fix(clients): prevent symlink races in LazyCodex role mirror reads

[luvs01]

Summary

• Bind validation and reading of the LazyCodex omo.jsonc mirror to the same descriptor. Reject non-regular files and pathname/device/inode mismatches, handle ELOOP as invalid, and close the descriptor in finally.
• On POSIX, combine O_RDONLY | O_NOFOLLOW | O_NONBLOCK so a FIFO without a writer cannot stall synchronous openSync before regular-file validation.
• Windows omits those POSIX flags and retains descriptor/path identity checks. This is not a claim that Windows provides POSIX no-follow open semantics.
• Cover both read and write FIFO rejection in subprocesses with a three-second deadline and forced termination on timeout. The POSIX-only cases are explicitly skipped on Windows; the existing symlink-substitution, normal-file, and unreadable-route tests remain.
• The complete PR changes four files: the loader, its client tests, the management-route test harness, and structure/clients/integrations.md.

Verification

Linux / Bun 1.4.0, exact tree bf7875a46c654faad0f5da270bafd3b4b6783bff:

• Before the fix, both new FIFO cases hit their three-second subprocess timeout. After the fix, both return invalid in about 35–40 ms and leave the FIFO unchanged.
• bun test tests/clients/omo-role-models.test.ts tests/server/codex-agent-role-routes.test.ts: 19 pass, 0 fail, 91 assertions.
• bun node_modules/typescript/bin/tsc --noEmit, bun scripts/structure-ssot.ts, bun scripts/privacy-scan.ts, bun scripts/file-size-ratchet.ts, and git diff --cached --check: pass.
• Focused validation was used instead of a full local suite because concurrent worktrees make the broad run disproportionate. test:changed was not run against this exact-tree snapshot, which does not have the remote branch ancestry locally; the affected loader and management route were exercised explicitly. Native Windows execution was not available, so no native Windows pass is claimed.
• Exact-head hosted checks for fd838d3ce0adb600ba85d96c434c4d6e87c337bf completed successfully: Cross-platform CI, React Doctor, and CodeQL. Relevant Windows/macOS test matrices were skipped; the successful workflow does not establish that native coverage.

Checklist

• Scope stays focused and avoids unrelated cleanup.
• Integration documentation includes descriptor validation, nonblocking POSIX open, and Windows limitations.
• File identity, symlink refusal, descriptor lifetime, and blocking special-file handling were checked.
• Focused local validation passed with its scope documented.

Original Codex Task

Summary by CodeRabbit

• Bug Fixes
  • Configuration files that are replaced with symlinks or otherwise change during reading are now rejected as invalid, rather than being read from a different file.
  • Missing configuration files continue to be treated as absent, and other read errors continue to be reported.

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📝 Walkthrough

Walkthrough

The role model loader now opens its configuration file without following symlinks, validates the opened file against the current path, and reads through the opened descriptor. Tests cover symlink substitution and permission errors.

Changes

Role model loading

Layer / File(s)	Summary
Descriptor-based validation and reading src/clients/omo-role-models.ts, structure/clients/integrations.md	The loader opens the file with O_NOFOLLOW, checks that the opened file and current path are regular files with matching device and inode values, and reads through the descriptor. It returns invalid for mismatches and symlink-loop errors, preserves absent for missing files, rethrows other errors, and closes the descriptor. The documentation describes this behavior.
Loader error and symlink tests tests/clients/omo-role-models.test.ts, tests/server/codex-agent-role-routes.test.ts	A test replaces the integration file with a symlink during opening and checks that the loader returns invalid without changing the target contents. The unreadable-file test now simulates EACCES through openSync.

Priority: ⬆️ High

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Suggested reviewers: lidge-jun

Merge Risk: 🟡 Moderate · up to cc747

The change closes the symlink race when loading the role-model configuration. However, a special file such as a named pipe at the configuration path can now hang the management server. Add a non-blocking open before merging.

Security Architecture Review

Security architecture risk: 🟡 Moderate · up to cc747

The change strengthens protection against symlink-based disclosure. However, a local actor able to replace the configuration file with a named pipe can now make an authenticated role-management request block the server's request-processing thread. The exposure requires filesystem control and an active LazyCodex integration; it is not an arbitrary remote file-access capability.

Retained concerns

• Medium · security · inferred: A FIFO at the integration path can block synchronous open before regular-file validation. An actor able to replace ~/.omo/omo.jsonc can leave a named pipe without a writer and wait for an admitted role-management request when LazyCodex is detected. This can stall the serving event loop; during PUT, the authoritative role TOML may already have been updated before the mirror operation blocks. Unlike base behavior, an already-present FIFO no longer reaches immediate invalid classification.

Security review details

Security Blast Radius

• inferred — The identified denial-of-service path requires control over the process user's integration pathname and a role-management request admitted by existing authentication, with LazyCodex detected. An attacker need not hold a management credential if a legitimate user triggers the request. Impact can extend to requests sharing the blocked event loop; separate processes, tenants, or deployments are not established by the available evidence.

Security Findings and Attack Paths

• inferred — O_NOFOLLOW prevents final-component symlink traversal but does not make opening a FIFO nonblocking. A FIFO without a writer can keep openSync waiting before fstat rejects its type. The attack no longer requires substitution between a regular-file check and a read, although that raced blocking condition was possible in base.

Trust Boundaries and Controls

• observed — Management authentication remains enforced before route dispatch. Mirror writes retain their integration-ownership check and existing atomic no-follow writer. The PR strengthens file-read identity validation without granting callers additional path selection or filesystem privileges.

Resilience and Maintainability Implications

• inferred — Finally closes descriptors after ordinary returns and exceptions, but cannot provide containment while synchronous open has not returned. The route's exception-to-status handling likewise cannot complete during that wait, potentially leaving a successful TOML update without a response or completed mirror status.

Hardening Proposals

• proposed — Use a nonblocking no-follow open where supported, validate the resulting descriptor as a regular file, and retain descriptor-based reading. Verify that an already-present FIFO cannot stall either reader or writer. Do not restore a pathname reopen that would recreate the symlink race.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 3 files. (1 skipped: 1 …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: preventing symlink races in LazyCodex role mirror reads. It matches the implementation, tests, and stated PR objective.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 3 files. (1 skipped: 1 unsupported.)

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Inline comments:
Review comments at @src/clients/omo-role-models.ts:
- Line 45: Add O_NONBLOCK to the openSync flags in the loader used by
readOmoRoleModels and writeOmoRoleModel, preserving the descriptor-based
regular-file and identity checks. Add a focused POSIX regression test confirming
that a FIFO without a writer returns invalid without blocking.

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📥 Commits

Reviewing files that changed from the base of the PR and between 17d6e84 and cc74707.

📒 Files selected for processing (4)

• src/clients/omo-role-models.ts
• structure/clients/integrations.md
• tests/clients/omo-role-models.test.ts
• tests/server/codex-agent-role-routes.test.ts

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[luvs01]

Preserved upstream in lidge-jun#6460 at 7bf3553689d03071f9a9e12edad125ebb40f14d3. All implementation, regression-test, and documentation changes are carried exactly, with newer upstream route-test context retained. The 19 focused tests pass, and exact-head main CI passed. Upstream remains Draft because its metadata enforcement check was cancelled; review readiness is still separate. Closing this duplicate fork PR while keeping its branch and commits.