When You're
The Blocker

A push notification hook for Amplifier, built by Amplifier

Amplifier · Hooks · Notifications

The Frame

Amplifier runs for a long time alone — but you keep watching for the moment it needs you

A long autonomous session is only truly "walk away" if something tells you when the agent is actually blocked on a human. Until then, you babysit the terminal.

amplifier-hooks-notifications is that missing signal — and it's tiny.

The promise: start a session, go do other things.
The tax: you can't tell from across the room when it's stuck on YOU.
The fix: a targeted push, sent only when it matters.

Proof · It's Real And It's Small

The whole hook is one 180-line Python file — and Amplifier co-authored every commit

Shipped and public as robotdad/amplifier-hooks-notifications, a "Push notification hook for Amplifier events via ntfy.sh." The repo tracks just three files.

A tool small enough to build its own notifier. So why isn't it simpler still?

180

lines in __init__.py — the entire module

3

tracked files: README, pyproject, __init__.py

5

commits, all by Marc Goodner + the Amplifier bot

v0.1.0

requires Python ≥3.11, amplifier-core ≥0.1.0

The Tension

Naive alerting is worthless — a ping on every tool call is just noise you learn to ignore

The hard problem was never sending notifications. It's sending the RIGHT one, so signal survives contact with a long, busy session.

The design's whole job: keep the alert meaningful. Here's how it does that.

Notify on everything

ping · ping · ping · ping · ping…

You mute it by lunch.

Notify only when it counts

— — "waiting for your input" —

You look up, because it earned it.

Mechanism · Restraint By Default

By default it stays quiet, firing on only two lifecycle events

The default enabled_events is exactly tool:error and session:end — not every sub-step. Restraint by default is what makes each alert mean something.

Quiet by design — and just as importantly, safe by design.

# default constructor config
enabled_events = ["tool:error", "session:end"]
notify_on_ask_user = True

# these are real amplifier-core events:
# SESSION_START / SESSION_END
# TOOL_POST / PROMPT_SUBMIT

Mechanism · Safe By Default

Fire-and-forget at low priority 90 — it can never become the thing that costs you a session

It launches the notify script as an async subprocess and doesn't wait. It runs at priority 90 (low), after other hooks, and swallows its own errors.

Never blocks, never interferes, never breaks a run. Now — what does it actually say?

Fire-and-forget: create_subprocess_exec then create_task(process.wait()) — "Don't wait for completion."
Priority 90 (low): registers late so it "doesn't interfere with other hooks or affect session performance."
Error-swallowing: a missing notify script raises nothing — the session keeps going.

The Turn · Meaning Over Volume

The team dropped "N tool calls executed" for "Re: {your prompt}"

Commit 2e4dd0d replaced a raw tool-count message with a prompt preview; follow-up 71e08fb caches the prompt from session:start so session:end can name it.

One glance tells you which session finished. Meaning beats volume — and that sets up the climax.

Before — a raw metric

Session ended. {tool_count} tool calls executed.

After — a meaningful signal

Session Complete — Re: {preview}

The Payoff · The AskUserQuestion Trip-Wire

When Amplifier asks a question, a high-priority push lands on whatever device you're at

On tool:post, if the tool is AskUserQuestion, it sends a high-priority alert. Delivered via a portable 3-arg notify script.

The one moment a human is the blocker becomes unmissable — "walk away" finally means walk away.

Priority: High

User Input Needed

Amplifier is waiting for your input

Delivered fire-and-forget via a 3-arg notify <message> <title> <priority> script — ntfy.sh to your phone, or native macOS, Linux, Windows.

The Takeaway

One small hook turns "run it and hover" into "run it and leave"

You get pulled back only when it's actually your turn. The generalized pattern: targeted, low-noise notifications are what make async agent work real.

Status: Shipped & public — robotdad/amplifier-hooks-notifications

Sources

Research Methodology

Data as of: 2026-01-06 (last commit 71e08fb). Feature status: Shipped and public.

Source repo: robotdad/amplifier-hooks-notifications (cloned at /tmp/ahn); event system cross-checked in microsoft/amplifier-core.

Commands run:

gh repo view robotdad/amplifier-hooks-notifications --json name,description — description & name
wc -l amplifier_module_hooks_notifications/__init__.py (180 lines) + find /tmp/ahn -type f -not -path '*/.git/*' (3 files)
git log --pretty=format:'%an|%ae' and git log --oneline | wc -l (5 commits, all 2026-01-06)
git show 2e4dd0d ; git show 71e08fb — prompt-preview change and prompt caching
read_file __init__.py lines 17-21, 34-41, 91-109, 147/160/170 — defaults, AskUserQuestion path, fire-and-forget, priority 90
grep -rn 'session:end|tool:post|HookResult' amplifier-core/amplifier_core/*.py — verified lifecycle events

Primary contributors: Marc Goodner (all 5 commits), co-authored by the Amplifier bot on every commit.

Gaps: Real-world adoption / user counts are not verifiable from the repo (none stated). ntfy.sh delivery latency ("across the room" timing) is inherent to ntfy.sh, not benchmarked here. The module has no dedup/one-notification-per-run counter; it can fire on multiple configured events.

When You'reThe Blocker