feat(config): replace toml with figment for layered config

[panbanda]

Summary

• Replace toml crate with figment for layered configuration: defaults -> optional TOML file -> env vars
• Missing config files are silently skipped (no more early-return workarounds needed)
• Users can override any config value via OMEN_ prefixed env vars (use __ for nesting, e.g. OMEN_COMPLEXITY__CYCLOMATIC_WARN=5)
• from_file() still errors on missing files (for explicit --config flag)
• Remove Config::config_exists() and Error::Toml variant (no longer needed)

Test plan

• All existing config tests pass (migrated to figment::Jail for env var isolation)
• New tests: env var overrides file values, env var overrides defaults, from_file errors on missing file
• Full test suite passes (cargo test)
• Clippy clean (cargo clippy --all-targets --all-features -- -D warnings)
• CI passes
• Manual: omen -p /tmp score runs with defaults (no config file, no error)
• Manual: OMEN_COMPLEXITY__CYCLOMATIC_WARN=5 omen complexity respects env var
• Manual: omen -c nonexistent.toml score errors with "not found"

Summary by CodeRabbit

Release Notes

• Configuration
  • Configuration can now be overridden via environment variables using the OMEN_ prefix.
  • Expanded configuration options including satd, churn, duplicates, hotspot, score, feature_flags, temporal, output, and exclude_built_assets.
  • Configuration file validation now enforced for specified file paths.

[github-actions]

Omen Analysis

Diff Risk

Risk Score	38%
Risk Level	MEDIUM
Files Modified	4
Lines Added	+234
Lines Deleted	-111
Commits	2

Risk Factors

Factor	Score
file_churn	0.1
lines_added	0.0936
entropy	0.0515
lines_deleted	0.0444
num_files	0.0213
commits	0.0140
file_complexity	0.0061
ownership_diffusion	0.0029

Recommendations

• Touches historically volatile files - changes here often introduce bugs

Repository Health

Health Score	77.26451153340304 / 100
Grade	C
Files Analyzed	93
Critical Issues	1

Score Components

Component	Score	Weight
complexity	92	1
duplication	41.7	0.8
cohesion	94.2	0.6
tdg	84	0.6
coupling	50.6	0.4
satd	91.4	0.4
smells	100	0.2

Tips for AI agents

Use these commands to investigate and improve low-scoring areas.

Run full analysis:

omen -f json score    # health score with component breakdown
omen -f json diff     # PR risk analysis
omen hotspot          # high-churn + high-complexity files

Coupling (score: 50.56559139784946) -- needs attention

omen graph && omen smells

Break cyclic dependencies by introducing interfaces or extracting shared types. Reduce fan-out from hub modules by splitting responsibilities.

---

Duplication (score: 41.72579188338992) -- needs attention

omen clones

Look for Type-1 (exact) and Type-2 (renamed) clones. Extract shared logic into reusable functions or modules. Prioritize clones in high-churn files.

---

General workflow for improving scores:

1. Run the relevant analyzer command to identify specific files
2. Focus on the highest-weight components first (complexity 25%, duplication 20%, cohesion 15%, TDG 15%)
3. Make targeted improvements -- small refactors that reduce complexity or eliminate duplication
4. Re-run omen score to verify improvement

[coderabbitai]

📝 Walkthrough

Walkthrough

Replaced direct TOML parsing with Figment-based configuration loading across the project. Expanded Config struct with new fields and updated loading methods to support environment variable overrides (OMEN_ prefix). Simplified error handling by removing TOML-specific error variant.

Changes

Cohort / File(s)	Summary
Configuration Loading Refactor src/config/mod.rs	Migrated to Figment for config merging (defaults → TOML → environment). Added from_file(), load_default(), and alias methods. Expanded Config with 10 new fields. Changed exclude_patterns from alias to rename. Replaced TempDir tests with Jail-based tests.
Dependency Updates Cargo.toml	Replaced toml dependency with figment (0.10) including toml and env features. Added figment dev-dependency with test feature.
Error Simplification src/core/error.rs	Removed Toml error variant from Error enum. Figment handles TOML deserialization errors internally.

---

Important

Pre-merge checks failed

Please resolve all errors before merging. Addressing warnings is optional.

❌ Failed checks (1 error)

Check name	Status	Explanation	Resolution
Pr Test Coverage & Quality Check	❌ Error	PR objectives claim Config::config_exists(dir) method with 3 unit tests, but method does not exist in codebase.	Implement Config::config_exists(dir) method and add 3 unit tests, or update PR description to match actual implementation.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	Title accurately describes the main change: replacing toml with figment for layered configuration loading across the codebase.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feat/score-warn-no-config

---

No actionable comments were generated in the recent review. 🎉

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}