[devohmycode]

Summary

skills-atlas, mcp-atlas and plugins-atlas share an origin. Should their common code move into a shared package? Measured on each main (line similarity against skills-atlas):

Files	mcp-atlas	plugins-atlas
browser.ts, ui/mouse.ts, ui/palette.ts, ui/render.ts, ui/width.ts (about 270 lines)	identical	identical
ui/ListSelect.tsx (169)	identical	0.99: its own messages module
ui/Layout.tsx (121)	0.98: name, steps	0.93: name, steps, messages
ui/TreeSelect.tsx	0.66	0.64
ui/App.tsx	0.57	0.57
completion.ts	0.55	0.55
mcp.ts	0.37	0.30
web/server.ts, web/page.ts	0.31, 0.22	0.26, 0.02
audit and risk rules	0.12	0.13
i18n messages	0.2	none (English only)

Only the terminal primitives, about 440 lines, are still common. The tree, the review screen, the audit, the web interface and the messages have each followed their domain (skills, MCP servers, plugins). A shared package would cost a fourth published package, versions kept in step and releases across repositories, to save about 440 lines that rarely change. Decision: no shared package.

What this adds instead: a check that the copies stay identical, so that a fix made in one atlas is not forgotten in the others.

• npm run check:shared compares six files under src/ with each sibling's main on GitHub (raw files, no token). --local compares with sibling checkouts next to this one. Line endings are ignored. It exits with 1 and names each file and repository out of step, or unreadable.
• The list (SHARED in scripts/check-shared.ts) records which repositories must match each file. ui/ListSelect.tsx is checked against mcp-atlas only. ui/Layout.tsx is left out because its differences are intended.
• A shared files workflow runs it on pull requests that touch those files, and every Monday against the siblings' current main.

Validation

• npm run check:shared and npm run check:shared -- --local: 11 shared copies match.
• After appending a line to src/ui/width.ts: differs src/ui/width.ts mcp-atlas, the same for plugins-atlas, exit 1.
• New unit test for differing, unreadable and CRLF copies; TypeScript checks.