hermes-agent/optional-skills/devops/watchers/SKILL.md
Teknium ea8e608821
feat(skills): watchers skill — poll RSS / HTTP JSON / GitHub via cron no-agent (#21881)
* feat(skills): watchers skill — poll RSS / HTTP JSON / GitHub via cron no-agent

Ships three reusable polling scripts plus a shared watermark helper as an
optional skill.  Users wire them into the existing cron (no_agent=True)
mode rather than learning a new subsystem.

Supersedes the closed PR #21497 (parallel watcher subsystem).  Same value,
zero new core surface.

## What ships

- optional-skills/devops/watchers/SKILL.md: pattern + three example cron commands
- optional-skills/devops/watchers/scripts/_watermark.py: shared helper
  (atomic state writes, bounded ID set, first-run baseline)
- optional-skills/devops/watchers/scripts/watch_rss.py: RSS 2.0 + Atom
- optional-skills/devops/watchers/scripts/watch_http_json.py: any JSON endpoint
  with configurable id_field / items_path / headers
- optional-skills/devops/watchers/scripts/watch_github.py: issues / pulls /
  releases / commits (uses GITHUB_TOKEN if present)

## Invariants enforced by the shared helper

- First run records baseline, emits nothing (never replays existing feed)
- Watermark file is <state_dir>/<name>.json, atomic replace on write
- Bounded to 500 IDs (configurable)
- Empty stdout when no new items — cron treats that as silent delivery

## Validation
- watch_rss.py against news.ycombinator.com/rss first run → empty stdout, watermark populated
- Removed one seen-id, second run → emitted exactly that item
- No DeprecationWarnings (ET element truth-value footgun dodged explicitly)

End-user pattern: 'hermes cron create my-feed --schedule "*/15 * * * *" --no-agent --script $HERMES_HOME/skills/devops/watchers/scripts/watch_rss.py --script-args "--name hn --url https://news.ycombinator.com/rss" --deliver telegram'

* docs(skills/watchers): tighten description to match peer optional skills

* docs(skills/watchers): align frontmatter + structure with peer optional skills

* docs(skills/watchers): gate to linux/macos (shell syntax in examples)
2026-05-08 09:27:15 -07:00

4.4 KiB

name description version author license platforms metadata
watchers Poll RSS, JSON APIs, and GitHub with watermark dedup. 1.0.0 Hermes Agent MIT
linux
macos
hermes
tags category requires_toolsets related_skills
cron
polling
rss
github
http
automation
monitoring
devops
terminal

Watchers

Poll external sources on an interval and react only to new items. Three ready-made scripts plus a shared watermark helper; wire them into a cron job (or run them ad-hoc from the terminal).

When to Use

  • User wants to watch an RSS/Atom feed and be notified of new entries
  • User wants to watch a GitHub repo's issues / pulls / releases / commits
  • User wants to poll an arbitrary JSON endpoint and get notified on new items
  • User asks for "a watcher for X" or "notify me when X changes"

Mental model

A watcher is just a script that:

  1. Fetches data from the external source
  2. Compares against a watermark file of previously-seen IDs
  3. Writes the new watermark back
  4. Prints new items to stdout (or nothing on no-change)

The scripts below handle all three. The agent runs them via the terminal tool — from a cron job, a webhook, or an interactive chat — and reports what's new.

Ready-made scripts

All three live in $HERMES_HOME/skills/devops/watchers/scripts/ once the skill is installed. Each reads WATCHER_STATE_DIR (defaults to $HERMES_HOME/watcher-state/) for its state file, keyed by the --name argument.

Script What it watches Dedup key
watch_rss.py RSS 2.0 or Atom feed URL <guid> / <id>
watch_http_json.py Any JSON endpoint returning a list of objects Configurable id field
watch_github.py GitHub issues / pulls / releases / commits for a repo id / sha

All three:

  • First run records a baseline — never replays existing feed
  • Watermark is a bounded ID set (max 500) to cap memory
  • Output format: ## <title>\n<url>\n\n<optional body> per item
  • Empty stdout on no-new — the caller treats that as silent
  • Non-zero exit on fetch errors

Usage

Run a watcher directly from the terminal tool:

python $HERMES_HOME/skills/devops/watchers/scripts/watch_rss.py \
  --name hn --url https://news.ycombinator.com/rss --max 5

Watch a GitHub repo (set GITHUB_TOKEN in ~/.hermes/.env to avoid the 60 req/hr anonymous rate limit):

python $HERMES_HOME/skills/devops/watchers/scripts/watch_github.py \
  --name hermes-issues --repo NousResearch/hermes-agent --scope issues

Poll an arbitrary JSON API:

python $HERMES_HOME/skills/devops/watchers/scripts/watch_http_json.py \
  --name api --url https://api.example.com/events \
  --id-field event_id --items-path data.events

Wiring into cron

Ask the agent to schedule a cron job with a prompt like:

Every 15 minutes, run watch_rss.py --name hn --url https://news.ycombinator.com/rss. If it prints anything, summarize the headlines and deliver them. If it prints nothing, stay silent.

The agent invokes the script via the terminal tool inside the cron job's agent loop; no changes to cron's built-in --script flag are needed.

State files

Every watcher writes $HERMES_HOME/watcher-state/<name>.json. Inspect:

cat $HERMES_HOME/watcher-state/hn.json

Force a replay (next run treated as first poll):

rm $HERMES_HOME/watcher-state/hn.json

Writing your own

All three scripts use the same template: load watermark, fetch, diff, save, emit. scripts/_watermark.py is the shared helper; import it to get atomic writes + bounded ID set + first-run baseline for free. See any of the three reference scripts for how little boilerplate it takes.

Common Pitfalls

  1. Printing a "no new items" header every tick. Callers rely on empty stdout = silent. If you print anything on an empty delta, you spam the channel. The shipped scripts handle this; custom scripts must too.
  2. Expecting the first run to emit items. It won't — first run records a baseline. If you need an initial digest, delete the state file after the first run or add a --prime-with-latest N flag in your own script.
  3. Unbounded watermark growth. The shared helper caps at 500 IDs. Raise it for high-churn feeds; lower it on constrained filesystems.
  4. Putting the state dir where the agent's sandbox can't write. $HERMES_HOME/watcher-state/ is always writable. Docker/Modal backends may not see arbitrary host paths.