feat(fleet): auto-enable units on install + drift recognizes wrapped runtimes (#583)

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

docs/fleet/north-star.md

@@ -115,6 +115,11 @@ Every artifact, starting Phase 2, MUST:
 - Observation: **read-only default, opt-in takeover**.
 - Multi-host: **designed-for from day one**; control plane **rides federation (W1)**.
 - Delivery: **CLI-first now**, dogfood against the live stub fleet; webUI deferred to Phase 5.
+- Runtimes: fleet agents default to **Codex / pi-on-Codex**; **Claude is reserved for Claude
+  Code only** (avoid alternate-harness API pricing). Validated durable recipe:
+  `mosaic yolo pi --model openai-codex/gpt-5.5:high`. Durable detached launch requires the
+  runtime-bin on PATH (baked into the pane command) + boot-survival (`enable` + linger),
+  which `fleet init` should automate.
 
 ## Assumptions (veto-able)
 

docs/scratchpads/fleet-observability-phase2.md

@@ -73,3 +73,28 @@ with a second agent on `dragon-lin`.
      tmux session-name fallback; the systemd/tmux env handoff needs a real fix.
 - Next: rebase on merged main, open Phase-2 PR, dual-engine review, merge, close
   `fleet-observability-1`. Defer launch-path + env-propagation fixes to Phase 3.
+- 2026-06-21 (session 3): Phase-2 PR #579 merged (3 dual-engine rounds hardened
+  verify+watch). Then closed the launch-path question with Jason's input — CORRECTING
+  earlier findings:
+  - The ad-hoc launch deaths were NOT a fundamental TTY blocker: (a) codex was a stale
+    version (Jason updated it); (b) pi was misconfigured to Claude auth (Jason removed it;
+    default is now Codex). The REAL durable-launch bug is **PATH**: the detached tmux
+    launch shell is login+non-interactive, so it misses `~/.npm-global/bin` (added only in
+    `~/.bashrc`) -> `mosaic: command not found` (127) -> pane dies. tmux panes inherit the
+    tmux _server_ env, so PATH must be baked into the pane command.
+  - **Durable real-agent recipe (validated live on gpt-5.5, Claude-free):**
+    `mosaic yolo pi --model openai-codex/gpt-5.5:high` — pi tolerates detached tmux; a raw
+    interactive TUI (codex CLI) exits without an attached client. Status line confirmed
+    `(openai-codex) gpt-5.5 • high`.
+  - PATH fix landed in `start-agent-session.sh` (commit 32efc13, branch
+    feat/fleet-launch-path): derive runtime-bin prefix (MOSAIC_RUNTIME_BIN | npm prefix |
+    ~/.npm-global/bin | ~/.local/bin), bake `export PATH=...; exec <cmd>` into the pane;
+    `exec` also fixes the drift false-positive. Live-tested under stripped PATH -> durable.
+  - Boot-survival: Jason ran `systemctl --user enable` (+ linger). TODO: auto-enable in
+    **fleet init** so operators never have to remember it (agentic-enhancement cycle).
+  - Future custom Pi harness build: pi cannot self-report its model (track
+    runtime/model/effort as fleet metadata); drift detection should recognize `node` as
+    pi's pane command (a node-wrapped pane can currently read as drift).
+  - Findings recorded in AI Guide playbooks/tmux-fleet.md (aiguide PR #7, merged).
+  - Policy: avoid Claude outside Claude Code (API pricing for alt-harness use) — fleet
+    runtimes default to Codex / pi-on-Codex; Claude stays in Claude Code only.

packages/mosaic/framework/defaults/AGENTS.md

@@ -70,6 +70,9 @@ Skills, hooks, MCP, and plugins are force multipliers you MUST use when applicab
 ## Missing core file
 
 If `CONSTITUTION.md`, `AGENTS.md`, `SOUL.md`, or the runtime contract is missing, stop and report it.
+This agent-facing strictness is intentional and stricter than the launcher: the launcher injects
+`CONSTITUTION.md` tolerantly (skipping it if absent so pre-upgrade hosts keep working), but once a host
+is re-seeded a genuinely missing core file is a stop-and-report condition — not something to proceed past.
 
 ## Session Closure
 

packages/mosaic/framework/defaults/CONSTITUTION.md

@@ -2,8 +2,11 @@
 
 The irreducible, non-negotiable law for every Mosaic agent on every harness.
 
-**Framework-owned.** This file is overwritten verbatim on every upgrade — do not edit it. To change
-behavior, add a `.local.md` overlay or a `policy/` file (tighten-only; see `constitution/LAYER-MODEL.md`).
+**Framework-owned.** This file is overwritten verbatim on every upgrade — do not edit it. There is
+**no `CONSTITUTION.local.md`**: hard gates are not locally overridable. A lower layer may only make
+behavior _stricter_, never relax or override a gate (see Precedence). Operator customization lives in
+other layers — `SOUL.md` / `USER.md` and the tighten-only overlays `STANDARDS.local.md` /
+`SOUL.local.md` / `USER.local.md` / `policy/*.md` (see `constitution/LAYER-MODEL.md`).
 Authored in **capability verbs**: where a gate names a capability ("structured reasoning", "queue
 guard"), the runtime adapter binds it to a concrete tool and states whether absence is a hard stop.
 

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

@@ -26,5 +26,75 @@ if [ -z "$MOSAIC_AGENT_COMMAND" ]; then
   MOSAIC_AGENT_COMMAND="mosaic yolo $MOSAIC_AGENT_RUNTIME"
 fi
 
+# ── Derive a runtime-bin PATH prefix ─────────────────────────────────────────
+# Precedence:
+#   1. $MOSAIC_RUNTIME_BIN (explicit override)
+#   2. $(npm config get prefix)/bin  (if npm is on PATH)
+#   3. Fallbacks: $HOME/.npm-global/bin and $HOME/.local/bin
+#
+# Only directories that already exist are included.  The prefix is baked into
+# the pane command regardless of what the LAUNCHER process's $PATH contains,
+# because the tmux pane inherits the tmux SERVER environment (not this script's
+# environment).  A dir on the launcher's PATH may be absent from the server PATH,
+# so every existing candidate must always be included.  Dedup within the
+# constructed prefix avoids listing the same dir twice.
+_build_runtime_bin_prefix() {
+  local candidates=()
+
+  if [ -n "${MOSAIC_RUNTIME_BIN:-}" ]; then
+    candidates+=("$MOSAIC_RUNTIME_BIN")
+  fi
+
+  if command -v npm >/dev/null 2>&1; then
+    local npm_prefix
+    npm_prefix=$(npm config get prefix 2>/dev/null) || true
+    if [ -n "$npm_prefix" ]; then
+      candidates+=("${npm_prefix}/bin")
+    fi
+  fi
+
+  candidates+=("$HOME/.npm-global/bin")
+  candidates+=("$HOME/.local/bin")
+
+  local prefix=""
+  for dir in "${candidates[@]}"; do
+    [ -d "$dir" ] || continue
+    if [ -z "$prefix" ]; then
+      prefix="$dir"
+    else
+      case ":${prefix}:" in
+        *":${dir}:"*) ;;  # already in our prefix — skip
+        *) prefix="${prefix}:${dir}" ;;
+      esac
+    fi
+  done
+
+  printf '%s' "$prefix"
+}
+
+MOSAIC_RUNTIME_BIN_PREFIX=$(_build_runtime_bin_prefix)
+
+# ── Build the pane command ────────────────────────────────────────────────────
+# The pane command must:
+#   - Export the augmented PATH so the runtime binary is found.
+#   - exec the agent command so the runtime is the pane's foreground process
+#     (makes `fleet ps` pane_current_command check reliable; no DRIFT false-positive).
+#
+# Quoting strategy: single-quote the inner shell snippet so that variable
+# references in MOSAIC_AGENT_COMMAND are NOT expanded here — they expand inside
+# the pane shell.  However, MOSAIC_RUNTIME_BIN_PREFIX and PATH must be expanded
+# NOW (in this script) because the pane shell inherits the tmux server
+# environment, not this script's env.
+#
+# We build the snippet as a double-quoted here-string embedded in a printf call
+# to avoid nested quoting problems.
+
+if [ -n "$MOSAIC_RUNTIME_BIN_PREFIX" ]; then
+  PANE_SHELL_SNIPPET="export PATH=\"${MOSAIC_RUNTIME_BIN_PREFIX}:\${PATH}\"; exec ${MOSAIC_AGENT_COMMAND}"
+else
+  PANE_SHELL_SNIPPET="exec ${MOSAIC_AGENT_COMMAND}"
+fi
+
 mkdir -p "$MOSAIC_AGENT_WORKDIR"
-exec tmux -L "$MOSAIC_TMUX_SOCKET" new-session -d -s "$AGENT_NAME" -c "$MOSAIC_AGENT_WORKDIR" "$MOSAIC_AGENT_COMMAND"
+exec tmux -L "$MOSAIC_TMUX_SOCKET" new-session -d -s "$AGENT_NAME" -c "$MOSAIC_AGENT_WORKDIR" \
+  bash -c "$PANE_SHELL_SNIPPET"

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

@@ -6,13 +6,26 @@ START="$SCRIPT_DIR/start-agent-session.sh"
 SOCKET="mosaic-agent-test-$RANDOM-$$"
 AGENT="agent-$RANDOM"
 WORKDIR=$(mktemp -d)
-trap 'tmux -L "$SOCKET" kill-server >/dev/null 2>&1 || true; rm -rf "$WORKDIR"' EXIT
+
+# Keep a single cleanup trap that accumulates resources.
+CLEANUP_DIRS=("$WORKDIR")
+CLEANUP_SOCKETS=("$SOCKET")
+trap '_cleanup' EXIT
+_cleanup() {
+  for s in "${CLEANUP_SOCKETS[@]:-}"; do
+    tmux -L "$s" kill-server >/dev/null 2>&1 || true
+  done
+  for d in "${CLEANUP_DIRS[@]:-}"; do
+    rm -rf "$d"
+  done
+}
 
 fail() {
   echo "FAIL: $*" >&2
   exit 1
 }
 
+# ── Test 1: basic session creation with workdir check ─────────────────────────
 MOSAIC_TMUX_SOCKET="$SOCKET" \
 MOSAIC_AGENT_WORKDIR="$WORKDIR" \
 MOSAIC_AGENT_COMMAND='bash --noprofile --norc -i' \
@@ -22,6 +35,7 @@ tmux -L "$SOCKET" has-session -t "=$AGENT:0.0" || fail "agent session was not cr
 actual_dir=$(tmux -L "$SOCKET" display-message -p -t "=$AGENT:0.0" '#{pane_current_path}')
 [ "$actual_dir" = "$WORKDIR" ] || fail "agent workdir mismatch: $actual_dir"
 
+# ── Test 2: idempotency (duplicate start prints 'already running') ─────────────
 MOSAIC_TMUX_SOCKET="$SOCKET" \
 MOSAIC_AGENT_WORKDIR="$WORKDIR" \
 MOSAIC_AGENT_COMMAND='bash --noprofile --norc -i' \
@@ -29,4 +43,166 @@ MOSAIC_AGENT_COMMAND='bash --noprofile --norc -i' \
 
 grep -qF 'already running' /tmp/mosaic-start-agent-idempotent.out || fail "duplicate start was not idempotent"
 
+# ── Test 3: runtime-bin PATH prefix is baked into the pane command ────────────
+#
+# We capture the command the script would hand to tmux by injecting a fake
+# 'tmux' shim into PATH.  The shim:
+#   - Intercepts 'new-session' calls and records its arguments to a file.
+#   - For 'has-session' calls, exits 1 (session does not exist) so the script
+#     proceeds to launch instead of printing "already running".
+#   - For all other subcommands, exits 0.
+#
+# Assertions:
+#   a) 'export PATH=' with the synthetic MOSAIC_RUNTIME_BIN prefix appears.
+#   b) 'exec' appears so the runtime replaces the wrapper shell.
+#   c) MOSAIC_AGENT_COMMAND with flags is forwarded intact.
+
+FAKE_BIN=$(mktemp -d)
+FAKE_RUNTIME_BIN=$(mktemp -d)
+TMUX_ARGS_FILE=$(mktemp)
+CLEANUP_DIRS+=("$FAKE_BIN" "$FAKE_RUNTIME_BIN")
+
+# Write the fake tmux shim (uses only positional args, no sourced vars).
+cat > "$FAKE_BIN/tmux" <<SHIM
+#!/usr/bin/env bash
+# Fake tmux: record new-session args; report has-session as missing.
+subcmd="\$3"  # argv: tmux -L <socket> <subcmd> ...
+if [ "\$subcmd" = "has-session" ]; then
+  exit 1   # session not found → script will attempt new-session
+fi
+if [ "\$subcmd" = "new-session" ]; then
+  printf '%s\n' "\$@" > "$TMUX_ARGS_FILE"
+  exit 0
+fi
+exit 0
+SHIM
+chmod +x "$FAKE_BIN/tmux"
+
+SOCKET3="mosaic-agent-test3-$RANDOM-$$"
+AGENT3="agent3-$RANDOM"
+WORKDIR3=$(mktemp -d)
+CLEANUP_DIRS+=("$WORKDIR3")
+
+PATH="$FAKE_BIN:$PATH" \
+MOSAIC_TMUX_SOCKET="$SOCKET3" \
+MOSAIC_AGENT_WORKDIR="$WORKDIR3" \
+MOSAIC_AGENT_RUNTIME="pi" \
+MOSAIC_RUNTIME_BIN="$FAKE_RUNTIME_BIN" \
+MOSAIC_AGENT_COMMAND="mosaic yolo pi --model openai-codex/gpt-5.5:high" \
+  "$START" "$AGENT3"
+
+all_args=$(cat "$TMUX_ARGS_FILE" 2>/dev/null || true)
+rm -f "$TMUX_ARGS_FILE"
+
+echo "--- captured tmux new-session args ---"
+echo "$all_args"
+echo "--- end args ---"
+
+# a) PATH prefix containing FAKE_RUNTIME_BIN must appear.
+echo "$all_args" | grep -qF "export PATH=" || fail "pane command does not export PATH"
+echo "$all_args" | grep -qF "$FAKE_RUNTIME_BIN" || fail "pane command does not include MOSAIC_RUNTIME_BIN in PATH prefix"
+
+# b) exec must appear so the runtime replaces the wrapper shell.
+echo "$all_args" | grep -qF "exec " || fail "pane command does not use exec"
+
+# c) Full MOSAIC_AGENT_COMMAND (with flags) must be forwarded.
+echo "$all_args" | grep -qF "mosaic yolo pi --model openai-codex/gpt-5.5:high" || \
+  fail "pane command does not forward MOSAIC_AGENT_COMMAND with flags intact"
+
+# ── Test 4: when no extra runtime-bin dirs exist, exec still appears ───────────
+TMUX_ARGS_FILE2=$(mktemp)
+FAKE_BIN2=$(mktemp -d)
+CLEANUP_DIRS+=("$FAKE_BIN2")
+
+cat > "$FAKE_BIN2/tmux" <<SHIM2
+#!/usr/bin/env bash
+subcmd="\$3"
+if [ "\$subcmd" = "has-session" ]; then exit 1; fi
+if [ "\$subcmd" = "new-session" ]; then
+  printf '%s\n' "\$@" > "$TMUX_ARGS_FILE2"
+  exit 0
+fi
+exit 0
+SHIM2
+chmod +x "$FAKE_BIN2/tmux"
+
+SOCKET4="mosaic-agent-test4-$RANDOM-$$"
+AGENT4="agent4-$RANDOM"
+WORKDIR4=$(mktemp -d)
+CLEANUP_DIRS+=("$WORKDIR4")
+
+# MOSAIC_RUNTIME_BIN points to a non-existent dir so prefix will be empty;
+# .npm-global/bin and .local/bin may or may not exist but we just want exec.
+PATH="$FAKE_BIN2:$PATH" \
+MOSAIC_TMUX_SOCKET="$SOCKET4" \
+MOSAIC_AGENT_WORKDIR="$WORKDIR4" \
+MOSAIC_AGENT_RUNTIME="pi" \
+MOSAIC_RUNTIME_BIN="/nonexistent-dir-$$" \
+MOSAIC_AGENT_COMMAND="mosaic yolo pi" \
+  "$START" "$AGENT4"
+
+all_args4=$(cat "$TMUX_ARGS_FILE2" 2>/dev/null || true)
+rm -f "$TMUX_ARGS_FILE2"
+rm -rf "$WORKDIR4"
+
+echo "$all_args4" | grep -qF "exec " || fail "pane command (no prefix dirs) does not use exec"
+echo "$all_args4" | grep -qF "mosaic yolo pi" || fail "pane command does not include agent command when no prefix"
+
+# ── Test 5: candidate dir already in LAUNCHER $PATH is still baked into pane ──
+#
+# Regression guard for the bug where _build_runtime_bin_prefix() used to skip
+# a candidate because it was already present in the launcher process's $PATH.
+# That check was wrong: the pane inherits the tmux SERVER environment, not the
+# launcher's env.  Even if a dir is on the launcher's PATH it must always be
+# baked into the pane's PATH export.
+#
+# We prove this by setting PATH to include FAKE_RUNTIME_BIN5 (the candidate),
+# then asserting the generated new-session command still exports it.
+TMUX_ARGS_FILE5=$(mktemp)
+FAKE_BIN5=$(mktemp -d)
+FAKE_RUNTIME_BIN5=$(mktemp -d)  # this dir IS on the launcher's PATH below
+CLEANUP_DIRS+=("$FAKE_BIN5" "$FAKE_RUNTIME_BIN5")
+
+cat > "$FAKE_BIN5/tmux" <<SHIM5
+#!/usr/bin/env bash
+subcmd="\$3"
+if [ "\$subcmd" = "has-session" ]; then exit 1; fi
+if [ "\$subcmd" = "new-session" ]; then
+  printf '%s\n' "\$@" > "$TMUX_ARGS_FILE5"
+  exit 0
+fi
+exit 0
+SHIM5
+chmod +x "$FAKE_BIN5/tmux"
+
+SOCKET5="mosaic-agent-test5-$RANDOM-$$"
+AGENT5="agent5-$RANDOM"
+WORKDIR5=$(mktemp -d)
+CLEANUP_DIRS+=("$WORKDIR5")
+CLEANUP_SOCKETS+=("$SOCKET5")
+
+# FAKE_RUNTIME_BIN5 is deliberately placed on the LAUNCHER PATH so that the
+# old (buggy) code would have skipped it.  The correct code must still include
+# it in the pane PATH export.
+PATH="$FAKE_BIN5:$FAKE_RUNTIME_BIN5:$PATH" \
+MOSAIC_TMUX_SOCKET="$SOCKET5" \
+MOSAIC_AGENT_WORKDIR="$WORKDIR5" \
+MOSAIC_AGENT_RUNTIME="pi" \
+MOSAIC_RUNTIME_BIN="$FAKE_RUNTIME_BIN5" \
+MOSAIC_AGENT_COMMAND="mosaic yolo pi" \
+  "$START" "$AGENT5"
+
+all_args5=$(cat "$TMUX_ARGS_FILE5" 2>/dev/null || true)
+rm -f "$TMUX_ARGS_FILE5"
+rm -rf "$WORKDIR5"
+
+echo "--- test 5: launcher-PATH candidate must still appear in pane export ---"
+echo "$all_args5"
+echo "--- end test 5 args ---"
+
+echo "$all_args5" | grep -qF "export PATH=" || \
+  fail "test5: pane command does not export PATH when candidate is on launcher PATH"
+echo "$all_args5" | grep -qF "$FAKE_RUNTIME_BIN5" || \
+  fail "test5: candidate dir (already on launcher PATH) was NOT baked into pane PATH — regression"
+
 echo "ok - start-agent-session"

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

@@ -12,7 +12,7 @@
 #   2. STRUCTURAL (private $HOME default in *.sh) — scanned everywhere EXCEPT examples/,
 #        because worked example overlays/personas legitimately show placeholder paths.
 #
-# File types: *.md, *.sh, *.ps1, *.json, and the extensionless CLI scripts under
+# File types: *.md, *.sh, *.ps1, *.json, *.yml/*.yaml, *.toml, *.env, *.service, and the CLI scripts under
 # tools/_scripts/. Excludes node_modules/ and this gate file.
 #
 # NOTE: '\bPDA\b' intentionally matches "PDA-friendly" (the contamination removed in P2);
@@ -39,7 +39,7 @@ cd "$FRAMEWORK_ROOT" || { echo "FRAMEWORK_ROOT not found: $FRAMEWORK_ROOT" >&2;
 # Identity scope = ALL shipped text files (examples/ INCLUDED).
 _files_identity() {
   find . -type f \
-    \( -name '*.md' -o -name '*.sh' -o -name '*.ps1' -o -name '*.json' -o -path '*/tools/_scripts/*' \) \
+    \( -name '*.md' -o -name '*.sh' -o -name '*.ps1' -o -name '*.json' -o -name '*.yml' -o -name '*.yaml' -o -name '*.toml' -o -name '*.env' -o -name '*.service' -o -path '*/tools/_scripts/*' \) \
     -not -path '*/node_modules/*' -not -path "./$SELF_REL" -print0
 }
 # Structural scope = shipped scripts, examples/ EXCLUDED.

packages/mosaic/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@mosaicstack/mosaic",
-  "version": "0.0.34",
+  "version": "0.0.35",
   "repository": {
     "type": "git",
     "url": "https://git.mosaicstack.dev/mosaicstack/stack.git",

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

@@ -10,11 +10,14 @@ import {
   buildAgentWatchCreateViewerCommand,
   buildAgentWatchKillViewerCommand,
   buildAgentVerifyAcceptedCommand,
+  buildEnableLingerCommand,
   buildFleetServiceCommand,
+  buildSystemdEnableCommand,
   buildSystemdShowCommand,
   buildTmuxListPanesCommand,
   classifySendResult,
   detectDrift,
+  enableFleetUnits,
   generateAgentEnv,
   getDefaultOperatorSourceLabel,
   getDefaultTenantAndHost,
@@ -28,10 +31,12 @@ import {
   parseTmuxListPanes,
   registerFleetCommand,
   resolveFleetPaths,
+  RUNTIME_ACCEPTABLE_COMMANDS,
   VERIFY_DEFAULT_TIMEOUT_MS,
   VERIFY_POLL_INTERVAL_MS,
   type AgentPsRow,
   type CommandRunner,
+  type FleetRoster,
   type InteractiveRunner,
   type SleepFn,
 } from './fleet.js';
@@ -909,6 +914,118 @@ describe('fleet ps — drift detection', () => {
   it('does NOT flag drift when pane command is null (pane dead)', () => {
     expect(detectDrift('pi', null)).toBe(false);
   });
+
+  it('does NOT flag drift when pane=node for wrapped pi agent (mosaic yolo pi)', () => {
+    expect(detectDrift('pi', 'node')).toBe(false);
+  });
+
+  it('does NOT flag drift when pane=node for wrapped codex agent (mosaic yolo codex)', () => {
+    expect(detectDrift('codex', 'node')).toBe(false);
+  });
+
+  it('flags drift when pane=python3 for pi runtime (canary-pi dogfood regression guard)', () => {
+    expect(detectDrift('pi', 'python3')).toBe(true);
+  });
+
+  it('does NOT flag drift when pane=python3 for dogfood runtime', () => {
+    expect(detectDrift('dogfood', 'python3')).toBe(false);
+  });
+
+  it('flags drift for unknown pane command on known runtime', () => {
+    expect(detectDrift('claude', 'bash')).toBe(true);
+  });
+
+  it('RUNTIME_ACCEPTABLE_COMMANDS is exported and contains expected entries', () => {
+    expect(RUNTIME_ACCEPTABLE_COMMANDS['pi']).toContain('node');
+    expect(RUNTIME_ACCEPTABLE_COMMANDS['pi']).not.toContain('python3');
+    expect(RUNTIME_ACCEPTABLE_COMMANDS['dogfood']).toContain('python3');
+    expect(RUNTIME_ACCEPTABLE_COMMANDS['codex']).toContain('node');
+  });
+});
+
+describe('fleet install — auto-enable units for boot-survival', () => {
+  it('buildSystemdEnableCommand and buildEnableLingerCommand return correct command arrays', () => {
+    expect(buildSystemdEnableCommand('mosaic-tmux-holder.service')).toEqual([
+      'systemctl',
+      '--user',
+      'enable',
+      'mosaic-tmux-holder.service',
+    ]);
+    expect(buildEnableLingerCommand('testuser')).toEqual(['loginctl', 'enable-linger', 'testuser']);
+  });
+
+  it('enables holder and each agent unit via injected runner after install', async () => {
+    const minimalRoster: FleetRoster = {
+      version: 1,
+      transport: 'tmux',
+      tmux: { socketName: 'mosaic-factory', holderSession: '_holder' },
+      defaults: { workingDirectory: '~/src' },
+      runtimes: { codex: { resetCommand: '/clear' } },
+      agents: [{ name: 'coder0', runtime: 'codex', className: 'worker' }],
+    };
+
+    const calls: string[][] = [];
+    const runner: CommandRunner = async (command, args) => {
+      calls.push([command, ...args]);
+      return { stdout: '', stderr: '', exitCode: 0 };
+    };
+
+    await enableFleetUnits(runner, minimalRoster, {});
+
+    expect(calls).toContainEqual(['systemctl', '--user', 'enable', 'mosaic-tmux-holder.service']);
+    expect(calls).toContainEqual(['systemctl', '--user', 'enable', 'mosaic-agent@coder0.service']);
+  });
+
+  it('install still succeeds when systemctl enable returns non-zero (non-fatal)', async () => {
+    const minimalRoster: FleetRoster = {
+      version: 1,
+      transport: 'tmux',
+      tmux: { socketName: 'mosaic-factory', holderSession: '_holder' },
+      defaults: { workingDirectory: '~/src' },
+      runtimes: { codex: { resetCommand: '/clear' } },
+      agents: [{ name: 'coder0', runtime: 'codex', className: 'worker' }],
+    };
+
+    const calls: string[][] = [];
+    const runner: CommandRunner = async (command, args) => {
+      calls.push([command, ...args]);
+      // Simulate systemctl enable failure
+      if (command === 'systemctl' && args.includes('enable')) {
+        return { stdout: '', stderr: 'Unit not found', exitCode: 1 };
+      }
+      return { stdout: '', stderr: '', exitCode: 0 };
+    };
+
+    // Must NOT reject/throw even when enable calls fail
+    await expect(enableFleetUnits(runner, minimalRoster, {})).resolves.toBeUndefined();
+
+    // The enable attempt must have been made
+    expect(calls.some((c) => c.includes('enable'))).toBe(true);
+  });
+
+  it('--no-enable skips all systemctl enable and loginctl linger calls', async () => {
+    const minimalRoster: FleetRoster = {
+      version: 1,
+      transport: 'tmux',
+      tmux: { socketName: 'mosaic-factory', holderSession: '_holder' },
+      defaults: { workingDirectory: '~/src' },
+      runtimes: { codex: { resetCommand: '/clear' } },
+      agents: [{ name: 'coder0', runtime: 'codex', className: 'worker' }],
+    };
+
+    const calls: string[][] = [];
+    const runner: CommandRunner = async (command, args) => {
+      calls.push([command, ...args]);
+      return { stdout: '', stderr: '', exitCode: 0 };
+    };
+
+    await enableFleetUnits(runner, minimalRoster, { enable: false });
+
+    // No calls should include 'enable'
+    expect(calls.every((c) => !c.includes('enable'))).toBe(true);
+    // No loginctl calls at all
+    expect(calls.every((c) => c[0] !== 'loginctl')).toBe(true);
+  });
 });
 
 describe('fleet ps — tenant and host', () => {

packages/mosaic/src/commands/fleet.ts

@@ -210,6 +210,93 @@ export function buildFleetServiceCommand(action: FleetServiceAction, agentName?:
   return ['systemctl', '--user', action, service];
 }
 
+/**
+ * Returns the systemctl --user enable command for a given unit.
+ * Used by the install auto-enable step to persist units across reboots.
+ */
+export function buildSystemdEnableCommand(unit: string): string[] {
+  return ['systemctl', '--user', 'enable', unit];
+}
+
+/**
+ * Returns the loginctl enable-linger command for a given user.
+ * Linger allows user systemd services to survive logout.
+ */
+export function buildEnableLingerCommand(user: string): string[] {
+  return ['loginctl', 'enable-linger', user];
+}
+
+/**
+ * Enable fleet units for boot-survival after install.
+ * Non-fatal: if systemctl enable returns non-zero, a warning is printed and we continue.
+ * If opts.enable === false (--no-enable flag), the whole step is skipped.
+ */
+export async function enableFleetUnits(
+  runner: CommandRunner,
+  roster: FleetRoster,
+  opts: { enable?: boolean },
+): Promise<void> {
+  if (opts.enable === false) {
+    return;
+  }
+  try {
+    let succeeded = 0;
+    let failed = 0;
+
+    const holderResult = await runner(
+      ...splitCommand(buildSystemdEnableCommand('mosaic-tmux-holder.service')),
+    );
+    if (holderResult.exitCode === 0) {
+      succeeded++;
+    } else {
+      failed++;
+      process.stderr.write(
+        `Warning: could not enable mosaic-tmux-holder.service: ${holderResult.stderr || holderResult.stdout || 'non-zero exit'}\n`,
+      );
+    }
+
+    for (const agent of roster.agents) {
+      const unit = `mosaic-agent@${agent.name}.service`;
+      const result = await runner(...splitCommand(buildSystemdEnableCommand(unit)));
+      if (result.exitCode === 0) {
+        succeeded++;
+      } else {
+        failed++;
+        process.stderr.write(
+          `Warning: could not enable ${unit}: ${result.stderr || result.stdout || 'non-zero exit'}\n`,
+        );
+      }
+    }
+
+    if (succeeded > 0) {
+      console.log(`Enabled ${succeeded} unit(s) for boot-survival.`);
+    }
+    if (failed > 0) {
+      process.stderr.write(
+        `Warning: ${failed} unit(s) could not be enabled (systemctl unavailable?). Run manually if needed.\n`,
+      );
+    }
+
+    // Best-effort linger
+    let username: string;
+    try {
+      username = userInfo().username;
+    } catch {
+      username = process.env['USER'] ?? process.env['LOGNAME'] ?? 'unknown';
+    }
+    const lingerResult = await runner(...splitCommand(buildEnableLingerCommand(username)));
+    if (lingerResult.exitCode !== 0) {
+      process.stderr.write(
+        `Hint: run 'loginctl enable-linger ${username}' as root to survive logout.\n`,
+      );
+    }
+  } catch (err) {
+    process.stderr.write(
+      `Warning: auto-enable step failed unexpectedly: ${err instanceof Error ? err.message : String(err)}\n`,
+    );
+  }
+}
+
 export function buildAgentSendCommand(
   paths: FleetPaths,
   agentName: string,
@@ -437,32 +524,41 @@ export function parseTmuxListPanes(
   return { pid, command, dead, idleSeconds };
 }
 
+/**
+ * Maps each known runtime to the set of acceptable pane commands.
+ * A pane running any of these commands for the given runtime is NOT considered drifted.
+ * Runtimes launched via `mosaic yolo` wrap in node, so 'node' is acceptable for most.
+ * The dogfood runtime accepts python3/python (the canary-pi dogfood stub).
+ */
+export const RUNTIME_ACCEPTABLE_COMMANDS: Record<string, readonly string[]> = {
+  claude: ['claude', 'node'],
+  codex: ['codex', 'node'],
+  opencode: ['opencode', 'node'],
+  pi: ['pi', 'node'],
+  dogfood: ['python3', 'python'],
+};
+
 /**
  * Determine if there is a runtime drift: roster says one runtime but the pane
  * is actually running something from a different runtime. We detect this by
- * checking if the pane command doesn't match a known canonical command for the
+ * checking if the pane command doesn't match a known acceptable command for the
  * roster's declared runtime.
  *
- * Known canonical commands per runtime:
- *   claude → claude
- *   codex  → codex
- *   opencode → opencode
- *   pi     → pi
+ * Known acceptable commands per runtime (see RUNTIME_ACCEPTABLE_COMMANDS):
+ *   claude   → claude, node  (node covers mosaic yolo wrapper)
+ *   codex    → codex, node
+ *   opencode → opencode, node
+ *   pi       → pi, node      (python3 still flags drift for canary-pi dogfood stub)
+ *   dogfood  → python3, python
  *
  * If the pane is running something else (e.g., python3/dogfood-agent.py) for
  * an agent whose roster runtime is "pi", that's a drift.
  */
 export function detectDrift(rosterRuntime: string, paneCommand: string | null): boolean {
   if (!paneCommand) return false;
-  const knownCommands: Record<string, string[]> = {
-    claude: ['claude'],
-    codex: ['codex'],
-    opencode: ['opencode'],
-    pi: ['pi'],
-  };
-  const expected = knownCommands[rosterRuntime];
-  if (!expected) return false;
-  return !expected.includes(paneCommand);
+  const acceptable = RUNTIME_ACCEPTABLE_COMMANDS[rosterRuntime];
+  if (!acceptable) return false;
+  return !acceptable.includes(paneCommand);
 }
 
 /**
@@ -706,12 +802,22 @@ export function registerFleetCommand(program: Command, deps: FleetCommandDeps =
   cmd
     .command('install')
     .description('Install local fleet tools and user systemd units')
-    .action(async () => installFleet(cmd, frameworkRoot));
+    .option('--no-enable', 'Skip enabling units for boot-survival')
+    .action(async (opts: { enable?: boolean }) => {
+      await installFleet(cmd, frameworkRoot);
+      const roster = await loadRosterForCommand(cmd);
+      await enableFleetUnits(runner, roster, opts);
+    });
 
   cmd
     .command('install-systemd')
     .description('Install local fleet tools and user systemd units')
-    .action(async () => installFleet(cmd, frameworkRoot));
+    .option('--no-enable', 'Skip enabling units for boot-survival')
+    .action(async (opts: { enable?: boolean }) => {
+      await installFleet(cmd, frameworkRoot);
+      const roster = await loadRosterForCommand(cmd);
+      await enableFleetUnits(runner, roster, opts);
+    });
 
   for (const action of ['start', 'stop', 'restart'] as const) {
     cmd