#Practical Examples

Three progressive tasks that reuse this course: onboard an unfamiliar repo, ship a multi-file feature with Plan Mode, and install a team workflow with rules + MCP. Paste the prompts into Agent; adapt commands to your repo. Do not run these on production with review turned off.

#Example 1: Onboard an unfamiliar repo

Goal: In two hours, name the entry points, the test command, and one safe small change—without guessing.

Setup: Clone any mid-size open-source repo you do not know. Open the repo root in Cursor.

git clone <repo-url> unfamiliar-repo
cd unfamiliar-repo
cursor .

git clone <repo-url> unfamiliar-repo
cd unfamiliar-repo
cursor .

Ctrl+I / Cmd+I, then send in order:

Explain this codebase. Point me to the main entry points, key modules,
and anything I should read before making changes.

Quote the exact commands this repo uses for install, test, lint, and
dev server. Prefer package.json / Makefile / pyproject.toml / go.mod.
Do not invent scripts.

Run the install and test commands it quoted (examples):

# follow whatever the repo actually printed
npm ci
npm test

npm ci
npm test

If tests fail for missing secrets, paste the error back: These tests failed on a clean clone. Which env vars are required? Do not weaken tests.

Then ask for three small improvements and approve one (see Quick Start). Review the diff and rerun the same tests.

Done when:

#Example 2: Multi-file feature with Plan Mode

Goal: Add a read-only /health (or equivalent) endpoint that does not touch auth, plus a test in the repo’s style.

Setup: Pick an app that already has an HTTP layer (Express, FastAPI, Rails, Go net/http, …). Create a branch:

git checkout -b practice/health-endpoint

Shift+Tab into Plan Mode and send:

Add a public health endpoint that returns JSON { "ok": true }.

Constraints:
- Reuse the existing HTTP stack and folder layout
- Do not change authentication or existing routes
- Do not add dependencies
- Follow existing test style

Research the repo, ask clarifying questions, and write a plan that lists
every file, the test command, and rollback. Do not edit files until I approve.

Review the plan:

1. Files are only the route + test (plus whatever register the framework requires)?
2. The test command already exists?
3. No “refactor while we are here”?

Save to workspace, e.g. docs/plans/health-endpoint.md. Approve the build. Afterward:

Run only the commands listed in the plan. Paste stdout and exit codes.
If a check failed, fix it without expanding scope.

Run them yourself too. If the implementation drifted: restore a checkpoint or git restore ., tighten the plan, build again (see Plan Mode).

Done when:

PowerShell probe (change the port):

Invoke-RestMethod http://127.0.0.1:3000/health

curl -s http://127.0.0.1:3000/health

#Example 3: Team workflow with MCP + rules

Goal: A new teammate (or future you) clones the repo and Agent already follows the same norms, plus one MCP server they can call safely.

3a. Check in rules and shared instructions

At the repo root:

New-Item -ItemType Directory -Force -Path .cursor\rules, docs\plans | Out-Null

mkdir -p .cursor/rules docs/plans

.cursor/rules/team.mdc:

---
alwaysApply: true
---

- Read AGENTS.md before the first edit in a session
- Do not add dependencies without asking
- Never commit `.env`, credentials, or `mcp.json` secrets
- Prefer Plan Mode when a task will touch more than five files

Root AGENTS.md:

# Agent instructions

- Install: use the commands already documented in README
- Test: use the existing script (do not invent a new runner)
- Public API changes require a plan saved under docs/plans/

Commit those files. Start a new Agent chat and say: Add lodash for a one-liner. A well-ruled agent should refuse or ask first.

3b. Project MCP (no secrets in Git)

Commit a secret-free server in .cursor/mcp.json. Tokens go through ${env:NAME}. Shape only—replace with a real, reviewed server:

{
  "mcpServers": {
    "docs": {
      "command": "npx",
      "args": ["-y", "mcp-server"],
      "env": {
        "API_KEY": "${env:API_KEY}"
      }
    }
  }
}

Interpolation and transports: MCP. Protocol depth: MCP course.

Enable the server in Customize; confirm Output → MCP Logs. Then:

Use only the enabled MCP tools to fetch the current issue/doc titled
"<name>". Summarize acceptance criteria. Do not edit product code.
Then draft a Plan Mode plan that implements those criteria with our
AGENTS.md constraints.

3c. Team contract

Done when:

#Anti-patterns

#Next

• Resources
• Workflow with CLI Agents
• Quick Start