feat(fleet): F4 Phase 2a — Matrix CS-API connector client + factory (#616)

Implements the Matrix connector behind the F4 abstraction (stacked on #617).
Speaks the Matrix client-server API directly over HTTPS (injectable fetch, no
SDK) so it is homeserver-agnostic (Conduit default, Synapse alt).

- MatrixConnector implements OrchestratorConnector:
  - send  → PUT /_matrix/client/v3/rooms/{room}/send/m.room.message/{txn}
            (thread-aware via m.thread relation), returns event_id.
  - subscribe → /sync long-poll loop driven by the pure parseSyncResponse
            (skips the orchestrator's own echoes; carries threadId).
  - health → /_matrix/client/versions (reachable) + /account/whoami (authed).
- Pure helpers buildMessageBody + parseSyncResponse → send/receive unit-testable.
- registerMatrixConnector(env) registers the factory; the access token comes from
  MATRIX_ACCESS_TOKEN, never the roster.

Verified: 13 Matrix + 7 registry = 20 connector tests green; tsc/eslint/prettier
clean. Still a self-contained connectors/ module (no fleet.ts changes).

Stacked on #617 (F4 Phase 1). Merge order: #617 -> this; rebases onto main after.

Refs #616, #613

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EsgTQzV5YUGk1JtCLP4B83

.woodpecker/publish.yml

@@ -4,6 +4,23 @@
 variables:
   - &node_image 'node:22-alpine'
   - &enable_pnpm 'corepack enable'
+  # Heavy kaniko image builds (~25 min) — gate them so a merge that only touches
+  # the npm-only CLI (@mosaicstack/mosaic) or docs does NOT rebuild the platform
+  # images (gateway/appservice/web do not depend on @mosaicstack/mosaic). Releases
+  # (tags) always build everything. Exclude-list keeps the default SAFE: any
+  # non-excluded change still builds, so no transitive dep can silently go stale.
+  # (Woodpecker: `when` entries are OR'd; `path` applies to push/PR only — hence
+  # the separate `event: tag` entry.)
+  - &image_build_when
+    - event: tag
+    - event: [push, manual]
+      branch: main
+      path:
+        exclude:
+          - 'packages/mosaic/**'
+          - 'docs/**'
+          - '**/*.md'
+          - '.woodpecker/**'
 
 when:
   - branch: [main]
@@ -26,6 +43,15 @@ steps:
 
   publish-npm:
     image: *node_image
+    # Publish only when a publishable package changed (or on a release tag); a
+    # pure-docs merge runs no publish. Cheap step, but gated for cleanliness.
+    when:
+      - event: tag
+      - event: [push, manual]
+        branch: main
+        path:
+          include:
+            - 'packages/**'
     environment:
       NPM_TOKEN:
         from_secret: gitea_token
@@ -91,6 +117,7 @@ steps:
 
   build-gateway:
     image: gcr.io/kaniko-project/executor:debug
+    when: *image_build_when
     environment:
       REGISTRY_USER:
         from_secret: gitea_username
@@ -116,6 +143,7 @@ steps:
 
   build-appservice:
     image: gcr.io/kaniko-project/executor:debug
+    when: *image_build_when
     environment:
       REGISTRY_USER:
         from_secret: gitea_username
@@ -141,6 +169,7 @@ steps:
 
   build-web:
     image: gcr.io/kaniko-project/executor:debug
+    when: *image_build_when
     environment:
       REGISTRY_USER:
         from_secret: gitea_username

docs/TASKS.md

@@ -59,6 +59,14 @@ Active workstream is **W1 — Federation v1**. Workers should:
 
 - Status: implemented + tested. Closes R13: `mosaic update` now re-seeds the framework (data-safe MOSAIC_SYNC_ONLY) after the CLI install so shipped launcher/runtime changes activate; `--relaunch` restarts rostered agents; `--no-reseed` opts out. Detail: scratchpads/f3-m3-update-reseed.md.
 
+## Fleet-polish bundle — boot-survival symmetry (#611) — feat/fleet-polish-bundle
+
+- Status: MERGED to main. disable-on-remove (boot-resurrection bug, TDD) + add-enable + init-R5 hard guarantee. 4 new + 147 existing fleet tests green. Detail: scratchpads/fleet-polish-bundle.md.
+
+## Fleet enhancer role + two-agent floor (#614) — feat/fleet-enhancer-floor
+
+- Status: MERGED to main. enhancer added to 4 presets; init guarantees 1 orchestrator + >=1 enhancer; remove protects the sole enhancer; enhancer role doc. 155 fleet tests green. Detail: scratchpads/fleet-enhancer-floor.md.
+
 ## F4 — Orchestrator chat connector + Matrix (#616) — feat/f4-matrix-connector
 
-- Status: Phase 1 done (abstraction + scaffold). Connector interface (send/subscribe/health) + registry + roster connector schema + design doc; tmux default/back-compat; matrix factory + CS-API client landed (Phase 2a, #617-stacked); 20 connector tests green; no fleet.ts changes (independent of #615). Detail: scratchpads/f4-matrix-connector.md.
+- Status: Phase 1 MERGED (#617: connector interface send/subscribe/health + registry + roster schema + design). Phase 2a (#618): Matrix CS-API client + factory. 20 connector tests green; no fleet.ts changes. Remaining Phase 2: init/configure connector-selection UX + roster wiring, systemd launch wiring, Conduit deploy guide. Detail: scratchpads/f4-matrix-connector.md.

docs/fleet/north-star.md

@@ -73,6 +73,37 @@ diff-sanity → squash-merge → verify), **decide-and-inform** cadence, and a d
 this model. See `mosaicstack-aiguide` whitepapers 01 (inter-agent comms) and 03
 (orchestration model) for the rationale.
 
+## Fleet roster — the two-agent floor and the role library
+
+A fleet is **never a single agent**. The minimum viable fleet is **two**:
+
+| Role             | Mandate                                                                                                                                                                                                                                                                                                                                                                 | Boundaries                                                                                 |
+| ---------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------ |
+| **Orchestrator** | The user's **single point of contact**. Owns the general flow, keeps agentic actions on-target, and **adds/removes agents from the fleet at will** to meet goals and user needs. Exactly **one** per fleet (the existing R5 invariant).                                                                                                                                 | Delegates source work; never the sole worker.                                              |
+| **Enhancer**     | The fleet's **continuous-improvement loop**. Monitors fleet activity, analyzes for enhancements/optimizations, builds a **plan of remediation**, and — **with the orchestrator** — upgrades fleet capability: tool creation/repair, skills, harness improvements, and **bug reports filed to Mosaic Stack** for proper remediation. Recommends which agents are needed. | **Does not code, review code, or perform delivery tasks.** Improvement and diagnosis only. |
+
+> **Why two, not one:** the orchestrator drives delivery; the enhancer makes the fleet
+> _get better at delivering_ over time. The enhancer is how the fleet self-heals its tools,
+> skills, and harnesses, and how real defects flow back to Mosaic Stack as bug reports.
+> Together they are the irreducible core — every other role is added on demand.
+
+A **general** fleet starts at this floor: the orchestrator (advised by the enhancer)
+materializes whatever roles prove necessary over the mission's life. Specialized presets
+(coding, research, etc.) seed additional roles up front, but all reduce to the same two-agent
+spine plus an on-demand **role library**:
+
+| Role profile        | Purpose                                                                           |
+| ------------------- | --------------------------------------------------------------------------------- |
+| **orchestrator**    | point of contact, flow control, fleet composition (1 per fleet)                   |
+| **enhancer**        | fleet monitoring, optimization, tool/skill/harness upgrades, upstream bug reports |
+| **coder**           | implementation (worker; stops at PR-open)                                         |
+| **code review**     | independent code review gate                                                      |
+| **security review** | security/auth/secret review gate                                                  |
+| **research**        | investigation, synthesis, options analysis                                        |
+| **board**           | deliberation panel — moonshot, contrarian, technical, business, financial lenses  |
+| **operations**      | infra, deploy, health, incident response                                          |
+| _…extensible_       | new profiles added as missions demand (orchestrator + enhancer decide)            |
+
 ## Invariants — "maximal vision, incremental delivery, zero foreclosure"
 
 Every artifact, starting Phase 2, MUST:
@@ -102,7 +133,7 @@ Every artifact, starting Phase 2, MUST:
 | ---------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- | ------- |
 | 0–1                    | tmux PoC, hardening, published CLI v0.0.34 (#565–#568)                                                                                       | ✅ done |
 | **2 — Observability**  | `fleet ps` (host+tenant aware join), heartbeat protocol + dogfood stub answers it, `agent watch` (read-only), `agent send --verify` receipts | ▶ now   |
-| 3 — Real runtimes      | claude/codex/pi/opencode answer heartbeat; **hybrid lifecycle** (core always-on: orchestrator+reviewer; ephemeral workers per lane)          | planned |
+| 3 — Real runtimes      | claude/codex/pi/opencode answer heartbeat; **hybrid lifecycle** (core always-on: **orchestrator + enhancer**; ephemeral workers per lane)    | planned |
 | 4 — Unified definition | one agent schema in gateway; `mosaic agent --new` → materialized per-tenant session; uid-tenant provisioning                                 | planned |
 | 5 — Control plane      | federation-backed cross-host × cross-tenant fleet view; **webUI** (surface chosen then) for MVP-X1 parity                                    | planned |
 
@@ -121,6 +152,28 @@ Every artifact, starting Phase 2, MUST:
   runtime-bin on PATH (baked into the pane command) + boot-survival (`enable` + linger),
   which `fleet init` should automate.
 
+## Decisions of record (2026-06-22, with Jason)
+
+- **Two-agent floor:** every fleet has, at minimum, an **orchestrator** and an **enhancer**.
+  The orchestrator is the user's point of contact and composes the fleet; the enhancer runs the
+  continuous-improvement loop (monitor → analyze → remediate → upgrade tools/skills/harness →
+  file Mosaic Stack bug reports) and **does not code or review**.
+- **Role library:** orchestrator, enhancer, coder, code review, security review, research,
+  board (moonshot/contrarian/technical/business/financial), operations — extensible; the
+  orchestrator (advised by the enhancer) adds roles as missions demand.
+- **Orchestrator chat connector:** the orchestrator is reachable over a user-chosen connector
+  (tmux now; Telegram/Discord/Matrix/Slack configurable). Validated live: **"Mos" orchestrator
+  on Discord** via the Claude Code discord channel plugin (w-jarvis).
+
+## Future enhancements (north-star, post-MVP — not on the MVP track)
+
+- **Mosaic Claude Discord Plugin** — a first-party Mosaic Discord connector that properly
+  implements the basic Discord functions **and native Discord threads**. Threads let a user
+  separate conversation topics with the orchestrator (the pattern proven by the Hermes agent).
+  A major enhancement over the current third-party channel plugin; **not required for the MVP**,
+  but a committed north-star target. `ASSUMPTION:` ships as a Mosaic-owned plugin so the fleet
+  controls Discord UX (threads, reactions, attachments, per-thread context) end-to-end.
+
 ## Assumptions (veto-able)
 
 - `ASSUMPTION:` first-class runtimes = claude, codex, pi, opencode; a "role" (analyst,

docs/scratchpads/fleet-enhancer-floor.md

@@ -0,0 +1,26 @@
+# Fleet enhancer role + two-agent floor (#614)
+
+- **Issue:** #614 · **Branch:** `feat/fleet-enhancer-floor` (stacked on #612 `feat/fleet-polish-bundle`)
+- **Doctrine:** `docs/fleet/north-star.md` (PR #613) — every fleet = orchestrator + enhancer minimum.
+
+## Changes
+
+- **Presets** (general, coding, research, hybrid): add `enhancer` (claude, `class: enhancer`,
+  `persistent_persona: true`) as a core always-on agent alongside the orchestrator. minimal/local-canary
+  unchanged.
+- **fleet.ts**: `countEnhancers` helper; init guarantee extended — non-minimal profiles must yield
+  exactly 1 orchestrator AND >=1 enhancer (hard-fail otherwise); `removeAgentFromRoster` refuses to drop
+  the sole enhancer (symmetric with the sole-orchestrator guard) so the floor holds at runtime, not just init.
+- **Role doc**: `framework/fleet/roles/enhancer.md` — the enhancer mandate (monitor → analyze → plan →
+  upgrade tools/skills/harness WITH orchestrator → file Mosaic Stack bug reports) + boundaries (does NOT
+  code or review).
+
+## Verification
+
+- 155 fleet tests green (new: countEnhancers; remove-sole-enhancer guard; remove-allows-when-another;
+  init two-agent-floor; every-non-minimal-preset-has-enhancer; updated preset rosters). tsc/eslint/
+  prettier/sanitize clean. TDD on the init guarantee + remove protection.
+
+## Stacking
+
+Built on #612's init-R5 code. PR shows #612 + enhancer until #612 merges; then rebase onto main → clean.

docs/scratchpads/fleet-polish-bundle.md

@@ -0,0 +1,20 @@
+# Fleet-polish bundle — boot-survival symmetry (#611)
+
+- **Issue:** #611 · **Branch:** `feat/fleet-polish-bundle` · From the Lead's Codex symmetry-gap finding.
+
+## Three fixes
+
+1. **disable-on-remove (BUG, TDD).** `fleet remove` stopped + deleted roster/env/heartbeat but never
+   `systemctl --user disable mosaic-agent@NAME.service` → a removed-but-enabled unit could resurrect on
+   reboot pointing at deleted config. Fix: `buildSystemdDisableCommand` + disable in `remove`
+   (best-effort, gated on !--keep-files).
+2. **add-enable.** `fleet add` now enables the new agent's unit for boot-survival (best-effort,
+   independent of --start) — symmetry with disable-on-remove.
+3. **init-R5 guarantee.** `fleet init --write` now FAILS HARD when a non-minimal profile doesn't yield
+   exactly one orchestrator (was a soft warning). `minimal` (sanctioned no-orchestrator) still allowed.
+
+## Verification
+
+- 4 new tests (disable builder; remove-invokes-disable; add-invokes-enable; init general → exactly 1
+  orchestrator) + 147 existing fleet tests green (151 total). tsc/eslint/prettier clean.
+- TDD on the disable bug per contract.

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

@@ -15,6 +15,10 @@ agents:
     runtime: claude
     class: orchestrator
     persistent_persona: true
+  - name: enhancer
+    runtime: claude
+    class: enhancer
+    persistent_persona: true
   - name: coder0
     runtime: pi
     class: implementer

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

@@ -15,6 +15,10 @@ agents:
     runtime: claude
     class: orchestrator
     persistent_persona: true
+  - name: enhancer
+    runtime: claude
+    class: enhancer
+    persistent_persona: true
   - name: generalist
     runtime: pi
     class: worker

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

@@ -15,6 +15,10 @@ agents:
     runtime: claude
     class: orchestrator
     persistent_persona: true
+  - name: enhancer
+    runtime: claude
+    class: enhancer
+    persistent_persona: true
   - name: coder0
     runtime: pi
     class: implementer

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

@@ -15,6 +15,10 @@ agents:
     runtime: claude
     class: orchestrator
     persistent_persona: true
+  - name: enhancer
+    runtime: claude
+    class: enhancer
+    persistent_persona: true
   - name: researcher0
     runtime: pi
     class: researcher

packages/mosaic/framework/fleet/roles/enhancer.md

@@ -0,0 +1,41 @@
+# Enhancer — fleet role definition
+
+The **enhancer** is one half of the fleet's two-agent floor: every fleet runs, at
+minimum, an **orchestrator** and an **enhancer**. The orchestrator drives delivery;
+the enhancer makes the fleet _get better at delivering_ over time.
+
+It is a **core, always-on** agent (`class: enhancer`, `persistent_persona: true`),
+not an ephemeral per-lane worker.
+
+## Mandate
+
+The enhancer runs the fleet's **continuous-improvement loop**:
+
+1. **Monitor** fleet activity — agents, heartbeats, sessions, throughput, failures.
+2. **Analyze** for enhancements and optimizations — friction, gaps, recurring defects,
+   missing or broken tools, skill/harness shortfalls.
+3. **Plan** a remediation: a concrete improvement with rationale and expected effect.
+4. **Upgrade fleet capability — with the orchestrator** — tool creation/repair, skills,
+   harness improvements. The orchestrator owns fleet composition; the enhancer advises and
+   implements improvements to the _means of production_, not the product.
+5. **File upstream bug reports** to Mosaic Stack for real defects, so they flow back to the
+   framework for proper remediation rather than being patched over locally.
+6. **Recommend which agents are needed** — advise the orchestrator on roles to add/remove as
+   the mission evolves.
+
+## Boundaries
+
+- **Does NOT write product/source code.**
+- **Does NOT review code** (that is the code-review / security-review roles).
+- **Does NOT perform delivery tasks.**
+
+Improvement and diagnosis only. When the enhancer finds work that requires coding or review,
+it files it (bug report / recommendation) and the orchestrator materializes the right worker.
+
+## Why two, not one
+
+The orchestrator alone optimizes for _this_ delivery; the enhancer optimizes for _every future_
+delivery — self-healing the fleet's tools, skills, and harnesses, and routing real defects
+upstream. Together they are the irreducible core; every other role is added on demand.
+
+> Doctrine: `docs/fleet/north-star.md` (two-agent floor + role library).

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

@@ -14,11 +14,13 @@ import {
   buildEnableLingerCommand,
   buildFleetServiceCommand,
   buildSystemdEnableCommand,
+  buildSystemdDisableCommand,
   buildSystemdShowCommand,
   buildTmuxListPanesCommand,
   buildTmuxListSessionsCommand,
   classifySendResult,
   countOrchestrators,
+  countEnhancers,
   detectDrift,
   enableFleetUnits,
   FLEET_PROFILES,
@@ -983,6 +985,129 @@ describe('fleet ps — drift detection', () => {
   });
 });
 
+describe('fleet-polish bundle — boot-survival symmetry', () => {
+  async function rosterHome(agents: string): Promise<string> {
+    const home = await tempDir();
+    await mkdir(join(home, 'fleet'), { recursive: true });
+    await writeFile(join(home, 'fleet', 'roster.yaml'), agents);
+    return home;
+  }
+
+  it('buildSystemdDisableCommand returns the systemctl --user disable array', () => {
+    expect(buildSystemdDisableCommand('mosaic-agent@coder0.service')).toEqual([
+      'systemctl',
+      '--user',
+      'disable',
+      'mosaic-agent@coder0.service',
+    ]);
+  });
+
+  it('fleet remove DISABLES the unit so a removed agent cannot resurrect on boot', async () => {
+    const home = await rosterHome(
+      [
+        'version: 1',
+        'transport: tmux',
+        'agents:',
+        '  - name: orchestrator',
+        '    runtime: pi',
+        '    class: orchestrator',
+        '  - name: coder0',
+        '    runtime: codex',
+        '    class: worker',
+      ].join('\n') + '\n',
+    );
+    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 });
+    try {
+      await program.parseAsync(['node', 'mosaic', 'fleet', 'remove', 'coder0']);
+      expect(calls).toContainEqual([
+        'systemctl',
+        '--user',
+        'disable',
+        'mosaic-agent@coder0.service',
+      ]);
+      // stop must still happen too
+      expect(calls).toContainEqual(['systemctl', '--user', 'stop', 'mosaic-agent@coder0.service']);
+    } finally {
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+
+  it('fleet add ENABLES the new agent unit for boot-survival', async () => {
+    const home = await rosterHome(
+      ['version: 1', 'transport: tmux', 'agents:', '  - name: coder0', '    runtime: codex'].join(
+        '\n',
+      ) + '\n',
+    );
+    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 });
+    try {
+      await program.parseAsync([
+        'node',
+        'mosaic',
+        'fleet',
+        'add',
+        'coder1',
+        '--runtime',
+        'codex',
+        '--class',
+        'worker',
+        '--no-start',
+      ]);
+      expect(calls).toContainEqual([
+        'systemctl',
+        '--user',
+        'enable',
+        'mosaic-agent@coder1.service',
+      ]);
+    } finally {
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+
+  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();
+    registerFleetCommand(program, {
+      runner: async () => ({ stdout: '', stderr: '', exitCode: 0 }),
+      mosaicHome: home,
+    });
+    try {
+      await program.parseAsync([
+        'node',
+        'mosaic',
+        'fleet',
+        'init',
+        '--profile',
+        'general',
+        '--write',
+      ]);
+      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 });
+    }
+  });
+});
+
 describe('fleet install — auto-enable units for boot-survival', () => {
   it('buildSystemdEnableCommand and buildEnableLingerCommand return correct command arrays', () => {
     expect(buildSystemdEnableCommand('mosaic-tmux-holder.service')).toEqual([
@@ -2188,47 +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');
@@ -2370,6 +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');

packages/mosaic/src/commands/fleet.ts

@@ -227,6 +227,15 @@ export function buildSystemdEnableCommand(unit: string): string[] {
   return ['systemctl', '--user', 'enable', unit];
 }
 
+/**
+ * Returns the systemctl --user disable command for a given unit.
+ * Used by `fleet remove` so a removed agent's enabled unit cannot resurrect on
+ * boot pointing at deleted config (boot-survival symmetry with enable-on-add).
+ */
+export function buildSystemdDisableCommand(unit: string): string[] {
+  return ['systemctl', '--user', 'disable', unit];
+}
+
 /**
  * Returns the loginctl enable-linger command for a given user.
  * Linger allows user systemd services to survive logout.
@@ -872,20 +881,33 @@ export function registerFleetCommand(program: Command, deps: FleetCommandDeps =
       await mkdir(dirname(destination), { recursive: true });
       await writeFile(destination, content);
 
-      // Validate: exactly one orchestrator required (R5) — friendly summary on success.
+      // Guarantee the two-agent floor: exactly one orchestrator AND at least
+      // one enhancer for every profile except the sanctioned no-orchestrator
+      // `minimal` preset. A mismatch means a corrupted/edited preset — fail hard
+      // rather than write a malformed fleet.
       const written = await loadFleetRoster(destination);
       const orchCount = countOrchestrators(written);
-      if (orchCount !== 1) {
+      const enhancerCount = countEnhancers(written);
-        process.stderr.write(
+      if (profile === 'minimal') {
-          `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`,
+          `Initialized ${profile} fleet: ${written.agents.length} agent(s) (no orchestrator). Next: mosaic fleet install`,
+        );
+      } else if (orchCount !== 1) {
+        throw new Error(
+          `Fleet init failed: the "${profile}" roster has ${orchCount} orchestrator agent(s), ` +
+            `expected exactly 1 (R5). The preset may be corrupted — re-install the framework.`,
+        );
+      } else if (enhancerCount < 1) {
+        throw new Error(
+          `Fleet init failed: the "${profile}" roster has no enhancer agent. Every fleet keeps an ` +
+            `orchestrator + enhancer minimum (two-agent floor). The preset may be corrupted — ` +
+            `re-install the framework.`,
         );
       } else {
-        const workerCount = written.agents.length - 1;
+        const workerCount = written.agents.length - 1 - enhancerCount;
         console.log(
-          `Initialized ${profile} fleet: 1 orchestrator + ${workerCount} agent(s). Next: mosaic fleet install`,
+          `Initialized ${profile} fleet: 1 orchestrator + ${enhancerCount} enhancer(s) + ` +
+            `${workerCount} worker(s). Next: mosaic fleet install`,
         );
       }
     });
@@ -1218,6 +1240,24 @@ export function registerFleetCommand(program: Command, deps: FleetCommandDeps =
 
         console.log(`Added ${name} (${opts.runtime}/${opts.class}) to the fleet.`);
 
+        // Enable the unit for boot-survival (non-fatal) — symmetry with
+        // disable-on-remove. Independent of --start so a queued agent still
+        // survives a reboot once its unit exists.
+        try {
+          const enableResult = await runner(
+            ...splitCommand(buildSystemdEnableCommand(`mosaic-agent@${name}.service`)),
+          );
+          if (enableResult.exitCode !== 0) {
+            process.stderr.write(
+              `Warning: could not enable mosaic-agent@${name}.service: ${enableResult.stderr || enableResult.stdout || 'non-zero exit'}\n`,
+            );
+          }
+        } catch (err) {
+          process.stderr.write(
+            `Warning: enable command failed for ${name}: ${err instanceof Error ? err.message : String(err)}\n`,
+          );
+        }
+
         if (opts.start !== false) {
           await runChecked(runner, buildFleetServiceCommand('start', name));
           console.log(`Started mosaic-agent@${name}.service.`);
@@ -1254,6 +1294,26 @@ export function registerFleetCommand(program: Command, deps: FleetCommandDeps =
         );
       }
 
+      // Disable the unit (non-fatal) so an enabled instance cannot resurrect on
+      // boot pointing at the now-deleted config — boot-survival symmetry with
+      // enable-on-add. Skipped only when --keep-files keeps the config in place.
+      if (!opts.keepFiles) {
+        try {
+          const disableResult = await runner(
+            ...splitCommand(buildSystemdDisableCommand(`mosaic-agent@${name}.service`)),
+          );
+          if (disableResult.exitCode !== 0) {
+            process.stderr.write(
+              `Warning: could not disable mosaic-agent@${name}.service: ${disableResult.stderr || disableResult.stdout || 'non-zero exit'}\n`,
+            );
+          }
+        } catch (err) {
+          process.stderr.write(
+            `Warning: disable command failed for ${name}: ${err instanceof Error ? err.message : String(err)}\n`,
+          );
+        }
+      }
+
       // Write updated roster
       await writeFile(rosterPath, serializeRosterToYaml(updatedRoster));
 
@@ -1894,6 +1954,15 @@ export function countOrchestrators(roster: FleetRoster): number {
   return roster.agents.filter((a) => a.className === 'orchestrator').length;
 }
 
+/**
+ * Count enhancer agents in a parsed roster. The two-agent floor (north-star)
+ * requires every non-minimal fleet to carry at least one enhancer alongside the
+ * sole orchestrator.
+ */
+export function countEnhancers(roster: FleetRoster): number {
+  return roster.agents.filter((a) => a.className === 'enhancer').length;
+}
+
 /** Valid runtime identifiers for fleet agents. */
 export const VALID_FLEET_RUNTIMES: readonly string[] = [
   'pi',
@@ -1936,6 +2005,15 @@ export function removeAgentFromRoster(roster: FleetRoster, name: string): FleetR
       `Cannot remove agent "${name}": it is the sole orchestrator. Add another orchestrator first (R5).`,
     );
   }
+  // Two-agent floor: never drop the last enhancer (the continuous-improvement
+  // loop). Symmetric with the sole-orchestrator guard.
+  const remainingEnhancerCount = remaining.filter((a) => a.className === 'enhancer').length;
+  if (remainingEnhancerCount === 0 && agent.className === 'enhancer') {
+    throw new Error(
+      `Cannot remove agent "${name}": it is the sole enhancer. Every fleet keeps at least one ` +
+        `enhancer (two-agent floor). Add another enhancer first.`,
+    );
+  }
   return {
     ...roster,
     agents: remaining,