feat(ui): edit session label in Chat tab

Adds a label input field in the Chat tab controls, allowing users to
edit the current session's label without navigating to the Sessions tab.

Fixes #3414

Changes:
- ui/src/ui/app-render.helpers.ts: Add label input with patchSession on change
- ui/src/styles/components.css: Styles for label input

ui/src/styles/components.css

@@ -1484,3 +1484,23 @@
   flex-wrap: wrap;
   gap: 8px;
 }
+
+/* Chat controls label input */
+.chat-controls__label {
+  width: 120px;
+  padding: 4px 8px;
+  font-size: 13px;
+  border: 1px solid var(--border);
+  border-radius: 4px;
+  background: var(--surface);
+  color: var(--text);
+}
+
+.chat-controls__label:focus {
+  outline: none;
+  border-color: var(--primary);
+}
+
+.chat-controls__label::placeholder {
+  color: var(--muted);
+}

ui/src/ui/app-render.helpers.ts

@@ -6,6 +6,7 @@ import { iconForTab, pathForTab, titleForTab, type Tab } from "./navigation";
 import { icons } from "./icons";
 import { loadChatHistory } from "./controllers/chat";
 import { refreshChat } from "./app-chat";
+import { patchSession } from "./controllers/sessions";
 import { syncUrlWithSessionKey } from "./app-settings";
 import type { SessionsListResult } from "./types";
 import type { ThemeMode } from "./theme";
@@ -46,6 +47,10 @@ export function renderChatControls(state: AppViewState) {
     state.sessionsResult,
     mainSessionKey,
   );
+  const activeSession = state.sessionsResult?.sessions?.find(
+    (row) => row.key === state.sessionKey,
+  );
+  const sessionLabel = activeSession?.label ?? "";
   const disableThinkingToggle = state.onboarding;
   const disableFocusToggle = state.onboarding;
   const showThinking = state.onboarding ? false : state.settings.chatShowThinking;
@@ -88,6 +93,22 @@ export function renderChatControls(state: AppViewState) {
           )}
         </select>
       </label>
+      <input
+        type="text"
+        class="chat-controls__label"
+        .value=${sessionLabel}
+        ?disabled=${!state.connected}
+        placeholder="Label"
+        title="Session label"
+        @change=${(e: Event) => {
+          const value = (e.target as HTMLInputElement).value.trim();
+          void patchSession(
+            state as Parameters<typeof patchSession>[0],
+            state.sessionKey,
+            { label: value || null },
+          );
+        }}
+      />
       <button
         class="btn btn--sm btn--icon"
         ?disabled=${state.chatLoading || !state.connected}