feat(routing): add pi canary guardrails and backend audit telemetry

src/daemon/routing.ts

@@ -164,6 +164,27 @@ function shouldForceNativeForCapabilityQuery(text: string): boolean {
   );
 }
 
+function shouldForceNativeForPiNoTools(text: string): boolean {
+  const normalized = text.trim().toLowerCase();
+  if (!normalized) {
+    return false;
+  }
+
+  if (
+    /`(?:shell\.exec|file\.(?:read|write|edit|patch|list)|web\.(?:fetch|search)|browser\.)/.test(normalized)
+    || /\b(?:gmail|calendar|docs|drive|tasks|k8s|docker|minio)\b/.test(normalized)
+  ) {
+    return true;
+  }
+
+  return (
+    /\b(?:run|execute)\s+(?:a\s+)?(?:shell|bash|command)\b/.test(normalized)
+    || /\b(?:read|open|show|edit|write|patch|delete|list)\s+(?:the\s+)?(?:file|files|directory|repo|code)\b/.test(normalized)
+    || /\b(?:search|fetch|browse|scrape)\s+(?:the\s+)?(?:web|internet|url|site)\b/.test(normalized)
+    || /\b(?:use|call)\s+(?:a\s+)?tool\b/.test(normalized)
+  );
+}
+
 function providerAcceptsNativeAudioContentParts(provider: string): boolean {
   return (
     provider === 'openai'
@@ -1390,11 +1411,26 @@ export function createMessageRouter(deps: {
 
       const requestedBackend = agentConfig?.backend ?? deps.defaultName;
       const forceNativeForCapabilityQuery = shouldForceNativeForCapabilityQuery(messageText);
-      const sessionIdForAudit = `${msg.channel}:${msg.senderId}`;
+      const hasAttachmentsForExternalBackend = Boolean(attachments && attachments.length > 0);
       const selectedBackend = requestedBackend && requestedBackend !== 'native'
         ? deps.externalBackends?.[requestedBackend]
         : undefined;
-      const selectedBackendForAudit: 'native' | ExternalBackendName = selectedBackend && requestedBackend && !forceNativeForCapabilityQuery
+      const externalBackendRequested = Boolean(selectedBackend && requestedBackend && requestedBackend !== 'native');
+      const forceNativeForPiNoTools = requestedBackend === 'pi_embedded'
+        && deps.config.backends.pi_embedded.no_tools_mode
+        && shouldForceNativeForPiNoTools(messageText);
+      let forcedNativeGuardReason: 'capability_query' | 'pi_no_tools_mode' | 'attachments_present' | undefined;
+      if (externalBackendRequested) {
+        if (forceNativeForCapabilityQuery) {
+          forcedNativeGuardReason = 'capability_query';
+        } else if (forceNativeForPiNoTools) {
+          forcedNativeGuardReason = 'pi_no_tools_mode';
+        } else if (hasAttachmentsForExternalBackend) {
+          forcedNativeGuardReason = 'attachments_present';
+        }
+      }
+      const sessionIdForAudit = `${msg.channel}:${msg.senderId}`;
+      const selectedBackendForAudit: 'native' | ExternalBackendName = selectedBackend && requestedBackend && !forcedNativeGuardReason
         ? requestedBackend
         : 'native';
 
@@ -1403,14 +1439,18 @@ export function createMessageRouter(deps: {
         channel: msg.channel,
         sender: msg.senderId,
         selected_backend: selectedBackendForAudit,
-        source: agentConfig?.backend
-          ? 'agent_override'
-          : selectedBackend
-            ? 'default_external'
-            : 'native',
+        source: forcedNativeGuardReason
+          ? 'forced_native_guard'
+          : agentConfig?.backend
+            ? 'agent_override'
+            : selectedBackend
+              ? 'default_external'
+              : 'native',
+        ...(forcedNativeGuardReason ? { guard_reason: forcedNativeGuardReason } : {}),
       });
 
-      if (selectedBackend && (!attachments || attachments.length === 0) && !forceNativeForCapabilityQuery) {
+      if (selectedBackend && !hasAttachmentsForExternalBackend && !forceNativeForCapabilityQuery && !forceNativeForPiNoTools) {
+        const backendStartedAt = Date.now();
         try {
           const history = toExternalHistory(session.getHistory());
           session.addMessage({ role: 'user', content: messageText });
@@ -1418,6 +1458,14 @@ export function createMessageRouter(deps: {
             prompt: messageText,
             history,
           });
+          auditLogger?.backendSuccess?.({
+            session_id: sessionIdForAudit,
+            channel: msg.channel,
+            sender: msg.senderId,
+            backend: selectedBackend.name,
+            duration_ms: Date.now() - backendStartedAt,
+            response_length: response.length,
+          });
           session.addMessage({ role: 'assistant', content: response });
           const ttsAttachment = await maybeBuildTtsAttachment(response, msg.channel);
           await reply({
@@ -1438,6 +1486,7 @@ export function createMessageRouter(deps: {
               : (selectedBackend.name as ExternalBackendName),
             to_backend: 'native',
             reason: detail,
+            duration_ms: Date.now() - backendStartedAt,
           });
         }
       }