fix(poll-loop): nudge agent when output lacks message wrapping

When the agent outputs bare text without <message to="..."> blocks,
nothing gets delivered — silent failure. Now the poll-loop pushes a
one-shot correction back into the active query telling the agent to
re-send with proper wrapping. Capped at once per user turn to avoid
loops; resets when a new follow-up message arrives.

Also updates destination instructions to require explicit <internal>
wrapping for scratchpad instead of treating bare text as implicit
scratchpad.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

container/agent-runner/src/destinations.test.ts

@@ -38,7 +38,7 @@ describe('buildSystemPromptAddendum — multi-destination routing guidance', ()
 
     const prompt = buildSystemPromptAddendum('Casa');
 
-    expect(prompt).toContain('Every response must be wrapped');
+    expect(prompt).toContain('All output must be wrapped');
     expect(prompt).toContain('<message to="name">');
     expect(prompt).toContain('`casa`');
   });
@@ -55,7 +55,7 @@ describe('buildSystemPromptAddendum — multi-destination routing guidance', ()
 
     const prompt = buildSystemPromptAddendum('Casa');
 
-    expect(prompt).toContain('Every response must be wrapped');
+    expect(prompt).toContain('All output must be wrapped');
     expect(prompt).toContain('<message to="name">');
     expect(prompt).toContain('Default routing');
     expect(prompt).toContain('`casa`');

container/agent-runner/src/destinations.ts

@@ -115,10 +115,9 @@ function buildDestinationsSection(): string {
     }
   }
   lines.push('');
-  lines.push('**Every response must be wrapped** in a `<message to="name">...</message>` block.');
+  lines.push('**All output must be wrapped.** Use `<message to="name">...</message>` for content to send, or `<internal>...</internal>` for scratchpad.');
   lines.push('You can include multiple `<message>` blocks in one response to send to multiple destinations.');
-  lines.push('Text outside of `<message>` blocks is scratchpad — logged but not sent anywhere.');
-  lines.push('Use `<internal>...</internal>` to make scratchpad intent explicit.');
+  lines.push('Bare text (outside of `<message>` or `<internal>` blocks) is not allowed and will not be delivered.');
   lines.push('');
   lines.push(
     '**Default routing**: when replying to an incoming message, address the same destination the message came `from` — every inbound `<message>` tag carries a `from="name"` attribute that names the origin destination. Only address a different destination when the request itself asks you to (e.g., "tell Laura that…").',

container/agent-runner/src/poll-loop.ts

@@ -1,4 +1,4 @@
-import { findByName, type DestinationEntry } from './destinations.js';
+import { findByName, getAllDestinations, type DestinationEntry } from './destinations.js';
 import { getPendingMessages, markProcessing, markCompleted, type MessageInRow } from './db/messages-in.js';
 import { writeMessageOut } from './db/messages-out.js';
 import { getInboundDb, touchHeartbeat, clearStaleProcessingAcks } from './db/connection.js';
@@ -265,6 +265,7 @@ async function processQuery(
 ): Promise<QueryResult> {
   let queryContinuation: string | undefined;
   let done = false;
+  let unwrappedNudged = false;
 
   // Concurrent polling: push follow-ups into the active query as they arrive.
   // We do NOT force-end the stream on silence — keeping the query open avoids
@@ -338,6 +339,7 @@ async function processQuery(
         const keptIds = keep.map((m) => m.id);
         const prompt = formatMessages(keep);
         log(`Pushing ${keep.length} follow-up message(s) into active query`);
+        unwrappedNudged = false;
         query.push(prompt);
         markCompleted(keptIds);
       } catch (err) {
@@ -376,7 +378,18 @@ async function processQuery(
         // at all — either way the turn is finished.
         markCompleted(initialBatchIds);
         if (event.text) {
-          dispatchResultText(event.text, routing);
+          const { hasUnwrapped } = dispatchResultText(event.text, routing);
+          if (hasUnwrapped && !unwrappedNudged) {
+            unwrappedNudged = true;
+            const destinations = getAllDestinations();
+            const names = destinations.map((d) => d.name).join(', ');
+            query.push(
+              `<system>Your response was not delivered — it was not wrapped in <message to="name">...</message> blocks. ` +
+                `All output must be wrapped: use <message to="name"> for content to send, or <internal> for scratchpad. ` +
+                `Your destinations: ${names}. ` +
+                `Please re-send your response with the correct wrapping.</system>`,
+            );
+          }
         }
       }
     }
@@ -415,7 +428,7 @@ function handleEvent(event: ProviderEvent, _routing: RoutingContext): void {
  * The agent must always wrap output in <message to="name">...</message>
  * blocks, even with a single destination. Bare text is scratchpad only.
  */
-function dispatchResultText(text: string, routing: RoutingContext): void {
+function dispatchResultText(text: string, routing: RoutingContext): { sent: number; hasUnwrapped: boolean } {
   const MESSAGE_RE = /<message\s+to="([^"]+)"\s*>([\s\S]*?)<\/message>/g;
 
   let match: RegExpExecArray | null;
@@ -450,9 +463,11 @@ function dispatchResultText(text: string, routing: RoutingContext): void {
     log(`[scratchpad] ${scratchpad.slice(0, 500)}${scratchpad.length > 500 ? '…' : ''}`);
   }
 
-  if (sent === 0 && text.trim()) {
+  const hasUnwrapped = sent === 0 && !!scratchpad;
+  if (hasUnwrapped) {
     log(`WARNING: agent output had no <message to="..."> blocks — nothing was sent`);
   }
+  return { sent, hasUnwrapped };
 }
 
 function sendToDestination(dest: DestinationEntry, body: string, routing: RoutingContext): void {