fix(coding-agent): report only matching prewalk arms

packages/coding-agent/src/session/prewalk.ts

@@ -205,13 +205,18 @@ export class PrewalkCoordinator {
 
 	/** Arms a prewalk immediately for an explicit slash-command request. */
 	arm(target: Model, thinkingLevel?: ConfiguredThinkingLevel): boolean {
-		if (this.#prewalk) {
+		const active = this.#prewalk;
+		if (active) {
 			this.#host.emitNotice(
 				"info",
-				`Prewalk: already armed for ${this.#prewalk.target.provider}/${this.#prewalk.target.id}, waiting for the first edit/write.`,
+				`Prewalk: already armed for ${active.target.provider}/${active.target.id}, waiting for the first edit/write.`,
 				"prewalk",
 			);
-			return true;
+			return (
+				active.target.provider === target.provider &&
+				active.target.id === target.id &&
+				active.thinkingLevel === thinkingLevel
+			);
 		}
 		const candidate = { target, thinkingLevel };
 		if (this.#isNoop(candidate)) {

packages/coding-agent/test/agent-session-prewalk.test.ts

@@ -795,6 +795,11 @@ describe("AgentSession prewalk", () => {
 		expect(showStatus).toHaveBeenCalledWith(
 			`Prewalk on: switching to ${target.provider}/${target.id} at the next edit/write (todo-gated).`,
 		);
+
+		// A different request cannot report success while the prior target remains armed.
+		settings.setModelRole("smol", `${primary.provider}/${primary.id}:medium`);
+		expect(await executeBuiltinSlashCommand("/prewalk", runtime)).toBe(true);
+		expect(showStatus).toHaveBeenCalledTimes(1);
 	});
 
 	it("requires a fresh todo before a later explicit prewalk can hand off", async () => {