test: make worker ledger-read regression deterministic

[Birfy]

Summary

• Replace the schedule-dependent total ledger-read budget with worker-thread provenance and an exact startup-snapshot assertion.
• Use one worker, 20 rollouts, lag/stall budgets of 64, and disabled commit-triggered resync so no refresh is due regardless of merger scheduling. The real merger still runs; its legitimate reads are excluded explicitly.
• Add negative controls injecting both a head-version read and a snapshot per rollout; each must fail the same worker-read assertion.

This is a standalone, test-only correction of an existing main regression guard, diagnosed in #196 (comment) . The previous three-reads-per-sweep estimate omitted the existing stable-distance snapshot. The exact Python 3.9 CI schedule (35 reads versus budget 34) was not reproduced locally. No engine changes, relaxed slack, skips, or #196 feature changes are included.

Verification

• Python 3.9.25 and 3.12.14: async semantics, async parity, and worker resilience suites, 26 passed on each.
• New guard plus both negative controls: ten repeated pytest invocations passed on each Python version.
• Independent review: no blocking findings; independently ran all 9 semantics tests on 3.12 and both focused guard tests on 3.9, and checked the refresh/budget semantics.
• Current-main Python 3.9 docs-links/packaging subset: 7 passed. This branch starts at edcd65c, which already includes fix: repair quickstart documentation CI gates #211; the earlier two docs failures are not assumed to apply here.
• git diff --check passed. Published tree d26f676147ad19d07bef2a0fd0ea94638706e177 exactly matches the reviewed and tested tree; API commit add675a differs only in commit metadata from the local commit.
• Full local Python 3.12 suite: 3,023 passed, 56 skipped, 19 failed. All 19 failing IDs also fail on unchanged exact base edcd65c: bwrap NETLINK_ROUTE restrictions and Chromium PDF execution. This is not a local full-suite pass.
• Exact-head hosted CI is pending: Python matrix and wheel gates, strict docs. Keep draft until exact-head gates pass.

No merge, tag, release, deployment, security change, or paid-model run is requested.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-10T07:35:14.527379Z	add675a	Draft marked ready

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