harness-scorecard 1.1.0

A read-only linter and A-F maturity grader for coding-agent harnesses (Claude Code, Codex).

Harness Scorecard

A read-only linter and A–F maturity grader for coding-agent harnesses. Point it at a Claude Code or Codex setup — Claude Code's hooks, permissions, rules/*.md, agents, and CLAUDE.md, or Codex's config.toml (sandbox, approval policy, trust levels), hooks.json, and AGENTS.md — and it returns a graded scorecard: the overall maturity grade, the specific gaps, and the guards that are missing, each with rationale. The harness type is auto-detected.

"Harness engineering" became a named discipline in 2026 and everyone is assembling harnesses with no way to tell if theirs is any good. The rubric is the product: every check traces to a documented red-team failure mode, not generic advice.

What it looks like

$ harness-scorecard scan examples/sample-harness

Harness Scorecard  v1.0.0
Target: examples/sample-harness   (claude-code)

  GRADE:  F        overall 0.28 / 1.00
  Scored 10 of 10 rubric dimensions (0 specced, pending).

  Capability gates tripped (grade capped):
    - HS-D5-01 caps at C  (Harness config write/read protected)

  D1  Secret protection & credential isolation    0.44  [weight 5]
      [PASS] HS-D1-01  Sensitive credential paths denied for read  [GATE->D]
             All core credential paths are denied for read.
             - covered: ~/.ssh, ~/.aws, ~/.gnupg, 1Password/op, gcloud, .env files
      [FAIL] HS-D1-02  Sensitive-read Bash backstop
             No Bash-level backstop for sensitive reads; deny lists cover only the Read tool.
             fix: Add a PreToolUse Bash hook that re-blocks reads of sensitive files.
      … (+4 more checks)

  D4  Destructive-action & git safety    0.63  [weight 5]
      [PASS] HS-D4-01  Push to protected branch effectively blocked  [GATE->C]
             Push to a protected branch is blocked by the effective floor.
             - hook:git-safety
             - permissions.deny
      [PASS] HS-D4-02  Catastrophic deletion blocked
             Catastrophic deletion is blocked by the effective floor.
             - hook:block-dangerous-cmds
             - hook:dangerous
      [FAIL] HS-D4-03  Destructive DB ops on non-local hosts blocked
             No effective guard against destructive DB operations on non-local hosts.
             - defaultMode=bypassPermissions: autoMode.hard_deny is INERT
             fix: Add a PreToolUse Bash db-guard hook that blocks destructive ops on non-local hosts.
      … (+2 more checks)

  … (+8 more dimensions)

That one line — defaultMode=bypassPermissions: autoMode.hard_deny is INERT — is the whole thesis rendered live: a rich hard_deny block earns nothing because the mode makes it inert. The sample above (examples/sample-harness) is deliberately incomplete to show the findings; run it yourself, or point the tool at your own ~/.claude — a mature harness scores an A.

What makes the grade real

Most config "linters" credit a harness for declaring a rule. This one models the effective enforcement floor. The headline example:

autoMode.hard_deny is inert when permissions.defaultMode == "bypassPermissions".

A naive scorer reads a rich hard_deny block and awards an A. Harness Scorecard reads the mode, discounts the inert block, and grades against what actually fires — permissions.deny globs plus the PreToolUse hooks. See docs/rubric.md for the full model, including capability gates that cap the grade when a critical hole is present (you can't score an A with readable credentials, no matter how many cheap checks pass).

It's honest about its own limits, too. A harness that funnels every guard through one opaque dispatcher script hides its logic from static analysis, so the named-guard checks under-credit it. Rather than silently mark it down, the report emits a caveat — "a low score here may be a static-analysis limit, not a missing guard" — so the grade is never misread as "insecure."

Usage

# Grade a harness directory (e.g. your ~/.claude)
harness-scorecard scan ~/.claude

# JSON for tooling, plus a self-contained HTML scorecard
harness-scorecard scan ~/.claude --format json --html scorecard.html

# SARIF 2.1.0 for CI / GitHub code scanning, failing the run below grade C
harness-scorecard scan ~/.claude --sarif harness.sarif --min-grade C

--min-grade {A,B,C,D,F} sets the bar (default B). Exit codes: 0 meets the bar · 1 below the bar · 2 no harness found.

Track drift over time

diff compares two scorecards and reports what changed — which checks flipped, which dimension scores moved, and whether a capability gate newly trips. Each argument is either a live harness directory or a saved JSON report (scan --json), so the same command covers a CI regression gate, a before/after audit, or drift between two snapshots:

# Record a baseline, then later fail if the harness grade regresses below it
harness-scorecard scan ~/.claude --json baseline.json
harness-scorecard diff baseline.json ~/.claude          # exit 1 if the grade dropped

# Compare two saved snapshots, machine-readable
harness-scorecard diff old.json new.json --format json

Exit codes: 0 no regression (same or better grade) · 1 grade regressed · 2 invalid input. Gate and dimension moves are reported for context; the letter grade is what fails the gate.

GitHub Action

Grade your harness in CI and upload the findings to code scanning:

- uses: saagpatel/harness-scorecard@v1
  with:
    path: .claude
    min-grade: B

The action writes SARIF and uploads it (requires security-events: write) even when the grade fails the build, so findings always reach code scanning. Commit a baseline.json and pass baseline: to also fail the job on any grade regression — a PR that weakens the harness can't merge:

- uses: saagpatel/harness-scorecard@v1
  with:
    path: .claude
    baseline: .github/harness-baseline.json   # fail if the grade drops below this

A complete workflow — permissions, weekly scheduling, SARIF upload — is in examples/github-workflow.yml.

Guarantees

• Read-only. It never writes to the harness it audits.
• Privacy-preserving. All output redacts secrets, tokens, emails, and absolute home paths. Nothing leaves the machine.
• Dependency-free runtime. The scorer ships stdlib-only — a tool that grades supply-chain hygiene should carry the smallest surface itself.

Scope (v1)

Implements all ten rubric dimensions end-to-end for both Claude Code and Codex: secret protection, egress/exfiltration control, tool-surface & inbound-injection defense, destructive-action & git safety, harness self-protection & integrity, verification gates, subagent isolation & governance, recovery/rollback safety, memory/provenance hygiene, and observability/audit trail (the critical gated trio is D1/D4/D5). Each harness has its own adapter and check suite over the shared scoring engine; the bypass-aware effective floor maps to Codex's sandbox_mode = "danger-full-access" + approval_policy = "never" just as it does to Claude Code's bypassPermissions. The rubric is versioned and emitted in every report.

Development

uv sync --frozen                                      # install dev tooling from the lockfile
uv run --no-sync python -m unittest discover -s tests # tests (stdlib runner, zero extra deps)
uv run --no-sync ruff check src/ tests/               # lint
uv run --no-sync ty check src/                        # type check