Arguments: $ARGUMENTS

Command	Behavior
`run`	Lint + type check + run tests
`write`	Generate tests, then run pipeline
`browser`	Visual verification
`all`	run + browser combined

Scope (optional, default: branch):

Scope	Command
`branch`	`git diff main...HEAD --name-only`
`staged`	`git diff --cached --name-only`
`uncommitted`	`git diff --name-only`

Run Mode

1. Detect Tools

Config	Tool	Command
`package.json` + vitest	Vitest	`npx vitest run`
`package.json` + jest	Jest	`npx jest`
`package.json` + `"test"`	npm	`npm test`
`pyproject.toml`	pytest	`pytest`
`Cargo.toml`	cargo	`cargo test`
`go.mod`	go	`go test ./...`
`.eslintrc` / `eslint.config.`	ESLint	`npx eslint .`
`biome.json`	Biome	`npx biome check .`
`tsconfig.json`	TypeScript	`npx tsc --noEmit`

2. Setup (if missing)

bash

# JS/TS test runner
npm install -D vitest

# JS/TS linter
npm install -D eslint @eslint/js

# JS/TS types
npm install -D typescript && npx tsc --init

# Python
pip install pytest ruff mypy

3. Run Pipeline

bash

# 1. Lint
npx eslint . --fix  # or: npx biome check . --write

# 2. Type check
npx tsc --noEmit    # or: mypy .

# 3. Test
npx vitest run      # or: pytest, cargo test, go test ./...

Fix errors, re-run until all pass.

Write Mode

1. Get Changed Files

bash

git diff main...HEAD --name-only  # branch scope
git diff --cached --name-only     # staged scope
git diff --name-only              # uncommitted scope

Filter to source files (exclude tests, configs, docs).

2. Launch Test Writers

Hand off files to test-writer subagents. They determine testability and write tests.

Files	Subagents
1-3	1
4-8	2-3
9+	3-5

javascript

// Task tool
{
  subagent_type: "test-writer",
  prompt: "Write tests for: [file list]. Runner: vitest. Convention: *.test.ts"
}

3. Run Pipeline

Same as Run Mode step 3.

Browser Mode

Visual verification using browser automation. See /browser skill for full API.

javascript

import { connect, waitForPageLoad } from '../otto/lib/browser/client.js'

const client = await connect({ headless: true })
const page = await client.page('test')

// Determine URL from package.json scripts or running processes
await page.goto(url)  // e.g., http://localhost:5173
await waitForPageLoad(page)
await page.screenshot({ path: '.otto/test-screenshots/page.png' })

// Interact using ARIA snapshot refs
const snapshot = await client.getAISnapshot('test')
const btn = await client.selectSnapshotRef('test', 'e3')
await btn.click()

await client.disconnect()

All Mode

•Run Mode (lint, type check, test)
•Browser Mode (visual verification)
•Report results