Targeted feature slices in an existing codebase

Case study in full

Example scenario

Stack profile: typescript-node-20-express · Example scenario with typical orders of magnitude.

An existing application gains one clearly scoped story, such as an additional API field with validation and persistence. The codebase is too large to load into a prompt. The run therefore works portion by portion: each slice gets exactly the context it needs and leaves its commit.

What stays with your team: You write and prioritise the story. You approve the plan before execution, and the merge stays with you.

What you need

• A tracker connected to the repository, holding the story.
• A stack profile with language, framework and layering of the existing code.
• Guardrails for the existing conventions: naming, layer boundaries, test obligation.
• Approval of the plan by a project member.

How the run works

1. The story is read from the tracker and broken down into a plan with individual slices.
2. Each slice works on one bounded portion of the codebase.
3. Implementation and validation run per slice, with tests for the new code path.
4. A slice that fails its check is reworked before it flows into the overall state.
5. The result arrives as a pull request in your repository, linked to the story.

What you get

• New and changed files per slice, readable in the commit history.
• Tests run and their status documented per slice.
• One pull request referencing the story in the tracker.
• Clear feedback on whether the change was accepted or needs another round.

Key figures

What stayed open

Nothing open.