| name | content-machine |
| description | Create social media posts, newsletters, and marketing content calibrated to your voice and platform. |
Content Machine
Create social posts, newsletters, and marketing copy that respects platform mechanics — truncation points, algorithm signals, and hook physics — not just "good writing."
When to Use
- Social posts (X/Twitter, LinkedIn, Instagram feed, Instagram Stories, TikTok captions, Threads)
- Newsletters, blog posts, content calendars, cross-platform repurposing
When NOT to Use
- Cold outreach (cold-email-writer) · Paid ad copy (ad-creative) · Research reports (deep-research) · SEO audits (seo-auditor)
Step 1: Voice Analysis
Ask for 3-5 existing posts. Extract: avg sentence length, contraction usage, emoji density, POV (I/we/you), signature phrases. If none exist, ask for 2 creators they want to sound like and use webFetch to pull recent posts as voice reference.
Step 2: Platform Mechanics (2025-2026 Specs)
LinkedIn — 3,000 char max, but truncation is what matters
- "...see more" cutoff: ~140 chars desktop, ~110 chars mobile. 57%+ of LinkedIn traffic is mobile — write the hook for 110 chars.
- Algorithm weights: comments count ~2x likes; dwell time is a primary signal; first 60-120 min engagement velocity determines reach ceiling.
- Optimal length: 800-1,000 chars (not 3,000). Short paragraphs (1-2 lines) + white space increase dwell time.
- Structure: Hook (110 chars, no throat-clearing like "I wanted to share...") → story/insight → single question CTA. Reply to every comment in the first hour to extend the test window.
- Hashtags: 3-5 max, at the very end. LinkedIn deprioritized hashtag discovery.
X/Twitter — 280 chars (free), 25,000 chars (Premium)
- Long posts on Premium truncate at ~280 chars in the feed — the hook rule still applies.
- Thread structure: Tweet 1 = the full promise ("How I went from X to Y in Z — thread 🧵"). Each tweet must stand alone for retweets. Last tweet = CTA + loop back to tweet 1.
- Line breaks double engagement vs. wall-of-text.
Instagram Feed — 2,200 char caption, ~125 chars visible before "...more"
- Hashtags: 3-5, not 30. Instagram's @creators account officially reversed the old advice; 20+ hashtags now reads as spam and can suppress reach. Put them inline or at the end, not in a comment.
- First line = hook. Emoji as bullet points scan faster than dashes on mobile.
- Format: Square (1080×1080) or portrait (1080×1350, 4:5 — outperforms square on CTR).
Instagram Stories — 1080×1920, 9:16
Stories are a fundamentally different medium from feed posts. Treat them as such.
Key differences from feed:
- Stories are ephemeral and sequential — viewers tap through in 2-3 seconds. There is no caption to read. The visual is the entire message.
- Stories are better for two-way interactions (polls, questions, DMs) than for broadcasting.
- Feed posts have copy doing the heavy lifting. Stories must work without it.
Safe zones — mandatory:
| Zone | Range | Why |
|---|
| Top dead zone | Top 14% (~270px) | Profile name, mute, close button UI |
| Bottom dead zone | Bottom 20% (~380px) | "Send message" bar + swipe-up area |
| Safe core | 14% – 80% from top | All content must live here |
Never place any text, logo, CTA, or key visual outside the safe core.
Story formats by content type:
| Content angle | Best story format | Why |
|---|
| Pain point | Single frame, stripped to one-liner | Needs immediate gut impact — no room for buildup |
| Educational | Poll (two-option) | Polls get 3× more taps than passive stories; drives return for "reveal" |
| Feature/product | 3-frame sequence: Problem → Solution → Result | Complex message needs beats; tap-through is an algorithm signal |
| Relationship/split concept | Vertical split visual | 9:16 is naturally tall — a top/bottom split reads instantly |
| Tips list | One tip per frame (e.g., "Tip 1 de 3") | Breaks up information; each frame drives tap-through to next |
Story copy rules:
- Strip feed copy to its absolute core. One line, not a paragraph.
- The hook becomes the entire visual headline — make it 9-12vw on screen and impossible to miss.
- CTAs live in the bottom safe zone (72-78vh) as a full-width strip or pill — not scattered across the frame.
- Progress indicators ("1 / 3", three dots) signal sequence to viewers and reduce drop-off between frames.
Poll stories:
- Two options, both plausible — avoid obvious right answers.
- Create a reason to return: "Mañana revelamos el promedio real" drives next-day traffic.
- Benchmark: 20-40% response rate on engaged audiences.
Multi-frame sequences:
- Each frame must have a clear progress indicator so viewers know there's more.
- Each frame must have a tap hint (e.g., "Toca para continuar →") except the last.
- Last frame ends with a CTA, not a tap hint.
- File naming:
story3a.html, story3b.html, story3c.html for the 3 frames of Story 3.
Same angle, different execution — never just resize a feed post:
| Feed post | Story adaptation |
|---|
| Pain point with supporting copy | Strip to the one-liner only — huge on screen, nothing else |
| Educational post with data | Turn into a poll question — let the audience engage, reveal answer next day |
| Feature walkthrough | 3-frame sequence: Frame 1 = problem, Frame 2 = solution stat, Frame 3 = result UI |
| Relationship/split concept | Vertical split (top half / bottom half) unified at the seam |
| Tips list (3 items) | 3 separate frames, one per tip, "Tip 1 de 3" format |
TikTok captions — 4,000 chars (up from 2,200)
- TikTok is now a search engine — ~40% of Gen Z searches here before Google. Front-load keywords in the caption for TikTok SEO. The caption is indexed; use it for terms your video doesn't say out loud.
TikTok Video Production (Composited Short-Form Video)
The skill CAN produce TikTok-format video (1080×1920, 9:16) using FFmpeg + AI-generated clips. This is not just captions — it is full video production.
API capability disclosure — mandatory before starting: When producing TikTok video, always inform the user upfront that two quality tiers exist:
- Without an external API (default): AI-generated clips via the built-in media-generation tool — cinematic-style footage, good for most use cases, no extra setup or cost.
- With an external API (higher quality): Services like Runway Gen-3, Pika, or Kling can produce significantly more realistic and controllable footage, but require a paid API key from the user.
Always present both options and ask which they prefer before generating any clips. Never silently call a paid external API. Never assume the user knows these options exist — they usually don't.
Production workflow:
- Write a scene brief: 3-5 scenes, each with a visual prompt, text overlays, and duration (6-8s per scene is ideal). Total target: 20-30s.
- Generate AI clips using the media-generation skill — one prompt per scene, 9:16 format.
- Prepare brand fonts and assets (logo PNG).
- Compose with FFmpeg using a Node.js script (
.cjs).
- Output to
client/public/videos/ — served at /videos/ on the Replit domain.
FFmpeg in Replit NixOS:
- FFmpeg v6+ is available. Locate it:
ls /nix/store/*ffmpeg-full*/bin/ffmpeg 2>/dev/null | head -1
- Run via
execFileSync('ffmpeg', args) — do NOT use shell string commands (escaping nightmare).
Font handling — Inter (or any Google Font):
- Download the GitHub release zip:
https://github.com/rsms/inter/releases/download/v4.0/Inter-4.0.zip
- Extract TTF files using Node.js
zlib.inflateRawSync() — do not assume unzip or Python are available.
- Write to
/tmp/tiktok/fonts/Inter-Black.ttf, Inter-Bold.ttf, Inter-Regular.ttf.
- Always use the brand font. DejaVu (FFmpeg's fallback) looks wrong on brand content.
FFmpeg filter techniques:
drawbox=x=0:y=0:w=iw:h=ih:color=0x000000@0.50:t=fill
drawtext=fontfile='/path/Inter-Black.ttf':fontsize=110:fontcolor=0xffffff:x=(w-text_w)/2:y=700:text='Tu texto aqui'
[logoInput]scale=185:-1,split=4[logo0][logo1][logo2][logo3]
[clip_pre][logo0]overlay=x=65:y=72:format=auto[clip_out]
[c0][c1]xfade=transition=fade:duration=0.4:offset=5.6[v01]
[musicInput]atrim=0:24.8,afade=t=in:st=0:d=1.0,afade=t=out:st=23.0:d=1.8[aout]
Scene structure that works (4-scene formula):
| Scene | Clip prompt | Text role | Duration |
|---|
| Hook | Person reacting to a pain point (wide shot) | Big provocative question, brand color accent | 6s |
| Pain | Close-up showing the problem (phone, account, etc.) | Short punchy lines, high contrast | 6s |
| Solution | App/product in use or aspirational moment | Feature bullets, subdued overlay (show the product) | 6s |
| CTA | Positive resolution, couple/family | Download prompt, URL badge, attribution | 8s |
Overlay composition rules:
- Dark overlay alpha: 0.40–0.55 for clips that need text; 0.35–0.45 for product/app clips (show them).
- Text hierarchy: headline in brand color or white at 110-130px (Inter Black), body at 50-70px (Inter Bold), captions at 36-44px (Inter Regular).
- Logo: top-left corner, ~185px wide, every scene — use
scale=185:-1,split=N.
- All content within 140px–1780px vertical (safe zone same as Stories: avoid top 14% and bottom 20%).
Output settings (always use these exactly):
-c:v libx264 -preset fast -crf 18 -pix_fmt yuv420p -movflags +faststart -c:a aac -b:a 192k
Music licensing:
- If using CC BY music (e.g., Kevin MacLeod), attribution must appear IN the video (small text overlay, last scene), not just in the caption. Caption-only attribution does not satisfy CC BY for video.
- Recommended free source: freemusicarchive.org, filter by CC BY.
Canvas embedding:
- Always resolve the domain with
echo $REPLIT_DOMAINS before setting a canvas video shape URL. Never hardcode a domain — Replit domains change between sessions.
- Video shape URL format:
https://<domain>/videos/filename.mp4
Newsletters — Optimize for clicks, not opens
- Apple Mail Privacy Protection (MPP) inflates open rates by ~18 percentage points. Apple Mail is ~46% market share and pre-fetches tracking pixels. A "42% open rate" in 2025 ≈ a 24% open rate in 2020. Track click rate (benchmark: ~2%) and CTOR (10-20%) instead.
- Subject line: 30-50 chars. Avoid "Free," ALL CAPS, multiple "!!!" — spam filter triggers. B2B: longer, specific subject lines outperform short clever ones.
- Preview/preheader text: adds ~6pp to open rate when used — but Gmail's Gemini now auto-generates previews, so don't rely on controlling it. Write the first sentence of the body as a second hook.
- One primary CTA. Every additional CTA cuts click rate.
Step 3: Hook Formulas (Named Patterns)
Don't say "write a hook" — pick a pattern:
| Pattern | Template | Why it works |
|---|
| Contrarian | "Everyone says X. Here's why that's wrong." | Cognitive dissonance forces resolution |
| Curiosity gap | "I tried X for 30 days. Day 17 broke me." | Open loop — brain needs closure |
| Specificity signal | "$47,212 in 90 days. Here's the exact stack." | Odd numbers read as true, round numbers read as marketing |
| Negative hook | "3 mistakes that cost me [outcome]" | Loss aversion > gain seeking |
| Callout | "If you're a [role] still doing X, read this." | Self-selection = higher-intent readers |
| Slippery slope | "It started with one Slack message." | Narrative momentum |
| Permission | "Unpopular opinion: [take]" | Pre-frames disagreement as expected |
Banned openers: "I'm excited to share," "Hey everyone," "As a [title]," "In today's fast-paced world."
Step 4: Repurposing Waterfall
One long-form piece → 8+ assets:
- Blog post (1,500 words) →
- X thread (extract each H2 as a tweet, intro = hook) →
- LinkedIn post (pick the single most contrarian point, 800 chars) →
- LinkedIn carousel (each H2 = 1 slide; carousels get highest dwell time) →
- Newsletter section (add personal context + behind-the-scenes) →
- Instagram feed post (hook + 3-5 supporting points, 1080×1080 or 1080×1350) →
- Instagram Story (strip the feed hook to a single line, or turn the educational point into a poll) →
- TikTok/Reel script (the hook + the #1 takeaway in 30 sec)
Key rule for Stories in the waterfall: same angle as the feed post, completely different execution. Never just crop or resize a feed post into a Story — re-author it according to the story format table above.
Build repurposing scripts in Python when batch-processing: parse markdown H2s → split into platform templates → enforce char limits programmatically.
Content Frameworks
- PAS (Problem → Agitate → Solve) — best for conversion-focused posts
- BAB (Before → After → Bridge) — best for transformation stories
- AIDA (Attention → Interest → Desire → Action) — best for launches
- SLAP (Stop → Look → Act → Purchase) — best for short-form (Reels/TikTok captions)
Validation
Before delivering, verify:
- Char counts against platform limits (count programmatically, don't eyeball)
- Hook fits in the truncation window (110 chars for LinkedIn mobile, 125 for Instagram feed)
- No banned openers
- One CTA per piece
- For Stories: all content confirmed inside the 14%–80% safe zone
Limitations
- Cannot post to platforms or access analytics
- Cannot generate static images directly — use the media-generation skill for images; use the ad-creative skill for HTML/CSS visual story designs
- CAN produce composited short-form video (TikTok/Reels) via FFmpeg + AI clip generation — see TikTok Video Production section above
- Paid external video APIs (Runway, Pika, Kling) require user consent and their own API key before use
- Voice matching quality scales with example count
