research: W2 validate Windows SID and ownership checks #147

Purpose

Follow-up W2 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: owner SID and DACL of the Codex home, the lock directory and lock
  and transcript files, compared with the current token user SID. Covers
  inherited versus explicit ACEs, and the fact that Administrators and
  backup/restore privileges bypass the DACL.
• Evidence: real-host records for files owned by the current user, another
  user and Administrators (fixture files only), plus the recorded refusal
  results.
• Acceptance: anything other than an exact current-user match yields
  unknown or a refusal. A matching owner SID is insufficient on its own:
  define and test refusal for write access granted to other ordinary users.
  State the threat-model limits for privileged Administrators/SYSTEM and
  backup/restore access. No ACL is changed and no privilege is enabled.
• Existing coverage: a protected single-ACE scratch DACL is verified before
  fixtures run, and the identity case matches the token SID of fixture
  processes. No check exists for lock-file owners in a Codex-shaped home.

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Use an isolated, unpublished research change with synthetic fixtures first.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.