surface pi process errors to web ui

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/servers/api/pi/pi-bridge.ts

@@ -346,8 +346,8 @@ export async function spawnPi(
           if (!line.trim()) continue;
           try {
             const event = JSON.parse(line) as Record<string, unknown>;
-            const piEvent = parsePiEvent(event, streamBuffer);
-            if (piEvent) {
+            const piEvents = parsePiEvent(event, streamBuffer);
+            for (const piEvent of piEvents) {
               if (piEvent.type === 'delta') {
                 streamBuffer += piEvent.text;
               } else if (piEvent.type === 'text' || piEvent.type === 'tool:start') {
@@ -404,37 +404,60 @@ export async function spawnPi(
   return proc;
 }
 
-function parsePiEvent(event: Record<string, unknown>, currentStreamBuffer: string): PiEvent | null {
+function parseErrorMessage(raw: string): string {
+  try {
+    const parsed = JSON.parse(raw.replace(/^\d+\s*/, ''));
+    const inner = parsed?.error;
+    if (inner?.message) return inner.message;
+  } catch {
+    // not JSON
+  }
+  return raw;
+}
+
+function extractMessageError(msg: Record<string, unknown>): string | null {
+  if (msg.stopReason !== 'error') return null;
+  const raw = msg.errorMessage as string | undefined;
+  if (!raw) return null;
+  return parseErrorMessage(raw);
+}
+
+function parsePiEvent(event: Record<string, unknown>, currentStreamBuffer: string): PiEvent[] {
   const type = event.type as string;
 
   // Handle response (success/failure for commands)
   if (type === 'response') {
     if (event.command === 'prompt' && !event.success) {
       const errorMsg = (event.error as string) ?? 'Prompt failed';
-      return { type: 'error', message: errorMsg };
+      return [{ type: 'error', message: errorMsg }];
     }
-    return null;
+    return [];
   }
 
   switch (type) {
     case 'agent_start':
-      // No event to emit, just resets state
-      return null;
+      return [];
 
     case 'message_update': {
       const ame = event.assistantMessageEvent as Record<string, unknown> | undefined;
       if (ame?.type === 'text_delta') {
         const delta = ame.delta as string;
-        return { type: 'delta', text: delta };
+        return [{ type: 'delta', text: delta }];
       }
-      return null;
+      return [];
     }
 
     case 'message_end': {
+      const events: PiEvent[] = [];
       if (currentStreamBuffer) {
-        return { type: 'text', text: currentStreamBuffer };
+        events.push({ type: 'text', text: currentStreamBuffer });
       }
-      return null;
+      const msg = event.message as Record<string, unknown> | undefined;
+      if (msg) {
+        const errorText = extractMessageError(msg);
+        if (errorText) events.push({ type: 'error', message: errorText });
+      }
+      return events;
     }
 
     case 'tool_execution_start': {
@@ -442,12 +465,12 @@ function parsePiEvent(event: Record<string, unknown>, currentStreamBuffer: strin
       const toolName = (event.toolName as string) ?? 'unknown';
       const args = (event.args as Record<string, unknown>) ?? {};
 
-      return {
+      return [{
         type: 'tool:start',
         toolCallId,
         toolName,
         toolInput: args,
-      };
+      }];
     }
 
     case 'tool_execution_end': {
@@ -466,37 +489,40 @@ function parsePiEvent(event: Record<string, unknown>, currentStreamBuffer: strin
       const isError = (event.isError as boolean) ?? (resultObj?.isError as boolean) ?? false;
       const output = result != null ? (typeof result === 'string' ? result : JSON.stringify(result)) : '';
 
-      return {
+      return [{
         type: 'tool:result',
         toolCallId,
         output,
         isError,
-      };
+      }];
     }
 
     case 'agent_end': {
       const cost: MessageCost = { inputTokens: 0, outputTokens: 0, totalUSD: 0 };
+      const events: PiEvent[] = [];
       const messages = event.messages as Array<Record<string, unknown>> | undefined;
       if (messages) {
         for (const msg of messages) {
           const usage = msg.usage as Record<string, unknown> | undefined;
-          if (!usage) continue;
-          cost.inputTokens += (usage.input as number) ?? 0;
-          cost.outputTokens += (usage.output as number) ?? 0;
-          const usageCost = usage.cost as Record<string, unknown> | undefined;
-          if (usageCost) cost.totalUSD += (usageCost.total as number) ?? 0;
+          if (usage) {
+            cost.inputTokens += (usage.input as number) ?? 0;
+            cost.outputTokens += (usage.output as number) ?? 0;
+            const usageCost = usage.cost as Record<string, unknown> | undefined;
+            if (usageCost) cost.totalUSD += (usageCost.total as number) ?? 0;
+          }
+          const errorText = extractMessageError(msg);
+          if (errorText) events.push({ type: 'error', message: errorText });
         }
       }
-      return { type: 'result', cost };
+      events.push({ type: 'result', cost });
+      return events;
     }
 
-    case 'extension_ui_request': {
-      // Will be handled separately
-      return null;
-    }
+    case 'extension_ui_request':
+      return [];
 
     default:
-      return null;
+      return [];
   }
 }