chat: rename the pi chat transport + model list to chat (Stage 4b/1)

Pure rename, no behavior change. Moves the misnamed "pi" chat harness into the
chat namespace:

- api/pi/{websocket,session-manager,types,logger,list-models} → api/chat/
- merge api/pi/rest.ts into api/chat/chat.ts (/pi/models → /chat/models,
  /pi/stt → /chat/stt); drop the piRestRouter mount
- PiEvent → ChatEvent, piWebsocket → chatWebsocket, listPiModels → listChatModels
- WS route /api/pi/chat/ws → /api/chat/ws, provider tag 'pi' → 'chat'
- frontend: useChat/useAudioRecording URLs, usePiModels→useModels /
  useVisiblePiModels→useVisibleModels / useEnabledPiModels→useEnabledModels,
  'PI_MODELS' query key → 'CHAT_MODELS', attachments provider 'pi-mono' → 'chat'

The /pi-mono provider/harness settings router is renamed separately (next commit).
Note: the WS route change requires the mobile app to point at /api/chat/ws.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/servers/api/chat-types.ts

@@ -1,8 +1,8 @@
 /**
- * @deprecated Legacy chat types - Use types from ./pi/types.ts instead
+ * @deprecated Legacy chat types - Use types from ./chat/types.ts instead
  * 
  * This file is kept for backward compatibility with existing code.
- * New code should import from ./pi/types.ts
+ * New code should import from ./chat/types.ts
  */
 
 // Re-export new Pi types for compatibility
@@ -13,8 +13,8 @@ export type {
   MessageCost,
   SessionMeta,
   ModelInfo,
-  PiEvent,
-} from './pi/types';
+  ChatEvent,
+} from './chat/types';
 
 // Legacy types (kept for compatibility)
 export type ImageData = { mediaType: string; data: string };

src/servers/api/chat/chat.ts

@@ -1,5 +1,6 @@
 import type { Context } from 'hono';
 import { createRouter } from '../../create-router';
+import { getUserSettings } from 'officerdb';
 import {
   getClaudeSessionsCwd,
   listClaudePwds,
@@ -8,6 +9,10 @@ import {
   deleteClaudeSession,
   renameClaudeSession,
 } from './claude-sessions';
+import { listChatModels } from './list-models';
+import { logger } from './logger';
+import { readSttConfig } from '../server-settings/stt';
+import { transcribeAudio } from '../stt/transcribe';
 
 export const chatRouter = createRouter();
 
@@ -52,3 +57,41 @@ chatRouter.patch('/sessions/:id/title', async (ctx) => {
   if (!ok) return ctx.text('Not found', 404);
   return ctx.json({ ok: true });
 });
+
+// GET /chat/models — Claude tiers only (the runner is the `claude` CLI).
+chatRouter.get('/models', async (ctx: Context) => {
+  try {
+    const models = await listChatModels();
+    const providerNames: Record<string, string> = { 'claude-code': 'Claude Code' };
+    return ctx.json({ models, providerNames, hostHome: process.env.HOME ?? '' });
+  } catch (err) {
+    logger.error('Failed to list models', { error: String(err) });
+    return ctx.json({ models: [], providerNames: {} });
+  }
+});
+
+// POST /chat/stt — proxy an audio clip to the configured Whisper server.
+chatRouter.post('/stt', async (ctx: Context) => {
+  const sttConfig = await readSttConfig();
+  if (!sttConfig?.url) {
+    return ctx.json({ error: 'Whisper not configured — set it up in Settings → Speech to Text' }, 400);
+  }
+
+  const user = ctx.get('user');
+  const body = await ctx.req.parseBody();
+  const file = body['file'];
+  if (!file || !(file instanceof File)) {
+    return ctx.json({ error: 'file is required' }, 400);
+  }
+
+  const settings = (await getUserSettings(user.id)) as { languages?: { spoken?: string[] } };
+  const spokenLanguages = settings.languages?.spoken ?? [];
+
+  try {
+    const result = await transcribeAudio({ file, whisperUrl: sttConfig.url, spokenLanguages });
+    return ctx.json(result);
+  } catch (err) {
+    logger.error('STT proxy failed', { error: String(err) });
+    return ctx.json({ error: err instanceof Error ? err.message : 'Failed to reach Whisper server' }, 502);
+  }
+});

src/servers/api/chat/list-models.ts

@@ -11,6 +11,6 @@ export function invalidateModelCache(): void {
   // No-op: the Claude model list is static. Kept for call-site compatibility.
 }
 
-export async function listPiModels(): Promise<ModelInfo[]> {
+export async function listChatModels(): Promise<ModelInfo[]> {
   return [...CLAUDE_CODE_MODELS];
 }

src/servers/api/chat/types.ts

@@ -120,7 +120,7 @@ export type ServerMessage =
       type: 'stopped';
     };
 
-export type PiEvent =
+export type ChatEvent =
   | { type: 'text'; text: string }
   | { type: 'delta'; text: string }
   | {

src/servers/api/chat/websocket.ts

@@ -1,9 +1,9 @@
 import type { ServerWebSocket } from 'bun';
 import { randomUUID } from 'crypto';
-import type { ClientMessage, ServerMessage, Message, PiEvent } from './types';
+import type { ClientMessage, ServerMessage, Message, ChatEvent } from './types';
 import { sessionManager } from './session-manager';
 import { sendClaudeCodeStreaming } from '@@/channels/send-claude-code';
-import { ensureClaudeSessionsCwd } from '../chat/claude-sessions';
+import { ensureClaudeSessionsCwd } from './claude-sessions';
 import * as sidecar from '@@/sidecar-registry';
 import { join } from 'path';
 import { getHomeDirForRole } from '../../../servers/data-path';
@@ -113,7 +113,7 @@ export function close(ws: ServerWebSocket<WSData>): void {
 }
 
 function createEventHandler(sessionId: string, model: string, cwd: string) {
-  return async (event: PiEvent): Promise<void> => {
+  return async (event: ChatEvent): Promise<void> => {
     const session = sessionManager.getSession(sessionId);
     if (!session) return;
 
@@ -441,7 +441,7 @@ async function handleStop(ws: ServerWebSocket<WSData>): Promise<void> {
   sendToClient(ws, { type: 'stopped' });
 }
 
-export const piWebsocket = {
+export const chatWebsocket = {
   open,
   message,
   close,

src/servers/api/pi/rest.ts

@@ -1,51 +0,0 @@
-import type { Context } from 'hono';
-import { createRouter } from '../../create-router';
-import { readSttConfig } from '../server-settings/stt';
-import { listPiModels } from './list-models';
-import { logger } from './logger';
-import { transcribeAudio } from '../stt/transcribe';
-import { getUserSettings } from 'officerdb';
-
-export const piRestRouter = createRouter();
-
-/**
- * GET /api/pi/models — Claude tiers only.
- */
-piRestRouter.get('/pi/models', async (ctx: Context) => {
-  try {
-    const models = await listPiModels();
-    const providerNames: Record<string, string> = { 'claude-code': 'Claude Code' };
-    return ctx.json({ models, providerNames, hostHome: process.env.HOME ?? '' });
-  } catch (err) {
-    logger.error('Failed to list models', { error: String(err) });
-    return ctx.json({ models: [], providerNames: {} });
-  }
-});
-
-/**
- * POST /api/pi/stt
- */
-piRestRouter.post('/pi/stt', async (ctx: Context) => {
-  const sttConfig = await readSttConfig();
-  if (!sttConfig?.url) {
-    return ctx.json({ error: 'Whisper not configured — set it up in Settings → Speech to Text' }, 400);
-  }
-
-  const user = ctx.get('user');
-  const body = await ctx.req.parseBody();
-  const file = body['file'];
-  if (!file || !(file instanceof File)) {
-    return ctx.json({ error: 'file is required' }, 400);
-  }
-
-  const settings = (await getUserSettings(user.id)) as { languages?: { spoken?: string[] } };
-  const spokenLanguages = settings.languages?.spoken ?? [];
-
-  try {
-    const result = await transcribeAudio({ file, whisperUrl: sttConfig.url, spokenLanguages });
-    return ctx.json(result);
-  } catch (err) {
-    logger.error('STT proxy failed', { error: String(err) });
-    return ctx.json({ error: err instanceof Error ? err.message : 'Failed to reach Whisper server' }, 502);
-  }
-});

src/servers/api/server-settings/pi-mono.ts

@@ -1,8 +1,8 @@
 import { join } from 'node:path';
 import { createRouter } from '../../create-router';
 import { PI_CONFIG_DIR } from '../../data-path';
-import { invalidateModelCache } from '../pi/list-models';
-import { logger } from '../pi/logger';
+import { invalidateModelCache } from '../chat/list-models';
+import { logger } from '../chat/logger';
 import { readConfigValue, writeConfigValue } from 'officerdb';
 
 export const piMonoRouter = createRouter();

src/servers/api/tasks/pipeline-executor.ts

@@ -6,10 +6,10 @@ import { tmpdir } from 'node:os';
 import { getUserSettings } from 'officerdb';
 import { getTaskByDirName } from './task-files';
 import { getHomeDirForRole, getHomeDir } from '../../data-path';
-import { resolveBaseCwd } from '../pi/websocket';
+import { resolveBaseCwd } from '../chat/websocket';
 import { SANDBOX_HOME } from '../../sidecar/sandbox';
 import { sendClaudeCodeStreaming } from '../../channels/send-claude-code';
-import type { PiEvent, MessageCost } from '../pi/types';
+import type { ChatEvent, MessageCost } from '../chat/types';
 import * as jobManager from './pipeline-job-manager';
 
 const DEFAULT_MODEL = 'claude-code';
@@ -117,7 +117,7 @@ async function runAgenticStep({ userId, email, username, role, taskDirName, prom
       fn();
     };
 
-    const onEvent = (event: PiEvent) => {
+    const onEvent = (event: ChatEvent) => {
       if (abortSignal.aborted) return;
       lastActivity = Date.now();