DO NOT MERGE: CI baseline for unmodified main

[derek-miller]

Diagnostic only, to be closed.

An empty commit on unmodified main. main last ran green in January 2026 and the test matrix is failing on #12 today, so this establishes whether that failure predates #12 or was introduced by it. gh run rerun refuses runs older than a month, and the workflow only triggers on main or a PR, hence this.

If this run is red, the matrix failure is environment drift in the pinned actions and belongs in its own issue rather than in a typecheck PR.

[derek-miller]

Answered: red on unmodified main, so the matrix failure predates #12.

Lua 5.3 and Lua 5.4 pass; luajit-2.1 fails identically to #12, with the same mask(0xFFFFFFFF) -> 0xFFFFFFFFFFFFFFFF.

Cause is a LuaJIT upgrade in leafo/gh-actions-lua. CI now builds 2.1.1785763465 (2026), which parses a & b; the last green run in January had a build that did not. So _compat's native-operator probe now succeeds on LuaJIT and selects the Lua 5.3+ path, which sets is_luajit = false and skips to_unsigned. LuaJIT's bitwise results are signed 32-bit, so negatives leak out and format as 64-bit.

CI log confirms it: Using: native operators (Lua 5.3+) on a LuaJIT leg.

Fixing separately; this branch was diagnostic only.