feat: add Pi subagent scheduler and child runtime

electron/coding-runtime/pi/session-projector.ts

@@ -12,6 +12,7 @@ import type {
   PiImageProjectionInput,
   PiProjectedAttachment,
 } from './event-projector';
+import { subagentDetailsOfResult } from '../subagent-protocol';
 
 export interface PiSessionSnapshotInput {
   snapshot: ConversationSnapshot;
@@ -184,6 +185,7 @@ async function projectEntries(
 ): Promise<ConversationNode[]> {
   const nodes: ConversationNode[] = [];
   const tools = new Map<string, ConversationToolNode>();
+  const subagentIds = new Set<string>();
   for (const entry of path) {
     if (entry.type === 'compaction') {
       nodes.push({
@@ -211,6 +213,27 @@ async function projectEntries(
         'output',
       );
       tool.status = message.isError === true ? 'error' : 'complete';
+      const details = subagentDetailsOfResult(message);
+      if (details) {
+        tool.details = details;
+        const id = `subagent:${details.dispatchId}`;
+        if (!subagentIds.has(id)) {
+          subagentIds.add(id);
+          nodes.push({
+            kind: 'subagent',
+            id,
+            runId: input.snapshot.run.runId ?? `session:${entry.id}`,
+            details,
+          });
+        }
+      } else if (tool.toolName === 'subagent' && message.details !== undefined) {
+        tool.output = [{
+          kind: 'text',
+          id: `${tool.id}:output:unavailable`,
+          text: 'Subagent details are unavailable for this version.',
+          status: 'complete',
+        }];
+      }
       continue;
     }
     if (message.role !== 'user' && message.role !== 'assistant') continue;