Fix agents.json race condition on concurrent starts

Re-read agents.json immediately before writing in startAgent to avoid
one start overwriting another's entry. Also clean stale sockets before
starting new agents.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/agent-manager.ts

@@ -251,6 +251,9 @@ export async function startAgent(
   mkdirSync(CONFIG.socketDir, { recursive: true });
   mkdirSync(CONFIG.runsDir, { recursive: true });
 
+  // Clean stale socket from previous run
+  try { unlinkSync(socketPath); } catch {}
+
   // Prepare rootfs
   copyFileSync(AGENT_ROOTFS, rootfsPath);
   injectAgentConfig(
@@ -321,8 +324,11 @@ export async function startAgent(
     startedAt: new Date().toISOString(),
   };
 
-  agents[name] = info;
-  saveAgents(agents);
+  // Re-read agents.json before writing to avoid race conditions
+  // (another startAgent may have written since we last read)
+  const currentAgents = loadAgents();
+  currentAgents[name] = info;
+  saveAgents(currentAgents);
 
   log(`Agent "${name}" started: nick=${nick} ip=${ip}`);
   return info;

src/overseer.ts

@@ -197,7 +197,7 @@ export async function runOverseer(config: OverseerConfig) {
     for (const name of knownAgents) {
       if (!currentNames.has(name)) {
         log(`Agent "${name}" died, cleaned up.`);
-        bot.say("#agents", `Agent "${name}" has died and been cleaned up.`);
+        bot.say(config.channel, `Agent "${name}" has died and been cleaned up.`);
       }
     }
     knownAgents = currentNames;