---
name: session-inbox-monitor
version: 0.2.1
description: >
  Raises a persistent Monitor (Monitor tool, NOT background Bash) on the
  project's `.claude-inbox/` at the start of an interactive session, so
  inter-session messages page the session in real time; the monitor dies on
  session end on its own. A paired SessionStart hook injects the
  raise-instruction and first sweeps orphaned monitors of this inbox (a
  `/clear` leaves them running → re-raise would stack duplicates). Triggers:
  CLAUDE.md line `inbox monitor: raise on start`, or «подними монитор почты»,
  «настрой авто-монитор инбокса», «raise inbox monitor», «auto-arm inbox
  watcher». Headless (`claude -p`): does NOT raise — Monitor doesn't work
  there; rely on the Stop-hook inbox pickup + Notify/ntfy. NOT for how to
  handle a received message (→ inter-session-peer-discipline) nor the
  multi-machine inbox backend (→ cross-machine-inbox design).
---

# session-inbox-monitor

Auto-raises a session-length Monitor on `.claude-inbox/` at interactive-session
start (via a paired SessionStart hook that injects the instruction and sweeps
orphans), so inter-session messages page the session in real time. Tears down
for free on session end. Headless sessions skip it and rely on the pull-model
(Stop-hook pickup + Notify).

## When to use

- **Automatic (the common path).** The paired SessionStart hook injects an
  instruction at the start of every interactive session of an opted-in project.
  You act on that injection — raise the monitor as your first action — without a
  user phrase.
- **On request.** CLAUDE.md line `inbox monitor: raise on start`, or «подними
  монитор почты», «настрой авто-монитор инбокса», «raise inbox monitor»,
  «auto-arm inbox watcher».
- **NOT for** handling the content of a received message (→
  `inter-session-peer-discipline`), nor the multi-machine delivery backend (→
  `cross-machine-inbox`). This skill is only the monitor's *lifecycle* on one
  machine.

## Inputs

- `<project>/.claude-inbox/` — the watched directory. Direct-child `*.md` files
  are inbox messages (the Stop-hook moves them to `.read/` once handled).
- The SessionStart hook supplies the **exact Monitor command** to run, with the
  sweep sentinel (`CLAUDE_INBOX_MONITOR`) and the absolute inbox path baked in.
  Use it verbatim — do not hand-author a different poll command, or the sweep
  won't recognise the process it spawns.

## Steps

1. **Mode check.** If this is a headless / non-interactive run (`claude -p`),
   **STOP — do not raise a monitor.** The Stop-hook inbox pickup plus `Notify:`/
   ntfy cover delivery there; a Monitor can't idle-watch in headless and is
   killed ~5s after the run. There is no hook-level headless signal, so this is
   your judgement call from the run context.
2. **Raise exactly one persistent Monitor** using the command the hook injected:
   the **Monitor tool** with `persistent: true`, `description: "inbox watcher"`.
   The hook already swept any orphan before injecting, so you start from a clean
   slate — raise one, not more.
3. **Do not sweep yourself.** Killing orphans is the hook's job (it runs before
   you, at SessionStart, when no other session activity is live).
4. **On an event** (`New inter-session message in inbox: <name>`), read
   `.claude-inbox/` and handle the message per `inter-session-peer-discipline`.
   The Stop-hook also force-delivers any inbox messages at end of turn as a
   backstop, so nothing is lost if the monitor missed a beat.
5. **Teardown is automatic.** The Monitor dies at session end. Do **not** add a
   SessionEnd teardown — and note `/clear` does not fire SessionEnd anyway
   (that's why the sweep lives in SessionStart, not SessionEnd).

## Deployment (machine-local)

- Hook script: `skills/session-inbox-monitor/hooks/inbox-monitor.ps1` (versioned
  here) → deploy to `~/.claude/hooks/inbox-monitor.ps1`.
- Register in `~/.claude/settings.json` under `hooks.SessionStart` (no matcher →
  fires on startup/resume/clear/compact), e.g.:
  ```json
  { "hooks": [ { "type": "command",
      "command": "powershell -NoProfile -ExecutionPolicy Bypass -File \"C:\\Users\\<you>\\.claude\\hooks\\inbox-monitor.ps1\"",
      "timeout": 15, "statusMessage": "inbox-monitor" } ] }
  ```
- Twin pattern: `poller-interactive-lock-writer` (`interactive-lock.ps1`).
- Opt-in per project: the hook fires only when the project has a `.claude-inbox/`
  directory **or** a CLAUDE.md line `inbox monitor: raise on start`.

## Failure modes

- **No inbox, no opt-in line** → the hook injects nothing; no monitor. Expected
  for projects that don't use inter-session messaging.
- **Two live interactive sessions on the same project** → the second session's
  SessionStart sweep kills the first session's monitor (the match is
  per-inbox-path, not per-session). Known limitation; the deliberate invariant is
  "exactly one monitor per inbox per machine." If the first session is still
  active, its next Stop-hook turn still delivers inbox mail — only the real-time
  paging is lost until it re-raises. See `inter-session-peer-discipline`.
- **Sweep over-match** → any *live* process whose command line contains both the
  sentinel `CLAUDE_INBOX_MONITOR` and the inbox path is killed. At a real
  SessionStart no agent/tool processes are running yet, so only the orphaned
  monitor matches. Don't echo or run a command carrying that sentinel+path during
  a session's startup.
- **Headless didn't skip** → a monitor raised in headless is a harmless no-op,
  killed ~5s after the run ends. The default errs toward raising because a
  false-skip in an interactive session would silently lose the feature.
- **Monitor auto-stopped** → the harness stops monitors that emit too many
  events. The injected poll command de-dups by filename (pages once per message,
  not every 15s) to stay under that bar.
- **Mojibake on force-delivery** → the Stop-hook (`stop-dispatcher.ps1`) injects
  message bodies to stdout; WinPS 5.1 must set `[Console]::OutputEncoding =
  [System.Text.Encoding]::UTF8` or non-ASCII (Cyrillic) bodies arrive mangled
  (it emits in the OEM code page under a harness-spawned redirected pipe). Inbox
  messages must be written as **no-BOM UTF-8, LF** — the Write tool does this;
  PowerShell writers must use
  `[IO.File]::WriteAllText($p,$t,[Text.UTF8Encoding]::new($false))`, NOT
  `Set-Content`/`Out-File -Encoding utf8` (which adds a BOM under 5.1). Same
  WinPS-5.1 encoding class as the hook-source em-dash gotcha. Fixed + in-situ
  verified 2026-06-17.

## Side effects

- Spawns one Monitor (and its backing Git-Bash poll process) per interactive
  session; both die at session end.
- Force-kills orphaned monitor processes of this inbox at every SessionStart.
- **No repo writes.** The hook and its `~/.claude/settings.json` registration are
  machine-local; only this skill (docs) and `.claude-inbox/` activity are in play.

## What NOT to do

- **Don't watch the inbox with a background Bash** (`run_in_background`) — it
  leaks across `/clear` and accumulates zombies. Use the Monitor tool.
- **Don't add a SessionEnd teardown hook** — the Monitor self-terminates, and
  `/clear` never fires SessionEnd.
- **Don't raise more than one monitor.** The hook guarantees a clean slate before
  you raise.
- **Don't handle message content here** — that's `inter-session-peer-discipline`.
- **Don't rely on this in headless** — use the pull model (Stop-hook + Notify).
  Active headless polling, if ever needed, is a separate cron Routine, not this
  skill.