AGENTS.md: one-source instruction file (MX-846)

[MGrin]

AGENTS.md is the only instruction source; CLAUDE.md is the byte-exact 11-byte pointer @AGENTS.md; there is no .bb/AGENTS.md; the ceiling is stamped at the file's current line count.

New AGENTS.md; no instruction file before.

Verified by running, 2026-09-09

• npm install (rc=0)
• npm test — 12 tests, 0 fail
• npm run typecheck (rc=0)

mx instructions lint on this tree

$ mx instructions lint .
repo         . (own)
  imports      1 seen, deepest 1 hop(s) of 4 — 0 seen is a pass, not a blind
  size-lines   60 of 60 (ceiling from the stamp)
  size-bytes   3221 of 4194304
  pair-no-bb   .bb/ present: false — the directory is fine, .bb/AGENTS.md is not
  overlap      0.0%  0 of 495 shingles also in ~/.bb/AGENTS.md
  nested       none below the root
exit 0

🤖 Generated with Claude Code