diff --git a/packages/ai/src/changes.md b/packages/ai/src/changes.md
index 73dab1aee..e51375e0a 100644
--- a/packages/ai/src/changes.md
+++ b/packages/ai/src/changes.md
@@ -1,5 +1,18 @@
 # AI Source Changes
 
+## 2026-07-26 - Retry transient Codex upstream websocket failures
+
+### What changed and why
+
+- `utils/retry.ts` classifies `upstream_unavailable` provider errors as transient so the existing bounded retry policy
+  retries Codex websocket proxy disconnects such as `ConnectionClosedOK`.
+- The retry classifier and coding-agent event-contract tests pin the exact reported error through the existing retry
+  lifecycle rather than introducing provider-specific retry behavior.
+
+### Expected merge conflict zones
+
+- LOW: `utils/retry.ts` transient transport error patterns.
+
 ## 2026-07-26 - Repair unpaired Anthropic server-tool blocks and let the pairing 400 retry
 
 ### What changed and why
diff --git a/packages/ai/src/utils/retry.ts b/packages/ai/src/utils/retry.ts
index 9840a9f41..3e9fd7c90 100644
--- a/packages/ai/src/utils/retry.ts
+++ b/packages/ai/src/utils/retry.ts
@@ -55,6 +55,7 @@ const RETRYABLE_PROVIDER_ERROR_PATTERN = buildProviderErrorPattern([
 	"ENOTFOUND",
 	"EAI_AGAIN",
 	"upstream.?connect",
+	"upstream.?unavailable",
 	"reset before headers",
 	"socket hang up",
 	"socket connection was closed",
diff --git a/packages/ai/test/retry.test.ts b/packages/ai/test/retry.test.ts
index 9297b425c..10cd466d7 100644
--- a/packages/ai/test/retry.test.ts
+++ b/packages/ai/test/retry.test.ts
@@ -12,6 +12,8 @@ const bunFetchSocketClosedMessage =
 const openAIResponsesEarlyEofMessage = "OpenAI Responses stream ended before a terminal response event";
 const wrappedDnsLookupError =
 	"The pending stream has been canceled (caused by: getaddrinfo ENOTFOUND bedrock-runtime.us-east-1.amazonaws.com)";
+const codexUpstreamUnavailableMessage =
+	"Error: upstream_unavailable: Codex upstream websocket send failed via proxy endpoint unknown: ConnectionClosedOK";
 const anthropicOrphanServerToolMessage =
 	'400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.1: `web_search` tool use with id `srvtoolu_01Gchdhqw1UaCNUuVq2LhMH9` was found without a corresponding `web_search_tool_result` block"},"request_id":"req_011CdQL9JsEk5NWJxWQX4NiG"}';
 const anthropicInvalidMaxTokensMessage =
@@ -44,6 +46,14 @@ describe("provider retry classification", () => {
 		).toBe(true);
 	});
 
+	it("matches Codex upstream websocket unavailability", () => {
+		expect(
+			isRetryableAssistantError(
+				fauxAssistantMessage("", { stopReason: "error", errorMessage: codexUpstreamUnavailableMessage }),
+			),
+		).toBe(true);
+	});
+
 	it("classifies agent-loop stream idle timeouts as retryable", () => {
 		// Emitted by @earendil-works/pi-agent-core when a provider stream stops
 		// delivering events (e.g. a connection that died after a network change).
diff --git a/packages/coding-agent/test/suite/retry-fallback-engine.test.ts b/packages/coding-agent/test/suite/retry-fallback-engine.test.ts
index 076563330..646240c0f 100644
--- a/packages/coding-agent/test/suite/retry-fallback-engine.test.ts
+++ b/packages/coding-agent/test/suite/retry-fallback-engine.test.ts
@@ -6,6 +6,8 @@ import { createHarness, type Harness } from "./harness.ts";
 
 const primary = "faux/faux-1";
 const fallback = "faux/faux-2";
+const codexUpstreamUnavailableMessage =
+	"Error: upstream_unavailable: Codex upstream websocket send failed via proxy endpoint unknown: ConnectionClosedOK";
 
 type EventTranscriptEntry =
 	| { type: "message_start" | "message_end"; role: string }
@@ -637,7 +639,7 @@ describe("retry fallback engine", () => {
 		harness.setResponses([
 			fauxAssistantMessage("", {
 				stopReason: "error",
-				errorMessage: "overloaded_error",
+				errorMessage: codexUpstreamUnavailableMessage,
 			}),
 			fauxAssistantMessage("recovered"),
 		]);
@@ -662,7 +664,7 @@ describe("retry fallback engine", () => {
 				attempt: 1,
 				maxAttempts: 3,
 				delayMs: 1,
-				errorMessage: "overloaded_error",
+				errorMessage: codexUpstreamUnavailableMessage,
 			},
 			{ type: "agent_start" },
 			{ type: "turn_start" },