fix(pi): require Reload after the native process exits (#8718)

Reject new turns before accepting work into a known dead Pi runtime. Keep process liveness separate from explicit session cleanup so Reload can still release resources and resume the conversation.

Co-authored-by: paseo-bot[bot] <266920839+paseo-bot[bot]@users.noreply.github.com>

packages/server/src/server/agent/providers/pi/agent.test.ts

@@ -2194,6 +2194,33 @@ describe("PiRpcAgentSession", () => {
     });
   });
 
+  test.each([false, true])(
+    "rejects new turns with Reload guidance after the Pi process exits (active: %s)",
+    async (active) => {
+      const { pi, session, events } = await createSession();
+      try {
+        if (active) {
+          await session.startTurn("before crash");
+        }
+        const runtime = pi.latestSession();
+        runtime.emit({ type: "process_exit", error: "Pi exited" });
+        if (active) {
+          await expect(events.nextTurnFailure()).resolves.toMatchObject({ error: "Pi exited" });
+        }
+        const promptCount = runtime.prompts.length;
+
+        for (let attempt = 0; attempt < 2; attempt += 1) {
+          await expect(session.startTurn("after crash")).rejects.toThrow(
+            "Pi process exited. Reload agent before sending another message.",
+          );
+        }
+        expect(runtime.prompts).toHaveLength(promptCount);
+      } finally {
+        await session.close();
+      }
+    },
+  );
+
   test("fails an autonomous turn when the Pi process exits before settlement", async () => {
     const { pi, events } = await createSession();
     const fakeSession = pi.latestSession();

packages/server/src/server/agent/providers/pi/agent.ts

@@ -1223,6 +1223,7 @@ export class PiRpcAgentSession implements AgentSession {
   private readonly logger: Logger;
   private readonly usagePoller: PiUsagePoller;
   private closed = false;
+  private runtimeDead = false;
   private readonly closeController = new AbortController();
   private readonly pendingExtensionHydrations = new Set<Promise<void>>();
   private pendingOutput: Promise<void> | null = null;
@@ -1305,6 +1306,9 @@ export class PiRpcAgentSession implements AgentSession {
   }
 
   async startTurn(prompt: AgentPromptInput, options?: AgentRunOptions): Promise<StartTurnResult> {
+    if (this.runtimeDead) {
+      throw new Error("Pi process exited. Reload agent before sending another message.");
+    }
     if (this.activeTurnId) {
       throw new Error("A Pi turn is already active");
     }
@@ -2190,6 +2194,7 @@ export class PiRpcAgentSession implements AgentSession {
   }
 
   private handleProcessExit(error: string): void {
+    this.runtimeDead = true;
     this.rejectAllExtensionResults(new Error(error));
     this.interruptingTurn = null;
     if (!this.activeTurnId && !this.activeTurnStarted) {