fix: persist usage from rpc

src/agents/agents.test.ts

@@ -57,4 +57,15 @@ describe("pi agent helpers", () => {
     expect(tool?.toolName).toBe("bash");
     expect(tool?.meta).toBe("ls -la");
   });
+
+  it("keeps usage meta even when assistant message has no text", () => {
+    const stdout = [
+      '{"type":"message_start","message":{"role":"assistant"}}',
+      '{"type":"message_end","message":{"role":"assistant","content":[{"type":"thinking","thinking":"hmm"}],"usage":{"input":10,"output":5},"model":"pi-1","provider":"inflection","stopReason":"end"}}',
+    ].join("\n");
+    const parsed = piSpec.parseOutput(stdout);
+    expect(parsed.texts?.length ?? 0).toBe(0);
+    expect((parsed.meta?.usage as { input?: number })?.input).toBe(10);
+    expect(parsed.meta?.model).toBe("pi-1");
+  });
 });

src/agents/pi.ts

@@ -95,10 +95,11 @@ function parsePiJson(raw: string): AgentParseResult {
         .trim();
 
       if (isAssistantMessage) {
+        // Always remember the last assistant message so we keep usage/model meta even when no text.
+        lastAssistant = msg;
         if (msgText && msgText !== lastPushed) {
           texts.push(msgText);
           lastPushed = msgText;
-          lastAssistant = msg;
         }
       } else if (isToolResult && msg.content) {
         const toolText = msg.content
@@ -119,15 +120,14 @@ function parsePiJson(raw: string): AgentParseResult {
     }
   }
 
-  const meta: AgentMeta | undefined =
-    lastAssistant && texts.length
-      ? {
-          model: lastAssistant.model,
-          provider: lastAssistant.provider,
-          stopReason: lastAssistant.stopReason,
-          usage: lastAssistant.usage,
-        }
-      : undefined;
+  const meta: AgentMeta | undefined = lastAssistant
+    ? {
+        model: lastAssistant.model,
+        provider: lastAssistant.provider,
+        stopReason: lastAssistant.stopReason,
+        usage: lastAssistant.usage,
+      }
+    : undefined;
 
   return {
     texts,