research: W1 validate Windows file identity on NTFS and ReFS #146

Purpose

Follow-up W1 from #122 and merged PR #144. The initial Rust feasibility evaluation is complete; this issue tracks one remaining evidence gate. Windows remains unsupported by the production CLI.

• Scope: stable identity for the Codex home, thread-writer-locks,
  .coordination.lock, thread lock files and transcripts: volume serial plus
  128-bit FILE_ID_INFO, link count, and attributes. Covers no-follow opening
  of reparse points (junctions, symlinks, mount points), hard links,
  parent-directory replacement between observations, path/handle agreement and
  case-insensitive names.
• Evidence: real-host JSONL on NTFS and ReFS (Dev Drive or a ReFS
  volume), with a recorded hypothesis for each case. Include a compare-before
  and compare-after on the same handle.
• Acceptance: every case is match. Any reparse point or identity change
  yields unknown. The 64-bit nFileIndex is not used as the only identity on
  ReFS. Unix lossless identity (lossless-file-identity.md)
  stays unchanged.
• Existing coverage: fixture junction:nofollow and
  junction:follow_control, and a recorded scratch-directory file ID (NTFS,
  High integrity only). Path scoping is lexical. ReFS has not been tested.

Delivery boundary

Use an isolated, unpublished research change with synthetic fixtures first. Record source/binary revisions, environment, hypotheses, actual outcomes and unverified conditions. Keep safeToUnlock=false; completing this gate alone does not authorize recovery or release. No production lock files, real user sessions, host policies or privileges are changed as part of this issue definition.

The proposed architecture keeps the TypeScript CLI. A Rust helper can be reconsidered after W1–W3 establish a concrete need; a full rewrite is deferred. W7 observations are prerequisites for the native classification portion of W3 and for W5; W6 must cover each integrity level claimed. W4 and W5 remain required for any automatic recovery design.

Priority: P3 research.
Milestone v0.4.7 is a planning target, not a Windows support or publication promise.

Source contract: Windows/Rust evaluation.