fix(session): retried bare Request was aborted error-stop turns

A stalled or dropped provider stream that surfaces as stopReason:"error"
carrying the bare "Request was aborted" sentinel fell through both retry
gates: #isRetryableReasonlessAbort required stopReason:"aborted", and
#isRetryableError's classifier returns no retriable kinds for the generic
sentinel. The turn died immediately despite retry.enabled.

- Relaxed #isRetryableReasonlessAbort to accept an empty generic-abort
  sentinel turn under stopReason "aborted" or "error", tagging it Abort so
  #handleRetryableError retries it without model fallback.
- Kept the deliberate-abort guards intact: user interrupts and silent aborts
  carry their own markers (not the generic sentinel), and #abortInProgress /
  #isDisposed / #streamingEditAbortTriggered still settle without retry.
- Rewrote the stale fallback test that froze the buggy no-retry behavior to
  assert retry-and-recover for the error-stop sentinel.

Fixes #5375

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed a bare `Request was aborted` provider abort that arrives as `stopReason: "error"` (a stalled or dropped stream reported as an error rather than an abort) never being auto-retried despite `retry.enabled`. The reason-less-abort retry gate now recognizes the empty generic-abort sentinel under either `stopReason: "aborted"` or `"error"`, while deliberate user interrupts, dispose-driven aborts, and streaming-edit guard aborts still settle without retry ([#5375](https://github.com/can1357/oh-my-pi/issues/5375)).
+
 ## [16.5.0] - 2026-07-13
 
 ### Breaking Changes

packages/coding-agent/src/session/agent-session.ts

@@ -13829,19 +13829,23 @@ export class AgentSession {
 	}
 
 	/**
-	 * Retry an empty, reason-less provider abort: a turn that ended `aborted`
-	 * with no content and the generic sentinel (bare `abort()`), but only while
-	 * the session is neither aborting nor tearing down. A user/lifecycle abort
-	 * (`#abortInProgress`), a dispose-driven abort (`#isDisposed`), or a
-	 * session-induced streaming-edit guard abort (`#streamingEditAbortTriggered` —
-	 * auto-generated-file guard or failed-patch preview) is deliberate and MUST
-	 * settle the turn instead: routing it through retry would orphan
-	 * `#retryPromise` on a continuation the guard skips (hanging the in-flight
-	 * `prompt()`) or silently undo the guard's intended abort.
+	 * Retry an empty, reason-less provider abort: a turn with no content that
+	 * carries the generic sentinel (bare `abort()`), whether the provider
+	 * finalized it as `stopReason: "aborted"` or leaked it as `stopReason:
+	 * "error"` (a stalled/dropped stream reported as an error rather than an
+	 * abort — issue #5375). Only fires while the session is neither aborting nor
+	 * tearing down. A user/lifecycle abort (`#abortInProgress`), a dispose-driven
+	 * abort (`#isDisposed`), or a session-induced streaming-edit guard abort
+	 * (`#streamingEditAbortTriggered` — auto-generated-file guard or failed-patch
+	 * preview) is deliberate and MUST settle the turn instead: routing it through
+	 * retry would orphan `#retryPromise` on a continuation the guard skips
+	 * (hanging the in-flight `prompt()`) or silently undo the guard's intended
+	 * abort. Deliberate user interrupts (`UserInterrupt`) and silent aborts carry
+	 * their own marker, not the generic sentinel, so they never match here.
 	 */
 	#isRetryableReasonlessAbort(message: AssistantMessage): boolean {
 		if (
-			message.stopReason !== "aborted" ||
+			(message.stopReason !== "aborted" && message.stopReason !== "error") ||
 			message.content.length !== 0 ||
 			this.#abortInProgress ||
 			this.#isDisposed ||
@@ -13851,7 +13855,7 @@ export class AgentSession {
 		}
 
 		const id = this.#classifyRetryMessage(message);
-		if (AIError.is(id, AIError.Flag.Abort)) return true;
+		if (message.stopReason === "aborted" && AIError.is(id, AIError.Flag.Abort)) return true;
 		if (!this.#isGenericAbortSentinel(message)) return false;
 
 		message.errorId = AIError.create(AIError.Flag.Abort);

packages/coding-agent/test/agent-session-retry-fallback.test.ts

@@ -1602,14 +1602,18 @@ describe("AgentSession retry fallback", () => {
 		expect(lastAssistant.errorMessage).toBe(envelopeError);
 	});
 
-	it("does not auto-retry generic Request was aborted. errors", async () => {
+	it("auto-retries a bare Request was aborted error-stop turn (issue #5375)", async () => {
 		const model = getBundledModel("openai", "gpt-4o-mini");
 		if (!model) {
 			throw new Error("Expected bundled OpenAI test model to exist");
 		}
 
 		const requestedModels: string[] = [];
-		const mock = createMockModel({ handler: () => ({ throw: "Request was aborted." }) });
+		// A stalled/dropped stream that the provider surfaces as stopReason:"error"
+		// carrying the bare abort sentinel, then a clean recovery on the retry.
+		const mock = createMockModel({
+			responses: [{ throw: "Request was aborted." }, { content: ["recovered after bare abort error"] }],
+		});
 		const agent = new Agent({
 			getApiKey: model => `${model.provider}-test-key`,
 			initialState: {
@@ -1637,17 +1641,23 @@ describe("AgentSession retry fallback", () => {
 			settings,
 			modelRegistry,
 		});
+		vi.spyOn(scheduler, "wait").mockResolvedValue(undefined);
 		const { retryStartEvents, retryEndEvents } = trackRetryEvents(session);
 
-		await session.prompt("Do not retry generic abort text");
+		await session.prompt("Retry the bare abort error");
 		await session.waitForIdle();
 
-		expect(requestedModels).toEqual([`${model.provider}/${model.id}`]);
-		expect(retryStartEvents).toHaveLength(0);
-		expect(retryEndEvents).toHaveLength(0);
+		// Same model, retried once (no model fallback for a reason-less abort).
+		expect(requestedModels).toEqual([`${model.provider}/${model.id}`, `${model.provider}/${model.id}`]);
+		expect(retryStartEvents).toHaveLength(1);
+		expect(retryEndEvents).toHaveLength(1);
+		expect(retryEndEvents[0]).toMatchObject({ success: true, attempt: 1 });
 		const lastAssistant = getLastAssistantMessage(session);
-		expect(lastAssistant.stopReason).toBe("error");
-		expect(lastAssistant.errorMessage).toBe("Request was aborted.");
+		expect(lastAssistant.stopReason).toBe("stop");
+		expect(lastAssistant.content).toContainEqual({
+			type: "text",
+			text: "recovered after bare abort error",
+		});
 	});
 
 	it("matches plain fallback roles for compat-routed primary models", async () => {