implementing-feature

# Implementing feature

Implement a feature from a specification document, from reading the spec through to a merge-ready PR.

## Usage examples

Use by pointing to a spec folder:
```
/implementing-feature specs/2025-12-12-menu-button
```

Or with a URL to a raw document:
```
/implementing-feature https://raw.githubusercontent.com/streamlit/streamlit/refs/heads/develop/specs/2025-12-12-menu-button/product-spec.md
```

Or with a GitHub issue (feature request as spec):
```
/implementing-feature https://github.com/streamlit/streamlit/issues/12345
```

## When to use

- You have a spec folder, URL, or GitHub issue to implement
- You want end-to-end implementation: spec → code → tests → PR
- You want a guided workflow that ensures all implementation steps are followed

## Workflow

Copy this checklist and track your progress:

```
Progress:
- [ ] Phase 1: Read and understand the spec
- [ ] Phase 2: Research and plan
- [ ] Phase 3: Implement and test
- [ ] Phase 4: Verify against spec
- [ ] Phase 5: Finalize for merge
```

### Phase 1: Read and understand the spec

- If given a folder path (e.g., `specs/YYYY-MM-DD-feature-name`):
  - Read all files in the folder (specs, images, code samples)
- If given a URL to a raw document:
  - Fetch the spec content directly from the URL
- If given a GitHub issue URL:
  - Use the `gh` client to read the issue and all comments
  - Treat the issue description and discussion as the feature specification

### Phase 2: Research and plan

- Search for similar existing features to follow patterns
- Use the /understanding-streamlit-architecture skill to understand relevant internals
- If there is technical complexity, write a tech-spec / implementation plan in `work-tmp/`

### Phase 3: Implement and test

- Implement the feature based on the provided spec. Read `wiki/new-feature-guide.md` for tips.
- Run `make protobuf` after any protobuf changes
- Add unit tests (Python in `lib/tests/`, frontend co-located) and E2E tests in `e2e_playwright/`
- Use the /debugging-streamlit skill to test and debug backend, frontend, and UI

### Phase 4: Verify against spec

- Re-read the spec to verify all requirements are met; document any necessary divergences in `work-tmp/`

### Phase 5: Finalize for merge

- Run /finalizing-pr skill to execute quality checks, create the PR, and make it merge-ready
- Follow all steps until the PR is merge-ready

## Important notes

- **Be fully autonomous** - Do NOT stop or pause to ask for confirmation. You are tasked to go from spec to merge-ready PR without human intervention. Note any open questions or ambiguities in the PR description rather than blocking on them.
- **Follow Streamlit patterns** - Check existing similar features for conventions
- **Reference the spec in PR** - Include spec link in PR description
- **Test thoroughly** - Use /debugging-streamlit before finalizing
- **Commit incrementally** - Make logical commits as you implement each phase