[schlessera]

Closes #2373

What changed

Generated CSS/theme and inclusion self-tests now obtain positive producer fixtures from raw Git blobs owned by audited revision 498270fbdc4ef2788fdd3babb259b647d77f6c77. Current producer bytes are checked separately and refuse binding on genuine audit drift. The real locked offline compiler, temporary theme compilation and installed-asset byte/mode controls remain intact.

Why this shape

Copying arbitrary current source into a frozen positive made legitimate #2370 caller changes fail generic self-tests. A pinned independent owner preserves the audit without refreshing any production hash or relaxing refusal. Git history is required offline, as supplied by CI's full-history checkout.

Proof

Base b7a0885181445125d576e02f61c562d704c81099; actual head recorded with the candidate confirmation.

• Original three test files with fix(ci): refuse slow Linux sandbox setup before local preflight #2372's changed check-pr.ts reproduce the reported assertion failures; restored corrected fixtures pass all 20 tests / 88 assertions, including against that same changed caller.
• Bypassing the production producer digest comparison fails both producer/execution-path negative tests on their intended assertions (18 pass / 2 fail). Changing the frozen fixture owner to fix(ci): refuse slow Linux sandbox setup before local preflight #2372's changed revision fails the positive CSS/theme/inclusion controls (14 pass / 6 fail). Both mutations restored byte-for-byte; restored suite passes 20/20.
• bun run check:pr --base origin/main passes all contribution gates, fast invariants and 20 affected import-feedback tests. Strict bun run typecheck passes.
• No production binder, qualification pins, test discovery, images or runtime assertions changed. Documentation records positive ownership and current drift separation.

Checklist

• Focused local preflight/behavioral receipts and complete selected hosted proof passed; actual head/base/job checkout evidence is recorded below.
• Acceptance criteria from the issue are all met, or the gap is named below.
• The PR and completed/advanced issues have verified release milestones under docs/process/github.md.
• A changeset is included, or this changes nothing a consumer can see (tests/docs only).
• No personal data anywhere in the diff — the leakage gate covers the whole tree.
• The integration contract index or relevant component is updated in this same commit, or nothing in the machine surface moved.
• Docs under docs/ reflect the change, or nothing documented moved.
• Provider history stays append-only: nothing on a turn's path changed.

Anything left open

Nothing for #2373. Delivered by squash fcb7d5c5357c550f74300a53b5af5c46570b215f, parent 68e12f27eb249c9fe7262a498a0397c04bbda8f4, tree 63d5f502f85c5a76722451a29ed329fb98cd550c, exactly matching qualified synthetic checkout 2b355c03d1bbc3114c1a98c989ede59bcba56c2f. Confirmation 39085115921, attempt 1, passes metadata, strict/fast verification, all four selected unit shards and aggregate. Every selected job's actual checkout agrees; requested base, immutable parents/tree and aggregate receipt match. Remaining skips are planner-intended. Matching-head merge, fetched main ancestry, exact squash tree, issue closure and PR/issue milestone 0.44.0 are verified. Automatic main-push run 39087160233 also completes successfully.

Dependent #2372 requires its own complete proof for its actual candidate; this fixture delivery does not qualify later caller edits. Original failed and superseded/cancelled receipts remain historical evidence.