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:

1. 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.
2. Generate AI clips using the media-generation skill — one prompt per scene, 9:16 format.
3. Prepare brand fonts and assets (logo PNG).
4. Compose with FFmpeg using a Node.js script (

   .cjs

   ).
5. 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:

# Dark overlay for text readability on top of any clip
drawbox=x=0:y=0:w=iw:h=ih:color=0x000000@0.50:t=fill

# Text overlay — use execFileSync (array args), never shell strings, so UTF-8 works directly
drawtext=fontfile='/path/Inter-Black.ttf':fontsize=110:fontcolor=0xffffff:x=(w-text_w)/2:y=700:text='Tu texto aqui'

# Logo overlay — scale first, split for N scenes, then overlay each
[logoInput]scale=185:-1,split=4[logo0][logo1][logo2][logo3]
[clip_pre][logo0]overlay=x=65:y=72:format=auto[clip_out]

# Xfade transition between clips (0.4s fade)
[c0][c1]xfade=transition=fade:duration=0.4:offset=5.6[v01]

# Audio: music bed, trim to total duration, fade in/out
[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:

1. Blog post (1,500 words) →
2. X thread (extract each H2 as a tweet, intro = hook) →
3. LinkedIn post (pick the single most contrarian point, 800 chars) →
4. LinkedIn carousel (each H2 = 1 slide; carousels get highest dwell time) →
5. Newsletter section (add personal context + behind-the-scenes) →
6. Instagram feed post (hook + 3-5 supporting points, 1080×1080 or 1080×1350) →
7. Instagram Story (strip the feed hook to a single line, or turn the educational point into a poll) →
8. 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