diff --git a/packages/opencode/src/kilocode/provider/error.ts b/packages/opencode/src/kilocode/provider/error.ts
index f432a85fc3..f6550544f4 100644
--- a/packages/opencode/src/kilocode/provider/error.ts
+++ b/packages/opencode/src/kilocode/provider/error.ts
@@ -9,8 +9,8 @@ export type Frame = {
 } & Record<string, unknown>
 
 const payload = z.looseObject({
-  code: z.union([z.string(), z.number()]).optional(),
-  message: z.string().optional(),
+  code: z.union([z.string(), z.number()]).nullish(),
+  message: z.string().nullish(),
 })
 
 // OpenAI Responses API terminal frame forwarded by @ai-sdk/openai >= 3.0.82
@@ -29,7 +29,7 @@ const wrapper = z.looseObject({
 // fields so gateway wrappers keep the specific inner code
 const bare = z.looseObject({
   type: z.undefined().optional(),
-  code: z.union([z.string(), z.number()]),
+  code: z.union([z.string(), z.number(), z.null()]),
   message: z.string(),
 })
 
@@ -49,6 +49,9 @@ export function frame(body: unknown): Frame {
 }
 
 const RETRYABLE = /rate.?limit|too.?many.?requests|rate increased too quickly|exhausted|overload|server|unavailable|timeout/i
+// Session.retryable only matched these phrases against free-form message
+// text; the wider pattern above is for structured code/type fields only
+const RETRYABLE_TEXT = /rate increased too quickly|rate limit|too many requests/i
 
 // Must stay at least as permissive as the Session.retryable heuristics that
 // applied when these frames still surfaced as NamedError.Unknown, or
@@ -63,7 +66,7 @@ function retryable(error: Frame["error"], message: string) {
   }
   const type = error?.type
   if (typeof type === "string" && RETRYABLE.test(type)) return true
-  return RETRYABLE.test(message)
+  return RETRYABLE_TEXT.test(message)
 }
 
 /**
diff --git a/packages/opencode/test/kilocode/provider/error.test.ts b/packages/opencode/test/kilocode/provider/error.test.ts
index 3db0548a3a..8139abdcc0 100644
--- a/packages/opencode/test/kilocode/provider/error.test.ts
+++ b/packages/opencode/test/kilocode/provider/error.test.ts
@@ -187,6 +187,45 @@ describe("responses api terminal frames", () => {
     expect(result.data.isRetryable).toBe(true)
   })
 
+  test("normalizes error objects with explicit null fields", () => {
+    const payload = {
+      error: {
+        message: "The server had an error while processing your request",
+        type: "server_error",
+        param: null,
+        code: null,
+      },
+    }
+    const result = MessageV2.fromError(payload, { providerID: ProviderV2.ID.make("openai") })
+
+    expect(MessageV2.APIError.isInstance(result)).toBe(true)
+    if (!MessageV2.APIError.isInstance(result)) throw new Error("expected APIError")
+    expect(result.data.message).toBe(payload.error.message)
+    expect(result.data.isRetryable).toBe(true)
+  })
+
+  test("normalizes response.failed frames with a null error code", () => {
+    const payload = {
+      type: "response.failed",
+      response: { error: { code: null, message: "mid-stream failure" }, incomplete_details: null },
+    }
+    const result = MessageV2.fromError(payload, { providerID: ProviderV2.ID.make("openai") })
+
+    expect(MessageV2.APIError.isInstance(result)).toBe(true)
+    if (!MessageV2.APIError.isInstance(result)) throw new Error("expected APIError")
+    expect(result.data.message).toBe("mid-stream failure")
+    expect(result.data.isRetryable).toBe(false)
+  })
+
+  test("does not retry terminal errors that merely mention availability", () => {
+    const payload = { code: "invalid_request", message: "The model is unavailable in your region" }
+    const result = MessageV2.fromError(payload, { providerID: ProviderV2.ID.make("openai") })
+
+    expect(MessageV2.APIError.isInstance(result)).toBe(true)
+    if (!MessageV2.APIError.isInstance(result)) throw new Error("expected APIError")
+    expect(result.data.isRetryable).toBe(false)
+  })
+
   test("ignores response.failed frames without an error payload", () => {
     const payload = { type: "response.failed", response: { error: null, incomplete_details: null } }
     const result = MessageV2.fromError(payload, { providerID: ProviderV2.ID.make("openai") })