v1.1 batch 1: markdown, message actions, tok/s+ctx, AI naming

Four features land together on this branch:

1. Markdown rendering — assistant messages go through react-markdown +
   remark-gfm. Fenced code blocks render via existing CodeBlock (with copy
   button); inline `code` is styled inline. User messages stay plain text.
   No raw HTML (no rehype-raw).

2. Per-message Copy + Regenerate. New endpoint
   POST /api/sessions/:id/messages/:message_id/regenerate validates the
   target (404/400/409), atomically deletes the target plus any later
   messages in the session, inserts a fresh streaming assistant row, and
   enqueues a normal inference run. The DELETE bound uses a SQL subquery
   (`created_at >= (SELECT created_at FROM messages WHERE id = $1)`)
   instead of a JS round-trip so postgres TIMESTAMPTZ µs precision is
   preserved — otherwise sub-ms clock_timestamp() differences between the
   user row and the assistant row collapsed to the same JS Date, pulling
   the triggering user message into the >= bound. New `messages_deleted`
   WS frame so already-connected clients prune the stale tail without
   needing a full snapshot resend.

3. tok/s + ctx counter. Five new nullable message columns: tokens_used,
   ctx_used, ctx_max, started_at, finished_at. started_at is set right
   before the OpenAI call in services/inference.ts (not in the route, not
   in the frame handler); finished_at + tokens_used + ctx_used + ctx_max
   are committed in the same UPDATE that flips status to 'complete'. The
   inference request now opts into stream_options.include_usage so the
   final chunk carries usage; defensive parsing also picks up timings.n_ctx
   when llama.cpp emits it (currently absent for our llama-swap models, so
   ctx_max stays NULL and the UI just shows `<used> ctx`). message_complete
   frame extended with tokens_used / ctx_used / ctx_max / started_at /
   finished_at / model. Frontend StatsLine in MessageBubble computes tok/s
   client-side from the timestamps and renders muted mono text below the
   body of completed assistant messages.

4. AI chat naming after the first turn. Backend services/auto_name.ts
   runs via setImmediate after the top-level inference resolves; it
   checks that there is exactly one completed assistant message and that
   the session has not been user-renamed (`name IS NULL OR name = '' OR
   name = 'New session'`), then fires a single non-streaming chat
   completion with the spec prompt. Qwen3 chat templates emit chain-of-
   thought into reasoning_content and burn the entire max_tokens budget
   without producing visible output, so the request includes
   `chat_template_kwargs: { enable_thinking: false }` and max_tokens=30.
   Title is trimmed, quote-stripped, "Title:" prefix dropped, and
   truncated to 60 chars before a guarded UPDATE on sessions.name. New
   `session_renamed` WS frame propagates to the open session view
   directly and to the project's session list via a tiny module-scope
   event bus (apps/web/src/hooks/sessionEvents.ts) — kept dumb: one event
   type, two methods, no library.

Cleanups: dropped the now-unused splitCodeBlocks export from CodeBlock.tsx
(react-markdown supersedes it), and added a long-form NOTE in auto_name.ts
documenting the enable_thinking + max_tokens pattern for any future Qwen-
family non-streaming utility calls (planned: fork-message, agent-routing,
web-search summarization).

Schema bootstrap remains idempotent (ADD COLUMN IF NOT EXISTS). Auth,
broker, clock_timestamp() conventions, and zod validation all unchanged.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/src/pages/Session.tsx

@@ -5,6 +5,7 @@ import { toast } from 'sonner';
 import { api } from '@/api/client';
 import type { Session as SessionType } from '@/api/types';
 import { useSessionStream } from '@/hooks/useSessionStream';
+import { sessionEvents } from '@/hooks/sessionEvents';
 import { MessageList } from '@/components/MessageList';
 import { ChatInput } from '@/components/ChatInput';
 import { ModelPicker } from '@/components/ModelPicker';
@@ -39,6 +40,16 @@ export function Session() {
       .catch(() => {});
   }, [id]);
 
+  useEffect(() => {
+    if (!id) return;
+    return sessionEvents.subscribe((event) => {
+      if (event.type !== 'session_renamed') return;
+      if (event.session_id !== id) return;
+      setSession((prev) => (prev ? { ...prev, name: event.name } : prev));
+      setName((prev) => (editingName ? prev : event.name));
+    });
+  }, [id, editingName]);
+
   async function saveName() {
     if (!id || !session) return;
     const trimmed = name.trim();
@@ -111,7 +122,7 @@ export function Session() {
         )}
       </header>
 
-      <MessageList messages={stream.messages} />
+      {id && <MessageList messages={stream.messages} sessionId={id} />}
 
       <ChatInput disabled={streaming} onSend={handleSend} />
     </div>