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+# Handoff — what the x86 backend costs, and keeping it from rotting
+
+Branch: `dev-loop`. This lane is item 7 of `HANDOFF-x86-rt.md`'s "What remains" — code size and speed, measured
+rather than guessed — plus the closing note under it, which asks for the survey to run on its own so a refusal
+cannot sit unnoticed for a month again.
+
+Nothing in `lib/` is touched. Another lane is rewriting `lib/x86.ml` at the same time, so everything here lives in
+`spike/x86` and in `test/dune`, and anything this lane finds that would want a compiler change is written down at
+the bottom rather than made.
+
+## The plan, in the order it is being done
+
+1. `test/dune` grows an `@x86` alias beside `@sanitize` and `@valgrind`, running `spike/x86/survey.sh` in a strict
+   mode that exits nonzero when anything DIFFERs or is refused by name. Done first because it is the half that
+   stops the rot and it is bounded.
+2. `spike/x86/cost.sh` measures binary size, the program's own text, and best-of-N wall time for each corpus
+   program both ways, and `spike/x86/COST.md` reads the numbers out.
+
+## Status
+
+Stub. Nothing measured yet.