Track lock correctness and lifecycle hardening

[gaborbernat]

The audit at ec3abb5 found
correctness, security, lifecycle, and performance gaps across native locks, soft locks, async wrappers, fork, and the
SQLite read/write backend. This issue tracks the dependency order. Each linked issue contains its source evidence,
upstream references, required contract, and regression checks.

Each change must preserve supported imports and call signatures. Use additive interfaces and targeted deprecation
warnings when a safer contract needs a new API. Protocol changes must test old/new contention and publish the minimum
participating version for each guarantee. Every pull request needs a changelog fragment; user-facing features and API
changes need matching documentation.

Wave 1: independent validation and platform fixes

• #627 Validate lifetime at construction and assignment
• #628 Reject unsupported subclass lock options
• #630 Capture Windows process-probe errors through ctypes

Wave 2: state and error transactions

• #631 Detach release context in dual-failure groups
• #632 Keep the acquisition canonical key through release
• #633 Prevent SoftFileLock from retrying an ambiguous close
• #640 Make async acquire and release cancellation-safe

Issue #640 depends on #631, #632, and #633.

Wave 3: process ownership

• #634 Preserve parent lock ownership across fork
• #635 Make ReadWriteLock connection lifecycle fork-safe

Issue #635 builds on the process-ownership rules from #634 and must account for the inherited SQLite atexit hook.

Wave 4: strict locks and leases

• #636 Separate strict soft locks from expiring leases
• #637 Replace shared soft markers with owner-specific claims
• #639 Add process-start identity and lease compromise reporting

Issue #636 defines the contract. Issue #637 implements claim publication and cleanup under that contract. Issue #639
adds owner identity and the signal sent when a lease holder loses its claim.

Wave 5: portability, documentation, and release evidence

• #629 Define descriptor behavior without fcntl
• #641 Clarify lock trust boundaries and filesystem guarantees
• #642 Run the cross-platform lock regression and performance matrix

Issue #641 depends on the public contracts from waves 2 through 4. Issue #642 runs after each implementation issue and
supplies the measured platform claims for #641.

Completion rule

Close this tracker after the linked issues have merged, the platform matrix has no unresolved mutual-exclusion or
lifecycle failures, and the documentation matches the shipped contracts.

[gaborbernat]

All fifteen tracked issues have landed and closed, across the whole plan: lifetime and option validation (#627, #628), the descriptor and probe fixes (#629, #630, #631, #632, #633), fork ownership for the native and SQLite locks (#634, #635), the strict-soft/lease split with owner-specific claims and process-start identity (#636, #637, #639), async cancellation safety (#640), the trust-boundary and filesystem-guarantee docs (#641), and the cross-platform regression and performance matrix (#642).

The matrix now guards the outcome on every push: it enforces StrictSoftFileLock on NFSv4 and NFSv3 and the native FileLock on SMB, and records the measured limits (native flock does not exclude across NFS caches; the poll-based soft lock starves under NFS latency) that back the documented support matrix. Closing the tracker.