fix(tui): restore streaming steer image draft on prompt error

Wrap the streaming Enter steer dispatch in try/catch so prompt failures restore text plus pendingImages / pendingImageLinks / imageLinks and surface showError instead of losing an image-only draft.\n\nAlso remove a forbidden ReturnType<> from the follow-up image regression helper.\n\nFixes #3467

packages/coding-agent/src/modes/controllers/input-controller.ts

@@ -719,11 +719,25 @@ export class InputController {
 				// (a user-role `message_start` event) leaves any draft the user has
 				// typed since queuing intact. Same protection as #783, applied to
 				// the streaming/queue path.
-				await this.ctx.withLocalSubmission(
-					text,
-					() => this.ctx.session.prompt(text, { streamingBehavior: "steer", images }),
-					{ imageCount: images?.length ?? 0 },
-				);
+				try {
+					await this.ctx.withLocalSubmission(
+						text,
+						() => this.ctx.session.prompt(text, { streamingBehavior: "steer", images }),
+						{ imageCount: images?.length ?? 0 },
+					);
+				} catch (error) {
+					// Don't lose the queued steer draft: restore text and images so
+					// the user can retry after dispatch validation/queue failures.
+					this.ctx.editor.setText(text);
+					if (images && images.length > 0) {
+						this.ctx.editor.pendingImages = [...images];
+						this.ctx.editor.pendingImageLinks = inputImageLinks
+							? [...inputImageLinks]
+							: images.map(() => undefined);
+						this.ctx.editor.imageLinks = this.ctx.editor.pendingImageLinks;
+					}
+					this.ctx.showError(error instanceof Error ? error.message : String(error));
+				}
 				this.ctx.updatePendingMessagesDisplay();
 				this.ctx.ui.requestRender();
 				return;

packages/coding-agent/test/input-controller-followup-image.test.ts

@@ -51,6 +51,7 @@ function createContext(opts: {
 	const prompt = vi.fn(async (_text: string, _options?: PromptOptionsLike) => {});
 	const updatePendingMessagesDisplay = vi.fn();
 	const requestRender = vi.fn();
+	const showError = vi.fn();
 
 	const ctx = {
 		editor,
@@ -68,11 +69,11 @@ function createContext(opts: {
 		compactionQueuedMessages: [],
 		locallySubmittedUserSignatures: new Set<string>(),
 		updatePendingMessagesDisplay,
-		showError: vi.fn(),
+		showError,
 		withLocalSubmission: async (_text: string, fn: () => unknown) => fn(),
 	} as unknown as InteractiveModeContext;
 
-	return { ctx, editor, prompt, showError: ctx.showError as ReturnType<typeof vi.fn> };
+	return { ctx, editor, prompt, showError };
 }
 
 describe("InputController.handleFollowUp image forwarding", () => {

packages/coding-agent/test/issue-interrupt-and-flush-empty-messages.test.ts

@@ -4,7 +4,11 @@ import { InputController } from "@oh-my-pi/pi-coding-agent/modes/controllers/inp
 import type { InteractiveModeContext } from "@oh-my-pi/pi-coding-agent/modes/types";
 import { USER_INTERRUPT_LABEL } from "@oh-my-pi/pi-coding-agent/session/messages";
 
-function createContext(options?: { queuedMessageCount?: number; pendingImages?: ImageContent[] }) {
+function createContext(options?: {
+	queuedMessageCount?: number;
+	pendingImages?: ImageContent[];
+	pendingImageLinks?: (string | undefined)[];
+}) {
 	let editorText = "";
 	const abort = vi.fn(async () => {});
 	const prompt = vi.fn(async () => {});
@@ -22,7 +26,10 @@ function createContext(options?: { queuedMessageCount?: number; pendingImages?:
 			},
 			addToHistory: vi.fn(),
 			pendingImages: options?.pendingImages ? [...options.pendingImages] : ([] as ImageContent[]),
-			pendingImageLinks: options?.pendingImages?.map(() => undefined) ?? ([] as (string | undefined)[]),
+			pendingImageLinks:
+				options?.pendingImageLinks ??
+				options?.pendingImages?.map(() => undefined) ??
+				([] as (string | undefined)[]),
 		},
 		ui: { requestRender },
 		session: {
@@ -86,6 +93,31 @@ describe("empty submit with queued messages", () => {
 		expect(requestRender).toHaveBeenCalledTimes(1);
 	});
 
+	it("restores an image-only steer when streaming dispatch rejects", async () => {
+		const image: ImageContent = { type: "image", mimeType: "image/png", data: "aW1hZ2U=" };
+		const { ctx, abort, prompt, showError, updatePendingMessagesDisplay, requestRender } = createContext({
+			queuedMessageCount: 0,
+			pendingImages: [image],
+			pendingImageLinks: ["local://draft.png"],
+		});
+		prompt.mockImplementationOnce(async () => {
+			throw new Error("queue rejected");
+		});
+		const controller = new InputController(ctx);
+		controller.setupEditorSubmitHandler();
+
+		await ctx.editor.onSubmit?.("");
+
+		expect(abort).not.toHaveBeenCalled();
+		expect(showError).toHaveBeenCalledWith("queue rejected");
+		expect(ctx.editor.getText()).toBe("");
+		expect(ctx.editor.pendingImages).toEqual([image]);
+		expect(ctx.editor.pendingImageLinks).toEqual(["local://draft.png"]);
+		expect(ctx.editor.imageLinks).toEqual(["local://draft.png"]);
+		expect(updatePendingMessagesDisplay).toHaveBeenCalledTimes(1);
+		expect(requestRender).toHaveBeenCalledTimes(1);
+	});
+
 	it("queues an image-only steer instead of aborting when messages are already queued", async () => {
 		const image: ImageContent = { type: "image", mimeType: "image/png", data: "aW1hZ2U=" };
 		const { ctx, abort, prompt } = createContext({ queuedMessageCount: 1, pendingImages: [image] });