feat(task): add per-spawn effort ceiling

packages/coding-agent/test/task/executor-pass-through.test.ts

@@ -233,6 +233,48 @@ describe("runSubprocess parent-discovery pass-through (issue #2190)", () => {
 		expect(Object.hasOwn(result, "structuredOutput")).toBe(false);
 	});
 
+	it("caps caller-requested effort at task.maxEffort", async () => {
+		const model = getBundledModel("openai-codex", "gpt-5.6-sol");
+		if (!model) throw new Error("Expected gpt-5.6-sol model to exist");
+		const settings = Settings.isolated({ "task.maxEffort": "low" });
+		settings.setModelRole("task", `${model.provider}/${model.id}`);
+		const session = yieldEmittingSession();
+		const spy = vi.spyOn(sdkModule, "createAgentSession").mockResolvedValue(createSessionResult(session));
+
+		const result = await runSubprocess({
+			...baseOptions,
+			agent: { ...baseAgent, model: ["@task"] },
+			id: "subagent-effort-ceiling",
+			effort: "hi",
+			settings,
+			modelRegistry: createModelRegistry(model),
+		});
+
+		expect(result.exitCode).toBe(0);
+		expect(spy.mock.calls[0]?.[0]?.thinkingLevel).toBe(ThinkingLevel.Low);
+	});
+
+	it("preserves the model's full effort range by default", async () => {
+		const model = getBundledModel("openai-codex", "gpt-5.6-sol");
+		if (!model) throw new Error("Expected gpt-5.6-sol model to exist");
+		const settings = Settings.isolated();
+		settings.setModelRole("task", `${model.provider}/${model.id}`);
+		const session = yieldEmittingSession();
+		const spy = vi.spyOn(sdkModule, "createAgentSession").mockResolvedValue(createSessionResult(session));
+
+		const result = await runSubprocess({
+			...baseOptions,
+			agent: { ...baseAgent, model: ["@task"] },
+			id: "subagent-default-effort-ceiling",
+			effort: "hi",
+			settings,
+			modelRegistry: createModelRegistry(model),
+		});
+
+		expect(result.exitCode).toBe(0);
+		expect(spy.mock.calls[0]?.[0]?.thinkingLevel).toBe(ThinkingLevel.Max);
+	});
+
 	it("resolves an explicit task-role effort suffix over the agent-definition default", async () => {
 		const model = getBundledModel("anthropic", "claude-sonnet-4-5");
 		if (!model) throw new Error("Expected claude-sonnet-4-5 model to exist");