fix(policy): handle OSError from is_file() on macOS PATH_MAX limit

[chaobo8484]

When load_policy() receives a YAML string that exceeds ~1023 bytes, the is_file() syscall fails on macOS (PATH_MAX ≈ 1024) with OSError [Errno 63] File name too long. Wrap the call in try/except to gracefully fall back to treating the input as a YAML string.

Fixes #848

Description

Brief description of changes and motivation.

Fixes # (issue)

Type of change

• Bug fix
• New feature
• Documentation
• Maintenance / refactor

Testing

• Tested locally
• All existing tests pass
• Added tests for new functionality (if applicable)

[Copilot]

Pull request overview

Fixes load_policy() to avoid crashing on macOS when given a long YAML string that triggers Path.is_file() to raise OSError: [Errno 63] File name too long, preserving the intended "path or YAML content" input behavior.

Changes:

• Wraps the Path.is_file() probe in try/except OSError and falls back to treating the input as YAML content when the probe fails.

Show a summary per file

File	Description
src/apm_cli/policy/parser.py	Adds defensive handling around Path.is_file() so long YAML inputs do not raise on macOS PATH_MAX limits.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 2

[danielmeppiel]

Per Copilot reviewer

[chaobo8484]

@danielmeppiel I have made adjustments according to Copilot's suggestion.Have a good day！

[github-actions]

DevX UX Review — PR #860

Scope: CLI error ergonomics & silent-failure risk. No command surface / flag / help-text changes in this PR — review is limited to internal load_policy() behaviour and its downstream user-visible effects.

---

Findings

1. ✅ Error recovery is solid. When ENAMETOOLONG fires, the code falls back to treating the input as YAML. If that YAML is malformed, yaml.safe_load raises YAMLError, which is wrapped into a PolicyValidationError with a human-readable message. The user still gets a clear "YAML parse error: ..." diagnostic — no silent swallowing of bad input.

2. ✅ _looks_like_yaml_content() is a reasonable fast-path. The heuristics (newlines, ---, - , {, [, : ) match what every YAML-literate developer would expect. This avoids the filesystem probe entirely for the vast majority of inline YAML, which is the right default. No UX concern here.

3. ⚠️ Minor: a valid-looking file path that doesn't exist is silently parsed as YAML. This is pre-existing behaviour, not introduced by this PR, but worth noting: load_policy("apm-policy.yml") where the file is missing will try to YAML-parse the string "apm-policy.yml" and return {name: apm-policy.yml} (bare YAML scalar coerced to a mapping? — actually it would hit "Policy must be a YAML mapping"). So the failure mode is noisy enough. No new risk from this PR.

4. ✅ No user-facing output changes. apm audit --policy <path> UX is unaffected — callers in discovery.py already pass either a Path object or pre-read content strings. The fix only matters when raw YAML strings happen to exceed PATH_MAX, which is a programmatic edge case (not a CLI-surface issue).

5. ✅ Test coverage is appropriate. The new test constructs a >1 KiB YAML payload and asserts it parses without OSError. Good enough for a defensive fix — no over-engineering.

Verdict: Ship it. Clean defensive fix, no UX regressions, no silent failures introduced. 👍

Generated by PR Review Panel for issue #860 · ● 4M · ◷