Fix: strip page-controlled poller fields before they reach the agent (#488)

A page-supplied _instructions suppressed the locally generated next step and was presented as authoritative over live.md. Drop reserved poller-owned fields at ingest and always overwrite them locally.

AI assistance: implemented with Cursor Grok 4.6.

Co-authored-by: Cursor <cursoragent@cursor.com>

skill/scripts/live-poll.mjs

@@ -238,10 +238,9 @@ export async function completeAcceptHandling(event, base, token) {
     });
   } catch (err) {
     event._completionAck = { ok: false, error: err.message };
+    return event;
   }
-  if (!event._completionAck) {
-    event._completionAck = completionAckForAcceptResult(event.id, completionType, event._acceptResult);
-  }
+  event._completionAck = completionAckForAcceptResult(event.id, completionType, event._acceptResult);
   return event;
 }
 
@@ -269,9 +268,11 @@ export function printPollEvent(event) {
   // Situational plumbing rides with the event itself: `_instructions` is the
   // authoritative next step, with real ids and paths substituted, so the
   // reference doc can stay lean and can never drift from script behavior.
-  if (event && typeof event === 'object' && !event._instructions) {
+  // A wire-supplied value must never win over the locally generated one.
+  if (event && typeof event === 'object') {
     const instructions = instructionsForEvent(event, { scriptsPath: SELF_DIR });
     if (instructions) event._instructions = instructions;
+    else delete event._instructions;
   }
   console.log(JSON.stringify(event));
 }

skill/scripts/live-server.mjs

@@ -181,8 +181,16 @@ function chatAgentLikelyActive() {
 // cap at 10 MB to guard against runaway writes from a misbehaving client.
 const MAX_ANNOTATION_BYTES = 10 * 1024 * 1024;
 
+const POLLER_OWNED_EVENT_FIELDS = ['_instructions', '_completionAck', '_acceptResult'];
+
+function stripPollerOwnedEventFields(event) {
+  if (!event || typeof event !== 'object') return;
+  for (const key of POLLER_OWNED_EVENT_FIELDS) delete event[key];
+}
+
 function enqueueEvent(event) {
   if (!event) return;
+  stripPollerOwnedEventFields(event);
   // Dedupe by (session, type), except mount failures, which are per-variant:
   // variant 2 failing must not be swallowed because variant 1's failure is
   // still queued.
@@ -1026,6 +1034,7 @@ function createRequestHandler({ detectScript, liveScriptParts }) {
           res.end(JSON.stringify({ error }));
           return;
         }
+        stripPollerOwnedEventFields(msg);
         if (msg.type === 'agent_phase') {
           recordAgentPhase(msg.id, msg.phase, {
             ...(Number.isFinite(msg.durationMs) ? { durationMs: msg.durationMs } : {}),