rss-feed-generator - SKILL.md Agent Skill

name: RSS Feed Generator description: Generate an Atom XML feed from articles, validate it, and notify only when it actually changes var: "" tags: [content]

${var} — Repo slug override (owner/repo) for feed URLs. If empty, the script auto-detects from the git remote. Pass through unchanged; do not invent a value.

Generate a valid Atom XML feed from all markdown articles in articles/, validate it, and notify only when the feed content actually changed. Unchanged runs are a silent no-op.

Steps

1. Read context

Read memory/MEMORY.md.

2. Capture the baseline

Before regenerating, snapshot the current feed so we can tell whether anything changed:

if [[ -f articles/feed.xml ]]; then
  PREV_HASH="$(sha256sum articles/feed.xml | awk '{print $1}')"
  grep -oP '(?<=<title>)[^<]+' articles/feed.xml | tail -n +2 | sort -u > /tmp/rss-feed-prev-titles.txt
else
  PREV_HASH=""
  : > /tmp/rss-feed-prev-titles.txt
fi

The tail -n +2 skips the feed-level <title> so only entry titles remain.

3. Regenerate the feed

Run the script. Pass ${var} as the repo slug override only if it is non-empty:

if [[ -n "${var}" ]]; then
  bash scripts/generate-feed.sh "${var}"
else
  bash scripts/generate-feed.sh
fi

4. Validate the XML

Invalid XML breaks every subscriber. Fail loud if the feed is malformed:

if command -v xmllint >/dev/null 2>&1; then
  xmllint --noout articles/feed.xml || { STATUS="RSS_FEED_ERROR"; VALIDATION_ERR="xmllint failed"; }
else
  # Fallback: verify the root element and a closing tag
  head -2 articles/feed.xml | grep -q '<feed' || { STATUS="RSS_FEED_ERROR"; VALIDATION_ERR="missing <feed> root"; }
  tail -1 articles/feed.xml | grep -q '</feed>' || { STATUS="RSS_FEED_ERROR"; VALIDATION_ERR="missing </feed> close"; }
fi

If STATUS=RSS_FEED_ERROR, stop, notify with the error, log it, and exit without committing. Do not commit a broken feed.

5. Detect what changed

Compare new feed against the baseline:

NEW_HASH="$(sha256sum articles/feed.xml | awk '{print $1}')"
grep -oP '(?<=<title>)[^<]+' articles/feed.xml | tail -n +2 | sort -u > /tmp/rss-feed-new-titles.txt

ADDED="$(comm -13 /tmp/rss-feed-prev-titles.txt /tmp/rss-feed-new-titles.txt)"
REMOVED="$(comm -23 /tmp/rss-feed-prev-titles.txt /tmp/rss-feed-new-titles.txt)"
ENTRY_COUNT="$(wc -l < /tmp/rss-feed-new-titles.txt | tr -d ' ')"

Classify the run:

RSS_FEED_NO_CHANGE — PREV_HASH == NEW_HASH (byte-identical). Exit silently after logging. No commit, no notify.
RSS_FEED_METADATA_ONLY — hashes differ but ADDED and REMOVED are both empty (e.g. <updated> timestamp drifted). Commit so the feed stays fresh, but do not notify — it is not a subscriber-visible change.
RSS_FEED_OK — ADDED or REMOVED is non-empty. Commit and notify.

6. Commit (only if changed)

Skip entirely for RSS_FEED_NO_CHANGE. Otherwise build a descriptive commit message:

if [[ "$STATUS" == "RSS_FEED_OK" ]]; then
  MSG="chore(feed): $(echo "$ADDED" | grep -c .) added, $(echo "$REMOVED" | grep -c .) removed ($ENTRY_COUNT total)"
else
  MSG="chore(feed): metadata refresh ($ENTRY_COUNT entries)"
fi

git add articles/feed.xml
git diff --cached --quiet || git commit -m "$MSG"
git push || true

If the push fails because the runner can't push directly, that's fine — the generated file remains in the workspace and a later skill/PR can carry it.

7. Notify (only on RSS_FEED_OK)

Silence is the feature. Do not notify on RSS_FEED_NO_CHANGE or RSS_FEED_METADATA_ONLY. On RSS_FEED_OK, build a concise message:

*RSS feed updated* — $ENTRY_COUNT entries

New:
- <first added title>
- <second added title>
[Removed: <removed titles> — only include this line if REMOVED is non-empty]

Subscribe: https://raw.githubusercontent.com/${repo}/main/articles/feed.xml

Keep it to one paragraph plus the bullet list. Cap at 5 added titles; if there are more, show the first 5 and append (+N more). Send via ./notify "<message>".

On RSS_FEED_ERROR, notify with:

*RSS feed ERROR* — $VALIDATION_ERR
Feed not committed. Investigate scripts/generate-feed.sh or articles/ inputs.

8. Log

Append to memory/logs/${today}.md:

### rss-feed
- Status: RSS_FEED_OK | RSS_FEED_METADATA_ONLY | RSS_FEED_NO_CHANGE | RSS_FEED_ERROR
- Entries: $ENTRY_COUNT
- Added: <titles or "none">
- Removed: <titles or "none">
- Prev hash: <first 8 chars>, new hash: <first 8 chars>

Always log, even on RSS_FEED_NO_CHANGE — the log line is how the operator distinguishes "ran and was idle" from "never ran."

Sandbox note

This skill is entirely local: it reads/writes files and shells out to scripts/generate-feed.sh. No network calls required. If git push is blocked by the sandbox, the commit still lands locally and the workflow's post-step commit/push path will handle it.

Constraints

Never commit a feed that fails validation.
Never notify on an unchanged feed — noise destroys the signal.
Preserve the script interface: scripts/generate-feed.sh [repo_slug]. Do not rewrite the generator inline.
Keep ${var} semantics aligned with what the script actually accepts (repo slug, not base URL).