Sounds the wake-up call for sleeping AI agents
Bugler is an open-source event relay. Point GitHub, Stripe, Sentry, CI, any webhook at it. Agents in any harness subscribe with filters and sleep until a matching event arrives. Zero polling, zero tokens while idle, and a queryable event history to catch up from.
Self-hosting works today, free forever. The hosted relay is in early access: join the waitlist, we onboard in small batches.
Condensed from the recorded proof run: real GitHub events on a real repository, timestamps from machine logs.
from GitHub sending a PR-opened event to a fully stopped agent's written wake summary.
Machine-logged timelinefrom a GitHub comment landing to a parked Codex CLI agent's completed reply, via the in-session MCP wait.
Machine-logged timelineGitHub API calls between events, corroborated by GitHub's own delivery log: push-only traffic, three deliveries, all HTTP 200.
Externally corroboratedinference tokens while waiting. No model request is in flight while an agent sleeps; the bill starts at the wake.
By construction, not measuredLatencies measured on real GitHub events with machine-log timestamps. The token figure is structural, true by construction rather than benchmarked: there is simply no request to bill.
01 · How it works
One relay, three moving parts. Events are stored and delivered as CloudEvents 1.0 envelopes, so every source and every subscriber speaks the same shape.
STEP 1
Verifier presets for GitHub, Stripe, Sentry, GitLab (Standard Webhooks), CircleCI, and generic token sources. A dozen-line bridge covers SQS, Pub/Sub, NATS, or Redis. Poll-only systems get the bundled poll agent: one poll, shared by fifty subscribers.
POST /ingest/github X-Hub-Signature-256: sha256=9f2c… → verified, appended as a CloudEvents 1.0 envelope
STEP 2
CloudEvents filter dialects, exact, prefix, and suffix composed with all, any, and not, evaluated relay-side. A subscriber's entire delivery state is a filter plus one integer bookmark in a shared append-only log. Committing the cursor is the ack.
{ "all": [
{ "exact": { "type":
"com.github.pull_request" } },
{ "prefix": { "subject":
"myteam/" } }
] }
state: this filter + cursor #1041
STEP 3
The waker holds one ordinary outbound long-poll, so nothing ever connects inward to your machine. It relaunches your stopped CLI, or resolves an in-session wait_for_event call. The cursor advances only on exit 0; a crash means redelivery, never a lost event.
$ bugler waker -- \
claude -p "review the new PR"
or, in-session MCP:
wait_for_event · check_events
exit 0 → cursor commits
crash → redelivered
Two harnesses, two wake modes, both proven on real GitHub events: Claude Code relaunched from fully stopped, and Codex CLI parked in-session on the bounded MCP wait. The waker daemon can relaunch any CLI; native push adapters cover OpenClaw hooks and Claude Code Routines; a generic signed webhook feeds Temporal, Inngest, Restate, LangGraph, and Cloudflare Workflows through a small bridge.
02 · The economics
Polling every 5 minutes is 288 wake-ups a day, almost all of them empty, and every empty one still spins up a model to hear "nothing yet." A subscribed agent wakes only when a matching event arrives, in seconds.
No model request in flight, so waiting costs zero inference tokens by construction. No consumer-side API calls to the source either: during the proof run, GitHub's own delivery log showed push-only traffic, and the only standing connection was one outbound long-poll to the relay.
The agent receives the matching event and can query the history API to catch up from its cursor. Non-matching events cost an agent nothing, because filters run relay-side. Babysit a PR for hours; spend tokens only when it moves.
03 · Runs anywhere
Five storage drivers ship today: bun:sqlite, pure memory, Cloudflare Durable Object SQLite, DynamoDB, and Cosmos DB NoSQL. All pass one shared conformance suite that defines correctness for every driver, and no storage behavior leaks outside src/storage.
bun run src/cli.ts init, then serve. One process, no external dependencies. bun run smoke drives a full signed GitHub flow locally.
docker compose up --build -d. First start initializes the database and prints a show-once admin key in the service logs; rotate it right away, since container logs persist.
The same binary or container on any spare machine. Webhooks arrive through a free Cloudflare Tunnel or Tailscale Funnel: outbound-only daemons, no open ports.
deploy/gcp/setup-vm.sh cross-compiles a Linux binary, creates one always-free e2-micro, and installs it under systemd. Never touches billing settings.
The standard container on request-based billing, scale to zero, sub-10 s cold starts. This is the ingest-and-push profile, queued behind the Firestore driver (P5d).
deploy/cloudflare/setup.sh: one named SQLite Durable Object owns the log, delivery, and a persisted single-alarm scheduler. Hard caps fail rather than bill.
deploy/aws/setup.sh provisions only a DynamoDB table and a least-privilege IAM user; you run the container on compute you already operate. AWS has no always-free home for a long-polling core, and we say so.
deploy/azure/setup.sh forces an explicit choice: scale-to-zero at exactly $0 idle with documented cold-start risk on ingest, or always-on to keep every GitHub delivery inside its 10-second deadline.
04 · The gap
An 8-agent research sweep with roughly 235 web fetches found no existing project that combines a permissive license, a single-process zero-dependency footprint, durability, and a harness-neutral agent wake contract. Here is where the nearest ones stop.
Authenticated, durable, filtered, and built around a wake contract.
Self-host free forever, and the consumer is an agent, not an endpoint.
A single process with zero dependencies, and a $0 → $12 → $29 ladder instead of a cliff.
The same trigger idea, generalized across harnesses and event sources, delivered at-least-once.
All four are good at what they aim for; none of them aim at waking agents. Based on each product's public docs and pricing: competitor prices and limits checked 2026-08-23.
05 · Pricing
Every hosted limit is volume, never capability: the full engine ships in the open-source build with no feature deltas. The hosted product sells operations, ingress URLs, uptime, and retention storage, not withheld code.
$0 forever
$0/mo
$12/mo
$29/mo
What counts: a delivered event is a verified webhook matched and delivered to a subscription. Unmatched requests and retries are free.
Why these numbers: outgrowing the free tier costs $12 here, not a $490 cliff. Pro's included volume equals Svix's entire free tier; Team stays under Hookdeck's $39 entry with 25x its included events, and 30-day retention at $29 matches what Svix gives away free. Each step in the ladder is 2.4x or less. Heavy free users are not a problem to solve: they have self-host.
Need SSO, an SLA, or VPC peering? That is the contact-us Scale line above Team. Write to us from the waitlist form below, or email hello@bugler.dev.
Honesty note: hosted tiers are not live yet. This is early-access pricing, published so you can decide before you commit, and subject to refinement before general availability. hello@bugler.dev is the contact address used across this page and is live; if you prefer, open a GitHub issue instead.
06 · Honest engineering
Delivery is at-least-once within retention. An agent that stays away past the window gets an explicit gap notification telling it to reconcile, never a silent hole in history. Because GitHub never auto-retries a failed delivery, Bugler acks only after a durable commit, dedupes on GitHub's delivery GUID, and can run GitHub's own list-and-redeliver recovery on a schedule.
Signature verification is recorded as provenance: verified means authentic, never safe to obey. Payload text is always delivered as labeled untrusted data and never interpolated into instruction fields. The waker scrubs the subscriber token from every spawned handler's environment, so a prompt-injected handler cannot acknowledge events away.
The design survived five independent review rounds before a line of product code, converging 22 → 19 → 11 → 1 → 0 findings. Every build phase then closed its loop at zero blocking, zero material, zero minor findings: code built under a Claude orchestrator, independently reviewed by GPT-5.6 Sol at high effort. Core tests grew 38 → 89 through those rounds, plus 17 DynamoDB, 14 Cosmos, and 11 workerd tests.
Tokens are shown once, carry CRC32 typo checks, are stored only as SHA-256 hashes, and are rejected in query strings. Signing secrets stay env: or file: references resolved at use time and fail closed when missing. Deploy scripts are consent-first: tested --dry-run transcripts, explicit --yes for external changes, secrets via stdin, ShellCheck 0.11.0 at zero findings.
07 · FAQ
Not yet. Hosted Bugler is in early access: you join the waitlist, we onboard in small batches, and the published prices are early-access pricing. None of this gates the open-source relay, which works today and is free forever.
It is a structural property, not a benchmark: while an agent is stopped, or parked inside a bounded wait_for_event tool call, no model request is in flight, so no inference tokens are consumed. The bill starts only at the wake. We label this "by construction" rather than "measured" because that is the honest description.
No. Nothing ever connects inward to your machine. The waker holds one ordinary outbound long-poll, the same pattern GitHub's self-hosted Actions runners use, so it works from a laptop behind NAT, a container, or a locked-down corporate network.
Any CLI the waker daemon can relaunch. Claude Code (wake-from-stopped) and Codex CLI (in-session MCP wait) are proven against real GitHub events. Native push adapters cover OpenClaw hooks and Claude Code Routines, and a generic signed webhook feeds Temporal, Inngest, Restate, LangGraph, and Cloudflare Workflows through a small bridge.
It receives an explicit gap notification telling it to reconcile, never a silent hole in history. Inside the window, delivery is at-least-once: the cursor advances only when your handler exits zero, so a crashed or failing handler means redelivery, not a lost event, with consecutive failures backing off to a cap.
No. There are no feature deltas between self-host and the paid tiers, and every hosted limit is volume, never capability. The hosted product sells operations: uptime, ingress URLs, and retention storage. There is no phone-home in the open-source build.
A bundled polling agent turns poll-only systems into events at the relay, so fifty subscribers share one poll instead of running fifty polling loops. On the push side, verifier presets cover GitHub, Stripe, Sentry, GitLab (Standard Webhooks), CircleCI, and generic token sources, and a dozen-line bridge covers SQS, Pub/Sub, NATS, or Redis.
First light for your agents
Self-host tonight from GitHub, or join the early-access waitlist for the hosted relay: we run it, you sign in and point webhooks at us.
Your mail client should now hold a pre-filled note. Send that email to finish joining. If nothing opened, write to hello@bugler.dev yourself and you are on the list all the same.
This opens a pre-filled email to hello@bugler.dev. One reply when your slot opens, nothing else. Prefer self-hosting? The relay is on GitHub.