0.70.2 T24: count the Python the gate path runs, at run time, not how scripts spell it (R12 replacement) #4742

R12 (#4684) stopped after two review rounds that did not pass on the same findings: a text scan of how tools are invoked does not converge.

This replacement measures at run time instead. A PATH shim for python, python3 and uv wraps every nightly lane and logs each call with its caller; an execve trace catches the absolute shebangs the shim misses. The count of distinct Python entry points the gate path ran lands as a ratchet from the first measured night (head vs base, never worse). It blocks only after three green nights.

Plants: a lane that calls Python through env, through a variable and through a heredoc must each raise the count.

Why P0: it is the mechanism for the operator's ruling that the build is Rust only and Python stays only as external validation.

Status: built on a branch; review stopped after two rounds that did not pass. A third round, or a park to 0.70.3, is the operator's call.

K^ 3. Owner aprender-a7r. Refs #4678. #4684 closes into this issue with a pointer.

Collapsed rows (APR-EPIC-001 rule 20, C334)

• 4754: 0.70.3: python run-time count: key what Python RAN, not how its argv is spelled (redesign of 0.70.2 T24: count the Python the gate path runs, at run time, not how scripts spell it (R12 replacement) #4742) (0.70.3: python run-time count: key what Python RAN, not how its argv is spelled (redesign of #4742) #4754 · last: none · owner:aprender-a7r9 · branches: build-kaizen/4754-python-runcount-files@bffb0337f7)

• R12 release-path Python inventory guard (collapsed from 0.70.2 T6: BLD-002 R12 release-path Python inventory guard, shadow first, then admit it (= R12-E) #4684).