diff --git a/src/hooks/runtime-fallback/ai-sdk-retryable-session-error.test.ts b/src/hooks/runtime-fallback/ai-sdk-retryable-session-error.test.ts
new file mode 100644
index 000000000..46155c15d
--- /dev/null
+++ b/src/hooks/runtime-fallback/ai-sdk-retryable-session-error.test.ts
@@ -0,0 +1,95 @@
+import { afterEach, describe, expect, test } from "bun:test"
+import { unsafeTestValue } from "../../../test-support/unsafe-test-value"
+import type { OhMyOpenCodeConfig, RuntimeFallbackConfig } from "../../config"
+import { SessionCategoryRegistry } from "../../shared/session-category-registry"
+import { releaseAllPromptAsyncReservationsForTesting } from "../shared/prompt-async-gate"
+import { createRuntimeFallbackHook } from "./hook"
+import type { RuntimeFallbackPluginInput } from "./types"
+
+describe("runtime-fallback AI SDK retryable session errors", () => {
+  afterEach(() => {
+    SessionCategoryRegistry.clear()
+    releaseAllPromptAsyncReservationsForTesting()
+  })
+
+  function createRuntimeFallbackConfig(): RuntimeFallbackConfig {
+    return {
+      enabled: true,
+      retry_on_errors: [429, 500, 502, 503, 504],
+      max_fallback_attempts: 3,
+      cooldown_seconds: 60,
+      notify_on_fallback: false,
+    }
+  }
+
+  function createPluginConfig(): OhMyOpenCodeConfig {
+    return {
+      git_master: {
+        commit_footer: true,
+        include_co_authored_by: true,
+        git_env_prefix: "GIT_MASTER=1",
+      },
+      categories: {
+        test: {
+          fallback_models: ["openai/gpt-5.4"],
+        },
+      },
+    }
+  }
+
+  test("dispatches fallback for nested AI SDK retryable Cloudflare timeout errors", async () => {
+    //#given
+    const promptCalls: Array<Record<string, unknown>> = []
+    const hook = createRuntimeFallbackHook(
+      unsafeTestValue<RuntimeFallbackPluginInput>({
+        client: {
+          tui: { showToast: async () => ({}) },
+          session: {
+            messages: async () => ({
+              data: [{ info: { role: "user" }, parts: [{ type: "text", text: "continue" }] }],
+            }),
+            promptAsync: async (args: unknown) => {
+              promptCalls.push(args as Record<string, unknown>)
+              return {}
+            },
+            abort: async () => ({}),
+          },
+        },
+        directory: "/test/dir",
+      }),
+      { config: createRuntimeFallbackConfig(), pluginConfig: createPluginConfig() },
+    )
+    const sessionID = "test-session-ai-sdk-cloudflare-timeout"
+    SessionCategoryRegistry.register(sessionID, "test")
+
+    await hook.event({
+      event: {
+        type: "session.created",
+        properties: { info: { id: sessionID, model: "openai/gpt-5.5-fast" } },
+      },
+    })
+
+    //#when
+    await hook.event({
+      event: {
+        type: "session.error",
+        properties: {
+          sessionID,
+          error: {
+            error: {
+              name: "AI_APICallError",
+              statusCode: 524,
+              isRetryable: true,
+              responseBody: "<title>mengmota.com | 524: A timeout occurred</title>",
+            },
+          },
+        },
+      },
+    })
+
+    //#then
+    expect(promptCalls).toHaveLength(1)
+    const promptBody = promptCalls[0]?.body as { model?: { providerID?: string; modelID?: string } } | undefined
+    expect(promptBody?.model).toEqual({ providerID: "openai", modelID: "gpt-5.4" })
+  })
+})
diff --git a/src/hooks/runtime-fallback/error-classifier.test.ts b/src/hooks/runtime-fallback/error-classifier.test.ts
index a7f43210a..fb311990e 100644
--- a/src/hooks/runtime-fallback/error-classifier.test.ts
+++ b/src/hooks/runtime-fallback/error-classifier.test.ts
@@ -74,6 +74,61 @@ describe("runtime-fallback error classifier", () => {
     expect(retryable).toEqual([true, true, true])
   })
 
+  test("treats nested AI SDK retryable Cloudflare timeout errors as retryable", () => {
+    //#given
+    const error = {
+      error: {
+        name: "AI_APICallError",
+        statusCode: 524,
+        isRetryable: true,
+        responseBody: "<title>mengmota.com | 524: A timeout occurred</title>",
+      },
+    }
+
+    //#when
+    const retryable = isRetryableError(error, [429, 500, 502, 503, 504])
+
+    //#then
+    expect(retryable).toBe(true)
+  })
+
+  test("treats retryable AI SDK errors without configured status codes as retryable", () => {
+    //#given
+    const error = {
+      data: {
+        error: {
+          name: "AI_APICallError",
+          isRetryable: true,
+          message: "connection reset before response body arrived",
+        },
+      },
+    }
+
+    //#when
+    const retryable = isRetryableError(error, [429, 503, 529])
+
+    //#then
+    expect(retryable).toBe(true)
+  })
+
+  test("ignores malformed retryable flags on otherwise non-retryable errors", () => {
+    //#given
+    const error = {
+      error: {
+        name: "AI_APICallError",
+        statusCode: 400,
+        isRetryable: "true",
+        message: "Invalid request payload",
+      },
+    }
+
+    //#when
+    const retryable = isRetryableError(error, [429, 503, 529])
+
+    //#then
+    expect(retryable).toBe(false)
+  })
+
   test("classifies localized quota exhaustion messages as quota_exceeded", () => {
     //#given
     const errors = [
diff --git a/src/hooks/runtime-fallback/error-classifier.ts b/src/hooks/runtime-fallback/error-classifier.ts
index 6ba155101..76c970e81 100644
--- a/src/hooks/runtime-fallback/error-classifier.ts
+++ b/src/hooks/runtime-fallback/error-classifier.ts
@@ -97,6 +97,28 @@ export function extractErrorName(error: unknown): string | undefined {
   return undefined
 }
 
+export function extractRetryableSignal(error: unknown): boolean | undefined {
+  if (!error || typeof error !== "object") return undefined
+
+  const errorObj = error as Record<string, unknown>
+  const paths = [
+    errorObj,
+    errorObj.data,
+    errorObj.error,
+    (errorObj.data as Record<string, unknown> | undefined)?.error,
+    errorObj.cause,
+  ]
+
+  for (const obj of paths) {
+    if (obj && typeof obj === "object") {
+      const retryable = (obj as Record<string, unknown>).isRetryable
+      if (typeof retryable === "boolean") return retryable
+    }
+  }
+
+  return undefined
+}
+
 function isLocalizedQuotaExhaustionMessage(message: string): boolean {
   return (
     (/预扣费额度失败/i.test(message) && /用户剩余额度/i.test(message)) ||
@@ -199,5 +221,9 @@ export function isRetryableError(error: unknown, retryOnErrors: number[]): boole
     return true
   }
 
+  if (extractRetryableSignal(error) === true) {
+    return true
+  }
+
   return RETRYABLE_ERROR_PATTERNS.some((pattern) => pattern.test(message))
 }