lastest

name	lastest
slug	las-team/lastest
version	0.5.0
description	Run visual regression tests, review screenshot diffs, and manage baselines on a Lastest instance via the @lastest/mcp-server MCP tools.
category	testing
tags	["visual-regression","playwright","mcp","qa","screenshot-testing","ai-testing"]
author	las-team
license	FSL-1.1-ALv2
homepage	https://github.com/las-team/lastest
repository	https://github.com/las-team/lastest

Lastest — Visual Regression Testing

This skill teaches the agent to drive a Lastest instance — running visual regression tests, inspecting screenshot diffs, and approving or rejecting baselines — through the official @lastest/mcp-server MCP server.

When to use

Use this skill when the user:

• Asks to run visual regression tests, UI snapshot tests, or screenshot comparisons
• Mentions "Lastest", "baseline screenshots", "visual QA", or "pixel diff"
• Wants to review, approve, or reject visual diffs on a build
• Asks to heal a failing visual test with AI

Prerequisites

The agent needs the @lastest/mcp-server MCP server configured in the user's MCP client. If it is not present, guide the user through setup:

One-liner (Claude Code, stdio):

claude mcp add lastest -- npx -y @lastest/mcp-server@latest \
  --url <LASTEST_URL> \
  --api-key <LASTEST_API_KEY>

Claude Desktop / Cursor (stdio):

{
  "mcpServers": {
    "lastest": {
      "command": "npx",
      "args": [
        "-y",
        "@lastest/mcp-server@latest",
        "--url",
        "https://app.lastest.cloud",
        "--api-key",
        "YOUR_API_KEY"
      ]
    }
  }
}

Remote HTTP (no local Node required):

claude mcp add --transport http lastest https://app.lastest.cloud/api/mcp \
  --header "Authorization: Bearer YOUR_API_KEY"

The API key is created at Settings → Runners & API Access → Create API Key in the Lastest web UI. Tell the user it is shown only once.

Recommended flow

Always verify connectivity before mutating state.

1. Check health — call lastest_status with action: "health". If it fails, ask the user to verify the URL and API key, then stop.
2. Find the repo — call lastest_repo with action: "list". If there are multiple, ask the user which one.
3. Pick tests:
   • All tests in an area: call lastest_area with action: "list_tests" and skip to step 4.
   • A subset: call lastest_test with action: "list" (or lastest_area action: "list_tests") and confirm which ones with the user.
4. Run — call lastest_run_tests with the repo id and optional testIds. Poll lastest_build (action: "get") until the build finishes, surfacing progress to the user.
5. Review diffs:
   • Call lastest_build (action: "get") for the finished build. If there are visual diffs, inspect them with lastest_get_diffs (scope: "build", or scope: "single" per diff).
   • For each diff, describe it to the user and ask whether to approve or reject via lastest_decide_diff. Do not approve/reject without explicit confirmation.
6. Authoring a new test (MCP-first) — you write the test; Lastest gives you the contract and context. See "Authoring a test" below. In short: read the lastest://repo/{repositoryId}/authoring-guide resource, discover selectors (your Playwright MCP preferred, else lastest_ranger for a live SPA-aware map or lastest_scout_url for a static one), then call lastest_create_test in direct mode with { name, code }. The author-test prompt runs this whole flow. Healing a broken test: call lastest_heal_test after confirming (server-side; requires in-product AI configured).

Authoring a test (MCP-first)

Lastest no longer generates tests with its own AI by default — the calling agent (you) writes the code. Lastest supplies the contract + live repo context.

1. Read the contract. Open the resource lastest://repo/{repositoryId}/authoring-guide (or the generic lastest://authoring-guide). It defines the exact runner signature export async function test(page, baseUrl, screenshotPath, stepLogger), the no-imports / plain-JS rules, selector-robustness + resilience rules, and this repo's base URL, functional areas, setup scripts, and auth storage states.
2. Discover selectors before writing code.
   • Preferred: use your own Playwright MCP — open the page, snapshot it, read real roles/labels/text.
   • Live & watchable: lastest_ranger drives a Lastest Embedded Browser to the URL and returns a rendered (SPA-aware) map, viewable live in the activity feed. Async — poll lastest_ranger_status for the page map.
   • Static & instant: lastest_scout_url for a no-browser map of an SSR page.
3. Wire auth/setup if needed — discover with lastest_setup_script (action: "list") / lastest_storage_state (action: "list"), then attach via lastest_test (action: "update", setupScriptId / setupOverrides). Don't script login inside the test.
4. Create + verify — lastest_create_test in direct mode { repositoryId, name, code }, then lastest_run_tests → lastest_build (action: "get"). On failure, read the error, fix, and lastest_test (action: "update") until it passes.

A prompt/url (AI) mode on lastest_create_test still exists but only works if the Lastest instance has in-product AI configured; if it returns ai_generation_failed, fall back to direct mode as above.

Safety rules

• Never call lastest_decide_diff with a buildId (approve-all), lastest_test action: "delete", or lastest_decide_diff action: "reject" on a batch without the user explicitly confirming the scope first — these operations are destructive or change shared baselines for the whole team.
• Never create API keys or change team settings from within this skill.
• If lastest_status (action: "health") or any tool returns a 401, stop and ask the user to regenerate their API key; do not retry with a different key.

Tool reference (via @lastest/mcp-server)

Pure CRUD lives on resource tools that take an action (or scope) discriminator; workflow verbs are standalone.

Purpose	Tool(s)
Status & jobs	lastest_status (health | jobs | job)
Repositories	lastest_repo (list | get | create | update | get_settings | update_settings)
Functional areas	lastest_area (list | create | update | delete | list_tests)
Tests	lastest_test (list | get | update | delete), lastest_create_test, lastest_heal_test
Authoring aids	lastest_ranger + lastest_ranger_status (live EB page map, watchable); lastest_scout_url (static page map); resource lastest://repo/{id}/authoring-guide; prompt author-test
Builds & runs	lastest_build (list | get | review), lastest_run_tests, lastest_validate_diff
Diffs	lastest_get_diffs (single | build), lastest_decide_diff (approve | reject)
Verify phase	lastest_verify (view | change_map), lastest_approve_layer
Sharing	lastest_publish_share, lastest_share (list | revoke)
Insights	lastest_insights (coverage | qa)
Setup & storage	lastest_setup_script (5 actions), lastest_storage_state (list | create | delete)

Full docs: Lastest MCP Server wiki.

Troubleshooting

Symptom	Guide the user to...
Failed to connect to Lastest	Verify the URL is reachable and the API key hasn't been revoked.
Lastest API error 401	Regenerate the key at Settings → Runners & API Access.
No repositories returned	Confirm the key belongs to a team with at least one connected repository.