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/compose-contract.spec.ts

@@ -56,6 +56,55 @@ describe('composeContract — overlay composer', () => {
     rmSync(cwdDir, { recursive: true, force: true });
   });
 
+  it('injects the fleet comms cheat-sheet for a spawned fleet agent (situational)', () => {
+    // A spawned agent has MOSAIC_AGENT_NAME set + is a member of the roster.
+    mkdirSync(join(fixture.home, 'fleet'), { recursive: true });
+    writeFileSync(
+      join(fixture.home, 'fleet', 'roster.yaml'),
+      [
+        'version: 1',
+        'transport: tmux',
+        'agents:',
+        '  - name: orchestrator',
+        '    runtime: claude',
+        '    class: orchestrator',
+        '  - name: enhancer',
+        '    runtime: claude',
+        '    class: enhancer',
+        '  - name: coder0-0',
+        '    runtime: claude',
+        '    class: implementer',
+        '    host: 10.1.10.37',
+        '    ssh: jwoltje@10.1.10.37',
+        '',
+      ].join('\n'),
+    );
+    const prev = process.env['MOSAIC_AGENT_NAME'];
+    try {
+      process.env['MOSAIC_AGENT_NAME'] = 'enhancer';
+      const out = composeContract('claude', fixture.home);
+      expect(out).toContain('# Fleet Comms');
+      expect(out).toMatch(/`\[[^\]]+:enhancer\]`/); // own [host:session] identity (host machine-dependent)
+      // local peer → no -H; cross-host peer → -H ssh
+      expect(out).toContain('-s orchestrator -m "…"');
+      expect(out).toContain('-H jwoltje@10.1.10.37 -s coder0-0 -m "…"');
+      expect(out).not.toContain('-H jwoltje@10.1.10.37 -s orchestrator'); // local stays local
+    } finally {
+      if (prev === undefined) delete process.env['MOSAIC_AGENT_NAME'];
+      else process.env['MOSAIC_AGENT_NAME'] = prev;
+    }
+  });
+
+  it('does NOT inject fleet comms when MOSAIC_AGENT_NAME is unset (non-fleet launch)', () => {
+    const prev = process.env['MOSAIC_AGENT_NAME'];
+    try {
+      delete process.env['MOSAIC_AGENT_NAME'];
+      expect(composeContract('claude', fixture.home)).not.toContain('# Fleet Comms');
+    } finally {
+      if (prev !== undefined) process.env['MOSAIC_AGENT_NAME'] = prev;
+    }
+  });
+
   it('includes the per-tier anchors and the selected harness runtime', () => {
     const out = composeContract('claude', fixture.home);
     expect(out).toContain('GATE-1: the non-negotiable law.'); // L0

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');
 }