diff --git a/packages/coding-agent/test/vibe/spawn-model-role.test.ts b/packages/coding-agent/test/vibe/spawn-model-role.test.ts
new file mode 100644
index 000000000..ed124029e
--- /dev/null
+++ b/packages/coding-agent/test/vibe/spawn-model-role.test.ts
@@ -0,0 +1,107 @@
+/**
+ * Contract: a vibe worker's spawn options carry the pre-expansion model role.
+ *
+ * `#resolveWorker` expands the bundled worker's role alias (`good` -> `task` ->
+ * `@task`, `fast` -> `sonic` -> `@smol`) into concrete patterns, so the role
+ * survives only as a separate field forwarded across `ResolvedVibeWorker` ->
+ * `VibeRecord` -> `#buildSpawnOptions` -> `runSubprocess`. The executor keys the
+ * child's inherited `retry.fallbackChains` entry off it; drop any link in that
+ * chain and vibe children silently retry on the `default` role's chain.
+ */
+import { afterEach, describe, expect, it, vi } from "bun:test";
+import { AsyncJobManager } from "@oh-my-pi/pi-coding-agent/async/job-manager";
+import { Settings } from "@oh-my-pi/pi-coding-agent/config/settings";
+import { AgentRegistry } from "@oh-my-pi/pi-coding-agent/registry/agent-registry";
+import type { ExecutorOptions } from "@oh-my-pi/pi-coding-agent/task/executor";
+import * as executorModule from "@oh-my-pi/pi-coding-agent/task/executor";
+import type { SingleResult } from "@oh-my-pi/pi-coding-agent/task/types";
+import type { ToolSession } from "@oh-my-pi/pi-coding-agent/tools";
+import { type VibeCli, VibeSessionRegistry } from "@oh-my-pi/pi-coding-agent/vibe/runtime";
+
+function makeParentSession(settings: Settings): ToolSession {
+	return {
+		cwd: "/tmp",
+		settings,
+		asyncJobManager: new AsyncJobManager({ onJobComplete: () => {} }),
+		getSessionId: () => "parent-session",
+		// No session file: spawn skips lifecycle persistence and stays in-memory.
+		getSessionFile: () => null,
+		getArtifactsDir: () => null,
+		taskDepth: 0,
+		enableLsp: false,
+	} as unknown as ToolSession;
+}
+
+/** Spawn one worker and capture the ExecutorOptions the vibe path hands the executor. */
+async function spawnAndCaptureOptions(cli: VibeCli, settings: Settings): Promise<ExecutorOptions> {
+	const captured = Promise.withResolvers<ExecutorOptions>();
+	vi.spyOn(executorModule, "runSubprocess").mockImplementation(async options => {
+		captured.resolve(options);
+		return {
+			index: 0,
+			id: options.id,
+			agent: options.agent.name,
+			agentSource: "bundled",
+			task: options.task,
+			exitCode: 0,
+			output: "done",
+			stderr: "",
+			truncated: false,
+			durationMs: 1,
+			tokens: 0,
+			requests: 0,
+		} as SingleResult;
+	});
+
+	const registry = VibeSessionRegistry.global();
+	await registry.spawn(makeParentSession(settings), { cli, prompt: "work" });
+	return captured.promise;
+}
+
+describe("vibe worker spawn model role", () => {
+	afterEach(() => {
+		vi.restoreAllMocks();
+		VibeSessionRegistry.resetGlobalForTests();
+		AgentRegistry.resetGlobalForTests();
+	});
+
+	it("forwards the `task` role behind the `good` worker's expanded patterns", async () => {
+		const options = await spawnAndCaptureOptions(
+			"good",
+			Settings.isolated({
+				modelRoles: { default: "anthropic/opus", task: "anthropic/sonnet" },
+			}),
+		);
+
+		expect(options.modelOverride).toEqual(["anthropic/sonnet"]);
+		expect(options.modelRole).toBe("task");
+	});
+
+	it("forwards the `smol` role behind the `fast` worker's expanded patterns", async () => {
+		const options = await spawnAndCaptureOptions(
+			"fast",
+			Settings.isolated({
+				modelRoles: { default: "anthropic/opus", smol: "fast/hy3" },
+			}),
+		);
+
+		expect(options.modelOverride).toEqual(["fast/hy3"]);
+		expect(options.modelRole).toBe("smol");
+	});
+
+	it("keeps the role identity when a per-agent model override replaces the alias", async () => {
+		// `task.agentModelOverrides` wins over the agent definition, and an explicit
+		// selector carries no role — the child must then inherit `default`, not
+		// capture the routing of whichever role happens to name the same model.
+		const options = await spawnAndCaptureOptions(
+			"good",
+			Settings.isolated({
+				modelRoles: { default: "anthropic/opus", task: "anthropic/sonnet" },
+				"task.agentModelOverrides": { task: "openai-codex/sol" },
+			}),
+		);
+
+		expect(options.modelOverride).toEqual(["openai-codex/sol"]);
+		expect(options.modelRole).toBeUndefined();
+	});
+});