fix(interactive-subagents): avoid Orca polling fan-out

extensions/interactive-subagents/pi-extension/subagents/surface.ts

@@ -153,18 +153,28 @@ function readCompletionFile(path: string): PollResult | null {
   return { reason: "sentinel", exitCode };
 }
 
+type PollOptions = {
+  interval: number;
+  sessionFile?: string;
+  sentinelFile?: string;
+  completionFile?: string;
+  onTick?: (elapsed: number) => void;
+};
+
+/** Avoid launching a terminal CLI reader when a local completion signal is authoritative. */
+function shouldPollSurface(
+  options: Pick<PollOptions, "sessionFile" | "sentinelFile" | "completionFile">,
+): boolean {
+  return !options.sessionFile && !options.sentinelFile && !options.completionFile;
+}
+
 export const __pollForExitTest__ = { interpretExitSidecar, readCompletionFile };
 
 export async function pollForExit(
   surface: string,
   signal: AbortSignal,
-  options: {
-    interval: number;
-    sessionFile?: string;
-    sentinelFile?: string;
-    completionFile?: string;
-    onTick?: (elapsed: number) => void;
-  },
+  options: PollOptions,
+  readSurface: (surface: string, lines?: number) => Promise<string> = readScreenAsync,
 ): Promise<PollResult> {
   const start = Date.now();
 
@@ -197,12 +207,14 @@ export async function pollForExit(
       } catch {}
     }
 
-    try {
-      const screen = await readScreenAsync(surface, 5);
-      const match = screen.match(/__SUBAGENT_DONE_(\d+)__/);
-      if (match) return { reason: "sentinel", exitCode: Number.parseInt(match[1], 10) };
-    } catch {
-      // Surface reads are best-effort. Filesystem completion remains authoritative.
+    if (shouldPollSurface(options)) {
+      try {
+        const screen = await readSurface(surface, 5);
+        const match = screen.match(/__SUBAGENT_DONE_(\d+)__/);
+        if (match) return { reason: "sentinel", exitCode: Number.parseInt(match[1], 10) };
+      } catch {
+        // Surface reads are a best-effort fallback when no completion file is available.
+      }
     }
 
     const elapsed = Math.floor((Date.now() - start) / 1000);