arbiter-score 1.0.0

Deterministic, polyglot code quality scoring with governance integration

Arbiter

Agent-aware code quality scoring for multi-agent codebases.

In 2026, code is written by fleets of AI agents. Arbiter knows who wrote each line -- human or AI -- and scores quality accordingly.

Learn more at hummbl.io.

Repository health, validation, and stewardship expectations are tracked in docs/REPO_HEALTH.md.

Quick Start -- 5 Minutes

pip install "arbiter-score[analyzers]"
arbiter score .

Example output:

Arbiter Scorecard: my-repo (main)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Overall:  87.3  →  Grade: B

By Analyzer:
  Lint       91.2  (ruff — 3 style issues)
  Security   95.0  (bandit — clean)
  Complexity 78.5  (radon — 2 functions > complexity 10)
  Dead Code  92.0  (vulture — 1 unused import)

By Agent (last 30 days):
  claude-code   89.1  (42 commits, 1,240 LOC)
  codex         85.3  (18 commits, 890 LOC)
  human         92.7  (5 commits, 120 LOC)

Top Issues:
  • src/api/routes.py:47  complexity C (15)  — agent: codex
  • src/utils.py:12       unused import os   — agent: claude-code
  • src/models.py:89      line too long      — agent: codex

Run `arbiter serve` to view the full dashboard.

Install

The Python distribution is arbiter-score; the installed CLI command is arbiter. Do not install the separate PyPI project named arbiter for this tool.

pip install arbiter-score                  # core (stdlib only)
pip install "arbiter-score[analyzers]"     # + ruff, radon, vulture, bandit

# Or from source
git clone https://github.com/hummbl-dev/arbiter.git && cd arbiter
pip install -e ".[analyzers]"

Usage

# Quick score -- no persistence, instant feedback
arbiter score /path/to/repo

# Full analysis with per-commit agent attribution
arbiter analyze /path/to/repo

# Agent leaderboard -- who writes the best code?
arbiter agents

# Start the dashboard (single HTML file, no build step)
arbiter serve --port 8080

What It Scores

Arbiter wraps tools you already trust and combines them into a deterministic composite score:

Analyzer	Tool	Weight	What It Finds
Lint	ruff	35%	Style violations, import errors, bugbear patterns
Security	bandit	30%	Hardcoded secrets, shell injection, dangerous patterns
Complexity	radon	35%	Cyclomatic complexity (grade A-F per function)
Dead Code	vulture	penalty	Unused functions, imports, variables
Duplication	AST hash	penalty	Near-duplicate function bodies
Semgrep	semgrep	opt-in	Custom rule enforcement (enable via config)

Scoring: 100 - (penalty / LOC) * normalization. Grades: A (90+) | B (80+) | C (70+) | D (60+) | F (<60).

What Makes Arbiter Different

Feature	Traditional Tools	Arbiter
Agent attribution	None	First-class: tracks Claude, Codex, Gemini, Copilot, humans
Per-commit scoring	Repo-wide only	Scores each commit's changed files individually
Diff analysis	N/A	Score only what changed in a PR/branch
Agent-specific gates	N/A	Different quality thresholds per agent trust tier
Dashboard	SaaS login	Single HTML file with per-agent timelines and fleet view
Dependencies	Heavy	Analysis tools only; core is stdlib Python

CLI Reference

arbiter analyze <repo>                     # Full analysis + per-commit scoring + persist
arbiter score <repo> [--json] [--exclude]  # Quick score (no persist)
arbiter diff <repo> [--base main] [--json] # Score changed files vs base branch
arbiter agents                             # Agent leaderboard
arbiter trend [--days 30]                  # Quality trend
arbiter worst [--limit 20]                 # Worst files
arbiter commits [--agent claude]           # Recent commits with scores
arbiter audit-fleet <directory>            # Audit all repos in a directory
arbiter triage                             # Auto-classify repos: green/yellow/red/archive
arbiter fix <repo> [--dry-run]             # Auto-fix ruff findings + before/after score
arbiter serve [--port 8080]                # API + dashboard

Tests

pip install ".[test]"
PYTHONPATH=src python -m pytest tests/ -v

Quality Gate

Arbiter grades itself on every push and PR. The CI runs arbiter score . and fails if the score drops below 90 (A grade).

# Run the same check locally
arbiter score . --fail-under 90

# Score only your changed files against main
arbiter diff . --base main --fail-under 80

Requirements

• Python 3.11+
• git (for historian)
• Optional: ruff, radon, vulture, bandit (install via [analyzers] extra)

HUMMBL Ecosystem

Part of the HUMMBL cognitive AI architecture:

• hummbl-governance -- Governance primitives that Arbiter scores against
• base120 -- 120 mental models for structured reasoning
• hummbl-agent -- Governed control plane for AI agent systems
• hummbl-bibliography -- Bibliography for the HUMMBL cognitive framework
• mcp-server -- MCP server for AI agent integration

Learn more at hummbl.io.

License

Apache 2.0 -- see LICENSE.

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Built by HUMMBL LLC from production experience coordinating Claude, Codex, Gemini, and human engineers on a 14,000+ test codebase.