First Verifiable Vertical Slice

These examples and illustrative results are independently authored teaching materials, not measured model results.

Use case

An MVP accepts, stores and displays requests, with request-a and invalid-input behavior specified. Deliver this one complete path before implementing all models/views and discovering disconnected contracts.

Mechanism

Read locked scope/shared architecture, select a narrow complete input→persist→display/error path and define demonstrable acceptance. Verify integration before another type. Small slicing limits business paths rather than removing necessary states.

Bad example

Build every model, every storage layer and every view before attempting submission, without checking invalid input.

Good example

Implement teaching request-a submission→persistence→status. Verify identity-matched readback, invalid feedback and no false success on storage failure. Preserve architectural decisions/artifacts/check records and demonstrate the first path before other types, without inventing product behavior.

Why the change matters

A complete path exposes interface/error propagation early while scope is bounded. Required states remain complete and later expansion has a verified integration point.

Observable expectation

The illustrative checks cover valid, invalid and storage failure with matching request identity. Fill pass records only from actual runs. A page or model alone is not end-to-end completion.

Retain first-slice evidence before the second; no real MVP is built here.

Limits

Follow the spec; trial runs establish neither capacity nor production deployment/privacy. Shared setup may precede slicing. Source GAN scores/tools/commit choices are not universal prerequisites.