feat(fleet): orchestrator-mutable fleet — fleet add/remove (F5/R9)

- Pure helpers: addAgentToRoster, removeAgentFromRoster, serializeRosterToYaml
- fleet add <name> --runtime --class [--model] [--working-dir] [--no-start]
- fleet remove <name> [--keep-files]
- Guard: refuse to remove the sole orchestrator (R5)
- Unit tests for all pure helpers and command wiring via injected runner

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RMoEx7hfdFGjUiCHuN1RRi

packages/mosaic/framework/fleet/examples/coding.yaml

@@ -0,0 +1,32 @@
+version: 1
+transport: tmux
+tmux:
+  socket_name: mosaic-factory
+  holder_session: _holder
+defaults:
+  working_directory: ~
+runtimes:
+  claude:
+    reset_command: /clear
+  pi:
+    reset_command: /new
+agents:
+  - name: orchestrator
+    runtime: claude
+    class: orchestrator
+    persistent_persona: true
+  - name: coder0
+    runtime: pi
+    class: implementer
+    model_hint: openai-codex/gpt-5.5:high
+    reset_between_tasks: true
+  - name: coder1
+    runtime: pi
+    class: implementer
+    model_hint: openai-codex/gpt-5.5:high
+    reset_between_tasks: true
+  - name: reviewer
+    runtime: pi
+    class: reviewer
+    model_hint: openai-codex/gpt-5.5:high
+    reset_between_tasks: true

packages/mosaic/framework/fleet/examples/general.yaml

@@ -0,0 +1,22 @@
+version: 1
+transport: tmux
+tmux:
+  socket_name: mosaic-factory
+  holder_session: _holder
+defaults:
+  working_directory: ~
+runtimes:
+  claude:
+    reset_command: /clear
+  pi:
+    reset_command: /new
+agents:
+  - name: orchestrator
+    runtime: claude
+    class: orchestrator
+    persistent_persona: true
+  - name: generalist
+    runtime: pi
+    class: worker
+    model_hint: openai-codex/gpt-5.5:high
+    reset_between_tasks: true

packages/mosaic/framework/fleet/examples/hybrid.yaml

@@ -0,0 +1,32 @@
+version: 1
+transport: tmux
+tmux:
+  socket_name: mosaic-factory
+  holder_session: _holder
+defaults:
+  working_directory: ~
+runtimes:
+  claude:
+    reset_command: /clear
+  pi:
+    reset_command: /new
+agents:
+  - name: orchestrator
+    runtime: claude
+    class: orchestrator
+    persistent_persona: true
+  - name: coder0
+    runtime: pi
+    class: implementer
+    model_hint: openai-codex/gpt-5.5:high
+    reset_between_tasks: true
+  - name: researcher0
+    runtime: pi
+    class: researcher
+    model_hint: openai-codex/gpt-5.5:high
+    reset_between_tasks: true
+  - name: reviewer
+    runtime: pi
+    class: reviewer
+    model_hint: openai-codex/gpt-5.5:high
+    reset_between_tasks: true

packages/mosaic/framework/fleet/examples/research.yaml

@@ -0,0 +1,32 @@
+version: 1
+transport: tmux
+tmux:
+  socket_name: mosaic-factory
+  holder_session: _holder
+defaults:
+  working_directory: ~
+runtimes:
+  claude:
+    reset_command: /clear
+  pi:
+    reset_command: /new
+agents:
+  - name: orchestrator
+    runtime: claude
+    class: orchestrator
+    persistent_persona: true
+  - name: researcher0
+    runtime: pi
+    class: researcher
+    model_hint: openai-codex/gpt-5.5:high
+    reset_between_tasks: true
+  - name: researcher1
+    runtime: pi
+    class: researcher
+    model_hint: openai-codex/gpt-5.5:high
+    reset_between_tasks: true
+  - name: analyst
+    runtime: pi
+    class: analyst
+    model_hint: openai-codex/gpt-5.5:high
+    reset_between_tasks: true

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

@@ -4,6 +4,7 @@ import { dirname, join, resolve } from 'node:path';
 import { Command } from 'commander';
 import { afterEach, describe, expect, it, vi } from 'vitest';
 import {
+  addAgentToRoster,
   buildAgentSendCommand,
   buildAgentWatchAttachCommand,
   buildAgentWatchCommand,
@@ -17,8 +18,10 @@ import {
   buildTmuxListPanesCommand,
   buildTmuxListSessionsCommand,
   classifySendResult,
+  countOrchestrators,
   detectDrift,
   enableFleetUnits,
+  FLEET_PROFILES,
   generateAgentEnv,
   getDefaultOperatorSourceLabel,
   getDefaultTenantAndHost,
@@ -28,16 +31,21 @@ import {
   loadFleetRoster,
   mergeAgentEnv,
   parseHeartbeat,
+  parseInitProfile,
   parseSystemdShow,
   parseTmuxListPanes,
   parseTmuxListSessions,
   registerFleetCommand,
+  removeAgentFromRoster,
   resolveFleetPaths,
+  resolvePresetFilename,
   RUNTIME_ACCEPTABLE_COMMANDS,
+  serializeRosterToYaml,
   VERIFY_DEFAULT_TIMEOUT_MS,
   VERIFY_POLL_INTERVAL_MS,
   type AgentPsRow,
   type CommandRunner,
+  type FleetProfile,
   type FleetRoster,
   type InteractiveRunner,
   type SleepFn,
@@ -63,10 +71,12 @@ describe('registerFleetCommand', () => {
 
     expect(fleet).toBeDefined();
     expect(fleet!.commands.map((command) => command.name()).sort()).toEqual([
+      'add',
       'init',
       'install',
       'install-systemd',
       'ps',
+      'remove',
       'restart',
       'start',
       'status',
@@ -2132,3 +2142,736 @@ describe('agent send --verify', () => {
     expect(VERIFY_DEFAULT_TIMEOUT_MS).toBe(6_000);
   });
 });
+
+// ---------------------------------------------------------------------------
+// Fleet Phase F1: config-type presets + AI-free init wizard
+// ---------------------------------------------------------------------------
+
+describe('fleet preset rosters', () => {
+  const examplesDir = resolve(process.cwd(), 'framework', 'fleet', 'examples');
+
+  it.each(['general', 'coding', 'research', 'hybrid'] as FleetProfile[])(
+    '%s preset: loads via loadFleetRoster and has exactly one orchestrator',
+    async (preset) => {
+      const rosterPath = join(examplesDir, `${preset}.yaml`);
+      const roster = await loadFleetRoster(rosterPath);
+      expect(countOrchestrators(roster)).toBe(1);
+      expect(roster.agents.find((a) => a.name === 'orchestrator')).toBeDefined();
+    },
+  );
+
+  it('general preset: orchestrator + one generalist worker', async () => {
+    const roster = await loadFleetRoster(join(examplesDir, 'general.yaml'));
+    expect(roster.agents.map((a) => a.name)).toEqual(['orchestrator', 'generalist']);
+    expect(roster.agents.find((a) => a.name === 'orchestrator')?.runtime).toBe('claude');
+    expect(roster.agents.find((a) => a.name === 'generalist')?.runtime).toBe('pi');
+  });
+
+  it('coding preset: orchestrator + coder0 + coder1 + reviewer', async () => {
+    const roster = await loadFleetRoster(join(examplesDir, 'coding.yaml'));
+    expect(roster.agents.map((a) => a.name)).toEqual([
+      'orchestrator',
+      'coder0',
+      'coder1',
+      'reviewer',
+    ]);
+  });
+
+  it('research preset: orchestrator + researcher0 + researcher1 + analyst', async () => {
+    const roster = await loadFleetRoster(join(examplesDir, 'research.yaml'));
+    expect(roster.agents.map((a) => a.name)).toEqual([
+      'orchestrator',
+      'researcher0',
+      'researcher1',
+      'analyst',
+    ]);
+  });
+
+  it('hybrid preset: orchestrator + coder0 + researcher0 + reviewer', async () => {
+    const roster = await loadFleetRoster(join(examplesDir, 'hybrid.yaml'));
+    expect(roster.agents.map((a) => a.name)).toEqual([
+      'orchestrator',
+      'coder0',
+      'researcher0',
+      'reviewer',
+    ]);
+  });
+
+  it('worker agents in new presets use pi runtime with model_hint openai-codex/gpt-5.5:high', async () => {
+    for (const preset of ['general', 'coding', 'research', 'hybrid'] as FleetProfile[]) {
+      const roster = await loadFleetRoster(join(examplesDir, `${preset}.yaml`));
+      const workers = roster.agents.filter((a) => a.name !== 'orchestrator');
+      for (const worker of workers) {
+        expect(worker.runtime).toBe('pi');
+        expect(worker.modelHint).toBe('openai-codex/gpt-5.5:high');
+      }
+    }
+  });
+
+  it('orchestrator in new presets uses claude runtime with persistent_persona', async () => {
+    for (const preset of ['general', 'coding', 'research', 'hybrid'] as FleetProfile[]) {
+      const roster = await loadFleetRoster(join(examplesDir, `${preset}.yaml`));
+      const orch = roster.agents.find((a) => a.name === 'orchestrator');
+      expect(orch?.runtime).toBe('claude');
+      expect(orch?.persistentPersona).toBe(true);
+    }
+  });
+
+  it('new presets are sanitized: no operator identity tokens', async () => {
+    for (const preset of ['general', 'coding', 'research', 'hybrid'] as FleetProfile[]) {
+      const text = await readFile(join(examplesDir, `${preset}.yaml`), 'utf8');
+      expect(text).not.toMatch(/jarvis|jason|woltje/i);
+      // working_directory must not reference ~/src or /home
+      expect(text).not.toMatch(/~\/src|\/home\//);
+    }
+  });
+});
+
+describe('parseInitProfile', () => {
+  it('accepts all six fleet profiles', () => {
+    expect(parseInitProfile('general')).toBe('general');
+    expect(parseInitProfile('coding')).toBe('coding');
+    expect(parseInitProfile('research')).toBe('research');
+    expect(parseInitProfile('hybrid')).toBe('hybrid');
+    expect(parseInitProfile('minimal')).toBe('minimal');
+    expect(parseInitProfile('local-canary')).toBe('local-canary');
+  });
+
+  it('rejects unknown profiles with a message listing all valid names', () => {
+    expect(() => parseInitProfile('typo')).toThrow('Unsupported fleet profile');
+    expect(() => parseInitProfile('typo')).toThrow('general');
+    expect(() => parseInitProfile('typo')).toThrow('coding');
+  });
+
+  it('FLEET_PROFILES contains all six valid profile names', () => {
+    expect(FLEET_PROFILES).toContain('general');
+    expect(FLEET_PROFILES).toContain('coding');
+    expect(FLEET_PROFILES).toContain('research');
+    expect(FLEET_PROFILES).toContain('hybrid');
+    expect(FLEET_PROFILES).toContain('minimal');
+    expect(FLEET_PROFILES).toContain('local-canary');
+  });
+});
+
+describe('resolvePresetFilename', () => {
+  it.each(FLEET_PROFILES)('maps %s to %s.yaml', (profile) => {
+    expect(resolvePresetFilename(profile)).toBe(`${profile}.yaml`);
+  });
+});
+
+// ---------------------------------------------------------------------------
+// Fleet Phase F5: orchestrator-mutable fleet — pure helper tests (R9)
+// ---------------------------------------------------------------------------
+
+describe('fleet add/remove — pure helpers', () => {
+  const baseRoster: FleetRoster = {
+    version: 1,
+    transport: 'tmux',
+    tmux: { socketName: 'mosaic-factory', holderSession: '_holder' },
+    defaults: { workingDirectory: '~/src' },
+    runtimes: { codex: { resetCommand: '/clear' } },
+    agents: [
+      { name: 'orchestrator', runtime: 'claude', className: 'orchestrator' },
+      { name: 'coder0', runtime: 'codex', className: 'worker' },
+    ],
+  };
+
+  it('addAgentToRoster appends a new agent and returns a new roster object', () => {
+    const newAgent = { name: 'reviewer0', runtime: 'pi', className: 'worker' };
+    const updated = addAgentToRoster(baseRoster, newAgent);
+    expect(updated.agents).toHaveLength(3);
+    expect(updated.agents[2]).toEqual(newAgent);
+    // immutable — original unchanged
+    expect(baseRoster.agents).toHaveLength(2);
+    expect(updated).not.toBe(baseRoster);
+  });
+
+  it('addAgentToRoster throws on duplicate name', () => {
+    expect(() =>
+      addAgentToRoster(baseRoster, { name: 'coder0', runtime: 'claude', className: 'worker' }),
+    ).toThrow('Agent "coder0" already exists in the fleet roster.');
+  });
+
+  it('addAgentToRoster throws on invalid name (invalid characters)', () => {
+    expect(() =>
+      addAgentToRoster(baseRoster, { name: 'bad name!', runtime: 'claude', className: 'worker' }),
+    ).toThrow('Invalid fleet agent name');
+  });
+
+  it('addAgentToRoster throws on empty name', () => {
+    expect(() =>
+      addAgentToRoster(baseRoster, { name: '', runtime: 'claude', className: 'worker' }),
+    ).toThrow('Invalid fleet agent name');
+  });
+
+  it('removeAgentFromRoster removes the agent and returns new roster', () => {
+    const updated = removeAgentFromRoster(baseRoster, 'coder0');
+    expect(updated.agents).toHaveLength(1);
+    expect(updated.agents[0]!.name).toBe('orchestrator');
+    // immutable
+    expect(baseRoster.agents).toHaveLength(2);
+    expect(updated).not.toBe(baseRoster);
+  });
+
+  it('removeAgentFromRoster throws when agent not found', () => {
+    expect(() => removeAgentFromRoster(baseRoster, 'nonexistent')).toThrow(
+      'Agent "nonexistent" is not in the fleet roster.',
+    );
+  });
+
+  it('removeAgentFromRoster throws when removing the sole orchestrator (guard)', () => {
+    const rosterWithOnlyOrch: FleetRoster = {
+      ...baseRoster,
+      agents: [{ name: 'orchestrator', runtime: 'claude', className: 'orchestrator' }],
+    };
+    expect(() => removeAgentFromRoster(rosterWithOnlyOrch, 'orchestrator')).toThrow(
+      'sole orchestrator',
+    );
+  });
+
+  it('removeAgentFromRoster allows removing an orchestrator when another remains', () => {
+    const rosterWithTwoOrchs: FleetRoster = {
+      ...baseRoster,
+      agents: [
+        { name: 'orchestrator', runtime: 'claude', className: 'orchestrator' },
+        { name: 'orchestrator2', runtime: 'claude', className: 'orchestrator' },
+        { name: 'coder0', runtime: 'codex', className: 'worker' },
+      ],
+    };
+    const updated = removeAgentFromRoster(rosterWithTwoOrchs, 'orchestrator');
+    expect(updated.agents.map((a) => a.name)).toEqual(['orchestrator2', 'coder0']);
+  });
+
+  it('serializeRosterToYaml produces YAML that round-trips through loadFleetRoster', async () => {
+    const yaml = serializeRosterToYaml(baseRoster);
+    expect(typeof yaml).toBe('string');
+    expect(yaml).toContain('version: 1');
+    expect(yaml).toContain('name: orchestrator');
+    expect(yaml).toContain('name: coder0');
+
+    // Round-trip: write to disk and re-load
+    const dir = await mkdtemp(join(tmpdir(), 'mosaic-fleet-'));
+    const rosterPath = join(dir, 'roster.yaml');
+    try {
+      await writeFile(rosterPath, yaml);
+      const loaded = await loadFleetRoster(rosterPath);
+      expect(loaded.agents.map((a) => a.name)).toEqual(['orchestrator', 'coder0']);
+      expect(loaded.tmux.socketName).toBe('mosaic-factory');
+      expect(loaded.agents[0]!.className).toBe('orchestrator');
+    } finally {
+      await rm(dir, { recursive: true, force: true });
+    }
+  });
+
+  it('serializeRosterToYaml round-trips optional fields (modelHint, workingDirectory)', async () => {
+    const rosterWithOptionals: FleetRoster = {
+      ...baseRoster,
+      agents: [
+        {
+          name: 'orchestrator',
+          runtime: 'claude',
+          className: 'orchestrator',
+          modelHint: 'claude-3-5-sonnet',
+          workingDirectory: '/tmp/work',
+          persistentPersona: true,
+          resetBetweenTasks: false,
+        },
+      ],
+    };
+    const yaml = serializeRosterToYaml(rosterWithOptionals);
+    expect(yaml).toContain('model_hint: claude-3-5-sonnet');
+    expect(yaml).toContain('working_directory: /tmp/work');
+    expect(yaml).toContain('persistent_persona: true');
+
+    const dir = await mkdtemp(join(tmpdir(), 'mosaic-fleet-'));
+    const rosterPath = join(dir, 'roster.yaml');
+    try {
+      await writeFile(rosterPath, yaml);
+      const loaded = await loadFleetRoster(rosterPath);
+      expect(loaded.agents[0]!.modelHint).toBe('claude-3-5-sonnet');
+      expect(loaded.agents[0]!.workingDirectory).toBe('/tmp/work');
+      expect(loaded.agents[0]!.persistentPersona).toBe(true);
+    } finally {
+      await rm(dir, { recursive: true, force: true });
+    }
+  });
+});
+
+// ---------------------------------------------------------------------------
+// Fleet Phase F5: fleet add command tests
+// ---------------------------------------------------------------------------
+
+describe('fleet add command', () => {
+  let home: string;
+
+  afterEach(async () => {
+    if (home) {
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+
+  async function makeHome(agents = ['orchestrator']): Promise<string> {
+    const dir = await mkdtemp(join(tmpdir(), 'mosaic-fleet-add-'));
+    await mkdir(join(dir, 'fleet', 'agents'), { recursive: true });
+    const agentLines = agents.map((name) => {
+      const cls = name === 'orchestrator' ? 'orchestrator' : 'worker';
+      return `  - name: ${name}\n    runtime: claude\n    class: ${cls}`;
+    });
+    await writeFile(
+      join(dir, 'fleet', 'roster.yaml'),
+      ['version: 1', 'transport: tmux', 'agents:', ...agentLines].join('\n'),
+    );
+    return dir;
+  }
+
+  it('appends agent to roster file and writes env file', async () => {
+    home = await makeHome();
+    const runner: CommandRunner = async () => ({ stdout: '', stderr: '', exitCode: 0 });
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { runner, mosaicHome: home });
+
+    await program.parseAsync([
+      'node',
+      'mosaic',
+      'fleet',
+      'add',
+      'coder0',
+      '--runtime',
+      'codex',
+      '--class',
+      'worker',
+    ]);
+
+    const roster = await loadFleetRoster(join(home, 'fleet', 'roster.yaml'));
+    expect(roster.agents.map((a) => a.name)).toContain('coder0');
+
+    const envContent = await readFile(join(home, 'fleet', 'agents', 'coder0.env'), 'utf8');
+    expect(envContent).toContain('MOSAIC_AGENT_NAME=coder0');
+    expect(envContent).toContain('MOSAIC_AGENT_RUNTIME=codex');
+  });
+
+  it('--no-start skips the start command', async () => {
+    home = await makeHome();
+    const calls: string[][] = [];
+    const runner: CommandRunner = async (command, args) => {
+      calls.push([command, ...args]);
+      return { stdout: '', stderr: '', exitCode: 0 };
+    };
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { runner, mosaicHome: home });
+
+    await program.parseAsync([
+      'node',
+      'mosaic',
+      'fleet',
+      'add',
+      'coder0',
+      '--runtime',
+      'codex',
+      '--class',
+      'worker',
+      '--no-start',
+    ]);
+
+    // No start command should have been issued
+    const startCalls = calls.filter((c) => c.includes('start'));
+    expect(startCalls).toHaveLength(0);
+  });
+
+  it('without --no-start, issues start command for the new agent', async () => {
+    home = await makeHome();
+    const calls: string[][] = [];
+    const runner: CommandRunner = async (command, args) => {
+      calls.push([command, ...args]);
+      return { stdout: '', stderr: '', exitCode: 0 };
+    };
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { runner, mosaicHome: home });
+
+    await program.parseAsync([
+      'node',
+      'mosaic',
+      'fleet',
+      'add',
+      'coder0',
+      '--runtime',
+      'codex',
+      '--class',
+      'worker',
+    ]);
+
+    expect(calls).toContainEqual(['systemctl', '--user', 'start', 'mosaic-agent@coder0.service']);
+  });
+
+  it('throws when adding a duplicate agent name', async () => {
+    home = await makeHome(['orchestrator', 'coder0']);
+    const runner: CommandRunner = async () => ({ stdout: '', stderr: '', exitCode: 0 });
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { runner, mosaicHome: home });
+
+    await expect(
+      program.parseAsync([
+        'node',
+        'mosaic',
+        'fleet',
+        'add',
+        'coder0',
+        '--runtime',
+        'codex',
+        '--class',
+        'worker',
+      ]),
+    ).rejects.toThrow('already exists');
+  });
+
+  it('throws when runtime is invalid', async () => {
+    home = await makeHome();
+    const runner: CommandRunner = async () => ({ stdout: '', stderr: '', exitCode: 0 });
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { runner, mosaicHome: home });
+
+    await expect(
+      program.parseAsync([
+        'node',
+        'mosaic',
+        'fleet',
+        'add',
+        'coder0',
+        '--runtime',
+        'notaruntime',
+        '--class',
+        'worker',
+      ]),
+    ).rejects.toThrow('Invalid runtime');
+  });
+
+  it('accepts optional --model and --working-dir options', async () => {
+    home = await makeHome();
+    const runner: CommandRunner = async () => ({ stdout: '', stderr: '', exitCode: 0 });
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { runner, mosaicHome: home });
+
+    await program.parseAsync([
+      'node',
+      'mosaic',
+      'fleet',
+      'add',
+      'coder0',
+      '--runtime',
+      'claude',
+      '--class',
+      'worker',
+      '--model',
+      'claude-sonnet',
+      '--working-dir',
+      '/tmp/work',
+    ]);
+
+    const roster = await loadFleetRoster(join(home, 'fleet', 'roster.yaml'));
+    const agent = roster.agents.find((a) => a.name === 'coder0');
+    expect(agent?.modelHint).toBe('claude-sonnet');
+    expect(agent?.workingDirectory).toBe('/tmp/work');
+  });
+});
+
+// ---------------------------------------------------------------------------
+// Fleet Phase F5: fleet remove command tests
+// ---------------------------------------------------------------------------
+
+describe('fleet remove command', () => {
+  let home: string;
+
+  afterEach(async () => {
+    if (home) {
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+
+  async function makeHome(): Promise<string> {
+    const dir = await mkdtemp(join(tmpdir(), 'mosaic-fleet-remove-'));
+    await mkdir(join(dir, 'fleet', 'agents'), { recursive: true });
+    await mkdir(join(dir, 'fleet', 'run'), { recursive: true });
+    await writeFile(
+      join(dir, 'fleet', 'roster.yaml'),
+      [
+        'version: 1',
+        'transport: tmux',
+        'agents:',
+        '  - name: orchestrator',
+        '    runtime: claude',
+        '    class: orchestrator',
+        '  - name: coder0',
+        '    runtime: codex',
+        '    class: worker',
+      ].join('\n'),
+    );
+    // Create env and heartbeat files for coder0
+    await writeFile(join(dir, 'fleet', 'agents', 'coder0.env'), 'MOSAIC_AGENT_NAME=coder0\n');
+    await writeFile(join(dir, 'fleet', 'run', 'coder0.hb'), 'ts=2026-01-01T00:00:00.000Z\n');
+    return dir;
+  }
+
+  it('removes agent from roster and writes back', async () => {
+    home = await makeHome();
+    const runner: CommandRunner = async () => ({ stdout: '', stderr: '', exitCode: 0 });
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { runner, mosaicHome: home });
+
+    await program.parseAsync(['node', 'mosaic', 'fleet', 'remove', 'coder0']);
+
+    const roster = await loadFleetRoster(join(home, 'fleet', 'roster.yaml'));
+    expect(roster.agents.map((a) => a.name)).not.toContain('coder0');
+    expect(roster.agents.map((a) => a.name)).toContain('orchestrator');
+  });
+
+  it('stop is called before roster write (stop is the first runner call)', async () => {
+    home = await makeHome();
+    const calls: string[][] = [];
+    const runner: CommandRunner = async (command, args) => {
+      calls.push([command, ...args]);
+      return { stdout: '', stderr: '', exitCode: 0 };
+    };
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { runner, mosaicHome: home });
+
+    await program.parseAsync(['node', 'mosaic', 'fleet', 'remove', 'coder0']);
+
+    expect(calls[0]).toEqual(['systemctl', '--user', 'stop', 'mosaic-agent@coder0.service']);
+  });
+
+  it('stop failure is non-fatal — warns but still removes from roster', async () => {
+    home = await makeHome();
+    const stderrMessages: string[] = [];
+    const stderrSpy = vi.spyOn(process.stderr, 'write').mockImplementation((msg) => {
+      stderrMessages.push(String(msg));
+      return true;
+    });
+
+    const runner: CommandRunner = async (command, args) => {
+      if (args.includes('stop')) {
+        return { stdout: '', stderr: 'unit not found', exitCode: 5 };
+      }
+      return { stdout: '', stderr: '', exitCode: 0 };
+    };
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { runner, mosaicHome: home });
+
+    try {
+      // Must not reject
+      await expect(
+        program.parseAsync(['node', 'mosaic', 'fleet', 'remove', 'coder0']),
+      ).resolves.toBeDefined();
+
+      // Agent should be removed from roster despite stop failure
+      const roster = await loadFleetRoster(join(home, 'fleet', 'roster.yaml'));
+      expect(roster.agents.map((a) => a.name)).not.toContain('coder0');
+
+      // Warning must have been emitted
+      expect(stderrMessages.join('')).toMatch(/Warning/);
+    } finally {
+      stderrSpy.mockRestore();
+    }
+  });
+
+  it('--keep-files skips env file deletion', async () => {
+    home = await makeHome();
+    const runner: CommandRunner = async () => ({ stdout: '', stderr: '', exitCode: 0 });
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { runner, mosaicHome: home });
+
+    await program.parseAsync(['node', 'mosaic', 'fleet', 'remove', 'coder0', '--keep-files']);
+
+    // Env file should still exist
+    const envContent = await readFile(join(home, 'fleet', 'agents', 'coder0.env'), 'utf8');
+    expect(envContent).toContain('MOSAIC_AGENT_NAME=coder0');
+  });
+
+  it('env file is removed by default (no --keep-files)', async () => {
+    home = await makeHome();
+    const runner: CommandRunner = async () => ({ stdout: '', stderr: '', exitCode: 0 });
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { runner, mosaicHome: home });
+
+    await program.parseAsync(['node', 'mosaic', 'fleet', 'remove', 'coder0']);
+
+    await expect(readFile(join(home, 'fleet', 'agents', 'coder0.env'), 'utf8')).rejects.toThrow();
+  });
+
+  it('removing the sole orchestrator throws with a clear error about the guard', async () => {
+    home = await makeHome();
+    const runner: CommandRunner = async () => ({ stdout: '', stderr: '', exitCode: 0 });
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { runner, mosaicHome: home });
+
+    // First remove the worker so only the orchestrator remains
+    await program.parseAsync(['node', 'mosaic', 'fleet', 'remove', 'coder0']);
+
+    // Now attempt to remove the sole orchestrator
+    await expect(
+      program.parseAsync(['node', 'mosaic', 'fleet', 'remove', 'orchestrator']),
+    ).rejects.toThrow('sole orchestrator');
+  });
+});
+
+describe('fleet init wizard', () => {
+  let cleanup: string | undefined;
+
+  afterEach(async () => {
+    if (cleanup) {
+      await rm(cleanup, { recursive: true, force: true });
+      cleanup = undefined;
+    }
+  });
+
+  it('defaults to general when stdin is not a TTY and no --profile is given', async () => {
+    cleanup = await tempDir();
+    const rosterPath = join(cleanup, 'fleet', 'roster.yaml');
+    const frameworkRoot = resolve(process.cwd(), 'framework');
+    const stderrMessages: string[] = [];
+    const stderrSpy = vi.spyOn(process.stderr, 'write').mockImplementation((msg) => {
+      stderrMessages.push(String(msg));
+      return true;
+    });
+    const program = new Command();
+    program.exitOverride();
+    // isStdinTTY: false simulates non-interactive environment
+    registerFleetCommand(program, { frameworkRoot, mosaicHome: cleanup, isStdinTTY: false });
+
+    try {
+      await program.parseAsync([
+        'node',
+        'mosaic',
+        'fleet',
+        '--roster',
+        rosterPath,
+        'init',
+        '--write',
+      ]);
+      const content = await readFile(rosterPath, 'utf8');
+      // Should have written the general preset
+      expect(content).toContain('name: orchestrator');
+      expect(content).toContain('name: generalist');
+      // Stderr should explain the fallback
+      expect(stderrMessages.join('')).toMatch(/defaulting to fleet profile "general"/);
+    } finally {
+      stderrSpy.mockRestore();
+    }
+  });
+
+  it('uses --profile to select preset without wizard (non-TTY path)', async () => {
+    cleanup = await tempDir();
+    const rosterPath = join(cleanup, 'fleet', 'roster.yaml');
+    const frameworkRoot = resolve(process.cwd(), 'framework');
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { frameworkRoot, mosaicHome: cleanup, isStdinTTY: false });
+
+    try {
+      await program.parseAsync([
+        'node',
+        'mosaic',
+        'fleet',
+        '--roster',
+        rosterPath,
+        'init',
+        '--profile',
+        'coding',
+        '--write',
+      ]);
+      const content = await readFile(rosterPath, 'utf8');
+      expect(content).toContain('name: coder0');
+      expect(content).toContain('name: reviewer');
+    } finally {
+      // cleanup handled by afterEach
+    }
+  });
+
+  it('written roster has exactly one orchestrator agent (countOrchestrators validation)', async () => {
+    cleanup = await tempDir();
+    const frameworkRoot = resolve(process.cwd(), 'framework');
+    for (const preset of ['general', 'coding', 'research', 'hybrid'] as FleetProfile[]) {
+      const rosterPath = join(cleanup, `${preset}-roster.yaml`);
+      const program = new Command();
+      program.exitOverride();
+      registerFleetCommand(program, { frameworkRoot, mosaicHome: cleanup, isStdinTTY: false });
+      await program.parseAsync([
+        'node',
+        'mosaic',
+        'fleet',
+        '--roster',
+        rosterPath,
+        'init',
+        '--profile',
+        preset,
+        '--write',
+      ]);
+      const roster = await loadFleetRoster(rosterPath);
+      expect(countOrchestrators(roster)).toBe(1);
+    }
+  });
+
+  it('re-init with --write and existing roster requires --force (R8 idempotency)', async () => {
+    cleanup = await tempDir();
+    const rosterPath = join(cleanup, 'fleet', 'roster.yaml');
+    const frameworkRoot = resolve(process.cwd(), 'framework');
+    const program = new Command();
+    program.exitOverride();
+    registerFleetCommand(program, { frameworkRoot, mosaicHome: cleanup, isStdinTTY: false });
+
+    // First write
+    await program.parseAsync([
+      'node',
+      'mosaic',
+      'fleet',
+      '--roster',
+      rosterPath,
+      'init',
+      '--profile',
+      'general',
+      '--write',
+    ]);
+
+    // Second write without --force must fail
+    await expect(
+      program.parseAsync([
+        'node',
+        'mosaic',
+        'fleet',
+        '--roster',
+        rosterPath,
+        'init',
+        '--profile',
+        'general',
+        '--write',
+      ]),
+    ).rejects.toThrow('Fleet roster already exists');
+
+    // With --force must succeed
+    await program.parseAsync([
+      'node',
+      'mosaic',
+      'fleet',
+      '--roster',
+      rosterPath,
+      'init',
+      '--profile',
+      'coding',
+      '--write',
+      '--force',
+    ]);
+    const content = await readFile(rosterPath, 'utf8');
+    expect(content).toContain('name: coder0');
+  });
+});

packages/mosaic/src/commands/fleet.ts

@@ -1,9 +1,10 @@
 import { constants } from 'node:fs';
-import { access, chmod, copyFile, mkdir, readFile, writeFile } from 'node:fs/promises';
+import { access, chmod, copyFile, mkdir, readFile, unlink, writeFile } from 'node:fs/promises';
 import { homedir, hostname, userInfo } from 'node:os';
 import { dirname, join, resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { spawn } from 'node:child_process';
+import * as readline from 'node:readline';
 import type { Command } from 'commander';
 import YAML from 'yaml';
 
@@ -41,6 +42,11 @@ export interface FleetCommandDeps {
   sleepFn?: SleepFn;
   mosaicHome?: string;
   frameworkRoot?: string;
+  /**
+   * Injectable TTY check for `fleet init` wizard. Defaults to process.stdin.isTTY.
+   * Tests stub this to simulate interactive or non-interactive environments.
+   */
+  isStdinTTY?: boolean;
 }
 
 interface RawFleetRoster {
@@ -799,19 +805,42 @@ export function registerFleetCommand(program: Command, deps: FleetCommandDeps =
   cmd
     .command('init')
     .description('Initialize a local fleet roster')
-    .option('--profile <name>', 'Roster profile: minimal or local-canary', 'minimal')
+    .option(
+      '--profile <name>',
+      `Roster profile: ${FLEET_PROFILES.join(', ')} (skips interactive wizard)`,
+    )
     .option('--write', 'Write the roster to Mosaic home')
     .option('--force', 'Overwrite an existing roster when used with --write')
-    .action(async (opts: { profile: string; write?: boolean; force?: boolean }) => {
+    .action(async (opts: { profile?: string; write?: boolean; force?: boolean }) => {
       const commandOpts = cmd.opts<{ mosaicHome: string; roster?: string }>();
       const activePaths = resolveFleetPaths(commandOpts.mosaicHome);
-      const profile = parseInitProfile(opts.profile);
+
-      const source = join(frameworkRoot, 'fleet', 'examples', `${profile}.yaml`);
+      let profile: FleetProfile;
+      if (opts.profile !== undefined) {
+        // Explicit --profile flag: validate and use it (non-interactive path).
+        profile = parseInitProfile(opts.profile);
+      } else {
+        // No --profile: use wizard when stdin is a TTY, else default to 'general'.
+        const isTTY = deps.isStdinTTY ?? process.stdin.isTTY ?? false;
+        if (isTTY) {
+          profile = await promptFleetProfile();
+        } else {
+          process.stderr.write(
+            'Note: stdin is not a TTY; defaulting to fleet profile "general". ' +
+              'Use --profile <name> to select a different preset.\n',
+          );
+          profile = 'general';
+        }
+      }
+
+      const source = join(frameworkRoot, 'fleet', 'examples', resolvePresetFilename(profile));
       const content = await readFile(source, 'utf8');
+
       if (!opts.write) {
         console.log(content.trimEnd());
         return;
       }
+
       const destination = commandOpts.roster ?? activePaths.rosterPath;
       if (!opts.force && (await canRead(destination))) {
         throw new Error(
@@ -820,7 +849,23 @@ export function registerFleetCommand(program: Command, deps: FleetCommandDeps =
       }
       await mkdir(dirname(destination), { recursive: true });
       await writeFile(destination, content);
-      console.log(`Wrote fleet roster: ${destination}`);
+
+      // Validate: exactly one orchestrator required (R5) — friendly summary on success.
+      const written = await loadFleetRoster(destination);
+      const orchCount = countOrchestrators(written);
+      if (orchCount !== 1) {
+        process.stderr.write(
+          `Warning: fleet roster at ${destination} has ${orchCount} orchestrator agent(s) (expected exactly 1).\n`,
+        );
+        console.log(
+          `Initialized ${profile} fleet: ${written.agents.length} agent(s). Next: mosaic fleet install`,
+        );
+      } else {
+        const workerCount = written.agents.length - 1;
+        console.log(
+          `Initialized ${profile} fleet: 1 orchestrator + ${workerCount} agent(s). Next: mosaic fleet install`,
+        );
+      }
     });
 
   cmd
@@ -1098,6 +1143,112 @@ export function registerFleetCommand(program: Command, deps: FleetCommandDeps =
       }
     });
 
+  cmd
+    .command('add <name>')
+    .description('Add a new agent to the fleet roster and optionally start it')
+    .requiredOption('--runtime <runtime>', `Agent runtime (${VALID_FLEET_RUNTIMES.join(', ')})`)
+    .requiredOption('--class <class>', 'Agent class (e.g. worker, orchestrator, canary)')
+    .option('--model <hint>', 'Model hint for the agent')
+    .option('--working-dir <path>', 'Working directory for the agent')
+    .option('--no-start', 'Skip starting the agent after adding')
+    .action(
+      async (
+        name: string,
+        opts: {
+          runtime: string;
+          class: string;
+          model?: string;
+          workingDir?: string;
+          start: boolean;
+        },
+      ) => {
+        if (!VALID_FLEET_RUNTIMES.includes(opts.runtime)) {
+          throw new Error(
+            `Invalid runtime "${opts.runtime}". Valid runtimes: ${VALID_FLEET_RUNTIMES.join(', ')}.`,
+          );
+        }
+        const commandOpts = cmd.opts<{ mosaicHome: string; roster?: string }>();
+        const activePaths = resolveFleetPaths(commandOpts.mosaicHome);
+        const rosterPath = await resolveRosterPath(commandOpts.mosaicHome, commandOpts.roster);
+        const roster = await loadFleetRoster(rosterPath);
+
+        const newAgent: FleetAgent = {
+          name,
+          runtime: opts.runtime,
+          className: opts.class,
+          ...(opts.workingDir !== undefined && { workingDirectory: opts.workingDir }),
+          ...(opts.model !== undefined && { modelHint: opts.model }),
+        };
+
+        const updatedRoster = addAgentToRoster(roster, newAgent);
+        await writeFile(rosterPath, serializeRosterToYaml(updatedRoster));
+
+        const envPath = join(activePaths.agentEnvDir, `${name}.env`);
+        const existingEnv = (await canRead(envPath)) ? await readFile(envPath, 'utf8') : undefined;
+        await mkdir(activePaths.agentEnvDir, { recursive: true });
+        await writeFile(
+          envPath,
+          mergeAgentEnv(generateAgentEnv(updatedRoster, newAgent), existingEnv),
+        );
+
+        console.log(`Added ${name} (${opts.runtime}/${opts.class}) to the fleet.`);
+
+        if (opts.start !== false) {
+          await runChecked(runner, buildFleetServiceCommand('start', name));
+          console.log(`Started mosaic-agent@${name}.service.`);
+        } else {
+          console.log(`Agent queued (--no-start); run: mosaic fleet start ${name}`);
+        }
+      },
+    );
+
+  cmd
+    .command('remove <name>')
+    .description('Remove an agent from the fleet roster')
+    .option('--keep-files', 'Skip deleting env and heartbeat files')
+    .action(async (name: string, opts: { keepFiles?: boolean }) => {
+      const commandOpts = cmd.opts<{ mosaicHome: string; roster?: string }>();
+      const activePaths = resolveFleetPaths(commandOpts.mosaicHome);
+      const rosterPath = await resolveRosterPath(commandOpts.mosaicHome, commandOpts.roster);
+      const roster = await loadFleetRoster(rosterPath);
+
+      // Guard: throws if removing leaves 0 orchestrators or agent not in roster
+      const updatedRoster = removeAgentFromRoster(roster, name);
+
+      // Stop agent (non-fatal)
+      try {
+        const stopResult = await runner(...splitCommand(buildFleetServiceCommand('stop', name)));
+        if (stopResult.exitCode !== 0) {
+          process.stderr.write(
+            `Warning: could not stop mosaic-agent@${name}.service: ${stopResult.stderr || stopResult.stdout || 'non-zero exit'}\n`,
+          );
+        }
+      } catch (err) {
+        process.stderr.write(
+          `Warning: stop command failed for ${name}: ${err instanceof Error ? err.message : String(err)}\n`,
+        );
+      }
+
+      // Write updated roster
+      await writeFile(rosterPath, serializeRosterToYaml(updatedRoster));
+
+      // Delete env and heartbeat files (best-effort, non-fatal)
+      if (!opts.keepFiles) {
+        try {
+          await unlink(join(activePaths.agentEnvDir, `${name}.env`));
+        } catch {
+          // best-effort
+        }
+        try {
+          await unlink(heartbeatPath(name, activePaths.mosaicHome));
+        } catch {
+          // best-effort
+        }
+      }
+
+      console.log(`Removed ${name} from the fleet.`);
+    });
+
   return cmd;
 }
 
@@ -1668,11 +1819,195 @@ function splitCommand(command: string[]): [string, string[]] {
   return [bin, args];
 }
 
-function parseInitProfile(profile: string): 'minimal' | 'local-canary' {
+/** All supported fleet profile names. */
-  if (profile === 'minimal' || profile === 'local-canary') {
+export type FleetProfile =
-    return profile;
+  | 'general'
+  | 'coding'
+  | 'research'
+  | 'hybrid'
+  | 'minimal'
+  | 'local-canary';
+
+/** The list of all valid fleet profile names, for wizard menus and error messages. */
+export const FLEET_PROFILES: readonly FleetProfile[] = [
+  'general',
+  'coding',
+  'research',
+  'hybrid',
+  'minimal',
+  'local-canary',
+];
+
+/**
+ * Maps a fleet profile name to its example YAML filename (without the path).
+ * Pure function — testable without I/O.
+ */
+export function resolvePresetFilename(profile: FleetProfile): string {
+  return `${profile}.yaml`;
+}
+
+/**
+ * Validate and normalise a fleet profile name string.
+ * Throws with a clear message on unknown values.
+ */
+export function parseInitProfile(profile: string): FleetProfile {
+  if ((FLEET_PROFILES as readonly string[]).includes(profile)) {
+    return profile as FleetProfile;
   }
-  throw new Error(`Unsupported fleet profile "${profile}". Use: minimal, local-canary.`);
+  throw new Error(`Unsupported fleet profile "${profile}". Use: ${FLEET_PROFILES.join(', ')}.`);
+}
+
+/**
+ * Count orchestrator agents in a parsed roster.
+ * Returns the count; callers assert === 1.
+ */
+export function countOrchestrators(roster: FleetRoster): number {
+  return roster.agents.filter((a) => a.className === 'orchestrator').length;
+}
+
+/** Valid runtime identifiers for fleet agents. */
+export const VALID_FLEET_RUNTIMES: readonly string[] = [
+  'pi',
+  'claude',
+  'codex',
+  'opencode',
+  'dogfood',
+];
+
+/**
+ * Add a new agent to a fleet roster (immutable — returns a new FleetRoster).
+ * Throws on invalid name, duplicate name.
+ */
+export function addAgentToRoster(roster: FleetRoster, agent: FleetAgent): FleetRoster {
+  if (!agent.name || !/^[A-Za-z0-9_.-]+$/.test(agent.name)) {
+    throw new Error(`Invalid fleet agent name: ${agent.name || '<empty>'}`);
+  }
+  if (roster.agents.some((a) => a.name === agent.name)) {
+    throw new Error(`Agent "${agent.name}" already exists in the fleet roster.`);
+  }
+  return {
+    ...roster,
+    agents: [...roster.agents, agent],
+  };
+}
+
+/**
+ * Remove an agent from a fleet roster (immutable — returns a new FleetRoster).
+ * Throws if the agent is not found, or if removal would leave zero orchestrators.
+ */
+export function removeAgentFromRoster(roster: FleetRoster, name: string): FleetRoster {
+  const agent = roster.agents.find((a) => a.name === name);
+  if (!agent) {
+    throw new Error(`Agent "${name}" is not in the fleet roster.`);
+  }
+  const remaining = roster.agents.filter((a) => a.name !== name);
+  const remainingOrchCount = remaining.filter((a) => a.className === 'orchestrator').length;
+  if (remainingOrchCount === 0 && agent.className === 'orchestrator') {
+    throw new Error(
+      `Cannot remove agent "${name}": it is the sole orchestrator. Add another orchestrator first (R5).`,
+    );
+  }
+  return {
+    ...roster,
+    agents: remaining,
+  };
+}
+
+/**
+ * Serialize a FleetRoster to YAML text (snake_case keys).
+ * The output is parseable by loadFleetRoster.
+ */
+export function serializeRosterToYaml(roster: FleetRoster): string {
+  const agents = roster.agents.map((agent) => {
+    const raw: Record<string, unknown> = {
+      name: agent.name,
+      runtime: agent.runtime,
+      class: agent.className,
+    };
+    if (agent.workingDirectory !== undefined) {
+      raw['working_directory'] = agent.workingDirectory;
+    }
+    if (agent.modelHint !== undefined) {
+      raw['model_hint'] = agent.modelHint;
+    }
+    if (agent.persistentPersona !== undefined) {
+      raw['persistent_persona'] = agent.persistentPersona;
+    }
+    if (agent.resetBetweenTasks !== undefined) {
+      raw['reset_between_tasks'] = agent.resetBetweenTasks;
+    }
+    if (agent.kickstartTemplate !== undefined) {
+      raw['kickstart_template'] = agent.kickstartTemplate;
+    }
+    return raw;
+  });
+
+  const runtimes: Record<string, { reset_command: string }> = {};
+  for (const [runtime, config] of Object.entries(roster.runtimes)) {
+    runtimes[runtime] = { reset_command: config.resetCommand };
+  }
+
+  const raw: Record<string, unknown> = {
+    version: roster.version,
+    transport: roster.transport,
+    tmux: {
+      socket_name: roster.tmux.socketName,
+      holder_session: roster.tmux.holderSession,
+    },
+    defaults: {
+      working_directory: roster.defaults.workingDirectory,
+    },
+    runtimes,
+    agents,
+  };
+
+  return YAML.stringify(raw);
+}
+
+/**
+ * Prompt interactively for a fleet profile via stdin readline.
+ * AI-free: no LLM calls — pure readline menu.
+ * Resolves with the chosen profile string, or rejects on I/O error.
+ */
+function promptFleetProfile(): Promise<FleetProfile> {
+  return new Promise((resolve, reject) => {
+    const rl = readline.createInterface({ input: process.stdin, output: process.stdout });
+    const menu = [
+      '',
+      'Choose a fleet configuration type:',
+      '  1) general      — orchestrator + generalist worker',
+      '  2) coding       — orchestrator + coder0 + coder1 + reviewer',
+      '  3) research     — orchestrator + researcher0 + researcher1 + analyst',
+      '  4) hybrid       — orchestrator + coder0 + researcher0 + reviewer',
+      '  5) minimal      — single canary-pi agent (no orchestrator)',
+      '  6) local-canary — legacy canary preset with lead + coder + reviewer',
+      '',
+    ].join('\n');
+    process.stdout.write(menu);
+    rl.question('Enter number or name [1]: ', (answer) => {
+      rl.close();
+      const trimmed = answer.trim();
+      // Map numeric shortcut → name
+      const byNumber: Record<string, FleetProfile> = {
+        '1': 'general',
+        '2': 'coding',
+        '3': 'research',
+        '4': 'hybrid',
+        '5': 'minimal',
+        '6': 'local-canary',
+        '': 'general', // default on empty enter
+      };
+      if (trimmed in byNumber) {
+        resolve(byNumber[trimmed]!);
+        return;
+      }
+      try {
+        resolve(parseInitProfile(trimmed));
+      } catch (err) {
+        reject(err);
+      }
+    });
+  });
 }
 
 function writeCommandOutput(result: CommandResult): void {