feat: double-click tab to rename (PUT /conversations/:id/title)

Double-click a tab's title to enter inline edit mode. Enter or click
away (blur) saves; Escape cancels. The rename is optimistic — the
local tab updates immediately and PUT /title fires in the background.

683 tests green.

3 files changed, 72 insertions, 1 deletions

diff --git a/src/app/App.svelte b/src/app/App.svelte
index ae09bd5..9225cc7 100644
--- a/src/app/App.svelte
+++ b/src/app/App.svelte
@@ -309,6 +309,7 @@
 				onSelect={(id) => store.selectTab(id)}
 				onClose={(id) => store.closeTab(id)}
 				onNewDraft={() => store.newDraft()}
+				onRename={(id, title) => store.renameTab(id, title)}
 			/>
 			<span
 				class="shrink-0 select-none px-1 font-mono text-[10px] leading-none text-base-content/30"
diff --git a/src/app/store.svelte.ts b/src/app/store.svelte.ts
index 3f78a97..6cff5f8 100644
--- a/src/app/store.svelte.ts
+++ b/src/app/store.svelte.ts
@@ -18,6 +18,7 @@ import type {
 	SetCompactPercentRequest,
 	SetCwdRequest,
 	SetReasoningEffortRequest,
+	SetTitleRequest,
 	WarmRequest,
 	WarmResponse,
 } from "@dispatch/transport-contract";
@@ -114,6 +115,7 @@ export interface AppStore {
 	newDraft(): void;
 	selectTab(conversationId: string): void;
 	closeTab(conversationId: string): void;
+	renameTab(conversationId: string, title: string): void;
 	invoke(surfaceId: string, actionId: string, payload?: unknown): void;
 	/**
 	 * Manually warm the focused conversation's prompt cache (`POST /chat/warm`).
@@ -869,6 +871,17 @@ export function createAppStore(opts?: CreateAppStoreOptions): AppStore {
 			removeTabLocally(conversationId);
 		},
 
+		renameTab(conversationId: string, title: string): void {
+			tabsStore.setTitle(conversationId, title);
+			void fetchImpl(`${httpBase}/conversations/${encodeURIComponent(conversationId)}/title`, {
+				method: "PUT",
+				headers: { "Content-Type": "application/json" },
+				body: JSON.stringify({ title } satisfies SetTitleRequest),
+			}).catch(() => {
+				// Best-effort — the local tab is already renamed.
+			});
+		},
+
 		invoke(surfaceId: string, actionId: string, payload?: unknown): void {
 			const result = protocolInvoke(
 				protocol,
diff --git a/src/features/tabs/ui/TabBar.svelte b/src/features/tabs/ui/TabBar.svelte
index 9d224b9..f783412 100644
--- a/src/features/tabs/ui/TabBar.svelte
+++ b/src/features/tabs/ui/TabBar.svelte
@@ -9,6 +9,7 @@
 		onSelect,
 		onClose,
 		onNewDraft,
+		onRename,
 	}: {
 		tabs: readonly Tab[];
 		activeConversationId: string | null;
@@ -17,6 +18,7 @@
 		onSelect: (conversationId: string) => void;
 		onClose: (conversationId: string) => void;
 		onNewDraft: () => void;
+		onRename?: (conversationId: string, title: string) => void;
 	} = $props();
 
 	// The new-chat button is `position: sticky; right: 0`. It floats over the tabs
@@ -65,6 +67,31 @@
 			ro?.disconnect();
 		};
 	});
+	// Inline rename: double-click a tab's title to edit, Enter/blur to save.
+	let editingId = $state<string | null>(null);
+	let editValue = $state("");
+	let editEl = $state<HTMLInputElement>();
+
+	function startRename(tab: Tab): void {
+		if (onRename === undefined) return;
+		editingId = tab.conversationId;
+		editValue = tab.title;
+		// Focus the input after it renders.
+		queueMicrotask(() => editEl?.focus());
+	}
+
+	function commitRename(): void {
+		const id = editingId;
+		if (id !== null && onRename !== undefined) {
+			const trimmed = editValue.trim();
+			if (trimmed.length > 0) onRename(id, trimmed);
+		}
+		editingId = null;
+	}
+
+	function cancelRename(): void {
+		editingId = null;
+	}
 </script>
 
 <div bind:this={scrollEl} class="min-w-0 flex-1 overflow-x-auto">
@@ -86,7 +113,37 @@
 				>
 					{handles.get(tab.conversationId) ?? tab.conversationId}
 				</span>
-				<span class="min-w-0 flex-1 truncate text-left">{tab.title}</span>
+				{#if editingId === tab.conversationId}
+					<input
+						bind:this={editEl}
+						bind:value={editValue}
+						class="min-w-0 flex-1 rounded bg-base-100 px-1 py-0.5 text-left text-sm outline outline-1 outline-primary"
+						onclick={(e) => e.stopPropagation()}
+						onkeydown={(e) => {
+							if (e.key === "Enter") {
+								e.preventDefault();
+								commitRename();
+							} else if (e.key === "Escape") {
+								e.preventDefault();
+								cancelRename();
+							}
+						}}
+						onblur={commitRename}
+					/>
+				{:else}
+					<span
+						class="min-w-0 flex-1 cursor-pointer truncate text-left"
+						role="button"
+						tabindex="-1"
+						title="Double-click to rename"
+						ondblclick={(e) => {
+							e.stopPropagation();
+							startRename(tab);
+						}}
+					>
+						{tab.title}
+					</span>
+				{/if}
 				{#if statusFor?.(tab.conversationId) === "active"}
 					<span class="loading loading-spinner loading-xs shrink-0 text-primary"></span>
 				{/if}