chat: rename sessions in Claude's store + delete confirm

Rename appends a {"type":"summary",...} entry to the session's JSONL transcript
(Claude's own format, so the title lives in .claude); the reader takes the last
summary as the title, without a timestamp so it doesn't reorder the list.
PATCH /chat/sessions/:id/title backs it. The list gets inline rename (pencil ->
edit in place) and a two-step delete confirm so a stray click can't nuke a
transcript. Rename verified against a synthetic store.

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

src/servers/api/chat/chat.ts

@@ -1,5 +1,5 @@
 import { createRouter } from '../../create-router';
-import { getClaudeSessionsCwd, listClaudeSessions, loadClaudeSession, deleteClaudeSession } from './claude-sessions';
+import { getClaudeSessionsCwd, listClaudeSessions, loadClaudeSession, deleteClaudeSession, renameClaudeSession } from './claude-sessions';
 
 export const chatRouter = createRouter();
 
@@ -26,3 +26,13 @@ chatRouter.delete('/sessions/:id', (ctx) => {
   if (!ok) return ctx.text('Not found', 404);
   return ctx.json({ ok: true });
 });
+
+// PATCH /chat/sessions/:id/title — rename by writing a summary entry into Claude's transcript.
+chatRouter.patch('/sessions/:id/title', async (ctx) => {
+  const email = ctx.get('user').email;
+  const { title } = await ctx.req.json<{ title?: string }>();
+  if (!title?.trim()) return ctx.text('title is required', 400);
+  const ok = renameClaudeSession(email, getClaudeSessionsCwd(email), ctx.req.param('id'), title.trim());
+  if (!ok) return ctx.text('Not found', 404);
+  return ctx.json({ ok: true });
+});

src/servers/api/chat/claude-sessions.ts

@@ -1,4 +1,4 @@
-import { readdirSync, readFileSync, existsSync, statSync, mkdirSync, rmSync } from 'node:fs';
+import { readdirSync, readFileSync, existsSync, statSync, mkdirSync, rmSync, appendFileSync } from 'node:fs';
 import { join } from 'node:path';
 import { DATA_PATH } from '../../data-path';
 
@@ -52,6 +52,8 @@ type Entry = {
   timestamp?: string;
   sessionId?: string;
   cwd?: string;
+  uuid?: string;
+  summary?: string;
   message?: { role?: string; content?: unknown };
   isMeta?: boolean;
 };
@@ -64,7 +66,8 @@ function summarizeTranscript(filePath: string, id: string): ClaudeSessionSummary
     return null;
   }
 
-  let title = '';
+  let firstUserText = '';
+  let summaryTitle = ''; // a `summary` entry (our rename, appended to the transcript) wins over the first message
   let cwd = '';
   let firstTs = '';
   let lastTs = '';
@@ -83,10 +86,12 @@ function summarizeTranscript(filePath: string, id: string): ClaudeSessionSummary
       if (!firstTs) firstTs = entry.timestamp;
       lastTs = entry.timestamp;
     }
-    if (entry.type === 'user' || entry.type === 'assistant') {
+    if (entry.type === 'summary' && typeof entry.summary === 'string') {
+      summaryTitle = entry.summary; // last one wins
+    } else if (entry.type === 'user' || entry.type === 'assistant') {
       messageCount += 1;
-      if (!title && entry.type === 'user' && !entry.isMeta) {
-        title = entryText(entry.message).split('\n')[0]!.trim();
+      if (!firstUserText && entry.type === 'user' && !entry.isMeta) {
+        firstUserText = entryText(entry.message).split('\n')[0]!.trim();
       }
     }
   }
@@ -94,7 +99,7 @@ function summarizeTranscript(filePath: string, id: string): ClaudeSessionSummary
   const mtime = statSync(filePath).mtime.toISOString();
   return {
     id,
-    title: title || '(untitled)',
+    title: summaryTitle || firstUserText || '(untitled)',
     cwd,
     createdAt: firstTs || mtime,
     updatedAt: lastTs || mtime,
@@ -195,6 +200,35 @@ export function deleteClaudeSession(email: string, cwd: string, sessionId: strin
   return true;
 }
 
+/**
+ * Rename a session by appending a `summary` entry to its transcript — Claude's own on-disk format, so
+ * the title lives in .claude (source of truth). Our reader takes the last summary as the title; no
+ * timestamp is written so the rename doesn't reorder the list.
+ */
+export function renameClaudeSession(email: string, cwd: string, sessionId: string, title: string): boolean {
+  const filePath = join(claudeProjectsDir(email), projectSlug(cwd), `${sessionId}.jsonl`);
+  if (!existsSync(filePath)) return false;
+
+  // Attach the summary to the transcript's tip (the last entry carrying a uuid).
+  let leafUuid = sessionId;
+  const lines = readFileSync(filePath, 'utf-8').split('\n');
+  for (let i = lines.length - 1; i >= 0; i--) {
+    if (!lines[i]!.trim()) continue;
+    try {
+      const entry = JSON.parse(lines[i]!) as Entry;
+      if (entry.uuid) {
+        leafUuid = entry.uuid;
+        break;
+      }
+    } catch {
+      /* skip */
+    }
+  }
+
+  appendFileSync(filePath, `${JSON.stringify({ type: 'summary', summary: title, leafUuid })}\n`);
+  return true;
+}
+
 /** List sessions Claude has stored for a given working directory, newest first. */
 export function listClaudeSessions(email: string, cwd: string): ClaudeSessionSummary[] {
   const dir = join(claudeProjectsDir(email), projectSlug(cwd));