agentlint 1.5.1

Real-time quality guardrails for AI coding agents

agentlint

Real-time guardrails for AI coding agents — code quality, security, and infrastructure safety.

AI coding agents drift during long sessions — they introduce API keys into source, skip tests, force-push to main, and leave debug statements behind. AgentLint catches these problems as they happen, not at review time.

Vision

The short-term problem is code quality: secrets, broken tests, force-pushes, debug artifacts. AgentLint solves that today with 68 rules that run locally in milliseconds.

The longer-term question is harder: what does it mean for an agent to operate safely on real infrastructure? When an agent can run gcloud, kubectl, terraform, or iptables, the blast radius is no longer a bad commit — it's a production outage or a deleted database.

We don't have a mature answer to that yet. Nobody does. The autopilot pack is our first experiment in that direction — explicit, opt-in, and clearly labeled as such. The goal is to start building the intuition and tooling for autonomous agent safety at the infrastructure level, and to do it in the open.

What it catches

AgentLint ships with 68 rules across 8 packs, covering all 17 Claude Code hook events. The 19 universal rules and 7 quality rules work with any tech stack; 4 additional packs auto-activate based on your project files; the security pack is opt-in; and the autopilot pack is opt-in and experimental:

Rule	Severity	What it does
no-secrets	ERROR	Blocks writes containing API keys, tokens, passwords, private keys, JWTs
no-env-commit	ERROR	Blocks writing .env files (including via Bash)
no-force-push	ERROR	Blocks git push --force to main/master
no-push-to-main	WARNING	Warns on direct push to main/master
no-skip-hooks	WARNING	Warns on git commit --no-verify
no-destructive-commands	WARNING	Warns on rm -rf, DROP TABLE, chmod 777, mkfs, and more
no-test-weakening	WARNING	Detects skipped tests, assert True, commented-out assertions
dependency-hygiene	WARNING	Warns on ad-hoc pip install / npm install
max-file-size	WARNING	Warns when a file exceeds 500 lines
drift-detector	WARNING	Warns after many edits without running tests
no-debug-artifacts	WARNING	Detects console.log, print(), debugger left in code
test-with-changes	WARNING	Warns if source changed but no tests were updated
token-budget	WARNING	Tracks session activity and warns on excessive tool usage
git-checkpoint	INFO	Creates git stash before destructive ops (opt-in, disabled by default)
no-todo-left	INFO	Reports TODO/FIXME comments in changed files

ERROR rules block the agent's action. WARNING rules inject advice into the agent's context. INFO rules appear in the session report.

Quality pack (7 rules) — always active alongside universal

Rule	Severity	What it does
commit-message-format	WARNING	Validates commit messages follow conventional format
no-error-handling-removal	WARNING	Warns when try/except or .catch() blocks are removed
no-large-diff	WARNING	Warns when a single edit adds >200 or removes >100 lines
no-file-creation-sprawl	WARNING	Warns when >10 new files created in a session
naming-conventions	INFO	Checks file names match language conventions (snake_case, camelCase, PascalCase)
no-dead-imports	INFO	Detects unused imports in Python and JS/TS files
self-review-prompt	INFO	Injects adversarial self-review prompt at session end

Python pack (6 rules) — auto-activates when pyproject.toml or setup.py exists

Rule	Severity	What it does
no-bare-except	WARNING	Prevents bare except: clauses that swallow all exceptions
no-unsafe-shell	ERROR	Blocks unsafe shell execution via subprocess or os module
no-dangerous-migration	WARNING	Warns on risky Alembic migration operations
no-wildcard-import	WARNING	Prevents from module import *
no-unnecessary-async	INFO	Flags async functions that never use await
no-sql-injection	ERROR	Blocks SQL via string interpolation (f-strings, .format())

Frontend pack (8 rules) — auto-activates when package.json exists

Rule	Severity	What it does
a11y-image-alt	WARNING	Ensures images have alt text (WCAG 1.1.1)
a11y-form-labels	WARNING	Ensures form inputs have labels or aria-label
a11y-interactive-elements	WARNING	Checks ARIA attributes and link anti-patterns
a11y-heading-hierarchy	INFO	Ensures no skipped heading levels or multiple h1s
mobile-touch-targets	WARNING	Ensures 44x44px minimum touch targets (WCAG 2.5.5)
mobile-responsive-patterns	INFO	Warns about desktop-only layout patterns
style-no-arbitrary-values	INFO	Warns about arbitrary Tailwind values bypassing tokens
style-focus-visible	WARNING	Ensures focus indicators are not removed (WCAG 2.4.7)

React pack (3 rules) — auto-activates when react is in package.json dependencies

Rule	Severity	What it does
react-query-loading-state	WARNING	Ensures useQuery results handle loading and error states
react-empty-state	INFO	Suggests empty state handling for array.map() in JSX
react-lazy-loading	INFO	Suggests lazy loading for heavy components in page files

SEO pack (4 rules) — auto-activates when an SSR/SSG framework (Next.js, Nuxt, Gatsby, Astro, etc.) is detected

Rule	Severity	What it does
seo-page-metadata	WARNING	Ensures page files include title and description
seo-open-graph	INFO	Ensures pages with metadata include Open Graph tags
seo-semantic-html	INFO	Encourages semantic HTML over excessive divs
seo-structured-data	INFO	Suggests JSON-LD structured data for content pages

Security pack (3 rules) — opt-in, add security to your packs list

Rule	Severity	What it does
no-bash-file-write	ERROR	Blocks file writes via Bash (cat >, tee, sed -i, cp, heredocs, etc.)
no-network-exfil	ERROR	Blocks data exfiltration via curl POST, nc, scp, wget --post-file
env-credential-reference	WARNING	Warns when *_FILE env vars reference local paths (credential leakage risk)

The security pack addresses the most common agent escape hatch: bypassing Write/Edit guardrails via the Bash tool. Enable it by adding security to your packs list:

packs:
  - universal
  - security  # Blocks Bash file writes and network exfiltration

Configure allowlists for legitimate use cases:

rules:
  no-bash-file-write:
    allow_patterns: ["echo.*>>.*\\.log"]  # Allow appending to logs
    allow_paths: ["*.log", "/tmp/*"]       # Allow writes to temp/log
  no-network-exfil:
    allowed_hosts: ["internal.corp.com"]   # Allow specific hosts

Autopilot pack (18 rules) — ⚠️ experimental, opt-in

Alpha quality. The autopilot pack is an early experiment in agent safety guardrails for cloud and infrastructure operations. Regex-based heuristics will produce false positives and false negatives — a mature framework for this problem doesn't exist yet. Enable it, experiment with it, report what breaks. Use at your own risk in production environments.

Rule	Severity	What it does
production-guard	ERROR	Blocks Bash commands targeting production databases, gcloud projects, or AWS accounts
destructive-confirmation-gate	ERROR	Blocks DROP DATABASE, terraform destroy, kubectl delete namespace, etc. without explicit acknowledgment
dry-run-required	WARNING	Requires --dry-run/--check/plan preview before terraform apply, kubectl apply, ansible-playbook, helm upgrade/install, and pulumi up
bash-rate-limiter	WARNING	Circuit-breaks after N destructive commands within a time window (default: 5 ops / 300s)
cross-account-guard	WARNING	Warns when the agent switches between gcloud projects or AWS profiles mid-session
operation-journal	INFO	Records every Bash and file-write operation to an in-session audit log; emits a summary at Stop
cloud-resource-deletion	ERROR	Blocks AWS/GCP/Azure resource deletion without session confirmation
cloud-infra-mutation	ERROR	Blocks NAT, firewall, VPC, IAM, and load balancer mutations across AWS/GCP/Azure
cloud-paid-resource-creation	WARNING	Warns when creating paid cloud resources (VMs, DBs, static IPs)
system-scheduler-guard	WARNING	Warns on crontab, systemctl enable, launchctl, scheduler file writes
network-firewall-guard	ERROR	Blocks iptables flush, ufw disable, firewalld permanent rules, and default route changes
docker-volume-guard	WARNING/ERROR	Blocks privileged containers (ERROR); warns on volume deletion and force-remove (WARNING)
ssh-destructive-command-guard	WARNING/ERROR	Detects destructive commands via SSH (rm -rf, mkfs, dd, reboot, iptables flush, terraform destroy)
remote-boot-partition-guard	ERROR	Blocks rm or dd targeting /boot kernel and bootloader files via SSH
remote-chroot-guard	WARNING/ERROR	Detects bootloader package removal and risky repair commands inside chroot
package-manager-in-chroot	WARNING	Warns on apt/dpkg/yum/dnf/pacman usage inside chroot environments
subagent-safety-briefing	INFO	Injects safety notice into subagent context on spawn (SubagentStart)
subagent-transcript-audit	WARNING	Audits subagent transcripts for dangerous commands post-execution (SubagentStop)

Subagent safety: Parent session hooks don't fire for subagent tool calls — this is a Claude Code architectural property. The autopilot pack addresses this with safety briefing injection (SubagentStart) and post-hoc transcript auditing (SubagentStop). AgentLint's own plugin agents also have frontmatter PreToolUse hooks for real-time blocking. See docs/subagent-safety.md for details.

Enable by adding autopilot to your packs list:

packs:
  - universal
  - autopilot

Feedback welcome — open an issue if a rule blocks something legitimate or misses something it should catch.

Stack auto-detection

When stack: auto (the default), AgentLint detects your project and activates matching packs:

Detected file	Pack activated
pyproject.toml or setup.py	python
package.json	frontend
react in package.json dependencies	react
SSR/SSG framework in dependencies (Next.js, Nuxt, Gatsby, Astro, SvelteKit, Remix)	seo
AGENTS.md with relevant keywords	Additional packs based on content

The universal and quality packs are always active. To override auto-detection, list packs explicitly in agentlint.yml.

Quick start

pip install agentlint
cd your-project
agentlint setup

That's it! AgentLint hooks are now active in Claude Code. agentlint setup resolves the absolute path to the binary, so hooks work regardless of your shell's PATH — whether you installed via pip, pipx, uv, poetry, or a virtual environment.

When AgentLint blocks a dangerous action, the agent sees:

⛔ [no-secrets] Possible secret token detected (prefix 'sk_live_')
💡 Use environment variables instead of hard-coded secrets.

The agent's action is blocked before it can write the secret into your codebase.

The setup command:

• Installs hooks into .claude/settings.json
• Creates agentlint.yml with auto-detected settings (if it doesn't exist)

To remove AgentLint hooks:

agentlint uninstall

Installation options

# Install to project (default)
agentlint setup

# Install to user-level settings (~/.claude/settings.json)
agentlint setup --global

Claude Code marketplace

Add the AgentLint marketplace and install the plugin:

/plugin marketplace add mauhpr/agentlint-plugin
/plugin install agentlint@agentlint

Local plugin (development)

claude --plugin-dir /path/to/agentlint/plugin

Plugin agents

The AgentLint plugin includes specialized agents for multi-step operations:

• /agentlint:security-audit — Scan your codebase for security vulnerabilities, hardcoded secrets, and unsafe patterns
• /agentlint:doctor — Diagnose configuration issues, verify hook installation, suggest optimal pack settings
• /agentlint:fix — Auto-fix common violations (debug artifacts, accessibility, dead imports) with confirmation

Manual hook configuration

Note: The manual configuration below uses the bare agentlint command and requires it to be on your shell's PATH. For reliable resolution across all installation methods, use agentlint setup instead — it embeds the absolute path automatically.

agentlint setup registers 7 hook events. Add to your project's .claude/settings.json:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash|Edit|Write",
        "hooks": [{ "type": "command", "command": "agentlint check --event PreToolUse", "timeout": 5 }]
      }
    ],
    "PostToolUse": [
      {
        "matcher": "Edit|Write",
        "hooks": [{ "type": "command", "command": "agentlint check --event PostToolUse", "timeout": 10 }]
      }
    ],
    "UserPromptSubmit": [
      {
        "hooks": [{ "type": "command", "command": "agentlint check --event UserPromptSubmit", "timeout": 5 }]
      }
    ],
    "SubagentStart": [
      {
        "hooks": [{ "type": "command", "command": "agentlint check --event SubagentStart", "timeout": 5 }]
      }
    ],
    "SubagentStop": [
      {
        "hooks": [{ "type": "command", "command": "agentlint check --event SubagentStop", "timeout": 10 }]
      }
    ],
    "Notification": [
      {
        "hooks": [{ "type": "command", "command": "agentlint check --event Notification", "timeout": 5 }]
      }
    ],
    "Stop": [
      {
        "hooks": [{ "type": "command", "command": "agentlint report", "timeout": 30 }]
      }
    ]
  }
}

Configuration

Create agentlint.yml in your project root (or run agentlint init):

# Auto-detect tech stack or list packs explicitly
stack: auto

# strict: warnings become errors
# standard: default behavior
# relaxed: warnings become info
severity: standard

packs:
  - universal
  # - security        # Opt-in: blocks Bash file writes, network exfiltration
  # - python          # Auto-detected from pyproject.toml / setup.py
  # - frontend        # Auto-detected from package.json
  # - react           # Auto-detected from react in dependencies
  # - seo             # Auto-detected from SSR/SSG framework in dependencies

rules:
  max-file-size:
    limit: 300          # Override default 500-line limit
  drift-detector:
    threshold: 5        # Warn after 5 edits without tests (default: 10)
  no-secrets:
    enabled: false      # Disable a rule entirely
  # Python pack examples:
  # no-bare-except:
  #   allow_reraise: true
  # Frontend pack examples:
  # a11y-heading-hierarchy:
  #   max_h1: 1

# Load custom rules from a directory
# custom_rules_dir: .agentlint/rules/

AGENTS.md integration

AgentLint supports the AGENTS.md industry standard. Import conventions from your project's AGENTS.md into AgentLint config:

# Preview what would be generated
agentlint import-agents-md --dry-run

# Generate agentlint.yml from AGENTS.md
agentlint import-agents-md

# Merge with existing config
agentlint import-agents-md --merge

When AGENTS.md exists and stack: auto is set, AgentLint also uses it for pack auto-detection.

Discovering rules

# List all rules (built-in + custom)
agentlint list-rules

# List rules in a specific pack (built-in or custom)
agentlint list-rules --pack security
agentlint list-rules --pack fintech

# List rules for a different project
agentlint list-rules --project-dir /path/to/project

# Show current status (version, packs, rule count, session activity)
agentlint status

# Diagnose common misconfigurations (including custom rules validation)
agentlint doctor

# Scan changed files for CI pipelines
agentlint ci --diff origin/main...HEAD

Custom rules

Create a Python file in your custom rules directory:

# .agentlint/rules/no_direct_db.py
from agentlint.models import Rule, RuleContext, Violation, Severity, HookEvent

class NoDirectDB(Rule):
    id = "no-direct-db"
    description = "API routes must not import database layer directly"
    severity = Severity.WARNING
    events = [HookEvent.POST_TOOL_USE]
    pack = "myproject"

    def evaluate(self, context: RuleContext) -> list[Violation]:
        if not context.file_path or "/routes/" not in context.file_path:
            return []
        if context.file_content and "from database" in context.file_content:
            return [Violation(
                rule_id=self.id,
                message="Route imports database directly. Use repository pattern.",
                severity=self.severity,
                file_path=context.file_path,
            )]
        return []

Then activate the pack in your config:

packs:
  - universal
  - myproject      # activates all rules with pack = "myproject"

custom_rules_dir: .agentlint/rules/

Rules whose pack is not in packs: are loaded but silently skipped. Use agentlint doctor to detect orphaned packs.

Monorepo Support

Different subdirectories can use different rule packs:

packs:
  - universal          # fallback for files outside any project

projects:
  frontend/:
    packs: [universal, frontend, react]
  backend/:
    packs: [universal, python]
  infra/:
    packs: [universal, security, autopilot]

Files outside any project prefix use the global packs: list. Longest prefix wins for nested paths.

MCP Server

Expose agentlint to Claude and other MCP clients. Agents can pre-validate code before writing:

pip install agentlint[mcp]
agentlint-mcp  # run via stdio

Tools:

• check_content(content, file_path) — pre-validate code against rules
• list_rules(pack?) — discover available rules
• get_config() — read current configuration

Resources: agentlint://rules, agentlint://config

CI Mode

Run agentlint in CI pipelines — same rules, same config, different trigger:

# .github/workflows/agentlint.yml
name: AgentLint
on: [pull_request]
jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with: { fetch-depth: 0 }
      - run: pip install agentlint
      - run: agentlint ci --diff origin/${{ github.base_ref }}...HEAD

Only ERROR violations fail the build. Warnings are reported but don't block. Use --format json for machine-readable output.

File-Scope Governance

Restrict which files the agent can access. Deny patterns take precedence over allow:

rules:
  file-scope:
    allow: ["src/**", "tests/**", "docs/**"]
    deny: ["*.env", "credentials/**", ".github/workflows/**"]

Blocks Write, Edit, Read, and Bash file operations. Path traversal (../) is blocked. If no file-scope config is present, the rule is inactive.

CLI Integration

Run any command-line tool as a PostToolUse check. AgentLint executes the command after Write/Edit and reports non-zero exit codes as violations:

rules:
  cli-integration:
    commands:
      - name: ruff
        on: ["Write", "Edit"]
        glob: "**/*.py"
        command: "ruff check {file.path} --output-format=concise"
        timeout: 10
        severity: warning

      - name: pip-audit
        on: ["Write", "Edit"]
        glob: "**/requirements*.txt"
        command: "pip-audit -r {file.path}"
        timeout: 30
        severity: warning

      - name: pytest-related
        on: ["Write", "Edit"]
        glob: "src/**/*.py"
        command: "pytest tests/ -k {file.stem} -x -q --tb=short"
        timeout: 60
        severity: info

Available placeholders

Placeholder	Value	Example
{file.path}	Absolute file path	/home/user/project/src/app.py
{file.relative}	Relative to project	src/app.py
{file.name}	Filename	app.py
{file.stem}	Filename without extension	app
{file.ext}	Extension	py
{file.dir}	Parent directory	/home/user/project/src
{file.dir.relative}	Parent dir (relative)	src
{project.dir}	Project root	/home/user/project
{tool.name}	Tool that triggered	Write
{session.changed_files}	All changed files (space-separated)	src/a.py src/b.py
{env.VARNAME}	Environment variable	(value of $VARNAME)

Commands with unresolvable placeholders are silently skipped. All placeholder values are shell-escaped (shlex.quote) to prevent injection. File paths outside the project directory are rejected.

How it works

AgentLint supports all 17 Claude Code hook events. agentlint setup registers 7 events out of the box:

Event	When	Behavior
PreToolUse	Before Write/Edit/Bash	Can block the action
PostToolUse	After Write/Edit	Injects warnings into agent context
UserPromptSubmit	When user sends a prompt	Evaluates prompt-level rules
SubagentStart	When a subagent spawns	Injects safety briefing via additionalContext
SubagentStop	When a subagent completes	Audits subagent transcript for dangerous commands
Notification	On system notifications	Evaluates notification-triggered rules
Stop	End of session	Generates a quality report

Custom rules can target any of the 17 events (SessionStart, PreCompact, WorktreeCreate, TaskCompleted, etc.).

Each invocation loads your config, evaluates matching rules, and returns JSON that Claude Code understands. Session state persists across invocations so rules like drift-detector can track cumulative behavior.

Circuit breaker (Progressive Trust)

When a blocking rule fires repeatedly, it automatically degrades to avoid locking the agent in a loop:

Fire count	Severity	Effect
1-2	ERROR	Blocks the action (normal)
3-5	WARNING	Advises instead of blocking
6-9	INFO	Appears in session report only
10+	Suppressed	Silent until reset

The breaker resets after 5 consecutive clean evaluations or 30 minutes without firing.

Security-critical rules (no-secrets, no-env-commit) are exempt — they always block, regardless of fire count. Per-rule overrides are configurable:

circuit_breaker:
  enabled: true          # ON by default
  degraded_after: 3      # ERROR -> WARNING
  passive_after: 6       # -> INFO
  open_after: 10         # -> suppressed

rules:
  max-file-size:
    circuit_breaker:
      degraded_after: 5  # Override per-rule

Comparison with alternatives

Project	How AgentLint differs
guardrails-ai	Validates LLM I/O. AgentLint validates agent tool calls in real-time.
claude-code-guardrails	Uses external API. AgentLint is local-first, no network dependency.
Custom hooks	Copy-paste scripts. AgentLint is a composable engine with config + plugins.
Codacy Guardrails	Commercial, proprietary. AgentLint is fully open source.

FAQ

Does AgentLint slow down Claude Code? No. Rules evaluate in <10ms. AgentLint runs locally as a subprocess — no network calls, no API dependencies.

What if a rule is too strict for my project? Disable it in agentlint.yml: rules: { no-secrets: { enabled: false } }. Or switch to severity: relaxed to downgrade warnings to informational. The circuit breaker also helps — if a rule fires 3+ times in a session, it automatically degrades from blocking to advisory.

Is my code sent anywhere? No. AgentLint is fully offline. It reads stdin from Claude Code's hook system and evaluates rules locally. No telemetry, no network requests.

Can I use AgentLint outside Claude Code? The CLI works standalone — you can pipe JSON to agentlint check in any CI pipeline. However, the hook integration (blocking actions in real-time) is specific to Claude Code.

Contributing

See CONTRIBUTING.md for development setup and guidelines.

License

MIT