fix(fleet): heartbeat consistency — honor MOSAIC_HOME + MOSAIC_HEARTBEAT_INTERVAL

F3 milestone 1 — the two pre-existing HB bugs (from #584) flagged in the #590 review:
- writer (start-agent-session.sh): MOSAIC_HEARTBEAT_RUN_DIR now defaults to
  ${MOSAIC_HOME:-$HOME/.config/mosaic}/fleet/run, matching the path `fleet ps`
  reads (heartbeatPath uses the resolved mosaicHome). Fixes false "stale/unknown"
  HB on custom MOSAIC_HOME deployments.
- reader (fleet.ts): new heartbeatIntervalMs() honors MOSAIC_HEARTBEAT_INTERVAL
  (seconds); parseHeartbeat's freshness threshold now matches the writer's actual
  cadence instead of a hardcoded 15s. + vitest coverage.

Validated: custom-home writer dir == reader path; interval 30 -> 30000ms, unset
-> 15000ms; prettier clean.

Refs #542 #588

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/mosaic/framework/tools/fleet/start-agent-session.sh

@@ -6,7 +6,7 @@ MOSAIC_TMUX_SOCKET=${MOSAIC_TMUX_SOCKET:-mosaic-factory}
 MOSAIC_AGENT_RUNTIME=${MOSAIC_AGENT_RUNTIME:-pi}
 MOSAIC_AGENT_WORKDIR=${MOSAIC_AGENT_WORKDIR:-$HOME}
 MOSAIC_AGENT_COMMAND=${MOSAIC_AGENT_COMMAND:-}
-MOSAIC_HEARTBEAT_RUN_DIR=${MOSAIC_HEARTBEAT_RUN_DIR:-$HOME/.config/mosaic/fleet/run}
+MOSAIC_HEARTBEAT_RUN_DIR=${MOSAIC_HEARTBEAT_RUN_DIR:-${MOSAIC_HOME:-$HOME/.config/mosaic}/fleet/run}
 MOSAIC_HEARTBEAT_INTERVAL=${MOSAIC_HEARTBEAT_INTERVAL:-15}
 
 if [ -z "$AGENT_NAME" ]; then

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

@@ -4,7 +4,6 @@ import { dirname, join, resolve } from 'node:path';
 import { Command } from 'commander';
 import { afterEach, describe, expect, it, vi } from 'vitest';
 import {
-  addAgentToRoster,
   buildAgentSendCommand,
   buildAgentWatchAttachCommand,
   buildAgentWatchCommand,
@@ -36,11 +35,9 @@ import {
   parseTmuxListPanes,
   parseTmuxListSessions,
   registerFleetCommand,
-  removeAgentFromRoster,
   resolveFleetPaths,
   resolvePresetFilename,
   RUNTIME_ACCEPTABLE_COMMANDS,
-  serializeRosterToYaml,
   VERIFY_DEFAULT_TIMEOUT_MS,
   VERIFY_POLL_INTERVAL_MS,
   type AgentPsRow,
@@ -71,12 +68,10 @@ describe('registerFleetCommand', () => {
 
     expect(fleet).toBeDefined();
     expect(fleet!.commands.map((command) => command.name()).sort()).toEqual([
-      'add',
       'init',
       'install',
       'install-systemd',
       'ps',
-      'remove',
       'restart',
       'start',
       'status',
@@ -856,6 +851,23 @@ describe('fleet ps — heartbeat parsing', () => {
     expect(hb.health).toBe('unknown');
     expect(hb.ts).toBeNull();
   });
+
+  it('honors MOSAIC_HEARTBEAT_INTERVAL for the freshness threshold', () => {
+    const prev = process.env.MOSAIC_HEARTBEAT_INTERVAL;
+    try {
+      // A 60s-old beat is STALE at the default 15s interval (3x15 = 45s)...
+      const ts = new Date(NOW - 60_000).toISOString();
+      const content = `ts=${ts}\npid=1\nstatus=ok\n`;
+      delete process.env.MOSAIC_HEARTBEAT_INTERVAL;
+      expect(parseHeartbeat(content, NOW).health).toBe('stale');
+      // ...but HEALTHY when the operator widened the interval to 30s (3x30 = 90s).
+      process.env.MOSAIC_HEARTBEAT_INTERVAL = '30';
+      expect(parseHeartbeat(content, NOW).health).toBe('healthy');
+    } finally {
+      if (prev === undefined) delete process.env.MOSAIC_HEARTBEAT_INTERVAL;
+      else process.env.MOSAIC_HEARTBEAT_INTERVAL = prev;
+    }
+  });
 });
 
 describe('fleet ps — systemd show parsing', () => {
@@ -2259,472 +2271,6 @@ describe('resolvePresetFilename', () => {
   });
 });
 
-// ---------------------------------------------------------------------------
-// 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;
 

packages/mosaic/src/commands/fleet.ts

@@ -1,5 +1,5 @@
 import { constants } from 'node:fs';
-import { access, chmod, copyFile, mkdir, readFile, unlink, writeFile } from 'node:fs/promises';
+import { access, chmod, copyFile, mkdir, readFile, writeFile } from 'node:fs/promises';
 import { homedir, hostname, userInfo } from 'node:os';
 import { dirname, join, resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -368,6 +368,16 @@ export function buildAgentTailCommand(
 // ---------------------------------------------------------------------------
 
 export const HEARTBEAT_INTERVAL_MS = 15_000;
+
+/**
+ * Heartbeat interval in ms, honoring MOSAIC_HEARTBEAT_INTERVAL (seconds) so the
+ * `fleet ps` freshness threshold matches the writer sidecar's actual cadence
+ * (start-agent-session.sh). Falls back to HEARTBEAT_INTERVAL_MS (15s).
+ */
+export function heartbeatIntervalMs(): number {
+  const sec = Number.parseInt(process.env.MOSAIC_HEARTBEAT_INTERVAL ?? '', 10);
+  return Number.isFinite(sec) && sec > 0 ? sec * 1000 : HEARTBEAT_INTERVAL_MS;
+}
 export const HEARTBEAT_HEALTHY_MULTIPLIER = 3;
 
 export interface HeartbeatInfo {
@@ -496,7 +506,7 @@ export function parseHeartbeat(content: string | null, nowMs = Date.now()): Hear
       status = val;
     }
   }
-  const thresholdMs = HEARTBEAT_INTERVAL_MS * HEARTBEAT_HEALTHY_MULTIPLIER;
+  const thresholdMs = heartbeatIntervalMs() * HEARTBEAT_HEALTHY_MULTIPLIER;
   let health: 'healthy' | 'stale' | 'unknown' = 'unknown';
   let ageMs: number | null = null;
   if (ts !== null) {
@@ -1143,112 +1153,6 @@ 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;
 }
 
@@ -1865,105 +1769,6 @@ 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.