Newsletter Digest Agent Skill

Newsletter Digest

Aggregate content from RSS feeds, synthesize the week's top stories with Gemini, and publish a digest to Ghost CMS. Supports weekly digests, topic-focused roundups, and curated picks formats.

Writing Style

Apply to all generated digest content:

• Active voice only
• Short sentences, one idea per sentence
• No em dashes — use a period or comma instead
• No semicolons
• No markdown or asterisks in the final newsletter body
• No hashtags

Banned words — do not use any of these in the digest:

incredible, amazing, leveraging, synergize, game-changing, game changer, delve, harness, unlock, groundbreaking, cutting-edge, remarkable, paradigm, revolutionize, disruptive, transformative, thrilled, excited to share, powerful, innovative, comprehensive, actionable, crucial, vital, pivotal, elucidate, utilize, dive deep, tapestry, illuminate, revolutionize

CRITICAL RULE

Every claim, statistic, and summary in the digest must come from the fetched articles. Never fabricate data points, quotes, or facts. If a source article has no meaningful content, skip it.

Step 1: Check Setup

1a. Verify feeds are configured

Check if feeds.json exists in the skill directory:

ls /Users/ksd/Desktop/Varnan_skills/newsletter-digest/feeds.json 2>/dev/null

If missing, ask the user: "Which RSS feeds should I monitor? Share a list of URLs and I'll create feeds.json."

The format is:

[
  { "url": "https://example.com/feed", "name": "Source Name" },
  { "url": "https://another.com/rss", "name": "Another Source" }
]

1b. Verify required environment variables

Check that these are set:

• GEMINI_API_KEY (required): for synthesis
• GHOST_URL and GHOST_ADMIN_KEY (required for Ghost publishing, optional if output-only)

If GEMINI_API_KEY is missing, stop and ask the user to set it.

GHOST config is optional. If not set, the skill outputs formatted Markdown instead of publishing.

1c. Verify script dependencies

ls /Users/ksd/Desktop/Varnan_skills/newsletter-digest/node_modules 2>/dev/null | head -1

If missing:

cd /Users/ksd/Desktop/Varnan_skills/newsletter-digest && npm install

Step 2: Fetch and Parse Feeds

Run the fetch script:

node /Users/ksd/Desktop/Varnan_skills/newsletter-digest/scripts/fetch-feeds.js

The script:

• Reads feeds.json for the list of feeds
• Fetches each feed using rss-parser
• Filters items published in the last 7 days
• Deduplicates by URL
• Sorts by publish date, newest first
• Saves results to /tmp/newsletter-digest-articles.json

If the script errors on a specific feed, it logs a warning and continues. One bad feed does not stop the run.

After the script completes, verify the output:

node -e "
const fs = require('fs');
const data = JSON.parse(fs.readFileSync('/tmp/newsletter-digest-articles.json', 'utf8'));
console.log('Total articles:', data.articles.length);
console.log('From feeds:', data.feedsSummary.map(f => f.name + ': ' + f.count).join(', '));
console.log('Date range:', data.dateRange.from, 'to', data.dateRange.to);
"

If fewer than 3 articles are found, warn the user and ask if they want to extend the date range to 14 days. Pass --days=14 to the script to widen the window.

Step 3: Read Format Rules

Read references/digest-format.md in full before generating any content. Internalize:

• Three digest formats (Weekly Roundup, Topic Deep Dive, Curated Picks) and when to use each
• Section structure and length requirements per format
• Attribution rules (every claim links to a source)
• Tone and voice guidelines

Read references/output-template.md and select the template matching the requested format.

If the user did not specify a format, default to Weekly Roundup.

Step 4: Synthesize with Gemini

Read /tmp/newsletter-digest-articles.json and build a synthesis prompt.

Prompt structure:

You are a newsletter editor writing a digest of this week's top stories.

Sources (use ONLY these — do not invent facts):
[For each article: Title | Source | Date | Summary]

Task:
Write a [FORMAT] digest following this structure:
[Paste the selected template from references/output-template.md]

Rules:
- Every claim, statistic, and quote must come from the sources above
- Write in active voice, short sentences, contractions allowed
- Do not use: incredible, amazing, leveraging, game-changing, delve, groundbreaking, cutting-edge, revolutionize
- No em dashes, no semicolons, no hashtags
- Include [Source: Name](URL) attribution after each major claim
- Output plain text with HTML heading tags only (no markdown asterisks)

Call Gemini with this prompt. Target model: gemini-2.0-flash or the latest available.

If the response contains any banned words or invented statistics not present in the source articles, regenerate with a stricter prompt.

Step 5: Self-QA

Run every check before presenting. Fix violations first.

• [ ] Every claim, statistic, and quote traces to a source article
• [ ] No banned words in any section
• [ ] No em dashes in the text
• [ ] No semicolons in the text
• [ ] Every section has at least one source attribution with URL
• [ ] Word count is within the format's target range (see references/digest-format.md)
• [ ] No section repeated the same story twice
• [ ] Title is specific (includes the date range or issue number, not just "Weekly Digest")
• [ ] HTML output is valid (no unclosed tags if Ghost publishing)

Fix all violations before presenting to the user.

Step 6: Format and Preview

Present the digest to the user in this order:

• Title — Issue date range or topic
• Digest content — Full formatted text
• Source list — All articles used, with URLs
• Word count and article count

Ask: "Ready to publish to Ghost as a draft, or would you like to edit first?"

Step 7: Publish to Ghost or Output

If GHOST_URL and GHOST_ADMIN_KEY are set and user confirms:

Run the publish script:

node /Users/ksd/Desktop/Varnan_skills/newsletter-digest/scripts/ghost-publish.js \
  --title "DIGEST_TITLE" \
  --status "draft"

The script reads /tmp/newsletter-digest-output.json (written by the agent in Step 6) and posts to Ghost.

After posting, the script returns the Ghost admin URL for the draft. Present this to the user: "Draft saved at: [URL]. Review and publish from your Ghost dashboard."

If the user wants to publish immediately, pass --status "published" to the script.

If Ghost is not configured or user says "output only":

Output the digest in three formats:

• HTML — ready to paste into any CMS
• Markdown — for Substack, Notion, or Hashnode
• Plain text — for email clients

Add: "Substack does not offer a public API. Copy the Markdown version into your Substack editor directly."

Notes on Substack

Substack has no public API. Programmatic posting is not possible without reverse-engineering internal endpoints, which violates their terms. The skill outputs a formatted Markdown digest ready to paste into the Substack editor. This is the correct approach.