fix: lazy session_id — generated on first agent invocation, not at startup

agent.json

@@ -9,8 +9,12 @@
   "work_dir": "/root/projects/team-board",
   "model": "sonnet",
   "provider": "anthropic",
-  "capabilities": ["coding", "review"],
+  "capabilities": [
+    "coding",
+    "review"
+  ],
   "max_concurrent_tasks": 2,
   "heartbeat_interval_sec": 30,
-  "allowed_paths": []
+  "allowed_paths": [],
+  "session_id": "858c3419-e6a6-4487-940d-f28508784a49"
 }

src/config.ts

@@ -36,6 +36,33 @@ export interface AgentConfig {
   allowedPaths: string[];
   /** Persistent session UUID — survives renames. Stored in agent.json. */
   sessionId: string;
+  /** Internal: path to config file for lazy session_id write-back */
+  _configPath: string | null;
+  /** Internal: parsed config data for write-back */
+  _configData: Record<string, unknown>;
+}
+
+/**
+ * Ensure agent has a persistent session_id.
+ * Call lazily on first agent invocation, not at startup.
+ * Generates UUID and writes it back to agent.json.
+ */
+export function ensureSessionId(config: AgentConfig): string {
+  if (config.sessionId) return config.sessionId;
+
+  const id = crypto.randomUUID();
+  config.sessionId = id;
+
+  if (config._configPath) {
+    try {
+      config._configData.session_id = id;
+      fs.writeFileSync(config._configPath, JSON.stringify(config._configData, null, 2) + '\n');
+    } catch {
+      // Non-fatal
+    }
+  }
+
+  return id;
 }
 
 const homeDir = os.homedir();
@@ -162,30 +189,8 @@ export function loadAgentConfig(): AgentConfig {
     apiKey: process.env.PICOGENT_API_KEY || process.env.ANTHROPIC_API_KEY || (file.api_key as string) || '',
     heartbeatIntervalSec: (file.heartbeat_interval_sec as number) || 30,
     allowedPaths: (file.allowed_paths as string[]) || [],
-    sessionId: ensureSessionId(file, configPath),
+    sessionId: (file.session_id as string) || '',
+    _configPath: configPath,
+    _configData: file,
   };
 }
-
-/**
- * Ensure agent.json has a persistent session_id.
- * Generates UUID on first run and writes it back to the config file.
- */
-function ensureSessionId(file: Record<string, unknown>, configPath: string | null): string {
-  if (file.session_id && typeof file.session_id === 'string') {
-    return file.session_id;
-  }
-
-  const id = crypto.randomUUID();
-
-  // Persist to agent.json if we have a path
-  if (configPath) {
-    try {
-      file.session_id = id;
-      fs.writeFileSync(configPath, JSON.stringify(file, null, 2) + '\n');
-    } catch {
-      // Non-fatal — session works in memory
-    }
-  }
-
-  return id;
-}

src/router.ts

@@ -4,7 +4,7 @@ import { runAgent } from './agent.js';
 import { TrackerClient } from './tracker/client.js';
 import { createTrackerTools } from './tools/index.js';
 import type { ToolDefinition } from '@mariozechner/pi-coding-agent';
-import type { AgentConfig } from './config.js';
+import { ensureSessionId, type AgentConfig } from './config.js';
 import type { TrackerEvent, TrackerTask } from './tracker/types.js';
 
 export interface TaskTracker {
@@ -16,20 +16,16 @@ export class EventRouter {
   private log = logger.child({ component: 'event-router' });
   private activeTasks = 0;
   private trackerTools: ToolDefinition[];
-  /** Single session ID for the entire agent lifetime. */
-  private readonly sessionId: string;
-
   constructor(
     private config: AgentConfig,
     private client: TrackerClient,
     private taskTracker: TaskTracker,
   ) {
-    this.sessionId = config.sessionId;
     this.trackerTools = createTrackerTools({
       trackerClient: client,
       agentSlug: config.slug,
     });
-    this.log.info({ toolCount: this.trackerTools.length, sessionId: this.sessionId }, 'Tracker tools registered');
+    this.log.info({ toolCount: this.trackerTools.length }, 'Tracker tools registered');
   }
 
   async handleEvent(event: TrackerEvent): Promise<void> {
@@ -90,7 +86,7 @@ export class EventRouter {
       let collectedText = '';
       for await (const msg of runAgent(prompt, {
         workDir: this.config.workDir,
-        sessionId: this.sessionId,
+        sessionId: ensureSessionId(this.config),
         model: this.config.model,
         provider: this.config.provider,
         systemPrompt: this.config.prompt || undefined,
@@ -162,7 +158,7 @@ export class EventRouter {
     let collectedText = '';
     for await (const msg of runAgent(content, {
       workDir: this.config.workDir,
-      sessionId: this.sessionId,
+      sessionId: ensureSessionId(this.config),
       model: this.config.model,
       provider: this.config.provider,
       systemPrompt: this.config.prompt || undefined,