A checked-in design doc for the #645/#608/#750 chained-call mechanism — the
permanent, discoverable record the work previously lacked (it lived only in git
history, the tracking issue, and an untracked scratch handoff). Covers the 3-part
mechanism, the three shared resolvers + receiver styles, the per-language coverage
matrix (12 shipped with A/B results), the conformance pass, and the full 21-language
README classification (incl. why TypeScript + Luau were skipped and Pascal is blocked).
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>