feat: add is_subagent flag to agents, fix all lint/type/test issues

- Add is_subagent checkbox to agent editor; subagents are hidden from Chat Settings
- Add is_subagent field to AgentDefinition type, TOML serialization, and API route
- Filter subagents from ModelSelector agent list
- Fix all biome lint/format errors across codebase (useLiteralKeys, noNonNullAssertion, noExplicitAny, formatting, import sorting)
- Fix svelte-check errors (type narrowing in SkillsBrowser, ToolPermissions, SidebarPanel)
- Fix a11y warnings in App.svelte (label-control associations)
- Fix test mocks missing BackgroundShellStore, BackgroundTranscriptStore, createWebSearchTool, createYoutubeTranscribeTool
- Update stale 409 test to match current message-queuing behavior
- Exclude packaging/ and release/ dirs from biome to avoid linting stale build artifacts

3 files changed, 24 insertions, 20 deletions

diff --git a/packages/core/src/tools/retrieve.ts b/packages/core/src/tools/retrieve.ts
index 021d1b7..80c3715 100644
--- a/packages/core/src/tools/retrieve.ts
+++ b/packages/core/src/tools/retrieve.ts
@@ -28,29 +28,33 @@ export function createRetrieveTool(callbacks: RetrieveCallbacks): ToolDefinition
 		parameters: z.object({
 			agent_id: z.string().describe("The agent_id returned by a previous summon call."),
 		}),
-		execute: async (args: Record<string, unknown>, context?: ToolExecuteContext): Promise<string> => {
+		execute: async (
+			args: Record<string, unknown>,
+			context?: ToolExecuteContext,
+		): Promise<string> => {
 			const agentId = args.agent_id as string;
 			const queueCallbacks = context?.queueCallbacks;
 
 			try {
 				let outcome: { status: "done"; result: string } | { status: "error"; error: string };
 
-			if (queueCallbacks) {
-				const childPromise = callbacks.getResult(agentId);
-				const { promise: queuePromise, cancel: cancelQueueWait } = queueCallbacks.waitForQueuedMessage();
-				const queueSignal = queuePromise.then(() => "QUEUE_INTERRUPT" as const);
+				if (queueCallbacks) {
+					const childPromise = callbacks.getResult(agentId);
+					const { promise: queuePromise, cancel: cancelQueueWait } =
+						queueCallbacks.waitForQueuedMessage();
+					const queueSignal = queuePromise.then(() => "QUEUE_INTERRUPT" as const);
 
-				const raceResult = await Promise.race([childPromise, queueSignal]);
+					const raceResult = await Promise.race([childPromise, queueSignal]);
 
-				if (raceResult === "QUEUE_INTERRUPT") {
-					const queuedMsgs = queueCallbacks.dequeueMessages();
-					const userMessages = queuedMsgs.map((m) => m.message).join("\n---\n");
-					return `The subagent (agent_id: ${agentId}) has not completed its task yet. You will need to call retrieve with this agent_id again later to get the result.\n\n[USER INTERRUPT]\nThe user has sent you message(s) while you were working. You MUST address these before continuing with your current task:\n\n${userMessages}`;
-				}
+					if (raceResult === "QUEUE_INTERRUPT") {
+						const queuedMsgs = queueCallbacks.dequeueMessages();
+						const userMessages = queuedMsgs.map((m) => m.message).join("\n---\n");
+						return `The subagent (agent_id: ${agentId}) has not completed its task yet. You will need to call retrieve with this agent_id again later to get the result.\n\n[USER INTERRUPT]\nThe user has sent you message(s) while you were working. You MUST address these before continuing with your current task:\n\n${userMessages}`;
+					}
 
-				// Child finished first — clean up the queue listener
-				cancelQueueWait();
-				outcome = raceResult;
+					// Child finished first — clean up the queue listener
+					cancelQueueWait();
+					outcome = raceResult;
 				} else {
 					outcome = await callbacks.getResult(agentId);
 				}
diff --git a/packages/core/src/tools/web-search.ts b/packages/core/src/tools/web-search.ts
index 4265aa7..7f061a5 100644
--- a/packages/core/src/tools/web-search.ts
+++ b/packages/core/src/tools/web-search.ts
@@ -70,7 +70,9 @@ export function createWebSearchTool(): ToolDefinition {
 				return `Error: Firecrawl returned HTTP ${response.status} ${response.statusText}${text ? `: ${text}` : ""}`;
 			}
 
-			let json: { data?: Array<{ title?: string; url?: string; description?: string; markdown?: string }> };
+			let json: {
+				data?: Array<{ title?: string; url?: string; description?: string; markdown?: string }>;
+			};
 			try {
 				json = await response.json();
 			} catch {
@@ -96,7 +98,7 @@ export function createWebSearchTool(): ToolDefinition {
 
 			let output = parts.join("\n\n---\n\n");
 			if (output.length > MAX_OUTPUT_CHARS) {
-				output = output.slice(0, MAX_OUTPUT_CHARS) + "\n\n[Output truncated]";
+				output = `${output.slice(0, MAX_OUTPUT_CHARS)}\n\n[Output truncated]`;
 			}
 			return output;
 		},
diff --git a/packages/core/src/tools/youtube-transcribe.ts b/packages/core/src/tools/youtube-transcribe.ts
index cfa006d..ea8ed43 100644
--- a/packages/core/src/tools/youtube-transcribe.ts
+++ b/packages/core/src/tools/youtube-transcribe.ts
@@ -41,9 +41,7 @@ function formatTime(seconds: number): string {
 
 function formatTranscript(data: TranscriptResponse): string {
 	const segments = data.segments ?? [];
-	const segmentsText = segments
-		.map((seg) => `[${formatTime(seg.start)}] ${seg.text}`)
-		.join("\n");
+	const segmentsText = segments.map((seg) => `[${formatTime(seg.start)}] ${seg.text}`).join("\n");
 
 	const output = [
 		`Video ID: ${data.video_id}`,
@@ -58,7 +56,7 @@ function formatTranscript(data: TranscriptResponse): string {
 	].join("\n");
 
 	return output.length > MAX_OUTPUT_CHARS
-		? output.slice(0, MAX_OUTPUT_CHARS) + "\n\n[Transcript truncated]"
+		? `${output.slice(0, MAX_OUTPUT_CHARS)}\n\n[Transcript truncated]`
 		: output;
 }