bench: task-oneshape pack for gold-pack Arm C

[danieljohnmorris]

Summary

Draft pack so gold-pack Arm C can run on artefact-exp07. Arm B (--context task-modules) is unchanged. This PR does not spend a live key.

Canonical conditional, the only one the loaded excerpts teach:

?h cond then else

Nested else is parenthesised: (?h cond then else). HOF predicates stay >b comparison expressions. Other legal shapes are marked non-canonical in this pack only.

Invoke

Offline (no API key):

python3 scripts/closed-loop-bench.py --dry-run \
  --task-set artefact-exp07 --context task-oneshape

That loads oneshape_modules on the four artefact tasks:

task	module	context_chars
schedule-window	ilo-excerpt-schedule-oneshape	837
typed-rollup	ilo-excerpt-typed-oneshape	845
record-normalize	ilo-excerpt-record-oneshape	965
csv-sales-summary	ilo-excerpt-csv-oneshape	985

Arm B on the same set stays 659–777 chars (--context task-modules). Arm C is the same band (under 1k), not a curated balloon.

Live (parent only, after this offline note is accepted):

python3 scripts/closed-loop-bench.py \
  --provider deepseek --model deepseek-chat \
  --task-set artefact-exp07 \
  --context task-oneshape \
  --retry-cap 2 \
  --repair-shape-hint --header-recovery --fold-meta-stdout \
  --python --lang2-docs bench/closed-loop/context/python-control-docs.md \
  --output-dir bench/goldpack-v1-live-arm-c-YYYY-MM-DD/

Pins

Item	Value
Base tip	7b15b28dac876f977d5280387e6ae09c5bb56b8f
Pack tip	2683d13bfa9fd05f67464495a93ef7a00701863c
ilo CalVer	26.5.0
Card	bench/closed-loop/context/one-shape-conditional.md (34 lines, not loaded)
Card sha256	e3495fad4dd014e19e3ca34b2a27b1320fc570ec1859f2cbe46aedd63f12f98a
Run note	bench/closed-loop/arm-c-run-note.md

The two shape lines in the card are copied byte-for-byte into each excerpt. Re-hash the card if that file changes before the live.

Constraints

• Artefact-4 bank not widened. modules still names the Arm B excerpts.
• No new header rail. Rails stay shape-hint + header-recovery + fold-meta-stdout.
• No compiler change. Arm B's only code shared by two reds was ILO-P009 on @ (record-normalize and typed-rollup). Those two excerpts name the loop form. P007 was one task; P023 did not appear.
• Pinned goldens-exp07 are untouched. ilo check / ilo run on 26.5.0 are green. schedule-window already uses ?h. csv (match), record (brace exists{cnt}), and typed (braceless guards) still use a non-canonical form. A ?h-only rewrite of those three matches the recorded stdout offline and is not committed — that rewrite belongs in its own PR.
• ilo-next card mirror is not in this repo.

Tests

python3 scripts/test_closed_loop_context.py (20 tests, including the new arm). Dry-run of --context task-oneshape on artefact-exp07. Four goldens ilo check and ilo run.