fix(fleet): complete heartbeat reader/writer consistency + sidecar hardening

F3 follow-on to #595 (HB consistency) — the items flagged in the #595 review:
- defaultMosaicHome() honors MOSAIC_HOME env (not just --mosaic-home flag), so the
  reader matches the writer/launcher when MOSAIC_HOME is set in the shell. The
  systemd guard now checks the LITERAL ~/.config/mosaic (units use %h paths).
- heartbeatPath() honors MOSAIC_HEARTBEAT_RUN_DIR (the writer sidecar's override).
- sidecar: printf %q the interpolated hb path / pid / interval (defense-in-depth).
- vitest: heartbeatPath env-resolution coverage.

Deferred to next F3 milestone (need deeper code work): agent-watch viewer-leak
try/finally fix, and the test-start-agent-session.sh workdir-assumption fix.

Refs #588 #542

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

docs/fleet/PRD-fleet-suite.md

@@ -0,0 +1,105 @@
+# PRD — Mosaic Fleet Suite (init, configure, operate)
+
+> **Workstream:** W-FLEET (Fleet) under mission `mvp-20260312` · **Phase:** 3→4 productization
+> **North star:** [docs/fleet/north-star.md](./north-star.md) · prior: Phase-2 observability (#579), durable launch (#581), real-agent enablement (#583/#584/#586), releases 0.0.35–0.0.37
+> **Lead:** Jarvis @ `w-jarvis`. **Collaborator:** coder agent @ `dragon-lin` (jwoltje@10.1.10.37:coder0-0).
+> Owner of this file: Fleet workstream lead. Does not modify MVP single-writer control-plane files.
+
+## Mission
+
+Turn the proven fleet primitives into a **user-installable, AI-free-configurable fleet product**:
+a user runs `mosaic fleet init`, answers a few questions (general / coding / research / hybrid),
+gets a recommended set of agents plus one always-on orchestrator wired for chat-ops, and can
+operate, mutate, re-create, and observe the fleet — over tmux today and Matrix tomorrow — from
+CLI/TUI and (designed-for) the webUI.
+
+**Immediate tangible goal:** the **"Mos"** orchestrator agent running on `w-jarvis`, reachable
+in **Discord channel `1517622518662434996`** (server `1112631390438166618`). Once the fleet is
+functional, we use the fleet itself to continue the work.
+
+## Requirements
+
+### A. Configure-without-AI CLI
+| ID | Requirement |
+|---|---|
+| R1 | `mosaic fleet` command set is functional end-to-end (init/install/start/stop/status/ps/verify + agent verbs). |
+| R2 | `mosaic fleet init` is an interactive, **AI-free** CLI wizard. |
+| R3 | Init asks the **configuration type**: `general`, `coding`, `research`, `hybrid`, … (extensible). |
+| R4 | Based on the answer, the fleet is populated with a **recommended set of agents** (a preset). |
+| R5 | **Exactly one main orchestrator agent** is always configured, regardless of type. |
+| R10 | A set of **recommended configurations (presets)** ships for easy duplication. |
+| R8 | User can **re-create** the fleet when config needs change (idempotent re-init / reconfigure). |
+| R17 | Fleet controls are **simple and intuitive**. |
+
+### B. Comms & orchestrator chat-ops
+| ID | Requirement |
+|---|---|
+| R6 | Init can wire the orchestrator to a chat connector — **Telegram / Discord / Matrix / Slack** — for command + comms. |
+| R7 | Designed with the end-goal of **Matrix comms on a locally-controlled server**. |
+| R16 | Fleet supports **tmux AND Matrix** comms, **user-configurable** at init or any time. Not all users want Matrix. |
+| R19 | **"Mos" orchestrator on Discord** (`chan 1517622518662434996` / `srv 1112631390438166618`) on `w-jarvis` — the first live target. |
+
+### C. Runtime, health, lifecycle
+| ID | Requirement |
+|---|---|
+| R9 | Fleet is **mutable by the orchestrator agent** — add/remove agents per need. |
+| R13 | Fleet **gracefully handles Pi + Claude harness updates** — keep harnesses current. |
+| R14 | The **Pi harness is customized** for proper tool usage, etc. |
+| R15 | **Agent heartbeat** properly configured for **Claude AND GPT/Pi** agents. |
+
+### D. Surfaces, testing, docs
+| ID | Requirement |
+|---|---|
+| R18 | Fleet built so the **webUI can view / monitor / terminate / butt-in** on a session. |
+| R11 | Installed and **tested on both `w-jarvis` and `dragon-lin`**. |
+| R12 | **Documentation**: how to install, configure, and use the fleet. |
+
+## Architecture / approach
+
+- **Config model:** `roster.yaml` is the source of truth (already exists). Add **presets** (`general`/`coding`/`research`/`hybrid`) as shipped example rosters; `init` selects a preset, always injects the orchestrator, and writes the roster. Re-init = regenerate roster (preserve user/site overrides — mirrors install env-merge from #567).
+- **Orchestrator agent:** always present; carries the chat connector config (connector type + target IDs) so it can be commanded over chat. tmux is the substrate; the connector bridges chat ↔ the orchestrator session.
+- **Comms layers (R16):** (1) **tmux** inter-agent (`agent-send`, proven) — default, always available. (2) **chat connector** for human↔orchestrator (Discord now; Matrix the strategic target). (3) **Matrix** as the locally-controlled cross-agent bus (future). Connector is pluggable + reconfigurable.
+- **Heartbeat (R15):** runtime-agnostic launcher sidecar already covers pi/claude/codex (#584). Refine per-runtime (native HB) with the **custom Pi harness** (R14) + a Claude path.
+- **Updates (R13):** `mosaic update` (CLI) + a fleet-aware harness-update step that refreshes pi/claude/codex and re-launches agents safely (drain → update → relaunch via the durable launcher).
+- **webUI (R18):** the fleet exposes machine-readable state (`fleet ps --json` already carries tenant/host/heartbeat/managed) + control verbs (start/stop/watch/send); webUI consumes these (control plane rides federation per north star). Ensure a stable JSON contract + a terminate/attach(butt-in) path.
+
+## Phases (incremental, each shippable)
+
+| Phase | Deliverable | Notes |
+|---|---|---|
+| **F1 Presets + init wizard** | preset rosters (general/coding/research/hybrid) + always-orchestrator + AI-free `fleet init` selecting a preset; re-init idempotent | R1–R5, R8, R10, R17 |
+| **F2 Connector + Mos-on-Discord** | orchestrator chat-connector config (Discord first) + **Mos live on Discord `1517…`/`1112…`** on w-jarvis | R6, R19, partial R16 |
+| **F3 Heartbeat + harness** | HB confirmed for claude + pi/gpt; **custom Pi harness** (tool usage, native HB, model self-report); graceful harness updates | R13, R14, R15 |
+| **F4 Matrix + comms toggle** | Matrix connector (local server) + user toggle tmux/Matrix at init/anytime | R7, R16 |
+| **F5 Orchestrator-mutable fleet** | orchestrator can add/remove agents at runtime | R9 |
+| **F6 webUI hooks** | stable JSON contract + terminate/attach surface for webUI view/monitor/terminate/butt-in | R18 |
+| **F7 Test + docs** | install+test on w-jarvis AND dragon-lin; user docs (install/configure/use) | R11, R12 (runs alongside every phase) |
+
+## Work division (proposed — confirm with dragon-lin)
+
+- **Jarvis @ w-jarvis (Lead):** F1 presets+wizard, F2 connector+Mos-on-Discord, F5 mutability, F6 webUI hooks; merge authority + dual-engine reviews; co-testing on w-jarvis.
+- **coder @ dragon-lin:** F3 custom Pi harness + harness-update flow (pi/codex-savvy); plus its in-flight constitution P4–P6 (P4 installer rework underpins `fleet init`/updates — coordinate the install path). Co-testing on dragon-lin (R11).
+- **Shared:** F4 Matrix (whoever has bandwidth); F7 testing/docs continuous.
+
+## Immediate target: Mos on Discord (F2 first slice)
+
+The discord plugin is available (`~/.claude.json`). Path: configure the **orchestrator** as a durable
+fleet session running Claude Code with the discord plugin bridged to channel `1517622518662434996`
+(server `1112631390438166618`) on w-jarvis, with the existing Discord Bridge Protocol (ack within
+~3s, reply via `mcp__discord__reply`, no `AskUserQuestion`). Heartbeat via the launcher sidecar.
+
+## Success criteria
+
+- A non-AI user can `mosaic fleet init`, pick a type, and get a working fleet + orchestrator.
+- **Mos answers in Discord `1517…`** on w-jarvis.
+- Fleet runs + is observable (`fleet ps`) on **both** w-jarvis and dragon-lin.
+- Harness updates handled gracefully; HB healthy for claude + pi/gpt agents.
+- Docs let a new operator install/configure/use the fleet.
+- Re-init + orchestrator mutation work.
+
+## Assumptions (veto-able)
+
+- `ASSUMPTION:` presets ship as example rosters under the framework (`fleet/examples/*.yaml`), selected by `init`.
+- `ASSUMPTION:` chat connectors are pluggable; Discord first (target exists), Matrix is the strategic default later.
+- `ASSUMPTION:` "Mos" = a Claude Code orchestrator session with the discord plugin (reuses the documented Discord Bridge Protocol).
+- `ASSUMPTION:` per north star, runtimes default to Codex/pi-on-Codex for workers; the orchestrator "Mos" runs Claude Code (in Claude Code, which is allowed).

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/framework/install.sh

@@ -19,13 +19,23 @@ SOURCE_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 TARGET_DIR="${MOSAIC_HOME:-$HOME/.config/mosaic}"
 INSTALL_MODE="${MOSAIC_INSTALL_MODE:-prompt}"
 
-# Files/dirs preserved across upgrades (never overwritten).
+# Files/dirs protected from rsync --delete during sync. NOTE: framework-owned
+# entries (CONSTITUTION/AGENTS/STANDARDS) ARE re-applied afterward by
+# reconcile_framework_files (overwrite + backup-once); the rest stay user-owned.
 # User-created content in these paths survives rsync --delete.
-PRESERVE_PATHS=("AGENTS.md" "SOUL.md" "USER.md" "TOOLS.md" "STANDARDS.md" "memory" "sources" "credentials")
+PRESERVE_PATHS=("CONSTITUTION.md" "AGENTS.md" "SOUL.md" "USER.md" "TOOLS.md" "STANDARDS.md" "memory" "sources" "credentials")
+
+# Framework-owned contract files: re-copied from defaults/ on every upgrade (the
+# user must not edit them; a divergent copy is backed up once before overwrite).
+# USER_SEEDED files are written once on first install, then owned by the user.
+# Both lists are APPEND-FRIENDLY — add a new shipped framework file here and to the
+# matching list in packages/mosaic/src/config/file-adapter.ts.
+FRAMEWORK_OWNED=("CONSTITUTION.md" "AGENTS.md" "STANDARDS.md")
+USER_SEEDED=("TOOLS.md")
 
 # Current framework schema version — bump this when the layout changes.
 # The migration system uses this to run upgrade steps.
-FRAMEWORK_VERSION=2
+FRAMEWORK_VERSION=3
 
 # ─── colours ──────────────────────────────────────────────────────────────────
 if [[ -t 1 ]]; then
@@ -40,6 +50,47 @@ warn() { echo -e "  ${YELLOW}⚠${RESET} $1" >&2; }
 fail() { echo -e "  ${RED}✗${RESET} $1" >&2; }
 step() { echo -e "\n${BOLD}$1${RESET}"; }
 
+# ─── snapshot / restore (crash safety for upgrades) ──────────────────────────
+SNAPSHOT_DIR=""
+make_snapshot() {
+  is_existing_install || return 0
+  SNAPSHOT_DIR="$(mktemp -d "${TMPDIR:-/tmp}/mosaic-snapshot-XXXXXX")"
+  cp -a "$TARGET_DIR/." "$SNAPSHOT_DIR/" 2>/dev/null || true
+}
+restore_snapshot() {
+  [[ -n "$SNAPSHOT_DIR" && -d "$SNAPSHOT_DIR" ]] || return 0
+  fail "Install interrupted/failed — restoring previous state from snapshot"
+  rm -rf "$TARGET_DIR"; mkdir -p "$TARGET_DIR"
+  cp -a "$SNAPSHOT_DIR/." "$TARGET_DIR/" 2>/dev/null || true
+}
+cleanup_snapshot() { [[ -n "$SNAPSHOT_DIR" && -d "$SNAPSHOT_DIR" ]] && rm -rf "$SNAPSHOT_DIR"; SNAPSHOT_DIR=""; }
+
+# Reconcile contract files after sync: framework-owned overwrite (backup-once),
+# user-seeded seed-if-absent.
+reconcile_framework_files() {
+  local defaults="$TARGET_DIR/defaults" f
+  [[ -d "$defaults" ]] || return 0
+  for f in "${FRAMEWORK_OWNED[@]}"; do
+    [[ -f "$defaults/$f" ]] || continue
+    # Already current — skip to avoid mtime churn.
+    if [[ -f "$TARGET_DIR/$f" ]] && cmp -s "$TARGET_DIR/$f" "$defaults/$f"; then
+      continue
+    fi
+    if [[ -f "$TARGET_DIR/$f" && ! -f "$TARGET_DIR/${f}.pre-constitution.bak" ]]; then
+      cp "$TARGET_DIR/$f" "$TARGET_DIR/${f}.pre-constitution.bak"
+      warn "$f is now framework-owned and was updated; your previous copy is saved as ${f}.pre-constitution.bak — re-apply intended changes as a .local overlay or policy/ file (see CONSTITUTION.md / constitution/LAYER-MODEL.md)."
+    fi
+    cp "$defaults/$f" "$TARGET_DIR/$f"
+  done
+  for f in "${USER_SEEDED[@]}"; do
+    [[ -f "$defaults/$f" ]] || continue
+    if [[ ! -f "$TARGET_DIR/$f" ]]; then
+      cp "$defaults/$f" "$TARGET_DIR/$f"
+      ok "Seeded $f from defaults"
+    fi
+  done
+}
+
 # ─── helpers ──────────────────────────────────────────────────────────────────
 
 is_existing_install() {
@@ -113,11 +164,14 @@ sync_framework() {
   fi
 
   if command -v rsync >/dev/null 2>&1; then
-    local rsync_args=(-a --delete --exclude ".git" --exclude ".framework-version")
+    local rsync_args=(-a --delete --exclude ".git" --exclude ".framework-version" --exclude "*.pre-constitution.bak")
 
     if [[ "$INSTALL_MODE" == "keep" ]]; then
+      # Anchor to the transfer root (leading /) so we preserve the TOP-LEVEL
+      # ~/.config/mosaic/<file> without also excluding defaults/<file> from sync
+      # (reconcile_framework_files needs the freshly-synced defaults/ copies).
       for path in "${PRESERVE_PATHS[@]}"; do
-        rsync_args+=(--exclude "$path")
+        rsync_args+=(--exclude "/$path")
       done
     fi
 
@@ -137,7 +191,7 @@ sync_framework() {
     done
   fi
 
-  find "$TARGET_DIR" -mindepth 1 -maxdepth 1 ! -name ".git" ! -name ".framework-version" -exec rm -rf {} +
+  find "$TARGET_DIR" -mindepth 1 -maxdepth 1 ! -name ".git" ! -name ".framework-version" ! -name "*.pre-constitution.bak" -exec rm -rf {} +
   cp -R "$SOURCE_DIR"/. "$TARGET_DIR"/
   rm -rf "$TARGET_DIR/.git"
 
@@ -195,10 +249,15 @@ run_migrations() {
     fi
   fi
 
-  # ── Future migrations go here ──────────────────────────────────────────────
+  # ── Migration: v2 → v3 (Constitution split) ───────────────────────────────
-  # if [[ "$from_version" -lt 3 ]]; then
+  # CONSTITUTION.md / AGENTS.md / STANDARDS.md become framework-owned (overwritten
-  #   ...
+  # on upgrade). reconcile_framework_files() has already run before this point: it
-  # fi
+  # backed up any user-edited copy to <file>.pre-constitution.bak and installed the
+  # new framework version. Nothing further to do here — the advisory was emitted at
+  # reconcile time. (STANDARDS.local.md composition lands with the overlay composer.)
+  if [[ "$from_version" -lt 3 ]]; then
+    ok "Migrated to the Constitution layout (framework-owned CONSTITUTION/AGENTS/STANDARDS)"
+  fi
 }
 
 # ═══════════════════════════════════════════════════════════════════════════════
@@ -216,29 +275,25 @@ else
   ok "Install mode: overwrite"
 fi
 
+# Snapshot before any destructive file operation; restore on interrupt/failure.
+make_snapshot
+trap 'restore_snapshot' ERR INT TERM
+
 sync_framework
 
 # Ensure persistent directories exist
 mkdir -p "$TARGET_DIR/memory"
 mkdir -p "$TARGET_DIR/credentials"
 
-# Seed defaults — copy framework contract files from defaults/ to framework
+# Reconcile contract files from defaults/ into the framework root: framework-owned
-# root if not already present. These ship with sensible defaults but must
+# files (CONSTITUTION/AGENTS/STANDARDS) are overwritten every upgrade (a divergent
-# never be overwritten once the user has customized them.
+# copy is backed up once); user-seeded files (TOOLS) are written on first install only.
 #
 # This list must match the framework-contract whitelist in
 # packages/mosaic/src/config/file-adapter.ts (FileConfigAdapter.syncFramework).
 # SOUL.md and USER.md are intentionally NOT seeded here — they are generated
 # by `mosaic init` from templates with user-supplied values.
-DEFAULTS_DIR="$TARGET_DIR/defaults"
+reconcile_framework_files
-if [[ -d "$DEFAULTS_DIR" ]]; then
-  for default_file in CONSTITUTION.md AGENTS.md STANDARDS.md TOOLS.md; do
-    if [[ -f "$DEFAULTS_DIR/$default_file" ]] && [[ ! -f "$TARGET_DIR/$default_file" ]]; then
-      cp "$DEFAULTS_DIR/$default_file" "$TARGET_DIR/$default_file"
-      ok "Seeded $default_file from defaults"
-    fi
-  done
-fi
 
 # Ensure tool scripts are executable
 find "$TARGET_DIR/tools" -name "*.sh" -exec chmod +x {} + 2>/dev/null || true
@@ -249,6 +304,18 @@ ok "Framework synced to $TARGET_DIR"
 # Run migrations before post-install (migrations may remove old bin/ etc.)
 run_migrations
 
+# File-system phase complete and consistent — clear the restore trap.
+trap - ERR INT TERM
+cleanup_snapshot
+
+# Testability / minimal-install hook: stop after the file-system phase, before any
+# environment-touching post-install steps (runtime linking, MCP setup, skills, doctor).
+if [[ "${MOSAIC_SYNC_ONLY:-0}" == "1" ]]; then
+  write_framework_version
+  ok "Sync-only mode: file phase complete"
+  exit 0
+fi
+
 step "Post-install tasks"
 
 SCRIPTS="$TARGET_DIR/tools/_scripts"

packages/mosaic/framework/tools/_scripts/mosaic-init

@@ -274,6 +274,13 @@ detect_existing_config
 echo "[mosaic-init] Generating SOUL.md — agent identity contract"
 echo ""
 
+# Fail-closed persona: in non-interactive mode the agent NAME must be supplied
+# explicitly (--name) — never silently ship an agent named "Assistant".
+if [[ $NON_INTERACTIVE -eq 1 && -z "$AGENT_NAME" ]]; then
+  echo "[mosaic-init] ERROR: --name (agent name) is required in non-interactive mode." >&2
+  exit 1
+fi
+
 prompt_if_empty AGENT_NAME "What name should agents use" "Assistant"
 prompt_if_empty ROLE_DESCRIPTION "Agent role description" "execution partner and visibility engine"
 

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 "$AGENT_NAME" ]; then
@@ -129,7 +129,7 @@ _start_heartbeat_sidecar() {
   # references to any variables from this script's environment.
   local sidecar_script
   sidecar_script=$(printf \
-    'hb=%s; pid=%s; iv=%s; mkdir -p "$(dirname "$hb")"; while kill -0 "$pid" 2>/dev/null; do tmp="$hb.tmp.$$"; printf "ts=%%s\npid=%%s\nstatus=ok\n" "$(date +%%Y-%%m-%%dT%%H:%%M:%%S%%z)" "$pid" > "$tmp" && mv "$tmp" "$hb"; sleep "$iv"; done' \
+    'hb=%q; pid=%q; iv=%q; mkdir -p "$(dirname "$hb")"; while kill -0 "$pid" 2>/dev/null; do tmp="$hb.tmp.$$"; printf "ts=%%s\npid=%%s\nstatus=ok\n" "$(date +%%Y-%%m-%%dT%%H:%%M:%%S%%z)" "$pid" > "$tmp" && mv "$tmp" "$hb"; sleep "$iv"; done' \
     "$hb_file" "$pane_pid" "$interval")
 
   # setsid + disown ensures the sidecar survives this script exiting.

packages/mosaic/framework/tools/quality/scripts/test-install-migration.sh

@@ -0,0 +1,67 @@
+#!/usr/bin/env bash
+# test-install-migration.sh — fixture matrix for the v2→v3 (Constitution) upgrade
+# migration in install.sh. Runs the installer against throwaway MOSAIC_HOME dirs
+# with MOSAIC_SYNC_ONLY=1 (file phase only — no environment-touching post-install)
+# and asserts the framework-owned-overwrite + user-preserve + backup semantics.
+#
+# Mirrors the TS fixture suite in packages/mosaic/src/config/file-adapter.test.ts;
+# both installers MUST behave identically.
+#
+# Usage:  bash test-install-migration.sh
+set -uo pipefail
+
+FW="$(cd "$(dirname "${BASH_SOURCE[0]}")/../../.." && pwd)"   # packages/mosaic/framework
+INSTALL="$FW/install.sh"
+DEFA="$FW/defaults"
+
+pass=0; fail=0
+chk() { if eval "$2"; then echo "  ✓ $1"; pass=$((pass + 1)); else echo "  ✗ $1"; fail=$((fail + 1)); fi; }
+run() { MOSAIC_HOME="$1" MOSAIC_INSTALL_MODE="$2" MOSAIC_SYNC_ONLY=1 bash "$INSTALL" >/dev/null 2>&1; }
+
+echo "install.sh v2→v3 migration fixture matrix:"
+
+# F1 — fresh install
+T1=$(mktemp -d); run "$T1" overwrite
+chk "F1 fresh: CONSTITUTION/AGENTS/STANDARDS/TOOLS seeded" \
+  "[ -f '$T1/CONSTITUTION.md' ] && [ -f '$T1/AGENTS.md' ] && [ -f '$T1/STANDARDS.md' ] && [ -f '$T1/TOOLS.md' ]"
+chk "F1 fresh: AGENTS == shipped default" "cmp -s '$T1/AGENTS.md' '$DEFA/AGENTS.md'"
+chk "F1 fresh: framework-version stamped 3" "[ \"\$(cat '$T1/.framework-version' 2>/dev/null)\" = 3 ]"
+
+# F2 — legacy install with a user-edited AGENTS.md (the sanctioned pre-constitution customization)
+T2=$(mktemp -d); mkdir -p "$T2/credentials"
+printf '# user-edited AGENTS pre-constitution\n' > "$T2/AGENTS.md"
+printf '# my persona\n' > "$T2/SOUL.md"
+printf 'token\n' > "$T2/credentials/c.json"
+echo 2 > "$T2/.framework-version"
+run "$T2" keep
+chk "F2 legacy-edited: AGENTS overwritten to framework version" "cmp -s '$T2/AGENTS.md' '$DEFA/AGENTS.md'"
+chk "F2 legacy-edited: prior AGENTS saved to .pre-constitution.bak" \
+  "grep -q 'user-edited AGENTS pre-constitution' '$T2/AGENTS.md.pre-constitution.bak'"
+chk "F2 legacy-edited: SOUL.md preserved" "grep -q 'my persona' '$T2/SOUL.md'"
+chk "F2 legacy-edited: credentials preserved" "grep -q token '$T2/credentials/c.json'"
+chk "F2 legacy-edited: CONSTITUTION.md installed" "[ -f '$T2/CONSTITUTION.md' ]"
+run "$T2" keep
+chk "F2 idempotent: .pre-constitution.bak preserved across a 2nd upgrade" \
+  "grep -q 'user-edited AGENTS pre-constitution' '$T2/AGENTS.md.pre-constitution.bak'"
+
+# F3 — user-tuned STANDARDS.md
+T3=$(mktemp -d); printf '# tuned standards\n' > "$T3/STANDARDS.md"; printf '# persona\n' > "$T3/SOUL.md"; echo 2 > "$T3/.framework-version"
+run "$T3" keep
+chk "F3 tuned-standard: STANDARDS overwritten" "cmp -s '$T3/STANDARDS.md' '$DEFA/STANDARDS.md'"
+chk "F3 tuned-standard: tuned copy backed up" "grep -q 'tuned standards' '$T3/STANDARDS.md.pre-constitution.bak'"
+
+# F4 — unattended / no TTY (stdin closed): must complete without hanging, default to keep
+T4=$(mktemp -d); printf '# persona\n' > "$T4/SOUL.md"; printf '# old\n' > "$T4/AGENTS.md"; echo 2 > "$T4/.framework-version"
+MOSAIC_HOME="$T4" MOSAIC_SYNC_ONLY=1 bash "$INSTALL" </dev/null >/dev/null 2>&1
+chk "F4 no-TTY: completed, AGENTS updated" "cmp -s '$T4/AGENTS.md' '$DEFA/AGENTS.md'"
+
+# F5 — failure path must not corrupt existing data (invalid mode rejected before any file op)
+T5=$(mktemp -d); mkdir -p "$T5/credentials"; printf '# orig\n' > "$T5/SOUL.md"; printf 'keepme\n' > "$T5/credentials/c.json"; echo 2 > "$T5/.framework-version"
+MOSAIC_HOME="$T5" MOSAIC_INSTALL_MODE=bogus MOSAIC_SYNC_ONLY=1 bash "$INSTALL" >/dev/null 2>&1; rc=$?
+chk "F5 failure: invalid mode rejected (nonzero exit)" "[ $rc -ne 0 ]"
+chk "F5 failure: SOUL + credentials intact" "grep -q orig '$T5/SOUL.md' && grep -q keepme '$T5/credentials/c.json'"
+
+rm -rf "$T1" "$T2" "$T3" "$T4" "$T5"
+echo
+echo "RESULT: $pass passed, $fail failed"
+[ "$fail" -eq 0 ]

packages/mosaic/framework/tools/quality/scripts/verify-sanitized.sh

@@ -53,9 +53,15 @@ _selftest() {
   local tmp; tmp="$(mktemp -d)" || return 1
   printf 'contact jason.woltje at jarvis-brain (PDA-friendly)\n' > "$tmp/planted.md"
   printf 'X="${VAR:-$HOME/src/whatever/x.json}"\n' > "$tmp/planted.sh"
+  printf 'name: jason-woltje\n' > "$tmp/planted.yaml"
+  printf '[Service]\nUser=jarvis\n' > "$tmp/planted.service"
   local rc=0
   grep -qIEi "$DENYLIST" "$tmp/planted.md" || { echo "✗ SELF-TEST: identity denylist regex broken" >&2; rc=1; }
   grep -qIE  "$STRUCTURAL_SH" "$tmp/planted.sh" || { echo "✗ SELF-TEST: structural regex broken" >&2; rc=1; }
+  # Prove the identity scan covers the config formats it claims to (yaml/service/etc).
+  local n_ext
+  n_ext=$(find "$tmp" -type f \( -name '*.yaml' -o -name '*.service' \) -print0 | xargs -0 -r grep -lIEi "$DENYLIST" 2>/dev/null | wc -l)
+  [[ "$n_ext" -eq 2 ]] || { echo "✗ SELF-TEST: identity scan does not cover .yaml/.service extensions" >&2; rc=1; }
   rm -rf "$tmp"; return $rc
 }
 _selftest || exit 2

packages/mosaic/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@mosaicstack/mosaic",
-  "version": "0.0.36",
+  "version": "0.0.37",
   "repository": {
     "type": "git",
     "url": "https://git.mosaicstack.dev/mosaicstack/stack.git",

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',
@@ -846,6 +856,23 @@ 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', () => {
@@ -2132,3 +2159,766 @@ 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');
+  });
+});
+
+describe('fleet ps — heartbeat path resolution', () => {
+  const savedRunDir = process.env.MOSAIC_HEARTBEAT_RUN_DIR;
+  const savedHome = process.env.MOSAIC_HOME;
+  afterEach(() => {
+    if (savedRunDir === undefined) delete process.env.MOSAIC_HEARTBEAT_RUN_DIR;
+    else process.env.MOSAIC_HEARTBEAT_RUN_DIR = savedRunDir;
+    if (savedHome === undefined) delete process.env.MOSAIC_HOME;
+    else process.env.MOSAIC_HOME = savedHome;
+  });
+
+  it('honors MOSAIC_HEARTBEAT_RUN_DIR (matches the writer sidecar override)', () => {
+    process.env.MOSAIC_HEARTBEAT_RUN_DIR = '/run/hb';
+    expect(heartbeatPath('agent-x', '/any/home')).toBe(join('/run/hb', 'agent-x.hb'));
+  });
+
+  it('honors MOSAIC_HOME when no explicit mosaicHome is given', () => {
+    delete process.env.MOSAIC_HEARTBEAT_RUN_DIR;
+    process.env.MOSAIC_HOME = '/custom/mhome';
+    expect(heartbeatPath('agent-y')).toBe(join('/custom/mhome', 'fleet', 'run', 'agent-y.hb'));
+  });
+
+  it('falls back to <mosaicHome>/fleet/run by default', () => {
+    delete process.env.MOSAIC_HEARTBEAT_RUN_DIR;
+    delete process.env.MOSAIC_HOME;
+    expect(heartbeatPath('agent-z', '/home/u/.config/mosaic')).toBe(
+      join('/home/u/.config/mosaic', 'fleet', 'run', 'agent-z.hb'),
+    );
+  });
+});

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 {
@@ -146,13 +152,16 @@ export function resolveFleetPaths(mosaicHome = defaultMosaicHome()): FleetPaths
 }
 
 function defaultMosaicHome(): string {
-  return join(homedir(), '.config', 'mosaic');
+  // Honor MOSAIC_HOME so the reader matches the writer sidecar (and the launcher),
+  // even when MOSAIC_HOME is set in the shell without an explicit --mosaic-home flag.
+  return process.env.MOSAIC_HOME ?? join(homedir(), '.config', 'mosaic');
 }
 
 function assertDefaultMosaicHomeForSystemd(mosaicHome: string): void {
-  if (resolve(mosaicHome) !== resolve(defaultMosaicHome())) {
+  const literalHome = join(homedir(), '.config', 'mosaic');
+  if (resolve(mosaicHome) !== resolve(literalHome)) {
     throw new Error(
-      `install-systemd only supports the default Mosaic home (${defaultMosaicHome()}) because the user systemd units use %h/.config/mosaic paths.`,
+      `install-systemd only supports the default Mosaic home (${literalHome}) because the user systemd units use %h/.config/mosaic paths.`,
     );
   }
 }
@@ -362,6 +371,16 @@ 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 {
@@ -459,7 +478,10 @@ export function parseTmuxListSessions(output: string): string[] {
  * Returns the heartbeat file path for an agent.
  */
 export function heartbeatPath(agentName: string, mosaicHome = defaultMosaicHome()): string {
-  return join(mosaicHome, 'fleet', 'run', `${agentName}.hb`);
+  // Honor MOSAIC_HEARTBEAT_RUN_DIR (the writer sidecar's override); otherwise the
+  // canonical <mosaicHome>/fleet/run. Keeps reader and writer on the same path.
+  const runDir = process.env.MOSAIC_HEARTBEAT_RUN_DIR ?? join(mosaicHome, 'fleet', 'run');
+  return join(runDir, `${agentName}.hb`);
 }
 
 /**
@@ -490,7 +512,7 @@ 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) {
@@ -799,19 +821,42 @@ 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 +865,23 @@ 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 +1159,112 @@ 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 +1835,195 @@ 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 `${profile}.yaml`;
 }
-  throw new Error(`Unsupported fleet profile "${profile}". Use: minimal, local-canary.`);
+
+/**
+ * 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: ${FLEET_PROFILES.join(', ')}.`);
+}
+
+/**
+ * Count orchestrator agents in a parsed roster.
+ * Returns the count; callers assert === 1.
+ */
+export function countOrchestrators(roster: FleetRoster): number {
+  return roster.agents.filter((a) => a.className === 'orchestrator').length;
+}
+
+/** Valid runtime identifiers for fleet agents. */
+export const VALID_FLEET_RUNTIMES: readonly string[] = [
+  'pi',
+  'claude',
+  'codex',
+  'opencode',
+  'dogfood',
+];
+
+/**
+ * Add a new agent to a fleet roster (immutable — returns a new FleetRoster).
+ * Throws on invalid name, duplicate name.
+ */
+export function addAgentToRoster(roster: FleetRoster, agent: FleetAgent): FleetRoster {
+  if (!agent.name || !/^[A-Za-z0-9_.-]+$/.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 {

packages/mosaic/src/config/file-adapter.test.ts

@@ -99,11 +99,8 @@ describe('FileConfigAdapter.syncFramework — defaults seeding', () => {
     );
   });
 
-  it('preserves existing contract files — never overwrites user customization', async () => {
+  it('overwrites framework-owned files (backup-once) but preserves user-seeded files', async () => {
-    // Also plant a root-level AGENTS.md in sourceDir so that `syncDirectory`
+    // Plant a root-level AGENTS.md in sourceDir so syncDirectory's preserve is exercised.
-    // itself (not just the seed loop) has something to try to overwrite.
-    // Without this, the test would silently pass even if preserve semantics
-    // were broken in syncDirectory.
     writeFileSync(join(fixture.sourceDir, 'AGENTS.md'), '# shipped AGENTS from source root\n');
 
     writeFileSync(join(fixture.mosaicHome, 'TOOLS.md'), '# user-customized TOOLS\n');
@@ -112,18 +109,50 @@ describe('FileConfigAdapter.syncFramework — defaults seeding', () => {
     const adapter = new FileConfigAdapter(fixture.mosaicHome, fixture.sourceDir);
     await adapter.syncFramework('keep');
 
+    // User-seeded TOOLS.md is preserved.
     expect(readFileSync(join(fixture.mosaicHome, 'TOOLS.md'), 'utf-8')).toBe(
       '# user-customized TOOLS\n',
     );
-    expect(readFileSync(join(fixture.mosaicHome, 'AGENTS.md'), 'utf-8')).toBe(
+    // Framework-owned AGENTS.md is overwritten from defaults/ ...
+    expect(readFileSync(join(fixture.mosaicHome, 'AGENTS.md'), 'utf-8')).toBe('# AGENTS default\n');
+    // ... and the user's prior copy is backed up exactly once.
+    expect(readFileSync(join(fixture.mosaicHome, 'AGENTS.md.pre-constitution.bak'), 'utf-8')).toBe(
       '# user-customized AGENTS\n',
     );
-    // And the missing contract file still gets seeded.
+    // Framework-owned STANDARDS.md (absent) gets installed.
     expect(readFileSync(join(fixture.mosaicHome, 'STANDARDS.md'), 'utf-8')).toContain(
       '# STANDARDS default',
     );
   });
 
+  it('backs up a divergent framework-owned file only once (idempotent across re-sync)', async () => {
+    writeFileSync(join(fixture.mosaicHome, 'AGENTS.md'), '# user-customized AGENTS\n');
+    const adapter = new FileConfigAdapter(fixture.mosaicHome, fixture.sourceDir);
+
+    await adapter.syncFramework('keep'); // 1st: backup created, AGENTS overwritten
+    await adapter.syncFramework('keep'); // 2nd: AGENTS already == default, no new backup
+
+    expect(readFileSync(join(fixture.mosaicHome, 'AGENTS.md.pre-constitution.bak'), 'utf-8')).toBe(
+      '# user-customized AGENTS\n',
+    );
+  });
+
+  it('preserves SOUL.md and credentials through a framework-owned overwrite', async () => {
+    writeFileSync(join(fixture.mosaicHome, 'SOUL.md'), '# my persona\n');
+    writeFileSync(join(fixture.mosaicHome, 'AGENTS.md'), '# user-customized AGENTS\n');
+    mkdirSync(join(fixture.mosaicHome, 'credentials'), { recursive: true });
+    writeFileSync(join(fixture.mosaicHome, 'credentials', 'c.json'), 'token\n');
+
+    const adapter = new FileConfigAdapter(fixture.mosaicHome, fixture.sourceDir);
+    await adapter.syncFramework('keep');
+
+    expect(readFileSync(join(fixture.mosaicHome, 'SOUL.md'), 'utf-8')).toBe('# my persona\n');
+    expect(readFileSync(join(fixture.mosaicHome, 'credentials', 'c.json'), 'utf-8')).toBe(
+      'token\n',
+    );
+    expect(readFileSync(join(fixture.mosaicHome, 'AGENTS.md'), 'utf-8')).toBe('# AGENTS default\n');
+  });
+
   it('is a no-op for seeding when defaults/ dir does not exist', async () => {
     rmSync(fixture.defaultsDir, { recursive: true });
 

packages/mosaic/src/config/file-adapter.ts

@@ -13,12 +13,17 @@ import { join } from 'node:path';
  * This list must match the explicit seed loop in
  * packages/mosaic/framework/install.sh.
  */
-export const DEFAULT_SEED_FILES = [
+// Framework-owned contract files: re-copied from defaults/ on every upgrade (a
-  'CONSTITUTION.md',
+// divergent existing copy is backed up once to <file>.pre-constitution.bak first).
-  'AGENTS.md',
+// MUST match FRAMEWORK_OWNED in packages/mosaic/framework/install.sh (append-friendly).
-  'STANDARDS.md',
+export const FRAMEWORK_OWNED_FILES = ['CONSTITUTION.md', 'AGENTS.md', 'STANDARDS.md'] as const;
-  'TOOLS.md',
+
-] as const;
+// User-seeded contract files: written once on first install, then owned by the user.
+// MUST match USER_SEEDED in packages/mosaic/framework/install.sh.
+export const USER_SEEDED_FILES = ['TOOLS.md'] as const;
+
+// Union, retained for callers/tests that assert the full seed set on a fresh install.
+export const DEFAULT_SEED_FILES = [...FRAMEWORK_OWNED_FILES, ...USER_SEEDED_FILES] as const;
 import type { ConfigService, ConfigSection, ResolvedConfig } from './config-service.js';
 import type { SoulConfig, UserConfig, ToolsConfig, InstallAction } from '../types.js';
 import { soulSchema, userSchema, toolsSchema } from './schemas.js';
@@ -159,6 +164,7 @@ export class FileConfigAdapter implements ConfigService {
     const preservePaths =
       action === 'keep' || action === 'reconfigure'
         ? [
+            'CONSTITUTION.md',
             'AGENTS.md',
             'SOUL.md',
             'USER.md',
@@ -175,10 +181,10 @@ export class FileConfigAdapter implements ConfigService {
       excludeGit: true,
     });
 
-    // Copy framework-contract files (AGENTS.md, STANDARDS.md, TOOLS.md)
+    // Reconcile framework-contract files from framework/defaults/ into the mosaic
-    // from framework/defaults/ into the mosaic home root if they don't
+    // home root: framework-owned files (CONSTITUTION/AGENTS/STANDARDS) are overwritten
-    // exist yet. These are written on first install only and are never
+    // every upgrade (backup-once); user-seeded files (TOOLS) are written on first
-    // overwritten afterwards — the user may have customized them.
+    // install only. Mirrors reconcile_framework_files() in install.sh.
     //
     // SOUL.md and USER.md are deliberately NOT seeded here. They are
     // generated from templates by the soul/user wizard stages with
@@ -186,7 +192,22 @@ export class FileConfigAdapter implements ConfigService {
     // identity flow and leak placeholder content into the mosaic home.
     const defaultsDir = join(this.sourceDir, 'defaults');
     if (existsSync(defaultsDir)) {
-      for (const entry of DEFAULT_SEED_FILES) {
+      // Framework-owned: overwrite from defaults/ every sync; back up a divergent
+      // existing copy ONCE to <file>.pre-constitution.bak before the first overwrite.
+      for (const entry of FRAMEWORK_OWNED_FILES) {
+        const src = join(defaultsDir, entry);
+        const dest = join(this.mosaicHome, entry);
+        if (!existsSync(src) || !statSync(src).isFile()) continue;
+        // Already current — skip to avoid mtime churn.
+        if (existsSync(dest) && readFileSync(src).equals(readFileSync(dest))) continue;
+        const bak = `${dest}.pre-constitution.bak`;
+        if (existsSync(dest) && !existsSync(bak)) {
+          copyFileSync(dest, bak);
+        }
+        copyFileSync(src, dest);
+      }
+      // User-seeded: write only if absent.
+      for (const entry of USER_SEEDED_FILES) {
         const src = join(defaultsDir, entry);
         const dest = join(this.mosaicHome, entry);
         if (existsSync(dest)) continue;