Scrollclaw Assemble

Assemble

Three stages: stitch + audio → post-production → captions. Order matters.

Modes

This skill handles four intents. Choose the narrowest one that matches the user's request:

• stitch — timeline assembly and voice orchestration only
• post — post-production realism pass only
• captions — caption rendering and overlay only
• full-assemble — do all three in order; this is the default when the user says "assemble", "finish the video", or otherwise asks for the final output

If the user asks for one stage explicitly, do not force the full pipeline. If they ask for the final video, run full-assemble.

Prerequisites

• A-roll clips from /animate
• B-roll clips from /b-roll (if applicable)
• Script with timing from /persona

Stage 1: Stitch + Audio Orchestration

Read references/audio-orchestration.md for the full process.

The critical ordering (tested):

1. Stitch A-roll clips ONLY (these drive the timeline)
2. Extract audio → run through ElevenLabs S2S → one consistent voice
3. Lay S2S voice back on A-roll video
4. Cut A-roll at B-roll insertion points
5. Insert B-roll clips as VISUAL-ONLY (no audio) at timestamps matching the script
6. Lay S2S voice on the final assembled video

Voice never cuts. B-roll swaps visuals only. The wrong approach (stitch all clips then add voice) breaks timing because B-roll adds visual duration that doesn't exist in the voice track.

For single-clip talking head: Sora's built-in audio may be sufficient. For podcast format: always use ElevenLabs S2S.

Multi-Clip Stitching

For longer UGC, either use fal.ai's 20s duration or stitch clips:

Last-frame stitching (tested, works well):

1. Extract last frame: ffmpeg -sseof -0.1 -i clip1.mp4 -frames:v 1 last-frame.png
2. Use as first frame of clip 2 → seamless visual continuity
3. Concatenate with ffmpeg

bash scripts/extend-clip.sh \
  --input workspace/campaigns/<slug>/clips/a-roll-01.mp4 \
  --prompt-file workspace/campaigns/<slug>/extension-prompt.txt \
  --output workspace/campaigns/<slug>/clips/a-roll-01-extended.mp4 \
  --log-file workspace/campaigns/<slug>/output-log.md \
  --label a-roll-01-extended \
  --seconds 10

Use scripts/stitch-video.sh for resolution normalization. Read references/voice-system.md for voice design guidance.

Stage 2: Post-Production (mandatory)

Raw AI output → post-production → final asset. Never skip.

Use scripts/post-production.sh for automated color grade, grain, and frame rate normalization.

Read references/post-production.md for the full realism stack: color grade, grain (the 4K upscale trick), skin texture, frame rate lock, audio realism, lighting consistency.

If mixing Sora + Kling clips, pay special attention to cross-engine color matching — see references/orchestrator.md (in b-roll/references/).

The phone test: watch the final video on a phone screen, in the app, scrolling past it like a user. If anything pings as AI, fix it.

Read references/green-zone.md for platform safe zones.

Stage 3: Captions (ALWAYS LAST)

⚠️ Captions MUST be applied AFTER post-production, not before. Grain and color grade degrade clean caption text. This was the #1 process mistake in session 2.

Caption Overlay System

Use assemble/scripts/caption-overlay.py for all text overlays. It generates transparent PNGs with TikTok-native styling, auto-detects video resolution, and downloads TikTok Sans from Google Fonts if not cached.

# Generate caption overlay (auto-detects resolution from video)
python3 assemble/scripts/caption-overlay.py \
  --video workspace/campaigns/<slug>/clips/post-produced.mp4 \
  --preset tiktok-wall \
  --lines "things i didn't know,would bother me about,my boyfriend..." \
  --output workspace/campaigns/<slug>/frames/caption.png

# Overlay onto post-produced video (with compatible encoding)
ffmpeg -i workspace/campaigns/<slug>/clips/post-produced.mp4 \
  -i workspace/campaigns/<slug>/frames/caption.png \
  -filter_complex "[0:v][1:v]overlay=0:0:enable='between(t,0.2,3.8)'" \
  -c:v libx264 -profile:v main -pix_fmt yuv420p -crf 18 \
  -movflags +faststart -c:a copy \
  workspace/campaigns/<slug>/clips/final-01.mp4

Approved TikTok Text Presets

All presets use centered alignment and safe zone positioning (y=280 at 720x1280 base). Values scale automatically for other resolutions.

Full control via JSON config

For per-scene caption configs, pass a JSON file:

python3 assemble/scripts/caption-overlay.py \
  --config workspace/campaigns/<slug>/scripts/captions.json \
  --output workspace/campaigns/<slug>/frames/caption-s1.png

Legacy pill-style captions

The older scripts/generate-caption.py still supports pill-style (white rounded rect background) and wall-style captions using Inter font. Use assemble/scripts/caption-overlay.py for all new work — it has the correct TikTok-native styling.

Caption rules

• Caption PNG must match EXACT video resolution. Use --video flag to auto-detect.
• Use PIL for text overlays — more control than ffmpeg drawtext, no escaping issues.
• Use textfile approach if ffmpeg drawtext is ever needed (avoids apostrophe/escaping bugs).
• Visual Transformation format requires captions on EVERY scene, not just the hook.
• No background pills for TikTok-native text — stroke only.
• Always encode with compatible defaults after caption burn: -profile:v main -pix_fmt yuv420p -movflags +faststart

Resolution note: Sora outputs 720x1280, Kling outputs 1076x1924. Always normalize to one resolution before stitching.

Requires ffmpeg and python3 with Pillow (auto-installed if missing).

Brand Memory Integration

Reads

Writes

Context loading

🔧 Assemble context loaded:
  ✓ Campaign: ridge-q1
  ✓ A-roll clips: 3 (workspace/campaigns/ridge-q1/clips/a-roll-*.mp4)
  ✓ B-roll clips: 2 (workspace/campaigns/ridge-q1/clips/b-roll-*.mp4)
  ✓ Script: talking-head (workspace/campaigns/ridge-q1/scripts/talking-head-script.md)
  ✓ Creator voice profile: Maya

Contract

Input

• Required: A-roll clips plus a timing-aware script
• Optional: B-roll clips, creator voice profile, ElevenLabs S2S settings
• Format: workspace video files, script markdown, and optional voice metadata
• Source: /animate, /b-roll, /persona, and references/audio-orchestration.md

Output

• Produces: one assembled final video with stitched visuals, audio, post-production, and captions
• Format: final-<version>.mp4 in workspace/campaigns/<slug>/clips/ plus append-only assembly logs
• Default behavior: stitch A-roll first, apply voice orchestration, insert B-roll as visual-only cuts, run post-production, then add captions last
• Downstream use: /score

Validation

• Pre-conditions: source clips exist, script timing is usable, and all inputs are normalized enough to assemble
• Post-conditions: final video is saved locally, voice stays continuous, and captions sit on the post-produced file rather than the raw render
• Failure checks: fix resolution mismatches, broken timing, or synthetic-looking audio here before handing anything to /score

Stage checkpoints

• stitch: assembled timeline exists, cuts land on script beats, voice continuity holds across A-roll and B-roll
• post: post-produced file exists, mixed-engine clips look visually coherent, phone test does not immediately ping as AI
• captions: caption overlay matches exact video resolution, readability is mobile-safe, and captions were applied after post-production

Output

• Final assembled video (MP4) in workspace/campaigns/<slug>/clips/final-<version>.mp4
• All intermediate files preserved in workspace/campaigns/<slug>/
• Assembly params logged to workspace/campaigns/<slug>/output-log.md

Next Step

Assembly complete → run /score to verify virality score before publishing.