fix(bash): quarantined stalled shell sessions

Quarantined persistent session keys only while the native cancellation promise remains unsettled, so healthy cleanup restores persistent mode and stalled cleanup cannot accumulate live shell instances.

Added coverage for both stalled and settled native cleanup paths.

Fixes #1347

packages/coding-agent/test/bash-executor.test.ts

@@ -6,6 +6,7 @@ import { resetSettingsForTest, Settings } from "@oh-my-pi/pi-coding-agent/config
 import { executeBash } from "@oh-my-pi/pi-coding-agent/exec/bash-executor";
 import { DEFAULT_MAX_BYTES } from "@oh-my-pi/pi-coding-agent/session/streaming-output";
 import * as shellSnapshot from "@oh-my-pi/pi-coding-agent/utils/shell-snapshot";
+import type { Shell } from "@oh-my-pi/pi-natives";
 import * as piNatives from "@oh-my-pi/pi-natives";
 
 // Matches the schema default for `tools.artifactHeadBytes` (20 KB) used by
@@ -165,14 +166,20 @@ describe("executeBash", () => {
 		expect(result.output).toContain("Command cancelled");
 	});
 
-	it("returns promptly when native abort cleanup stalls", async () => {
+	it("returns promptly and quarantines the session key when native abort cleanup stalls", async () => {
 		if (process.platform === "win32") {
 			return;
 		}
 
-		vi.spyOn(piNatives.Shell.prototype, "run").mockImplementation((_options, onChunk) => {
-			onChunk?.(null, "started\n");
-			return new Promise(() => {});
+		const originalRun = piNatives.Shell.prototype.run;
+		let runCalls = 0;
+		vi.spyOn(piNatives.Shell.prototype, "run").mockImplementation(function (this: Shell, options, onChunk) {
+			runCalls++;
+			if (runCalls === 1) {
+				onChunk?.(null, "started\n");
+				return new Promise(() => {});
+			}
+			return originalRun.call(this, options, onChunk);
 		});
 		const abortSpy = vi.spyOn(piNatives.Shell.prototype, "abort").mockResolvedValue();
 
@@ -198,17 +205,51 @@ describe("executeBash", () => {
 		}
 		expect(abortSpy).toHaveBeenCalled();
 
+		const next = await executeBash("echo next", {
+			cwd: tempDir,
+			timeout: 5000,
+			sessionKey: "hung-native-abort",
+		});
+		expect(next.output.trim()).toBe("next");
+		expect(runCalls).toBe(1);
+	});
+
+	it("restores persistent sessions after native abort cleanup settles", async () => {
+		if (process.platform === "win32") {
+			return;
+		}
+
+		const nativeResult = Promise.withResolvers<{ exitCode: undefined; cancelled: true; timedOut: false }>();
+		vi.spyOn(piNatives.Shell.prototype, "run").mockImplementation((_options, onChunk) => {
+			onChunk?.(null, "started\n");
+			return nativeResult.promise;
+		});
+		vi.spyOn(piNatives.Shell.prototype, "abort").mockResolvedValue();
+
+		const controller = new AbortController();
+		const promise = executeBash("sleep 10", {
+			cwd: tempDir,
+			timeout: 5000,
+			signal: controller.signal,
+			sessionKey: "settled-native-abort",
+		});
+		await Bun.sleep(50);
+		controller.abort();
+		await promise;
+
+		nativeResult.resolve({ exitCode: undefined, cancelled: true, timedOut: false });
+		await Bun.sleep(0);
 		vi.restoreAllMocks();
 
 		await executeBash("export PI_AFTER_ABORT=still_persistent", {
 			cwd: tempDir,
 			timeout: 5000,
-			sessionKey: "hung-native-abort",
+			sessionKey: "settled-native-abort",
 		});
 		const next = await executeBash("printf '%s\n' \"$PI_AFTER_ABORT\"", {
 			cwd: tempDir,
 			timeout: 5000,
-			sessionKey: "hung-native-abort",
+			sessionKey: "settled-native-abort",
 		});
 		expect(next.output.trim()).toBe("still_persistent");
 	});