fix(opencode): classify ZlibError from Bun fetch as retryable instead of unknown (#19104)

Co-authored-by: Aiden Cline <63023139+rekram1-node@users.noreply.github.com>

packages/opencode/test/session/message-v2.test.ts

@@ -927,4 +927,31 @@ describe("session.message-v2.fromError", () => {
       },
     })
   })
+
+  test("classifies ZlibError from fetch as retryable APIError", () => {
+    const zlibError = new Error(
+      'ZlibError fetching "https://opencode.cloudflare.dev/anthropic/messages". For more information, pass `verbose: true` in the second argument to fetch()',
+    )
+    ;(zlibError as any).code = "ZlibError"
+    ;(zlibError as any).errno = 0
+    ;(zlibError as any).path = ""
+
+    const result = MessageV2.fromError(zlibError, { providerID })
+
+    expect(MessageV2.APIError.isInstance(result)).toBe(true)
+    expect((result as MessageV2.APIError).data.isRetryable).toBe(true)
+    expect((result as MessageV2.APIError).data.message).toInclude("decompression")
+  })
+
+  test("classifies ZlibError as AbortedError when abort context is provided", () => {
+    const zlibError = new Error(
+      'ZlibError fetching "https://opencode.cloudflare.dev/anthropic/messages". For more information, pass `verbose: true` in the second argument to fetch()',
+    )
+    ;(zlibError as any).code = "ZlibError"
+    ;(zlibError as any).errno = 0
+
+    const result = MessageV2.fromError(zlibError, { providerID, aborted: true })
+
+    expect(result.name).toBe("MessageAbortedError")
+  })
 })

packages/opencode/test/session/retry.test.ts

@@ -125,6 +125,18 @@ describe("session.retry.retryable", () => {
 
     expect(SessionRetry.retryable(error)).toBeUndefined()
   })
+
+  test("retries ZlibError decompression failures", () => {
+    const error = new MessageV2.APIError({
+      message: "Response decompression failed",
+      isRetryable: true,
+      metadata: { code: "ZlibError" },
+    }).toObject() as MessageV2.APIError
+
+    const retryable = SessionRetry.retryable(error)
+    expect(retryable).toBeDefined()
+    expect(retryable).toBe("Response decompression failed")
+  })
 })
 
 describe("session.message-v2.fromError", () => {