');
-const { getMode, MODES } = require('../modeManager');
-const { describeAssignment } = require('../assignmentService');
-const roverManager = require('../roverManager');
-const { getNickname } = require('../nicknameService');
-const { issueCommand } = require('../commandService');
-const { getAdminReason } = require('../adminReasonService');
-
-const RATE_LIMIT_WINDOW_MS = 8000;
-const RATE_LIMIT_MAX = 5;
-const rateBuckets = new Map(); // socketId -> [timestamps]
-
-const MAX_HISTORY = 100;
-const history = [];
-
-// Words in this list are removed from the profanity dataset entirely.
-const PROFANITY_ALLOWLIST = ['fuck', 'ass', 'shit'];
-const normalizedProfanityAllowlist = new Set(PROFANITY_ALLOWLIST
-  .filter((term) => typeof term === 'string')
-  .map((term) => term.trim().toLowerCase())
-  .filter(Boolean));
-const profanityDataset = new DataSet()
-  .addAll(englishDataset)
-  .removePhrasesIf((phrase) => normalizedProfanityAllowlist.has(phrase.metadata?.originalWord))
-  .build();
-const profanityMatcher = new RegExpMatcher({
-  ...profanityDataset,
-  ...englishRecommendedTransformers,
-  whitelistedTerms: profanityDataset.whitelistedTerms,
-});
-const DUPLICATE_WINDOW_MS = 15000;
-const lastMessageBySocket = new Map(); // socketId -> { text, ts }
-const typingBySocket = new Map(); // socketId -> boolean
-const TYPING_START_NOTE = 72;
-const TYPING_SEND_NOTE = 79;
-const TYPING_NOTE_DURATION = 8;
-const ACCESS_NOTICE_COOLDOWN_MS = 60000;
-const ACCESS_KEYWORD_RE = /\b(drive|roomba)\b/i;
-let lastAccessNoticeAt = 0;
-
-function withinRateLimit(socketId) {
-  const now = Date.now();
-  const entries = rateBuckets.get(socketId) || [];
-  const next = entries.filter((ts) => now - ts <= RATE_LIMIT_WINDOW_MS);
-  next.push(now);
-  rateBuckets.set(socketId, next);
-  return next.length <= RATE_LIMIT_MAX;
-}
-
-function hasProfanity(text) {
-  if (typeof text !== 'string' || !text) return false;
-  return profanityMatcher.hasMatch(text);
-}
-
-function isDuplicate(socketId, text) {
-  const prev = lastMessageBySocket.get(socketId);
-  const now = Date.now();
-  if (!prev) {
-    lastMessageBySocket.set(socketId, { text, ts: now });
-    return false;
-  }
-  lastMessageBySocket.set(socketId, { text, ts: now });
-  return prev.text === text && now - prev.ts <= DUPLICATE_WINDOW_MS;
-}
-
-function isKeymash(text) {
-  if (!text) return false;
-  if (/(.)\1{6,}/.test(text)) return true; // same char 7+
-  if (/^[asdfghjkl;'\-=\[\]\\]{6,}$/i.test(text)) return true;
-  if (/^[qwertyuiop]{6,}$/i.test(text)) return true;
-  return false;
-}
-
-function resolveRoverId(socketId) {
-  const primary = roverManager.getPrimaryRoverForSocket(socketId);
-  if (primary) return primary;
-  const assignment = describeAssignment(socketId);
-  return assignment?.roverId || null;
-}
-
-function resolveRoverColor(roverId) {
-  if (!roverId) return null;
-  const record = roverManager.rovers.get(String(roverId));
-  return record?.meta?.color || null;
-}
-
-function isPrivateClosedRoverId(roverId) {
-  if (!roverId) return false;
-  return roverManager.canReplayRoverId(roverId) !== true;
-}
-
-function normalizeUserText(raw) {
-  if (typeof raw !== 'string') return '';
-  return raw.replace(/\\n/g, '\n');
-}
-
-function buildMessage(socket, text, meta = {}) {
-  const roverId = meta.roverId || resolveRoverId(socket?.id);
-  const roverColor = meta.roverColor ?? resolveRoverColor(roverId);
-  return {
-    id: uuidv4(),
-    ts: Date.now(),
-    socketId: socket?.id || null,
-    nickname: meta.nickname || getNickname(socket) || null,
-    role: meta.role || getRole(socket),
-    roverId,
-    roverColor,
-    fromDiscord: Boolean(meta.fromDiscord),
-    discordGuildId: meta.discordGuildId || null,
-    discordGuildName: meta.discordGuildName || null,
-    discordGuildIconUrl: meta.discordGuildIconUrl || null,
-    discordChannelId: meta.discordChannelId || null,
-    discordUserId: meta.discordUserId || null,
-    discordUserName: meta.discordUserName || null,
-    discordUserAvatarUrl: meta.discordUserAvatarUrl || null,
-    roverCtx: meta.roverCtx || null,
-    text,
-    tts: meta.tts || null,
-    system: Boolean(meta.system),
-  };
-}
-
-function isChargingFromSensors(sensors = {}) {
-  const label = String(sensors?.chargingState?.label || '').toLowerCase();
-  if (label === 'waiting' || label === 'full charging' || label === 'trickle charging') {
-    return true;
-  }
-  const code = sensors?.chargingState?.code;
-  return code === 2 || code === 3 || code === 4;
-}
-
-function buildRoverCtxSnapshot(roverId) {
-  if (!roverId) return null;
-  const key = String(roverId);
-  const record = roverManager.rovers.get(key);
-  if (!record) return null;
-  const sensors = record?.lastSensor?.decoded || {};
-  const batteryState = record?.batteryState || null;
-  const { getActiveDrivers } = require('../turnService');
-  const activeDrivers = getActiveDrivers();
-  const driverSocketId = activeDrivers[key] || record?.drivers?.values?.().next?.().value || null;
-  const charging = isChargingFromSensors(sensors);
-  const docked = Boolean(sensors?.chargingSources?.homeBase);
-  const wheelsOffGround = Boolean(
-    sensors?.bumpsAndWheelDrops?.wheelDropLeft && sensors?.bumpsAndWheelDrops?.wheelDropRight,
-  );
-  const latestDistanceM = Math.round((Math.abs(Number(sensors?.distanceMm) || 0) / 1000) * 10) / 10;
-  const latestTurnDeg = Math.round(Math.abs(Number(sensors?.angleDeg) || 0));
-  const latestBumps =
-    (sensors?.bumpsAndWheelDrops?.bumpLeft ? 0.5 : 0) +
-    (sensors?.bumpsAndWheelDrops?.bumpRight ? 0.5 : 0);
-  const light = sensors?.lightBumper || {};
-  const contactState = docked
-    ? 'clear'
-    : latestBumps >= 0.5
-      ? 'bumps_recent'
-      : sensors?.wall ||
-          light.left ||
-          light.frontLeft ||
-          light.centerLeft ||
-          light.centerRight ||
-          light.frontRight ||
-          light.right
-        ? 'wall_brush'
-        : 'clear';
-  const hazardState = docked
-    ? 'normal'
-    : sensors?.virtualWall
-      ? 'virtual_wall_seen'
-      : sensors?.cliffLeft || sensors?.cliffFrontLeft || sensors?.cliffFrontRight || sensors?.cliffRight
-        ? 'cliff_alert'
-        : 'normal';
-  const mobilityState = wheelsOffGround ? 'wheels_off_ground' : 'normal';
-  const baseScore = Math.min(100, Math.round(Math.min(45, latestDistanceM * 25) + Math.min(30, latestTurnDeg / 12) + Math.min(25, latestBumps * 12)));
-  const activityScore = Math.max(
-    0,
-    Math.min(
-      100,
-      baseScore +
-        (contactState === 'wall_brush' ? 6 : 0) +
-        (contactState === 'bumps_recent' ? 12 : 0) +
-        (hazardState !== 'normal' ? 8 : 0) +
-        (wheelsOffGround ? -20 : 0),
-    ),
-  );
-  const activityBand =
-    activityScore >= 75
-      ? 'intense'
-      : activityScore >= 50
-      ? 'high'
-      : activityScore >= 25
-      ? 'medium'
-      : activityScore >= 8
-      ? 'low'
-      : 'idle';
-  const moving = latestDistanceM > 0.05 || latestTurnDeg > 10;
-  let statusTag = 'idle';
-  if (charging) {
-    statusTag = 'charging';
-  } else if (docked) {
-    statusTag = 'docked';
-  } else if (driverSocketId && moving) {
-    statusTag = 'driving';
-  } else if (driverSocketId) {
-    statusTag = 'active-idle';
-  }
-  return {
-    id: key,
-    status_tag: statusTag,
-    battery_low: Boolean(batteryState?.warnActive || batteryState?.urgentActive),
-    docked,
-    charging,
-    wheels_off_ground: wheelsOffGround,
-    contact_state: contactState,
-    hazard_state: hazardState,
-    mobility_state: mobilityState,
-    activity_score: activityScore,
-    activity_band: activityBand,
-    activity_trend: 'steady',
-    activity_30s: {
-      distance_m: latestDistanceM,
-      turn_deg: latestTurnDeg,
-      bumps: latestBumps,
-    },
-  };
-}
-
-function buildTypingPayload(socket, meta = {}) {
-  const roverId = meta.roverId || resolveRoverId(socket?.id);
-  const roverColor = meta.roverColor ?? resolveRoverColor(roverId);
-  const socketId = socket?.id || null;
-  const fromDiscord = Boolean(meta.fromDiscord);
-  let typingId = meta.typingId || null;
-  if (!typingId) {
-    if (fromDiscord) {
-      if (meta.discordUserId) {
-        typingId = `discord:${meta.discordUserId}`;
-      } else if (meta.discordUserName) {
-        typingId = `discord:${meta.discordUserName}`;
-      } else if (meta.nickname) {
-        typingId = `discord:${meta.nickname}`;
-      } else {
-        typingId = 'discord:unknown';
-      }
-    } else if (socketId) {
-      typingId = `socket:${socketId}`;
-    } else if (meta.nickname) {
-      typingId = `socket:${meta.nickname}`;
-    } else {
-      typingId = 'socket:unknown';
-    }
-  }
-  return {
-    id: uuidv4(),
-    ts: Date.now(),
-    typingId,
-    isTyping: Boolean(meta.isTyping),
-    socketId,
-    nickname: meta.nickname || getNickname(socket) || null,
-    role: meta.role || getRole(socket),
-    roverId,
-    roverColor,
-    fromDiscord,
-    discordGuildId: meta.discordGuildId || null,
-    discordGuildName: meta.discordGuildName || null,
-    discordGuildIconUrl: meta.discordGuildIconUrl || null,
-    discordChannelId: meta.discordChannelId || null,
-    discordUserId: meta.discordUserId || null,
-    discordUserName: meta.discordUserName || null,
-    discordUserAvatarUrl: meta.discordUserAvatarUrl || null,
-  };
-}
-
-function pushHistory(message) {
-  history.push(message);
-  if (history.length > MAX_HISTORY) {
-    history.shift();
-  }
-}
-
-function getRecentMessages(limit = 20, options = {}) {
-  const safeLimit = Number.isFinite(limit) ? Math.max(0, Math.floor(limit)) : 20;
-  const includeSystem = options?.includeSystem !== false;
-  const source = includeSystem ? history : history.filter((entry) => !entry?.system);
-  return source.slice(-safeLimit);
-}
-
-function broadcastMessage(message) {
-  pushHistory(message);
-  publishEvent({ source: 'chat', type: 'chat:message', payload: message });
-}
-
-function broadcastTyping(payload) {
-  publishEvent({ source: 'chat', type: 'chat:typing', payload });
-}
-
-function playTypingNote(roverId, note, socketId) {
-  if (!roverId) return;
-  try {
-    issueCommand(roverId, {
-      type: 'song',
-      song: {
-        notes: [{ note, duration: TYPING_NOTE_DURATION }],
-      },
-    });
-    const log = typeof logger.debug === 'function' ? logger.debug.bind(logger) : logger.info.bind(logger);
-    log('Typing tone sent', { roverId, note, socketId });
-  } catch (err) {
-    const log = typeof logger.debug === 'function' ? logger.debug.bind(logger) : logger.info.bind(logger);
-    log('Typing tone failed', { roverId, note, socketId, error: err.message });
-  }
-}
-
-function normalizeTtsOptions(raw = {}) {
-  if (!raw || typeof raw !== 'object') return null;
-  const speak = raw.speak !== false;
-  if (!speak) return null;
-  const engine = typeof raw.engine === 'string' && raw.engine.toLowerCase() === 'espeak' ? 'espeak' : 'flite';
-  const voice = typeof raw.voice === 'string' ? raw.voice.trim() : undefined;
-  let pitch = Number.isFinite(raw.pitch) ? Math.round(raw.pitch) : undefined;
-  if (typeof pitch === 'number') {
-    pitch = Math.max(0, Math.min(99, pitch));
-  }
-  return { speak, engine, voice, pitch };
-}
-
-function buildAccessNoticeText(mode, reasonText) {
-  const label = mode === MODES.LOCKDOWN ? 'lockdown' : 'admin';
-  const reason = reasonText ? ` Reason: ${reasonText}` : '';
-  return `Heads up: the server is in ${label} mode.${reason}`;
-}
-
-function shouldSendAccessNotice(message) {
-  if (!message?.text || message.system) return false;
-  const mode = getMode();
-  if (mode !== MODES.ADMIN && mode !== MODES.LOCKDOWN) return false;
-  if (!ACCESS_KEYWORD_RE.test(message.text)) return false;
-  const now = Date.now();
-  if (now - lastAccessNoticeAt < ACCESS_NOTICE_COOLDOWN_MS) return false;
-  lastAccessNoticeAt = now;
-  return true;
-}
+// Chat Service Orchestrator
+// Purpose: Composes chat submodules into the public service API and boots socket/event wiring.
+// Scope: Keeps external chat contracts stable while delegating logic to focused modules.
+const { history } = require('./state');
+const { normalizeUserText } = require('./contentFilters');
+const { buildMessage, buildTypingPayload } = require('./contextBuilders');
+const { broadcastMessage, getRecentMessages } = require('./broadcast');
+const { createHandlers } = require('./handlers');
+const { registerChatSocketHooks } = require('./socketHooks');
 
 function sendSystemMessage(text) {
   const normalized = normalizeUserText(text);
@@ -364,223 +23,9 @@ function sendSystemMessage(text) {
   return message;
 }
 
-function maybeSendAccessNotice(message) {
-  if (!shouldSendAccessNotice(message)) return;
-  const reason = getAdminReason()?.text || '';
-  const mode = getMode();
-  const notice = buildAccessNoticeText(mode, reason);
-  sendSystemMessage(notice);
-}
+const { handleIncoming, sendExternalMessage, sendExternalTyping } = createHandlers({ sendSystemMessage });
 
-function handleIncoming({ text, tts } = {}, socket, cb = () => {}) {
-  const role = getRole(socket);
-  // if (role === 'spectator') {
-  //   cb({ error: 'Spectators cannot chat' });
-  //   return;
-  // }
-  const normalized = normalizeUserText(text);
-  const clean = normalized.trim();
-  if (!clean) {
-    cb({ error: 'Message required' });
-    return;
-  }
-  if (!withinRateLimit(socket.id)) {
-    cb({ error: 'Slow down' });
-    return;
-  }
-  if (clean.length > 400) {
-    cb({ error: 'Message too long' });
-    return;
-  }
-  if (hasProfanity(clean)) {
-    cb({ error: 'Message blocked' });
-    return;
-  }
-  // if (isDuplicate(socket.id, clean)) {
-  //   cb({ error: 'Duplicate message' });
-  //   return;
-  // }
-  // if (isKeymash(clean)) {
-  //   cb({ error: 'Message looks like spam' });
-  //   return;
-  // }
-  const roverId = resolveRoverId(socket?.id);
-  const ttsOptions = normalizeTtsOptions(tts);
-  const message = buildMessage(socket, clean, {
-    fromDiscord: false,
-    roverId,
-    roverCtx: buildRoverCtxSnapshot(roverId),
-    tts: ttsOptions,
-  });
-  logger.info('Chat message', { socket: socket.id, roverId: message.roverId });
-  playTypingNote(roverId, TYPING_SEND_NOTE, socket?.id);
-  const privateClosed = isPrivateClosedRoverId(message.roverId);
-  if (privateClosed) {
-    const forcedTts = ttsOptions || { speak: true, engine: 'flite' };
-    maybeSpeak(socket, message, forcedTts);
-    cb({ success: true, privateOnly: true });
-    return;
-  }
-  broadcastMessage(message);
-  maybeSendAccessNotice(message);
-  maybeSpeak(socket, message, ttsOptions);
-  cb({ success: true });
-}
-
-function maybeSpeak(socket, message, ttsOptions) {
-  if (!ttsOptions || !message?.roverId) return;
-  const record = roverManager.rovers.get(message.roverId);
-  const audio = record?.meta?.audio || {};
-  const ttsEnabled = Boolean(audio.ttsEnabled);
-  if (!ttsEnabled) return;
-  const { isQueuedDriver } = require('../turnService');
-  if (
-    !roverManager.canDrive(message.roverId, socket) &&
-    !isQueuedDriver(message.roverId, socket?.id)
-  ) {
-    return;
-  }
-  try {
-    issueCommand(message.roverId, {
-      type: 'tts',
-      tts: {
-        text: message.text,
-        engine: ttsOptions.engine,
-        voice: ttsOptions.voice,
-        pitch: ttsOptions.pitch,
-        speak: true,
-      },
-    });
-    logger.info('TTS sent', { roverId: message.roverId, engine: ttsOptions.engine, socket: socket.id });
-  } catch (err) {
-    logger.warn('TTS send failed', { roverId: message.roverId, error: err.message });
-  }
-}
-
-function sendExternalMessage({
-  text,
-  nickname = 'Discord',
-  role = 'admin',
-  roverId = null,
-  discordGuildId = null,
-  discordGuildName = null,
-  discordGuildIconUrl = null,
-  discordChannelId = null,
-  discordUserId = null,
-  discordUserName = null,
-  discordUserAvatarUrl = null,
-}) {
-  const normalized = normalizeUserText(text);
-  const clean = normalized.trim();
-  if (!clean || clean.length > 400) {
-    throw new Error('Message invalid');
-  }
-  if (hasProfanity(clean)) {
-    throw new Error('Message blocked');
-  }
-  if (isKeymash(clean)) {
-    throw new Error('Message looks like spam');
-  }
-  if (isPrivateClosedRoverId(roverId)) {
-    throw new Error('Private rover chat is closed');
-  }
-  const message = buildMessage(null, clean, {
-    nickname,
-    role,
-    roverId,
-    roverCtx: buildRoverCtxSnapshot(roverId),
-    fromDiscord: true,
-    discordGuildId,
-    discordGuildName,
-    discordGuildIconUrl,
-    discordChannelId,
-    discordUserId,
-    discordUserName,
-    discordUserAvatarUrl,
-  });
-  logger.info('External chat message', { roverId, nickname });
-  broadcastMessage(message);
-  maybeSendAccessNotice(message);
-  return message;
-}
-
-function sendExternalTyping({
-  nickname = 'Discord',
-  role = 'user',
-  roverId = null,
-  discordGuildId = null,
-  discordGuildName = null,
-  discordGuildIconUrl = null,
-  discordChannelId = null,
-  discordUserId = null,
-  discordUserName = null,
-  discordUserAvatarUrl = null,
-  isTyping = true,
-}) {
-  if (isPrivateClosedRoverId(roverId)) {
-    return null;
-  }
-  const payload = buildTypingPayload(null, {
-    nickname,
-    role,
-    roverId,
-    fromDiscord: true,
-    discordGuildId,
-    discordGuildName,
-    discordGuildIconUrl,
-    discordChannelId,
-    discordUserId,
-    discordUserName,
-    discordUserAvatarUrl,
-    isTyping,
-  });
-  broadcastTyping(payload);
-  return payload;
-}
-
-io.on('connection', (socket) => {
-  socket.emit('chat:init', history);
-  socket.on('chat:send', (payload = {}, cb = () => {}) => handleIncoming(payload, socket, cb));
-  socket.on('chat:typing', (payload = {}) => {
-    const isTyping = Boolean(payload?.isTyping);
-    const wasTyping = typingBySocket.get(socket.id);
-    if (isTyping) {
-      typingBySocket.set(socket.id, true);
-      if (!wasTyping) {
-        const roverId = resolveRoverId(socket?.id);
-        playTypingNote(roverId, TYPING_START_NOTE, socket?.id);
-      }
-    } else {
-      typingBySocket.delete(socket.id);
-    }
-    const roverId = resolveRoverId(socket?.id);
-    if (isPrivateClosedRoverId(roverId)) {
-      return;
-    }
-    const typingPayload = buildTypingPayload(socket, { roverId, fromDiscord: false, isTyping });
-    broadcastTyping(typingPayload);
-  });
-  socket.on('disconnect', () => {
-    if (!typingBySocket.has(socket.id)) return;
-    typingBySocket.delete(socket.id);
-    const roverId = resolveRoverId(socket?.id);
-    if (isPrivateClosedRoverId(roverId)) {
-      return;
-    }
-    const typingPayload = buildTypingPayload(socket, { roverId, fromDiscord: false, isTyping: false });
-    broadcastTyping(typingPayload);
-  });
-});
-
-subscribe('chat:message', ({ payload }) => {
-  if (!payload) return;
-  io.emit('chat:message', payload);
-});
-
-subscribe('chat:typing', ({ payload }) => {
-  if (!payload) return;
-  io.emit('chat:typing', payload);
-});
+registerChatSocketHooks({ history, handleIncoming });
 
 module.exports = {
   handleIncoming,
diff --git a/server/src/services/chatService/notifications.js b/server/src/services/chatService/notifications.js
new file mode 100644
index 00000000..4fdbeb9d
--- /dev/null
+++ b/server/src/services/chatService/notifications.js
@@ -0,0 +1,100 @@
+// Chat Rover Notifications
+// Purpose: Sends rover typing tones, optional rover TTS, and access-mode system notices.
+// Scope: Owns rover-side notification effects derived from chat activity.
+const logger = require('../../globals/logger').child('chatService');
+const { getMode, MODES } = require('../modeManager');
+const { getRole } = require('../roleService');
+const roverManager = require('../roverManager');
+const { issueCommand } = require('../commandService');
+const { getAdminReason } = require('../adminReasonService');
+const {
+  TYPING_NOTE_DURATION,
+  ACCESS_NOTICE_COOLDOWN_MS,
+  ACCESS_KEYWORD_RE,
+  TYPING_START_NOTE,
+  TYPING_SEND_NOTE,
+} = require('./constants');
+const { getLastAccessNoticeAt, setLastAccessNoticeAt } = require('./state');
+
+function playTypingNote(roverId, note, socketId) {
+  if (!roverId) return;
+  try {
+    issueCommand(roverId, {
+      type: 'song',
+      song: { notes: [{ note, duration: TYPING_NOTE_DURATION }] },
+    });
+    const log = typeof logger.debug === 'function' ? logger.debug.bind(logger) : logger.info.bind(logger);
+    log('Typing tone sent', { roverId, note, socketId });
+  } catch (err) {
+    const log = typeof logger.debug === 'function' ? logger.debug.bind(logger) : logger.info.bind(logger);
+    log('Typing tone failed', { roverId, note, socketId, error: err.message });
+  }
+}
+
+function normalizeTtsOptions(raw = {}) {
+  if (!raw || typeof raw !== 'object') return null;
+  const speak = raw.speak !== false;
+  if (!speak) return null;
+  const engine = typeof raw.engine === 'string' && raw.engine.toLowerCase() === 'espeak' ? 'espeak' : 'flite';
+  const voice = typeof raw.voice === 'string' ? raw.voice.trim() : undefined;
+  let pitch = Number.isFinite(raw.pitch) ? Math.round(raw.pitch) : undefined;
+  if (typeof pitch === 'number') pitch = Math.max(0, Math.min(99, pitch));
+  return { speak, engine, voice, pitch };
+}
+
+function buildAccessNoticeText(mode, reasonText) {
+  const label = mode === MODES.LOCKDOWN ? 'lockdown' : 'admin';
+  const reason = reasonText ? ` Reason: ${reasonText}` : '';
+  return `Heads up: the server is in ${label} mode.${reason}`;
+}
+
+function shouldSendAccessNotice(message) {
+  if (!message?.text || message.system) return false;
+  const mode = getMode();
+  if (mode !== MODES.ADMIN && mode !== MODES.LOCKDOWN) return false;
+  if (!ACCESS_KEYWORD_RE.test(message.text)) return false;
+  const now = Date.now();
+  if (now - getLastAccessNoticeAt() < ACCESS_NOTICE_COOLDOWN_MS) return false;
+  setLastAccessNoticeAt(now);
+  return true;
+}
+
+function maybeSendAccessNotice(message, sendSystemMessage) {
+  if (!shouldSendAccessNotice(message)) return;
+  const reason = getAdminReason()?.text || '';
+  const notice = buildAccessNoticeText(getMode(), reason);
+  sendSystemMessage(notice);
+}
+
+function maybeSpeak(socket, message, ttsOptions) {
+  if (!ttsOptions || !message?.roverId) return;
+  const record = roverManager.rovers.get(message.roverId);
+  const ttsEnabled = Boolean(record?.meta?.audio?.ttsEnabled);
+  if (!ttsEnabled) return;
+  const { isQueuedDriver } = require('../turnService');
+  if (!roverManager.canDrive(message.roverId, socket) && !isQueuedDriver(message.roverId, socket?.id)) return;
+  try {
+    issueCommand(message.roverId, {
+      type: 'tts',
+      tts: {
+        text: message.text,
+        engine: ttsOptions.engine,
+        voice: ttsOptions.voice,
+        pitch: ttsOptions.pitch,
+        speak: true,
+      },
+    });
+    logger.info('TTS sent', { roverId: message.roverId, engine: ttsOptions.engine, socket: socket.id });
+  } catch (err) {
+    logger.warn('TTS send failed', { roverId: message.roverId, error: err.message });
+  }
+}
+
+module.exports = {
+  playTypingNote,
+  normalizeTtsOptions,
+  maybeSendAccessNotice,
+  maybeSpeak,
+  TYPING_START_NOTE,
+  TYPING_SEND_NOTE,
+};
diff --git a/server/src/services/chatService/socketHooks.js b/server/src/services/chatService/socketHooks.js
new file mode 100644
index 00000000..fb6ef803
--- /dev/null
+++ b/server/src/services/chatService/socketHooks.js
@@ -0,0 +1,53 @@
+// Chat Socket Hooks
+// Purpose: Registers chat socket handlers and event-bus fan-out listeners.
+// Scope: Bridges socket events to chat handlers and publishes chat updates to connected clients.
+const io = require('../../globals/io');
+const { subscribe } = require('../eventBus');
+const { typingBySocket } = require('./state');
+const { buildTypingPayload, resolveRoverId, isPrivateClosedRoverId } = require('./contextBuilders');
+const { broadcastTyping } = require('./broadcast');
+const { playTypingNote, TYPING_START_NOTE } = require('./notifications');
+
+function registerChatSocketHooks({ history, handleIncoming }) {
+  io.on('connection', (socket) => {
+    socket.emit('chat:init', history);
+    socket.on('chat:send', (payload = {}, cb = () => {}) => handleIncoming(payload, socket, cb));
+    socket.on('chat:typing', (payload = {}) => {
+      const isTyping = Boolean(payload?.isTyping);
+      const wasTyping = typingBySocket.get(socket.id);
+      if (isTyping) {
+        typingBySocket.set(socket.id, true);
+        if (!wasTyping) {
+          const roverId = resolveRoverId(socket?.id);
+          playTypingNote(roverId, TYPING_START_NOTE, socket?.id);
+        }
+      } else {
+        typingBySocket.delete(socket.id);
+      }
+      const roverId = resolveRoverId(socket?.id);
+      if (isPrivateClosedRoverId(roverId)) return;
+      broadcastTyping(buildTypingPayload(socket, { roverId, fromDiscord: false, isTyping }));
+    });
+    socket.on('disconnect', () => {
+      if (!typingBySocket.has(socket.id)) return;
+      typingBySocket.delete(socket.id);
+      const roverId = resolveRoverId(socket?.id);
+      if (isPrivateClosedRoverId(roverId)) return;
+      broadcastTyping(buildTypingPayload(socket, { roverId, fromDiscord: false, isTyping: false }));
+    });
+  });
+
+  subscribe('chat:message', ({ payload }) => {
+    if (!payload) return;
+    io.emit('chat:message', payload);
+  });
+
+  subscribe('chat:typing', ({ payload }) => {
+    if (!payload) return;
+    io.emit('chat:typing', payload);
+  });
+}
+
+module.exports = {
+  registerChatSocketHooks,
+};
diff --git a/server/src/services/chatService/state.js b/server/src/services/chatService/state.js
new file mode 100644
index 00000000..0bcfb6bf
--- /dev/null
+++ b/server/src/services/chatService/state.js
@@ -0,0 +1,53 @@
+// Chat Service State
+// Purpose: Stores mutable chat runtime state for rate limits, history, and typing bookkeeping.
+// Scope: Encapsulates in-memory collections shared by chat service modules.
+const { RATE_LIMIT_WINDOW_MS, RATE_LIMIT_MAX, MAX_HISTORY } = require('./constants');
+
+const rateBuckets = new Map();
+const history = [];
+const lastMessageBySocket = new Map();
+const typingBySocket = new Map();
+let lastAccessNoticeAt = 0;
+
+function withinRateLimit(socketId) {
+  const now = Date.now();
+  const entries = rateBuckets.get(socketId) || [];
+  const next = entries.filter((ts) => now - ts <= RATE_LIMIT_WINDOW_MS);
+  next.push(now);
+  rateBuckets.set(socketId, next);
+  return next.length <= RATE_LIMIT_MAX;
+}
+
+function pushHistory(message) {
+  history.push(message);
+  if (history.length > MAX_HISTORY) {
+    history.shift();
+  }
+}
+
+function getRecentMessages(limit = 20, options = {}) {
+  const safeLimit = Number.isFinite(limit) ? Math.max(0, Math.floor(limit)) : 20;
+  const includeSystem = options?.includeSystem !== false;
+  const source = includeSystem ? history : history.filter((entry) => !entry?.system);
+  return source.slice(-safeLimit);
+}
+
+function getLastAccessNoticeAt() {
+  return lastAccessNoticeAt;
+}
+
+function setLastAccessNoticeAt(ts) {
+  lastAccessNoticeAt = ts;
+}
+
+module.exports = {
+  rateBuckets,
+  history,
+  lastMessageBySocket,
+  typingBySocket,
+  withinRateLimit,
+  pushHistory,
+  getRecentMessages,
+  getLastAccessNoticeAt,
+  setLastAccessNoticeAt,
+};