fix(ai): retry HTTP/2 pending stream cancellation

Bedrock's HTTP/2 connection can stall until the SDK's 5-minute session
timeout, which fails the request with "The pending stream has been
canceled" (ERR_HTTP2_STREAM_CANCEL). The request was never sent, so it
is safe to retry, but the message was only retried when a DNS cause was
appended.

closes #10379

packages/ai/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed Bedrock requests that fail with `The pending stream has been canceled` after a stalled HTTP/2 connection not being retried automatically ([#10379](https://github.com/earendil-works/pi/issues/10379))
+
 ## [1.0.3] - 2026-10-05
 
 ### Breaking Changes

packages/ai/src/utils/retry.ts

@@ -81,6 +81,9 @@ const RETRYABLE_PROVIDER_ERROR_PATTERN = buildProviderErrorPattern([
 	"stream ended before message_stop",
 	"stream ended before a terminal response event",
 	"http2 request did not get a response",
+	// Node ERR_HTTP2_STREAM_CANCEL: the HTTP/2 session died before the request was
+	// sent, e.g. after the Bedrock SDK's 5-minute session timeout (#10379).
+	"pending stream has been canceled",
 
 	// Provider-requested retry delay cap failures should flow through the outer
 	// retry policy so callers can surface/abort the backoff (#1123).

packages/ai/test/retry.test.ts

@@ -62,6 +62,14 @@ describe("provider retry classification", () => {
 		expect(isRetryableAssistantError(fauxAssistantMessage("", { stopReason: "error", errorMessage }))).toBe(true);
 	});
 
+	it.each(["The pending stream has been canceled", "The pending stream has been canceled (caused by: socket closed)"])(
+		"matches HTTP/2 pending stream cancellation: %s",
+		(errorMessage) => {
+			// Regression for #10379.
+			expect(isRetryableAssistantError(fauxAssistantMessage("", { stopReason: "error", errorMessage }))).toBe(true);
+		},
+	);
+
 	it("matches OpenAI Responses streams that end before terminal events", () => {
 		expect(
 			isRetryableAssistantError(