fix: release Pi snapshots on failed initialization

backend/src/pi/pi-process-manager.ts

@@ -37,6 +37,7 @@ type SpawnFn = (
 
 export class PiProcessManager {
   private runtimes = new Map<string, SessionRuntime>();
+  private agentSnapshotCleanups = new WeakMap<ChildProcessWithoutNullStreams, () => void>();
   private spawnFn: (
     sessionId: string, author: string, provider: string | undefined, principal?: PrincipalContext,
     runtimeConfigPath?: string,
@@ -58,6 +59,13 @@ export class PiProcessManager {
     }
   }
 
+  private cleanupAgentSnapshot(child: ChildProcessWithoutNullStreams): void {
+    const cleanup = this.agentSnapshotCleanups.get(child);
+    if (!cleanup) return;
+    this.agentSnapshotCleanups.delete(child);
+    cleanup();
+  }
+
   private spawnPi(
     spawnFn: SpawnFn, sessionId: string, author: string, provider: string | undefined,
     principal?: PrincipalContext, runtimeConfigPath?: string,
@@ -104,16 +112,19 @@ export class PiProcessManager {
         cwd: this.cfg.harnessDir,
         env,
       });
-      child.once("exit", agent.cleanup);
-      child.once("close", agent.cleanup);
+      this.agentSnapshotCleanups.set(child, agent.cleanup);
+      child.once("exit", () => this.cleanupAgentSnapshot(child!));
+      child.once("close", () => this.cleanupAgentSnapshot(child!));
       // Log stderr for debugging (was silently drained)
       child.stderr.on("data", (d: Buffer) => console.error(`[pi:${sessionId}] stderr:`, d.toString().trim()));
       return child;
     } catch (error) {
       if (child) {
         try { child.kill(); } catch { /* preserve the initialization error */ }
+        this.cleanupAgentSnapshot(child);
+      } else {
+        agent.cleanup();
       }
-      agent.cleanup();
       throw error;
     }
   }
@@ -208,6 +219,7 @@ export class PiProcessManager {
       if (rt && this.runtimes.get(sessionId) === rt) this.runtimes.delete(sessionId);
       releaseRuntimeConfig();
       try { child.kill(); } catch { /* preserve the initialization error */ }
+      this.cleanupAgentSnapshot(child);
       throw error;
     }
   }
@@ -276,6 +288,7 @@ export class PiProcessManager {
     this.runtimes.delete(id);
     expected.releaseRuntimeConfig?.();
     expected.child.kill();
+    this.cleanupAgentSnapshot(expected.child);
     return true;
   }
 }