fix(ai): sync chat panel header title with conversation rename

apps/desktop/src/components/editor/AiAssistant.vue

@@ -1398,6 +1398,15 @@ function messagesForAgentHistory(historyMessages: ChatMessage[]): AiMessage[] {
 }
 
 const chatTitle = computed(() => {
+  // Same precedence as buildConversationSnapshot(): the user's rename wins,
+  // then the stored title, so renaming a conversation from the history list
+  // updates this header immediately instead of leaving the first-message
+  // excerpt stuck (issue #9904). Saved chats follow the stored title exactly
+  // like the history row (even if the first message is edited later); only
+  // unsaved/new chats derive from messages.
+  const activeConversation = conversations.value.find((conversation) => conversation.id === conversationId.value);
+  const conversationTitle = renamedConversationTitles.get(conversationId.value) || activeConversation?.title;
+  if (conversationTitle) return conversationTitle;
   const first = messages.value.find((m) => m.role === "user" && m.kind !== "contextSummary");
   return pluginContext.value?.title || (first ? messageTitle(first).slice(0, 30) : t("ai.newChat"));
 });
@@ -4302,7 +4311,10 @@ async function persistPendingInputRecovery(conversation: AiConversation, message
   const first = messages.find((m) => m.role === "user" && m.kind !== "contextSummary");
   const snapshot: AiConversation = {
     id: conversation.id,
-    title: conversation.pluginContext?.title || (first ? messageTitle(first).slice(0, 50) : conversation.title || "Untitled"),
+    // Same title precedence as buildConversationSnapshot(): a recovered run
+    // must not overwrite a title the user renamed; plugin-scoped chats keep
+    // the plugin-provided title.
+    title: conversation.pluginContext?.title || renamedConversationTitles.get(conversation.id) || conversation.title || (first ? messageTitle(first).slice(0, 50) : "Untitled"),
     pluginContext: conversation.pluginContext,
     connectionName: conversation.connectionName,
     database: conversation.database,
@@ -4367,6 +4379,9 @@ async function commitRenameConversation(conv: AiConversation) {
     const i = conversations.value.findIndex((item) => item.id === conv.id);
     if (i >= 0) conversations.value[i] = updated;
   } catch {
+    // Save failed: retract the claim so the header, the history row and the
+    // persisted record all stay on the old title until a rename succeeds.
+    renamedConversationTitles.delete(conv.id);
     toast(t("ai.conversationRenameFailed"), 5000);
   } finally {
     cancelRenameConversation();

apps/desktop/src/components/editor/__tests__/AiAssistant.chatTitle.spec.ts

@@ -0,0 +1,75 @@
+import { readFileSync } from "node:fs";
+import { describe, expect, it } from "vitest";
+
+// Regression coverage for https://github.com/t8y2/dbx/issues/9904:
+//
+// Renaming the current conversation from the history list updates
+// `conversations` and the `renamedConversationTitles` claim map, but the
+// panel header rendered `chatTitle` purely from the first user message of
+// the panel-local `messages` snapshot, so the top-left title stayed stale
+// (reopening the conversation didn't pick the stored title up either).
+// AiAssistant.vue is a ~6000-line SFC the suite never mounts, so these
+// assertions pin the template/computed wiring as text, matching the house
+// source-assertion style.
+const source = readFileSync(new URL("../AiAssistant.vue", import.meta.url), "utf8");
+
+function bodyOf(fnSignature: string): string {
+  const start = source.indexOf(fnSignature);
+  expect(start, `expected to find "${fnSignature}" in AiAssistant.vue`).toBeGreaterThanOrEqual(0);
+  const braceStart = source.indexOf("{", start);
+  let depth = 0;
+  for (let i = braceStart; i < source.length; i++) {
+    if (source[i] === "{") depth++;
+    else if (source[i] === "}") {
+      depth--;
+      if (depth === 0) return source.slice(braceStart, i + 1);
+    }
+  }
+  throw new Error(`unbalanced braces reading body of "${fnSignature}"`);
+}
+
+describe("AI assistant header title tracks the conversation title", () => {
+  it("chatTitle prefers the renamed/stored title of the open conversation over the first-message excerpt", () => {
+    // The claim map must stay reactive — it is the header's invalidation link
+    // to a rename that commits while the save is still in flight.
+    expect(source).toContain("const renamedConversationTitles = reactive(new Map<string, string>());");
+    const body = bodyOf("const chatTitle = computed");
+    // Both the rename-claim map and the conversation list must be reactive
+    // dependencies so a commitRenameConversation() write re-renders the header.
+    expect(body).toContain("renamedConversationTitles.get(conversationId.value)");
+    expect(body).toContain("conversations.value.find(");
+    expect(body).toContain("conversation.id === conversationId.value");
+    expect(body).toContain("messages.value.find");
+    // Same precedence as buildConversationSnapshot(): the rename claim wins,
+    // the stored title comes next, and the first-message excerpt is only the
+    // fallback for unsaved/new chats. (The toContain guards above keep these
+    // index orderings from passing vacuously at -1.)
+    expect(body.indexOf("renamedConversationTitles.get(conversationId.value)")).toBeLessThan(body.indexOf("activeConversation?.title"));
+    expect(body.indexOf("renamedConversationTitles.get(conversationId.value)")).toBeLessThan(body.indexOf("messages.value.find"));
+    expect(body).toContain("messageTitle(first).slice(0, 30)");
+    expect(body).toContain('t("ai.newChat")');
+  });
+
+  it("the header renders chatTitle and rename commits feed the sources chatTitle reads", () => {
+    expect(source).toContain("{{ chatTitle }}");
+    const commit = bodyOf("async function commitRenameConversation(conv: AiConversation)");
+    // The claim must be set before the async save (title race guard) and the
+    // list entry replaced afterwards — both writes are what make the header
+    // reactive to the rename.
+    expect(commit).toContain("renamedConversationTitles.set(conv.id, title);");
+    expect(commit.indexOf("renamedConversationTitles.set(conv.id, title);")).toBeLessThan(commit.indexOf("await saveAiConversation(updated)"));
+    expect(commit).toContain("conversations.value[i] = updated;");
+    // A failed save retracts the claim so the header, the history row and the
+    // persisted record all keep the old title.
+    expect(commit).toContain("renamedConversationTitles.delete(conv.id);");
+  });
+
+  it("pending-input recovery keeps a renamed title instead of re-deriving it from the first message", () => {
+    // A recovered queued run used to persist `messageTitle(first)` outright,
+    // overwriting a renamed title on disk (and, via syncPersistedConversation,
+    // in the list the header now reads).
+    const recovery = bodyOf("async function persistPendingInputRecovery(");
+    expect(recovery).toContain("renamedConversationTitles.get(conversation.id)");
+    expect(recovery.indexOf("renamedConversationTitles.get(conversation.id)")).toBeLessThan(recovery.indexOf("messageTitle(first)"));
+  });
+});