@@ -1525,7 +1525,7 @@ export namespace ACP {
     }
   }
 
-  async function defaultModel(config: ACPConfig, cwd?: string) {
+  export async function defaultModel(config: ACPConfig, cwd?: string) {
     const sdk = config.sdk
     const configured = config.defaultModel
     if (configured) return configured
@@ -1574,7 +1574,9 @@ export namespace ACP {
 
     if (specified) return specified
 
-    throw new Error("no providers found")
+    throw new Error(
+      'No providers found. Run `aictrl auth login`, set a provider API key, or define a provider under "provider" in aictrl.json.',
+    )
   }
 
   function parseUri(
 
@@ -49,3 +49,35 @@ describe("acp.agent interface compliance", () => {
     }
   })
 })
+
+describe("acp default model", () => {
+  type Sdk = Parameters<typeof ACP.defaultModel>[0]["sdk"]
+
+  // A client whose server reports no config model and the given providers.
+  function sdkWith(providers: unknown[]) {
+    return {
+      config: {
+        get: async () => ({ data: {} }),
+        providers: async () => ({ data: { providers } }),
+      },
+    } as unknown as Sdk
+  }
+
+  test("fails with an actionable error when no provider is configured", async () => {
+    const error = await ACP.defaultModel({ sdk: sdkWith([]) }, "/tmp").catch((e: Error) => e)
+    expect(error).toBeInstanceOf(Error)
+    expect((error as Error).message).toContain("aictrl auth login")
+    expect((error as Error).message).toContain('"provider" in aictrl.json')
+  })
+
+  test("resolves a configured provider instead of a hard-coded model", async () => {
+    const anthropic = {
+      id: "anthropic",
+      models: { "claude-sonnet-4-5": { id: "claude-sonnet-4-5", providerID: "anthropic" } },
+    }
+    expect(await ACP.defaultModel({ sdk: sdkWith([anthropic]) }, "/tmp")).toEqual({
+      providerID: "anthropic",
+      modelID: "claude-sonnet-4-5",
+    })
+  })
+})
@@ -12,7 +12,17 @@ async function runGuarded(entry: string, args: string[], env: Record<string, str
   await using tmp = await tmpdir()
   const proc = Bun.spawn(["bun", "--preload", guard, "--conditions=browser", entry, ...args], {
     cwd: tmp.path,
-    env: { ...process.env, ...env },
+    // Config, auth, cache and state live under the fresh tmpdir, so nothing shared can change what loads.
+    env: {
+      ...process.env,
+      XDG_DATA_HOME: path.join(tmp.path, "data"),
+      XDG_CACHE_HOME: path.join(tmp.path, "cache"),
+      XDG_CONFIG_HOME: path.join(tmp.path, "config"),
+      XDG_STATE_HOME: path.join(tmp.path, "state"),
+      AICTRL_TEST_HOME: tmp.path,
+      AICTRL_TEST_MANAGED_CONFIG_DIR: path.join(tmp.path, "managed"),
+      ...env,
+    },
     stdout: "pipe",
     stderr: "pipe",
   })
 
@@ -148,6 +148,27 @@ describe("provider registry", () => {
     })
   })
 
+  test("GLM Coding Plan models keep their forced reasoning-effort variants", async () => {
+    await using tmp = await tmpdir({ config: {} })
+    await Instance.provide({
+      directory: tmp.path,
+      init: async () => {
+        Env.set("ZHIPU_API_KEY", "key")
+      },
+      fn: async () => {
+        const models = (await Provider.list())["zai-coding-plan"].models
+        expect(models["glm-5.2"].variants).toEqual({
+          low: { reasoningEffort: "high" },
+          medium: { reasoningEffort: "high" },
+          high: { reasoningEffort: "high" },
+          xhigh: { reasoningEffort: "max" },
+          max: { reasoningEffort: "max" },
+        })
+        expect(models["glm-5.3"].variants?.["max"]).toEqual({ reasoningEffort: "max" })
+      },
+    })
+  })
+
   test("an openai-compatible provider defined in config works without the catalog", async () => {
     await using tmp = await tmpdir({
       config: {
Original file line number	Diff line number	Diff line change
`@@ -1525,7 +1525,7 @@ export namespace ACP {`
`1525`	`1525`	`}`
`1526`	`1526`	`}`
`1527`	`1527`
`1528`		`- async function defaultModel(config: ACPConfig, cwd?: string) {`
	`1528`	`+ export async function defaultModel(config: ACPConfig, cwd?: string) {`
`1529`	`1529`	`const sdk = config.sdk`
`1530`	`1530`	`const configured = config.defaultModel`
`1531`	`1531`	`if (configured) return configured`
`@@ -1574,7 +1574,9 @@ export namespace ACP {`
`1574`	`1574`
`1575`	`1575`	`if (specified) return specified`
`1576`	`1576`
`1577`		`- throw new Error("no providers found")`
	`1577`	`+ throw new Error(`
	`1578`	+ 'No providers found. Run `aictrl auth login`, set a provider API key, or define a provider under "provider" in aictrl.json.',
	`1579`	`+ )`
`1578`	`1580`	`}`
`1579`	`1581`
`1580`	`1582`	`function parseUri(`