Verify the clips. Same codec, resolution, and frame rate before joining (references/stitching.md). Mismatched clips are the #1 concat failure.
Join them. scripts/concat.py: checks, concatenates losslessly, and verifies the result. Transitions go between clips that need them, not everywhere.
Finish it. Title cards, watermark, burned-in or sidecar subtitles, credits. The small things are what make it look released instead of rendered.
Export per platform. 16:9 master, then 9:16 and 1:1 crops for social (references/exports.md). Never upscale; crop or pad.

Rules that don't bend

Master first, always. One full-quality 16:9 master (H.264 or H.265, high bitrate). Every platform export derives from the master. Never export a platform cut from another platform cut.
Check the joins. Watch 2 seconds on each side of every cut. AI clips drift at their tails; the join is where it shows.
Transitions are punctuation. Cuts for energy, dissolves for time passing, fades for beginnings and endings. A transition on every cut is the video equivalent of typing in all caps.
Audio is part of assembly. Room tone under everything, fades on the master head and tail. (Full mix: ../dialogue-and-audio/references/mix.md.)
Keep the project reproducible. The concat script, the clip list, the subtitle file, the export commands. All in the project folder. When clip 4 gets regenerated next week, re-running the build should take one command.

assembly-and-delivery