Cx Dev Log — 2026-05-19

#cx #programming

No new code landed in the last 24 hours. The activity was entirely infrastructure: a blog post for the May 9 dev log was published to the site, run_matrix.sh picked up an execute-permission fix, and the May 18 daily log was pushed to its branch. The matrix holds steady at 117 PASS / 0 FAIL. Days like this are worth documenting because the project state between commits still matters.

What actually happened

Three commits went out, all from the automated pipeline rather than manual development:

The May 9 blog post (commit 23672a9) was published to origin/site as src/content/blog/2026-05-09.mdx. Content publishing, not code.

The run_matrix.sh execute permission fix (86901ce) was pushed on the daily-log-2026-05-18 branch. Without the +x bit, the test matrix script required manual bash run_matrix.sh invocation instead of ./run_matrix.sh. Small thing, but these permission mismatches cause confusion in CI environments.

The May 18 daily log itself (1c2bd98) was committed and pushed to origin/daily-log-2026-05-18, but the PR was never merged to main. That log documented the real work from May 18: CX-233 (while-in IR lowering), CX-228 (19 parity fixtures), and PR #268 (the backend-determinism train merging into submain).

The while-in branch is ready and waiting

The most significant thing sitting unmerged is CX-233 on origin/stokowski/CX-233. This branch implements while-in loop source-to-IR lowering in a 307-line change across four files: src/ir/lower.rs, src/frontend/semantic.rs, src/frontend/semantic_types.rs, and the parity checklist.

The implementation uses a 5-block CFG: entry, header, body, increment, exit. It threads arr_binding and arr_ty through the semantic layer and adds Op::Mul cursor-deref unary lowering. With this work, WhileLoop parity moves from 6 PASS / 2 SKIP to 8 PASS / 0 SKIP. Once it merges to submain, all loop variants (while, for, while-in, loop/break/continue) will have full source-to-IR lowering.

The remaining unsupported statement kinds after that merge would be When (match/when blocks) and EnumDef.

The submain gap

The submain-to-main gap sits at 171 commits, unchanged from May 18. This number has been tracked in every daily log since May 6 and the growth has been steep: 16 on May 7, 40 on May 9, 164 on May 16, 171 on May 18. With CX-233, the actual divergence is 172 commits.

Nothing is blocking the merge technically. The matrix passes at 117/117. The gap is purely merge latency, and the integration risk grows with every day it stays open.

What's next

The obvious first move is merging CX-233 into submain. It is a clean single-commit PR that closes the last WhileLoop parity gap. After that, the parity targets shift to VariableDecl, DirectCall, InfiniteLoop, and BuiltinAssert categories.

The submain-to-main merge needs to happen. At 171 commits of divergence, this is not something that gets easier with time.

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