feat(fleet): onboarding-injection — comms cheat-sheet + peer roster per agent (#621)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

packages/mosaic/src/commands/launch.ts

@@ -19,6 +19,7 @@ import { createRequire } from 'node:module';
 import { homedir } from 'node:os';
 import { join, dirname } from 'node:path';
 import type { Command } from 'commander';
+import { readFleetCommsBlock } from '../fleet/comms-onboarding.js';
 
 const MOSAIC_HOME = process.env['MOSAIC_HOME'] ?? join(homedir(), '.config', 'mosaic');
 
@@ -383,6 +384,12 @@ For required push/merge/issue-close/release actions, execute without routine con
   // Runtime-specific contract
   parts.push('\n\n# Runtime-Specific Contract\n\n' + readFileSync(runtimeFile, 'utf-8'));
 
+  // Fleet onboarding: when this is a spawned fleet agent (MOSAIC_AGENT_NAME set
+  // and present in the roster), inject a comms cheat-sheet + peer roster so it
+  // knows how to reach the orchestrator and its peers from its first turn.
+  const fleetComms = readFleetCommsBlock(mosaicHome, process.env['MOSAIC_AGENT_NAME']);
+  if (fleetComms) parts.push('\n\n' + fleetComms);
+
   return parts.join('\n');
 }