Why Argus Exists
AI agents now write most of the code — and they judge their own work by whether it compiles and looks done, not by what actually happens in the browser. The uncaught exception on the third click. The form that posts credentials over HTTP. The 4-second LCP. The button that vanished in dark mode. The API endpoint hammered in an infinite loop.
Argus closes that gap. It drives a real Chrome (via the Chrome DevTools Protocol) against your locally-running app and hands the agent — or you — a structured, severity-ranked bug report. The agent fixes; Argus re-checks; the loop closes before the code leaves your machine.
| |
|---|
| 🧪 No test files, ever | Argus audits the rendered app — DOM, console, network, pixels — not your source. Nothing to write, nothing to maintain when the agent refactors |
| 🤖 Built for the agent loop | The only QA engine Claude can call natively over MCP. Audit → fix → re-audit without leaving the conversation |
| 🔒 Safe for agents by default | Aegis: findings are redacted at every egress boundary — secrets, PII, and exploit detail never reach the LLM's context window (OWASP LLM02, default-ON, fail-closed) |
| 🧰 Also a normal QA tool | CLI batch audits, a GitHub Action PR gate, Slack reports with screenshots, dev-vs-staging diffs, watch mode — with or without an agent |
Quick Start
No install. npx fetches Argus on first run.
1 — Add two lines to .mcp.json in your project root:
{
"mcpServers": {
"chrome-devtools": { "command": "npx", "args": ["-y", "chrome-devtools-mcp@latest"] },
"argus": { "command": "npx", "args": ["-y", "argusqa-os"] }
}
}
Or via the Claude Code CLI:
claude mcp add chrome-devtools -- npx -y chrome-devtools-mcp@latest
claude mcp add argus -- npx -y argusqa-os
2 — Launch Chrome (auto-detects your Chrome, sets the right flags):
npx -y -p argusqa-os argus-chrome
Prefer launching Chrome manually? (macOS / Windows / Linux commands)
open -a "Google Chrome" --args --remote-debugging-port=9222 --headless=new
& "C:\Program Files\Google\Chrome\Application\chrome.exe" --remote-debugging-port=9222 --headless=new --no-sandbox --disable-gpu --user-data-dir="$env:TEMP\chrome-argus"
google-chrome --remote-debugging-port=9222 --headless=new --no-sandbox
3 — Ask your agent:
Run argus_audit on http://localhost:3000
That's it. Findings come back structured and severity-ranked — into the conversation, to Slack, or as a local report.html. Something off? npx -y -p argusqa-os argus-doctor diagnoses your setup in one command.
The Fix Loop
This is what Argus looks like inside an agentic coding session:
You: Build me a checkout page with a card form.
Agent: [writes the code, dev server renders it]
You: Run argus_audit on http://localhost:3000/checkout
Argus: ● 2 critical · 3 warnings
● uncaught TypeError in checkout.js (visible on submit)
● form posts over HTTP — security_no_https
▲ card inputs missing labels + autocomplete (a11y/WCAG)
▲ LCP 4.1s — hero image unoptimized
▲ duplicate POST /api/cart ×7 — likely render loop
Agent: [fixes all five]
You: Run argus_get_context
Argus: ✓ resolved: 5 · persisting: 0 · new: 0
argus_get_context diffs against the previous snapshot, so the agent knows exactly what it fixed, what it broke, and what remains — no re-reading walls of output.
"But my agent can already drive a browser…" — it can. Driving isn't judging. A raw browser MCP (Playwright MCP, bare chrome-devtools-mcp) gives the agent hands and eyes; the agent must then re-derive what to check every session, burning context on console-log spelunking. Argus is the judgment layer on top: 149 codified finding types with thresholds, severity policy, cross-run baselines, flakiness filtering, dedup, root-cause hints — returned in one call, redacted by default.
What Argus Catches
32 analysis engines, 149 distinct issue types, zero test-file maintenance:
| Category | What it detects |
|---|
| JavaScript | Uncaught exceptions, unhandled promise rejections, console.error on critical routes |
| Network & API | HTTP 5xx, 401/403 auth failures, duplicate API calls (infinite loops), 4xx errors, broken links |
| Performance | LCP > 2500ms, CLS > 0.1, TTFB > 800ms, slow APIs > 1s/3s, payloads > 500KB/2MB, JS bundles > 500KB |
| Accessibility | axe-core (80+ WCAG rules), color-blind simulation, missing ARIA, keyboard focus, heading hierarchy |
| SEO | Missing meta description, OG tags, canonical, viewport, h1 |
| Security | Auth tokens in localStorage/URL, eval(), missing CSP/X-Frame-Options, CSP violations, missing SRI on external scripts, source map exposure, open redirects, npm CVEs |
| CSS | Cascade overrides, component style leaks, unused rules, React inline style conflicts |
| Content | null/undefined as visible text, lorem ipsum, broken images, empty data lists |
| Responsive | Horizontal overflow at 375px/768px, touch targets < 44×44px |
| Memory | Detached DOM nodes via V8 heap snapshot, heap growth across navigation |
| Visual | Pixel-level screenshot regression via pixelmatch (≥0.1% warning, ≥5% critical) |
| Figma | Design-to-implementation fidelity — 13 property types (color, spacing, typography, shadows, etc.) |
| Forms | Missing required, autocomplete, aria-describedby; unlabelled inputs |
| Fonts | FOIT, FOUT, missing fallbacks, slow loads > 1s, suboptimal formats |
| Motion | prefers-reduced-motion violations, autoplay without pause controls |
| Theme | Dark-mode gaps — static CSS vars, missing prefers-color-scheme handling |
| Network baseline | New requests, missing requests, status-code regressions vs saved HAR baseline |
| Environment diff | Dev vs staging — screenshot diff, DOM changes, console/network regressions |
And every finding is post-processed with:
| Post-processor | What it adds |
|---|
| Intelligent baseline filtering | Findings that flip-flop across runs are tagged noisy and downgraded to info — pure cross-run heuristics, no API calls (ARGUS_NOISE_FILTER=0 to disable) |
| Root cause linking | New findings are annotated with the recent git commits and files most likely to have caused them (ARGUS_ROOT_CAUSE=0 to disable) |
All findings are classified as critical / warning / info and routed to the right Slack channel — or surfaced in the local HTML report. For per-finding severity tables and detection methods, see REFERENCE.md.
Works With Your Stack
Argus audits the rendered output, not your source — so it is framework-agnostic by construction. If it runs in Chrome, Argus can audit it:
| |
|---|
| SPA frameworks | React, Vue, Angular, Svelte/SvelteKit, Solid, Preact, Astro… |
| Meta-frameworks | Next.js, Nuxt, Remix, Gatsby — plus framework-aware extras: Next.js & React Router route discovery, import-graph PR mapping ("this component changed → audit only the routes that render it"), monorepo path awareness |
| Server-rendered | Rails, Django, Laravel, Flask, Spring, PHP — anything that serves HTML to a browser |
| Static / no framework | Plain HTML/CSS/JS, docs sites, landing pages |
| APIs (via the page) | Response schema validation, status/timing checks on every request the page makes |
Honest limits: Chrome/Chromium rendering only (no Safari/Firefox engine differences), web only (no native mobile/desktop apps), and backend services are checked through the traffic the page generates — not as standalone API test suites.
Confidentiality — Aegis Egress Boundary
Default ON. Argus audits your app for secrets and vulnerabilities — so its findings are exactly the data you least want leaving your machine. Aegis redacts them at every external boundary before they cross. For teams adopting AI agents, this is the difference between "we use an AI QA tool" and "we can tell our security lead exactly why it's safe."
A finding sent to an external sink — an MCP tool response (which lands in the calling agent's context window and transits to that agent's model provider), a Slack message, a GitHub PR comment + its ::error annotations, the hosted/CI HTML report, or CI logs — is reduced to a need-to-know projection: a sensitive finding crosses as its type + route + severity + a 🔒 marker, and never its raw payload (message, evidence, request/response bodies, headers, cookies, stack). URLs are projected with the query string stripped (tokens hide there). A benign finding keeps its message — but that message is still scrubbed for any accidentally-embedded secret or PII.
| Principle | Behavior |
|---|
| Local fidelity preserved | The on-disk JSON report and the locally-opened HTML keep 100% detail — redaction only removes detail on the way out |
| Fail-closed | On any classifier error or unknown finding shape, Aegis redacts more, never less |
| Deny-by-default | Only an explicit allowlist of safe fields ever crosses; a new field leaks nothing until deliberately allowlisted |
| 5-layer detection | Category rules ∪ 13 secret regexes ∪ statistical rarity (entropy / token-efficiency) ∪ 7 Luhn-validated PII rules ∪ context boosting |
| Opt-out | ARGUS_REDACT_SENSITIVE=0 → output is byte-identical to pre-Aegis |
This implements the OWASP LLM02:2025 — Sensitive Information Disclosure mitigations (data minimization, redaction, deny-by-default egress filtering) at Argus's own boundaries. An optional, local-only re-hydration vault (ARGUS_REDACT_VAULT=1) can mint reversible, information-free tokens for diff-stable artifacts — re-inflate locally with npm run report:rehydrate. Full behavior change is documented in CHANGELOG.md.
Ask Claude (or any MCP client) — no terminal required:
| Tool | Description |
|---|
argus_audit | Fast pass — JS, network, accessibility, SEO, security, CSS, content |
argus_audit_full | Deep pass — adds Lighthouse, responsive checks, memory leak detection, hover-state bugs |
argus_compare | Diff dev vs staging — screenshots, findings delta, environment regressions |
argus_get_context | Capture everything broken on the open tab — with resolved / new / persisting diff vs the last snapshot (the fix loop) |
argus_watch_snapshot | Snapshot the open tab without navigating (preserves auth/form state) |
argus_last_report | Return last JSON report without re-running |
argus_design_audit | Figma URL → 13 design-token finding types (color, spacing, typography, shadows, etc.) |
argus_visual_diff | Screenshot baseline comparison. Pass updateBaseline: true to reset. |
argus_pr_validate | Fetch GitHub PR diff → map changed files to affected routes → targeted audit → baseline-aware block decision (blocks on findings the PR introduces) + idempotent PR comment + Check Run → { blocked, findings, baseline, reporting } |
Every tool response is projected through the Aegis egress boundary before it reaches the agent, and carries an optional redaction rider ({ redacted, total }) when sensitive detail was withheld.
Example prompts:
Run argus_audit on http://localhost:3000/checkout
Run argus_audit_full on http://localhost:3000/dashboard
Run argus_compare
Run argus_get_context
Battle-Tested, Not Vibe-Tested
Argus's own correctness is enforced the way it audits yours:
- 998/998 hard assertions across a 171-block integration harness driving real Chrome against 64 fixture pages — including per-category negative controls (zero over-fire), golden response schemas for all 9 MCP tools, and an upstream-drift canary that catches chrome-devtools-mcp API changes at version-bump time
- 562 Chrome-free unit tests (Vitest) + property-based parser fuzzing
npm audit: 0 vulnerabilities · CodeQL + Dependabot on every PR · Socket.dev: 100/100/100 on vulnerability/quality/license- Session files and captured tokens written
0600, owner-only
Full Setup
Prerequisites
| Requirement | Version |
|---|
| Node.js | v20.19+ |
| Chrome | Stable (desktop or headless) |
| Claude Code | Latest (npm install -g @anthropic-ai/claude-code) — or any MCP client |
| Slack workspace | Optional — omit for local report.html mode |
Option A — MCP Server (recommended for Claude Code users)
No local install needed. Use the Quick Start above, then add your target URL:
# .env in your project root
TARGET_DEV_URL=http://localhost:3000
TARGET_STAGING_URL=https://staging.example.com # optional — enables argus_compare
Optional — Slack notifications:
- api.slack.com/apps → Create New App → name it BugBot
- OAuth & Permissions → Bot Token Scopes:
chat:write, files:write, files:read
- Install to workspace → copy the
xoxb-... token
- Create channels
#bugs-critical, #bugs-warnings, #bugs-digest and run /invite @BugBot in each
SLACK_BOT_TOKEN=xoxb-...
SLACK_CHANNEL_CRITICAL=C0000000000
SLACK_CHANNEL_WARNINGS=C0000000001
SLACK_CHANNEL_DIGEST=C0000000002
Without Slack: Argus auto-generates reports/report.html and opens it in your browser — zero extra config.
Option B — npm Package (CI / dev dependency)
npm install --save-dev argusqa-os
npx argus init
npm run crawl
Option C — Clone the Repository (contributors / full source)
git clone https://github.com/ironclawdevs27/Argus.git
cd Argus
npm install
npm run init
Manual setup (skip the wizard):
Then configure your routes in src/config/targets.js:
export const routes = [
{ path: '/', name: 'Home', critical: true, waitFor: 'main' },
{ path: '/login', name: 'Login', critical: true, waitFor: 'form' },
{ path: '/dashboard', name: 'Dashboard', critical: true, waitFor: '[data-testid="dashboard"]' },
{ path: '/settings', name: 'Settings', critical: false, waitFor: null },
];
critical: true — errors on this route go to #bugs-criticalwaitFor — CSS selector Argus waits for before capturing (signals page-ready)
CLI Commands
npm run chrome
npm run doctor
npm run crawl
npm run compare
npm run watch
npm run report:html
npm run report:pdf
npm run server
npm run init
npm run test:unit
npm run test:harness
npm run test:harness:log
npm run test:coverage
Watch mode — live monitoring as you (or your agent) develop:
npm run dev
npm run watch
Slack slash command (on-demand from any channel):
/argus-retest https://staging.example.com/checkout
To expose the server via tunnel: cloudflared tunnel --url http://localhost:3001 (free, no account required). Set the resulting URL as the Request URL in Slack App → Slash Commands.
GitHub Actions CI — PR Gate
Argus ships as a composite GitHub Action: on every PR it maps the diff to affected routes, audits them, and blocks the merge only on findings the PR introduces (baseline-aware) — with an idempotent PR comment and a Check Run.
Add to your repo's secrets (Settings → Secrets → Actions):
| Secret | Required | Value |
|---|
TARGET_STAGING_URL | Yes | Your staging base URL |
SLACK_BOT_TOKEN | No | xoxb-... token (omit for HTML-only mode) |
SLACK_CHANNEL_CRITICAL | No* | Channel ID (needed when Slack is configured) |
SLACK_CHANNEL_WARNINGS | No* | Channel ID |
SLACK_CHANNEL_DIGEST | No* | Channel ID |
GITHUB_TOKEN | No | Auto-injected by Actions for PR comments + Check Runs |
The included workflow runs on push to main, daily at 6 AM UTC, and on manual trigger. If critical issues are found, the pipeline fails.
Environment Variables
Full reference (click to expand)
| Variable | Default | Description |
|---|
TARGET_DEV_URL | — | Required. Base URL of your dev environment |
TARGET_STAGING_URL | — | Staging URL — enables argus_compare; omit for CSS-only mode |
SLACK_BOT_TOKEN | — | xoxb-... token. Omit for local report.html mode |
SLACK_SIGNING_SECRET | — | For /argus-retest slash command verification |
SLACK_CHANNEL_CRITICAL | — | Channel ID for critical bugs |
SLACK_CHANNEL_WARNINGS | — | Channel ID for warnings |
SLACK_CHANNEL_DIGEST | — | Channel ID for info / daily digest |
PORT | 3001 | Slack slash-command server port |
REPORT_OUTPUT_DIR | ./reports | Where to write JSON reports |
ARGUS_CONCURRENCY | 1 | Parallel MCP clients for route crawling |
ARGUS_LOG_LEVEL | info | trace / debug / info / warn / error |
ARGUS_LOG_PRETTY | — | Set 1 for human-readable logs in dev |
ARGUS_RETRY_ATTEMPTS | 3 | Max retries for navigate/fill MCP calls |
ARGUS_WATCH_INTERVAL_MS | 1000 | Watch mode poll interval (ms) |
ARGUS_WATCH_UI_PORT | 3002 | Watch mode web dashboard port |
ARGUS_SOURCE_DIR | — | App source path — enables env-var / feature-flag / dead-route analysis and framework-aware PR route mapping (import-graph: a changed component/stylesheet → only the routes that render it) |
ARGUS_ENV_FILE | — | Path to app .env for codebase cross-reference |
SCREENSHOT_DIFF_THRESHOLD | 0.5 | Pixel diff % threshold for environment comparison |
GITHUB_TOKEN | — | For PR comments + Check Runs |
GITHUB_REPOSITORY | — | owner/repo format |
GITHUB_PR_NUMBER | — | Auto-injected by Actions from PR context |
ARGUS_CRITICAL_THRESHOLD | 1 | New criticals before blocking merge (0 = never block) |
ARGUS_DIFF_IMAGE_URL | — | Visual diff image URL to embed in PR comment |
OTEL_EXPORTER_OTLP_ENDPOINT | — | OTLP collector for Jaeger / Grafana Tempo |
FIGMA_API_TOKEN | — | Required for argus_design_audit |
FONT_SLOW_MS | 1000 | Slow web font load threshold (ms) |
A11Y_CONTRAST_AA | 4.5 | WCAG AA min contrast ratio for CVD simulation |
ARGUS_REDACT_SENSITIVE | ON | Aegis egress redaction. 0 disables (byte-identical pre-Aegis output) |
ARGUS_REDACT_MODE | mask | Matched-span style: mask / label / hash / token / drop |
ARGUS_REDACT_HTML | off local / ON in CI | 1 redacts the hosted HTML report too |
ARGUS_REDACT_VAULT | OFF | 1 (with ARGUS_REDACT_MODE=token) mints reversible AEGIS_<hmac16> tokens into a local 0600 vault; re-inflate with npm run report:rehydrate |
Troubleshooting
First stop for anything broken: npx -y -p argusqa-os argus-doctor — it checks Chrome reachability, MCP config validity, and required env keys, and prints the exact fix for each failure.
Chrome DevTools MCP not connecting
claude mcp add chrome-devtools -- npx chrome-devtools-mcp@latest
Slack messages not posting
- Token must start with
xoxb- (not xoxp-, xoxe-, or xapp-)
- Run
/invite @BugBot in each channel
- Required scopes:
chat:write, files:write, files:read
Screenshots are blank
- Page hasn't settled — increase
pageSettleMs in src/config/targets.js or add a waitFor selector for the route
/argus-retest returns "dispatch_failed"
- Tunnel URL changed — update the Request URL in Slack App → Slash Commands and reinstall
CSS analysis returns empty results
- Page may be behind auth — ensure you're logged in on the Chrome instance Argus is controlling
CI pipeline fails immediately
How Argus Differs From Playwright / Cypress
Argus is a complementary layer, not a replacement for unit or E2E tests:
| Playwright / Cypress | Raw browser MCP (Playwright MCP, chrome-devtools-mcp) | Argus |
|---|
| Purpose | Test your logic and API contracts | Give an agent browser hands & eyes | Give the agent (and you) judgment about what's broken |
| What you get | Pass / fail on scripts you wrote | Raw DOM/console/network access | 149 codified finding types, severities, baselines, noise filtering, root-cause hints |
| Maintenance | Test files, forever | Re-prompt the checks every session | Zero — audits the rendered app |
| When it runs | In your test suite | When the agent thinks to look | On demand, in CI as a PR gate, or continuously (watch mode) |
| Output | Pass / fail | Whatever the agent noticed | Structured reports with screenshots — Slack, HTML, PR comments — secrets redacted |
Known Limitations
All 998 harness assertions pass (998/998) — there are currently no known MCP- or Chrome-layer restrictions. Lighthouse runs headless (after the lighthouse_audit argument fix); the remaining soft assertions (perf traces, GC-dependent heap-growth) are promoted to counted hard assertions only in the weekly strict-soft lane (harness-strict.yml) via ARGUS_HARNESS_STRICT_SOFT. Scope limits: Chrome/Chromium only, web apps only — see Works With Your Stack.
Hosted Argus — Founding Members
Want audits without running Chrome or npm — with history, trends, schedules, and a team dashboard? Argus Cloud is in founding-member early access: $19/month, locked forever (regular $29).
Become a founding member → argus-qa.com
The open-source engine on this page stays MIT and fully-featured, always — the hosted tier sells convenience and memory, never detections.
Project Structure
src/
argus.js — single-page audit entry point
mcp-server.js — 9 MCP tools exposed to Claude / any MCP client
orchestration/ — crawl loop, Slack/GitHub dispatch, env comparison, watch mode
utils/ — 32 analysis engines (accessibility, security, performance, PDF, recording, etc.)
adapters/browser.js — CdpBrowserAdapter — wraps all chrome-devtools-mcp calls
config/targets.js — routes, thresholds, auth steps
cli/
init.js — argus init interactive setup wizard
chrome-launcher.js — npm run chrome / argus-chrome — launches Chrome with correct flags
doctor.js — npm run doctor / argus-doctor — pre-flight checks
pr-validate.js — headless CI entry point for GitHub Actions
test-harness/ — 171-block correctness harness, 998 hard assertions, 64 fixture pages
test/unit/ — 562 Vitest unit tests (no Chrome required)
landing/ — Product landing page (React 19 + Vite + Tailwind)
Full source map → CLAUDE.md · MCP/DSL reference → SKILL.md
Contributing
Contributions are welcome — fixture pages, new detection categories, framework route-discovery, docs. Start with CONTRIBUTING.md.
- Fork the repo and create a branch
npm run test:unit — verify without Chrome (562 tests)npm run test:harness — full integration coverage (requires Chrome on port 9222)- Open a PR — Argus audits itself via the CI workflow
License
MIT © ironclawdevs27
