Add AbortSignal support to extension UI dialogs

Closes #474

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Added
+
+- Extension UI dialogs (`ctx.ui.select()`, `ctx.ui.confirm()`, `ctx.ui.input()`) now accept an optional `AbortSignal` to programmatically dismiss dialogs. Useful for implementing timeouts. See `examples/extensions/timed-confirm.ts`. ([#474](https://github.com/badlogic/pi-mono/issues/474))
+
 ## [0.37.5] - 2026-01-06
 
 ### Added

packages/coding-agent/docs/extensions.md

@@ -1094,6 +1094,38 @@ ctx.ui.notify("Done!", "info");  // "info" | "warning" | "error"
 - `ctx.ui.editor()`: [handoff.ts](../examples/extensions/handoff.ts)
 - `ctx.ui.setEditorText()`: [handoff.ts](../examples/extensions/handoff.ts), [qna.ts](../examples/extensions/qna.ts)
 
+#### Auto-Dismissing Dialogs
+
+Dialogs can be programmatically dismissed using `AbortSignal`. This is useful for implementing timeouts:
+
+```typescript
+const controller = new AbortController();
+const timeoutId = setTimeout(() => controller.abort(), 5000);
+
+const confirmed = await ctx.ui.confirm(
+  "Timed Confirmation",
+  "This dialog will auto-cancel in 5 seconds. Confirm?",
+  { signal: controller.signal }
+);
+
+clearTimeout(timeoutId);
+
+if (confirmed) {
+  // User confirmed
+} else if (controller.signal.aborted) {
+  // Dialog timed out
+} else {
+  // User cancelled (pressed Escape or selected "No")
+}
+```
+
+**Return values on abort:**
+- `select()` returns `undefined`
+- `confirm()` returns `false`
+- `input()` returns `undefined`
+
+See [examples/extensions/timed-confirm.ts](../examples/extensions/timed-confirm.ts) for a complete example.
+
 ### Widgets, Status, and Footer
 
 ```typescript

packages/coding-agent/examples/extensions/README.md

@@ -44,6 +44,7 @@ cp permission-gate.ts ~/.pi/agent/extensions/
 | `status-line.ts` | Shows turn progress in footer via `ctx.ui.setStatus()` with themed colors |
 | `snake.ts` | Snake game with custom UI, keyboard handling, and session persistence |
 | `send-user-message.ts` | Demonstrates `pi.sendUserMessage()` for sending user messages from extensions |
+| `timed-confirm.ts` | Demonstrates AbortSignal for auto-dismissing `ctx.ui.confirm()` and `ctx.ui.select()` dialogs |
 
 ### Git Integration
 

packages/coding-agent/examples/extensions/timed-confirm.ts

@@ -0,0 +1,63 @@
+/**
+ * Example extension demonstrating AbortSignal for auto-dismissing dialogs.
+ *
+ * Commands:
+ * - /timed - Shows confirm dialog that auto-cancels after 5 seconds
+ * - /timed-select - Shows select dialog that auto-cancels after 10 seconds
+ */
+
+import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
+
+export default function (pi: ExtensionAPI) {
+	pi.registerCommand("timed", {
+		description: "Show a timed confirmation dialog (auto-cancels in 5s)",
+		handler: async (_args, ctx) => {
+			const controller = new AbortController();
+			const timeoutId = setTimeout(() => controller.abort(), 5000);
+
+			ctx.ui.notify("Dialog will auto-cancel in 5 seconds...", "info");
+
+			const confirmed = await ctx.ui.confirm(
+				"Timed Confirmation",
+				"This dialog will auto-cancel in 5 seconds. Confirm?",
+				{ signal: controller.signal },
+			);
+
+			clearTimeout(timeoutId);
+
+			if (confirmed) {
+				ctx.ui.notify("Confirmed by user!", "info");
+			} else if (controller.signal.aborted) {
+				ctx.ui.notify("Dialog timed out (auto-cancelled)", "warning");
+			} else {
+				ctx.ui.notify("Cancelled by user", "info");
+			}
+		},
+	});
+
+	pi.registerCommand("timed-select", {
+		description: "Show a timed select dialog (auto-cancels in 10s)",
+		handler: async (_args, ctx) => {
+			const controller = new AbortController();
+			const timeoutId = setTimeout(() => controller.abort(), 10000);
+
+			ctx.ui.notify("Select dialog will auto-cancel in 10 seconds...", "info");
+
+			const choice = await ctx.ui.select(
+				"Pick an option (auto-cancels in 10s)",
+				["Option A", "Option B", "Option C"],
+				{ signal: controller.signal },
+			);
+
+			clearTimeout(timeoutId);
+
+			if (choice) {
+				ctx.ui.notify(`Selected: ${choice}`, "info");
+			} else if (controller.signal.aborted) {
+				ctx.ui.notify("Selection timed out", "warning");
+			} else {
+				ctx.ui.notify("Selection cancelled", "info");
+			}
+		},
+	});
+}

packages/coding-agent/src/core/extensions/types.ts

@@ -52,13 +52,13 @@ export type { AgentToolResult, AgentToolUpdateCallback };
  */
 export interface ExtensionUIContext {
 	/** Show a selector and return the user's choice. */
-	select(title: string, options: string[]): Promise<string | undefined>;
+	select(title: string, options: string[], opts?: { signal?: AbortSignal }): Promise<string | undefined>;
 
 	/** Show a confirmation dialog. */
-	confirm(title: string, message: string): Promise<boolean>;
+	confirm(title: string, message: string, opts?: { signal?: AbortSignal }): Promise<boolean>;
 
 	/** Show a text input dialog. */
-	input(title: string, placeholder?: string): Promise<string | undefined>;
+	input(title: string, placeholder?: string, opts?: { signal?: AbortSignal }): Promise<string | undefined>;
 
 	/** Show a notification to the user. */
 	notify(message: string, type?: "info" | "warning" | "error"): void;

packages/coding-agent/src/modes/interactive/interactive-mode.ts

@@ -739,9 +739,9 @@ export class InteractiveMode {
 	 */
 	private createExtensionUIContext(): ExtensionUIContext {
 		return {
-			select: (title, options) => this.showExtensionSelector(title, options),
+			select: (title, options, opts) => this.showExtensionSelector(title, options, opts),
-			confirm: (title, message) => this.showExtensionConfirm(title, message),
+			confirm: (title, message, opts) => this.showExtensionConfirm(title, message, opts),
-			input: (title, placeholder) => this.showExtensionInput(title, placeholder),
+			input: (title, placeholder, opts) => this.showExtensionInput(title, placeholder, opts),
 			notify: (message, type) => this.showExtensionNotify(message, type),
 			setStatus: (key, text) => this.setExtensionStatus(key, text),
 			setWidget: (key, content) => this.setExtensionWidget(key, content),
@@ -761,16 +761,33 @@ export class InteractiveMode {
 	/**
 	 * Show a selector for extensions.
 	 */
-	private showExtensionSelector(title: string, options: string[]): Promise<string | undefined> {
+	private showExtensionSelector(
+		title: string,
+		options: string[],
+		opts?: { signal?: AbortSignal },
+	): Promise<string | undefined> {
 		return new Promise((resolve) => {
+			if (opts?.signal?.aborted) {
+				resolve(undefined);
+				return;
+			}
+
+			const onAbort = () => {
+				this.hideExtensionSelector();
+				resolve(undefined);
+			};
+			opts?.signal?.addEventListener("abort", onAbort, { once: true });
+
 			this.extensionSelector = new ExtensionSelectorComponent(
 				title,
 				options,
 				(option) => {
+					opts?.signal?.removeEventListener("abort", onAbort);
 					this.hideExtensionSelector();
 					resolve(option);
 				},
 				() => {
+					opts?.signal?.removeEventListener("abort", onAbort);
 					this.hideExtensionSelector();
 					resolve(undefined);
 				},
@@ -797,24 +814,45 @@ export class InteractiveMode {
 	/**
 	 * Show a confirmation dialog for extensions.
 	 */
-	private async showExtensionConfirm(title: string, message: string): Promise<boolean> {
+	private async showExtensionConfirm(
-		const result = await this.showExtensionSelector(`${title}\n${message}`, ["Yes", "No"]);
+		title: string,
+		message: string,
+		opts?: { signal?: AbortSignal },
+	): Promise<boolean> {
+		const result = await this.showExtensionSelector(`${title}\n${message}`, ["Yes", "No"], opts);
 		return result === "Yes";
 	}
 
 	/**
 	 * Show a text input for extensions.
 	 */
-	private showExtensionInput(title: string, placeholder?: string): Promise<string | undefined> {
+	private showExtensionInput(
+		title: string,
+		placeholder?: string,
+		opts?: { signal?: AbortSignal },
+	): Promise<string | undefined> {
 		return new Promise((resolve) => {
+			if (opts?.signal?.aborted) {
+				resolve(undefined);
+				return;
+			}
+
+			const onAbort = () => {
+				this.hideExtensionInput();
+				resolve(undefined);
+			};
+			opts?.signal?.addEventListener("abort", onAbort, { once: true });
+
 			this.extensionInput = new ExtensionInputComponent(
 				title,
 				placeholder,
 				(value) => {
+					opts?.signal?.removeEventListener("abort", onAbort);
 					this.hideExtensionInput();
 					resolve(value);
 				},
 				() => {
+					opts?.signal?.removeEventListener("abort", onAbort);
 					this.hideExtensionInput();
 					resolve(undefined);
 				},

packages/coding-agent/src/modes/rpc/rpc-mode.ts

@@ -67,11 +67,22 @@ export async function runRpcMode(session: AgentSession): Promise<never> {
 	 * Create an extension UI context that uses the RPC protocol.
 	 */
 	const createExtensionUIContext = (): ExtensionUIContext => ({
-		async select(title: string, options: string[]): Promise<string | undefined> {
+		async select(title: string, options: string[], opts?: { signal?: AbortSignal }): Promise<string | undefined> {
+			if (opts?.signal?.aborted) {
+				return undefined;
+			}
+
 			const id = crypto.randomUUID();
 			return new Promise((resolve, reject) => {
+				const onAbort = () => {
+					pendingExtensionRequests.delete(id);
+					resolve(undefined);
+				};
+				opts?.signal?.addEventListener("abort", onAbort, { once: true });
+
 				pendingExtensionRequests.set(id, {
 					resolve: (response: RpcExtensionUIResponse) => {
+						opts?.signal?.removeEventListener("abort", onAbort);
 						if ("cancelled" in response && response.cancelled) {
 							resolve(undefined);
 						} else if ("value" in response) {
@@ -86,11 +97,22 @@ export async function runRpcMode(session: AgentSession): Promise<never> {
 			});
 		},
 
-		async confirm(title: string, message: string): Promise<boolean> {
+		async confirm(title: string, message: string, opts?: { signal?: AbortSignal }): Promise<boolean> {
+			if (opts?.signal?.aborted) {
+				return false;
+			}
+
 			const id = crypto.randomUUID();
 			return new Promise((resolve, reject) => {
+				const onAbort = () => {
+					pendingExtensionRequests.delete(id);
+					resolve(false);
+				};
+				opts?.signal?.addEventListener("abort", onAbort, { once: true });
+
 				pendingExtensionRequests.set(id, {
 					resolve: (response: RpcExtensionUIResponse) => {
+						opts?.signal?.removeEventListener("abort", onAbort);
 						if ("cancelled" in response && response.cancelled) {
 							resolve(false);
 						} else if ("confirmed" in response) {
@@ -105,11 +127,22 @@ export async function runRpcMode(session: AgentSession): Promise<never> {
 			});
 		},
 
-		async input(title: string, placeholder?: string): Promise<string | undefined> {
+		async input(title: string, placeholder?: string, opts?: { signal?: AbortSignal }): Promise<string | undefined> {
+			if (opts?.signal?.aborted) {
+				return undefined;
+			}
+
 			const id = crypto.randomUUID();
 			return new Promise((resolve, reject) => {
+				const onAbort = () => {
+					pendingExtensionRequests.delete(id);
+					resolve(undefined);
+				};
+				opts?.signal?.addEventListener("abort", onAbort, { once: true });
+
 				pendingExtensionRequests.set(id, {
 					resolve: (response: RpcExtensionUIResponse) => {
+						opts?.signal?.removeEventListener("abort", onAbort);
 						if ("cancelled" in response && response.cancelled) {
 							resolve(undefined);
 						} else if ("value" in response) {