stably-verify

Verify App Behavior with stably verify

stably verify checks whether your application works correctly by describing expected behavior in plain English. It launches an AI agent that navigates your app in a real browser, interacts with it, takes screenshots, and reports a structured PASS / FAIL / INCONCLUSIVE verdict. No test files are generated.

Pre-flight

Always run stably --version first. If not found, install with npm install -g stably or use npx stably. Requires Node.js 20+ and a Stably account.

stably --version
echo "STABLY_API_KEY: ${STABLY_API_KEY:+set}"
echo "STABLY_PROJECT_ID: ${STABLY_PROJECT_ID:+set}"

Usage

# Verify a feature works
stably verify "the login form accepts email and password and redirects to /dashboard"

With a specific starting URL

stably verify "the pricing page shows 3 tiers" --url http://localhost:3000/pricing

Set a budget cap (default: $5)

stably verify "checkout flow completes successfully" --max-budget 10

Non-interactive mode (for CI or background agents)

stably verify "checkout flow completes" --no-interactive

Use cloud browser instead of local

stably verify "login works" --browser cloud


### Options

| Option | Description |
|--------|-------------|
| `-u, --url <url>` | Starting URL (auto-detected from localhost if omitted) |
| `--max-budget <dollars>` | Budget cap in USD (default: `5`) |
| `--no-interactive` | Skip preflight prompts |
| `--browser <type>` | Browser type: `local` or `cloud` (default: `local`). Also settable via `STABLY_CLOUD_BROWSER=1` |

### Exit Codes

| Code | Verdict | Meaning |
|------|---------|---------|
| `0` | PASS | All requirements verified |
| `1` | FAIL | One or more requirements not met |
| `2` | INCONCLUSIVE | Cannot determine (app unreachable, auth wall, etc.) |

## Iteration Loop

After making code changes, use `stably verify` to check the feature:

1. **Run verify** — `stably verify "description of expected behavior"`
2. **If FAIL** — Read the failure reason and evidence from the output
3. **Fix code** — Modify your application code based on the failure
4. **Re-verify** — Run the same `stably verify` command again
5. **Repeat** until PASS

`stably verify` does not create or modify any files. It only observes and reports. Fix the code yourself based on its findings.

## Composing in Scripts

```bash
# Gate on verification
stably verify "login works" && echo "Feature verified!"

# Handle all three outcomes
stably verify "checkout completes" ; code=$?
if [ $code -eq 0 ]; then echo "PASS";
elif [ $code -eq 1 ]; then echo "FAIL";
else echo "INCONCLUSIVE"; fi

Long-Running Commands (AI Agents)

stably verify is AI-powered and can take several minutes depending on complexity.

Agent	Configuration
Claude Code	`timeout: 600000` on Bash tool
Cursor	`block_until_ms: 900000`

Links

Docs · Verify Guide · CLI Quickstart · Dashboard

About this skill

Pre-flight

Usage

Long-Running Commands (AI Agents)

Links