[dhairya (dhairyajangir)]

Motivation & Context

Growing a Purview cache entry at capacity could subtract its old size twice: once in set() and again when eviction encountered the still-live old mapping. A cache limited to 20 bytes could retain 24 estimated bytes while reporting 16, then report a negative size when emptied.

Description & Review Guide

• What are the major changes? Remove the previous cache mapping before subtracting its size and evicting entries. Add a regression test that grows the earliest-expiring entry while the cache is near capacity.
• What is the impact of these changes? Eviction skips the replaced entry's stale heap record and evicts another entry when needed. The replacement remains available, and size accounting returns to zero when it is removed.
• What do you want reviewers to focus on? The ordering of replacement removal and eviction, and the regression's assertions on retained values and tracked bytes.

Implemented and tested with Codex assistance on Linux/Python 3.12.14. The regression fails before the fix and passes afterward. All 200 Purview unit tests pass with 89% package coverage. Package Ruff, changed-file formatting, strict source Pyright, all five configured test type checks, source/wheel builds, and git diff --check pass.

Optional warning-level Pyrefly output contains three existing diagnostics in unchanged middleware tests, so the no-warnings checklist item is left unchecked. The complete repository and live-service integration suites were not run.

Related Issue

Fixes #8988

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR is linked to an issue and there is no other open PR for this issue (see Related Issue above).
• This is not a breaking change. If it is a breaking change, add the breaking change label (or add "[BREAKING]" to the title prefix, before or after any language prefix) — a workflow keeps the label and title prefix in sync automatically.

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[dhairya (dhairyajangir)]

Could a maintainer authorize the waiting fork workflows for this PR and #8992 when convenient? Both fixes are ready for code-owner review; their descriptions include the regression tests, local validation, and any baseline limitations. The CLA checks have passed. I'll address any review feedback.

Codex assisted with the fixes, validation, and this follow-up.

[Eduard van Valkenburg (eavanvalkenburg)]

/review

[github-actions]

MAF Automated Review — Iteration 1

Result: No findings
Scope: full PR (2 commit(s)): 11225ab2b015, db8cc2e52c6f
Model: gpt-5.6-sol

Overview

The change removes an existing mapping before capacity eviction, preventing the stale heap record from subtracting the replaced value's size a second time. The operation remains atomic with respect to asyncio scheduling because set() has no suspension point, and the regression test verifies replacement retention, eviction of the other entry, exact byte accounting, and return to zero after removal. No PR-introduced Critical, High, or Medium issue was established.

Reviewed the supplied pull-request change set across correctness, security/reliability, architecture, and failure behavior.
No publishable findings remained after source verification for this scope.

[dhairya (dhairyajangir)]

Eduard van Valkenburg (@eavanvalkenburg) thanks for triggering the review. On head db8cc2e, the Python test matrix and code-quality jobs now pass, and the automated review reported no findings.

The remaining failed merge gate reports Failing checks: team_check, command_check (log). Those are cancelled prerequisite jobs from the original DevFlow PR Review run, rather than failing Purview tests (cancelled team check). The gatekeeper treats cancelled checks as failures.

Could you rerun the cancelled DevFlow prerequisites for this PR head and then the merge gate when convenient? The source change is unchanged; code-owner review is still pending.

[Eduard van Valkenburg (eavanvalkenburg)]

/review