fix(agent): guard coding-context cwd fallback against getcwd errors

[Frowtek]

What does this PR do?

_resolve_cwd() in agent/coding_context.py fell back to
Path(os.getcwd()) when resolve_agent_cwd() raised — but
resolve_agent_cwd() raises because os.getcwd() failed (a deleted
CWD with no TERMINAL_CWD/session override). The fallback re-invoked the
same failing syscall and propagated out of resolve_runtime_mode() and
build_coding_workspace_block(), crashing prompt build.

Path.resolve() can also call os.getcwd() for absolute paths, so
_git_root, _marker_root, _home, and the worktree probe were
additional crash sites.

The fix adds _safe_resolve() (a resolve() with a getcwd-free
normpath fallback on OSError) and uses it at every resolve() in the
resolution path. _resolve_cwd() now degrades to home, then the temp
dir, so posture detection settles on general/no-workspace instead of
crashing. resolve_agent_cwd()'s documented OSError contract is
unchanged — only its caller-side guard is fixed.

Related Issue

N/A — found via code audit.

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)

Changes Made

• agent/coding_context.py: add _safe_resolve(); guard the
  _resolve_cwd() fallback so it never re-calls a failing os.getcwd()
  (degrades to home → temp dir); route _git_root, _marker_root,
  _home, and the worktree probe through _safe_resolve().
• tests/agent/test_coding_context.py: add TestDeletedCwdTolerance
  (6 tests).

How to Test

pytest tests/agent/test_coding_context.py tests/agent/test_runtime_cwd.py -q

Result:

69 passed in 3.44s

The new tests fail against the unpatched code (_resolve_cwd re-raises
FileNotFoundError) and pass after the fix. Consumer/integration suites
also pass:

pytest tests/agent/test_system_prompt.py tests/agent/test_prompt_builder.py \
       tests/test_tui_gateway_server.py -q
# 473 passed, 1 skipped

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix
• I've run the relevant tests and they pass
• I've added tests for my changes

Documentation & Housekeeping

• Documentation — N/A
• cli-config.yaml.example — N/A
• CONTRIBUTING.md / AGENTS.md — N/A
• Cross-platform impact considered
• Tool descriptions/schemas — N/A

[tonydwb]

Code Review Summary

Verdict: Approved

Adds _safe_resolve() wrapper around Path.resolve() to tolerate a vanished/inaccessible CWD (Windows resolve() calls os.getcwd() even for absolute paths). The fallback degrades gracefully instead of crashing posture detection on every prompt build.

Strengths:

• Well-documented with clear explanation of the Windows-specific behavior
• Comprehensive test coverage: deleted CWD, explicit cwd bypass, home fallback, tempdir fallback
• _resolve_cwd() now has a clear contract (never raises) and the tests confirm it
• Changes are isolated to the affected functions

No blocking issues found.

Reviewed by Hermes Agent

[teknium1]

Thanks for the focused regression fix. The premise is verified against current main: agent/runtime_cwd.py:39-50 reaches os.getcwd() when no override exists, while agent/coding_context.py:380-388 catches that failure and calls os.getcwd() again. resolve_runtime_mode() and build_coding_workspace_block() consume that helper at agent/coding_context.py:588 and :848.

The PR's guarded fallback and _safe_resolve() coverage address those paths without changing the documented resolve_agent_cwd() behavior. No correctness issue was found in the reviewed diff.

This is an automated hermes-sweeper review.

[GottZ]

This was generated by AI during triage.

Summary

Two PRs form this complex: #43316 introduced the coding-context posture and its CWD-resolution path, while #45423 fixes the resulting deleted/inaccessible-CWD crash by replacing the repeated failing getcwd fallback with guarded home/temp-directory degradation and safe path resolution.

Related pull requests

• #43316 [merged] related — (+1319/-4) — merged foundation: #43316 remains relevant as the merged implementation that introduced agent/coding_context.py, including the fallback path that could repeat a failing os.getcwd() call.
• #45423 related — (+117/-4) — merge: #45423 directly fixes the root cause by adding getcwd-tolerant path resolution, degrading an unavailable implicit CWD to home or the temp directory, and covering runtime-mode and workspace-block paths with six regression tests. The contributor keep_open review explicitly verified the premise against current main and found no correctness issue; the separate APPROVED review also found no blocking issue but did not document a current-main verification.

Suggested consolidation

Merge #45423 — it is a focused regression fix for the CWD failure path introduced by the merged #43316, with both affected consumers and additional resolve() crash sites covered; this aligns with the contributor keep_open review. #43316 is the merged reference implementation, not a duplicate, so no PR should be closed as duplicative.

Cross-PR triage: Reviewed 2 pull requests and 0 issues in this complex. Each diff was read against this issue; Assessment working set: 72 kB of PR diffs, 12 kB of issue/PR text, 18 kB of discussion (7 comments), 0 verify verdicts. verdicts reflect diff content, not PR titles. Part of an automated triage batch.