feat(fleet): enhancer role + two-agent floor (orchestrator + enhancer) (#615)

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

packages/mosaic/src/commands/fleet.spec.ts

@@ -20,6 +20,7 @@ import {
   buildTmuxListSessionsCommand,
   classifySendResult,
   countOrchestrators,
+  countEnhancers,
   detectDrift,
   enableFleetUnits,
   FLEET_PROFILES,
@@ -1076,9 +1077,9 @@ describe('fleet-polish bundle — boot-survival symmetry', () => {
     }
   });
 
-  it('fleet init --write fails hard when a non-minimal profile lacks exactly one orchestrator', async () => {
-    // The general profile must yield exactly one orchestrator; the guarantee is
-    // enforced (not just warned). We assert the happy path writes cleanly.
+  it('fleet init --write enforces the two-agent floor (1 orchestrator + >=1 enhancer)', async () => {
+    // The general profile must yield exactly one orchestrator AND at least one
+    // enhancer; the guarantee is enforced (not just warned). Happy path writes cleanly.
     const home = await tempDir();
     const program = new Command();
     program.exitOverride();
@@ -1098,7 +1099,9 @@ describe('fleet-polish bundle — boot-survival symmetry', () => {
       ]);
       const written = await readFile(join(home, 'fleet', 'roster.yaml'), 'utf8');
       const orchestrators = (written.match(/class:\s*orchestrator/g) ?? []).length;
+      const enhancers = (written.match(/class:\s*enhancer/g) ?? []).length;
       expect(orchestrators).toBe(1);
+      expect(enhancers).toBeGreaterThanOrEqual(1);
     } finally {
       await rm(home, { recursive: true, force: true });
     }
@@ -2310,47 +2313,63 @@ describe('fleet preset rosters', () => {
     },
   );
 
-  it('general preset: orchestrator + one generalist worker', async () => {
+  it('general preset: orchestrator + enhancer + one generalist worker', async () => {
     const roster = await loadFleetRoster(join(examplesDir, 'general.yaml'));
-    expect(roster.agents.map((a) => a.name)).toEqual(['orchestrator', 'generalist']);
+    expect(roster.agents.map((a) => a.name)).toEqual(['orchestrator', 'enhancer', 'generalist']);
     expect(roster.agents.find((a) => a.name === 'orchestrator')?.runtime).toBe('claude');
+    expect(roster.agents.find((a) => a.name === 'enhancer')?.className).toBe('enhancer');
     expect(roster.agents.find((a) => a.name === 'generalist')?.runtime).toBe('pi');
   });
 
-  it('coding preset: orchestrator + coder0 + coder1 + reviewer', async () => {
+  it('coding preset: orchestrator + enhancer + coder0 + coder1 + reviewer', async () => {
     const roster = await loadFleetRoster(join(examplesDir, 'coding.yaml'));
     expect(roster.agents.map((a) => a.name)).toEqual([
       'orchestrator',
+      'enhancer',
       'coder0',
       'coder1',
       'reviewer',
     ]);
   });
 
-  it('research preset: orchestrator + researcher0 + researcher1 + analyst', async () => {
+  it('research preset: orchestrator + enhancer + researcher0 + researcher1 + analyst', async () => {
     const roster = await loadFleetRoster(join(examplesDir, 'research.yaml'));
     expect(roster.agents.map((a) => a.name)).toEqual([
       'orchestrator',
+      'enhancer',
       'researcher0',
       'researcher1',
       'analyst',
     ]);
   });
 
-  it('hybrid preset: orchestrator + coder0 + researcher0 + reviewer', async () => {
+  it('hybrid preset: orchestrator + enhancer + coder0 + researcher0 + reviewer', async () => {
     const roster = await loadFleetRoster(join(examplesDir, 'hybrid.yaml'));
     expect(roster.agents.map((a) => a.name)).toEqual([
       'orchestrator',
+      'enhancer',
       'coder0',
       'researcher0',
       'reviewer',
     ]);
   });
 
+  it('every non-minimal preset carries an enhancer (two-agent floor)', async () => {
+    for (const preset of ['general', 'coding', 'research', 'hybrid'] as FleetProfile[]) {
+      const roster = await loadFleetRoster(join(examplesDir, `${preset}.yaml`));
+      expect(countOrchestrators(roster)).toBe(1);
+      expect(countEnhancers(roster)).toBeGreaterThanOrEqual(1);
+      expect(roster.agents.find((a) => a.className === 'enhancer')?.runtime).toBe('claude');
+    }
+  });
+
   it('worker agents in new presets use pi runtime with model_hint openai-codex/gpt-5.5:high', async () => {
     for (const preset of ['general', 'coding', 'research', 'hybrid'] as FleetProfile[]) {
       const roster = await loadFleetRoster(join(examplesDir, `${preset}.yaml`));
-      const workers = roster.agents.filter((a) => a.name !== 'orchestrator');
+      // Core agents (orchestrator + enhancer) run claude; only ephemeral workers are pi.
+      const workers = roster.agents.filter(
+        (a) => a.className !== 'orchestrator' && a.className !== 'enhancer',
+      );
       for (const worker of workers) {
         expect(worker.runtime).toBe('pi');
         expect(worker.modelHint).toBe('openai-codex/gpt-5.5:high');
@@ -2492,6 +2511,43 @@ describe('fleet add/remove — pure helpers', () => {
     expect(updated.agents.map((a) => a.name)).toEqual(['orchestrator2', 'coder0']);
   });
 
+  it('countEnhancers counts enhancer-class agents (two-agent floor)', () => {
+    const roster: FleetRoster = {
+      ...baseRoster,
+      agents: [
+        { name: 'orchestrator', runtime: 'claude', className: 'orchestrator' },
+        { name: 'enhancer', runtime: 'claude', className: 'enhancer' },
+        { name: 'coder0', runtime: 'codex', className: 'worker' },
+      ],
+    };
+    expect(countEnhancers(roster)).toBe(1);
+    expect(countEnhancers(baseRoster)).toBe(0);
+  });
+
+  it('removeAgentFromRoster throws when removing the sole enhancer (two-agent floor)', () => {
+    const roster: FleetRoster = {
+      ...baseRoster,
+      agents: [
+        { name: 'orchestrator', runtime: 'claude', className: 'orchestrator' },
+        { name: 'enhancer', runtime: 'claude', className: 'enhancer' },
+      ],
+    };
+    expect(() => removeAgentFromRoster(roster, 'enhancer')).toThrow('sole enhancer');
+  });
+
+  it('removeAgentFromRoster allows removing an enhancer when another remains', () => {
+    const roster: FleetRoster = {
+      ...baseRoster,
+      agents: [
+        { name: 'orchestrator', runtime: 'claude', className: 'orchestrator' },
+        { name: 'enhancer', runtime: 'claude', className: 'enhancer' },
+        { name: 'enhancer2', runtime: 'claude', className: 'enhancer' },
+      ],
+    };
+    const updated = removeAgentFromRoster(roster, 'enhancer');
+    expect(updated.agents.map((a) => a.name)).toEqual(['orchestrator', 'enhancer2']);
+  });
+
   it('serializeRosterToYaml produces YAML that round-trips through loadFleetRoster', async () => {
     const yaml = serializeRosterToYaml(baseRoster);
     expect(typeof yaml).toBe('string');