incremental-implementation

Incremental Implementation

Deliver changes in thin, verifiable increments—one working slice at a time. Never write an entire multi-file feature in a single unverified pass.

Core Rule

One slice, one verification cycle. Do not start the next slice while the current slice has failing tests, type errors, or a broken build.

When to Apply

• Executing steps from workflow/PLAN.md or tasks from workflow/TASKS.md.
• Any change touching two or more files or exceeding ~100 lines of code.
• Refactoring existing modules where behavior must remain intact at every step.

The Increment Loop

For each step in workflow/PLAN.md (or task in workflow/TASKS.md):

1. Scope the Slice: Pick the smallest cohesive unit that delivers testable progress toward workflow/SPEC.md.
2. Implement Minimally: Write only the code required for this slice—avoid speculative scaffolding for future slices.
3. Test & Verify Immediately: Run targeted unit/integration tests, typecheck, and linter to confirm the slice works and introduces no regressions.
4. Checkpoint: Update status in workflow/PLAN.md or workflow/TASKS.md (e.g., mark done), and create a clean commit/checkpoint when appropriate so rollback is effortless.
5. Repeat: Advance to the next slice only after the current one is green.

Slicing Strategies

Choose the slicing strategy that best fits the work:

• Vertical Slices (Default): Implement one thin end-to-end capability across layers (e.g., schema -> service -> endpoint -> test) rather than building all backend files first and all frontend/test files last.
• Risk-First Slicing: Tackle the highest-uncertainty assumption, integration, or performance bottleneck in the earliest slice so surprises surface immediately.
• Contract-First Slicing: Define types, interfaces, and test assertions first, verify they compile/fail as expected, then implement the concrete behavior.

Guardrails

• No stacked brokenness: Fix failing checks in the current slice before moving on.
• Keep diffs reviewable: If a slice grows too large, split it into smaller sub-slices before continuing.
• Stay aligned with SPEC.md: Do not add unrequested features while implementing a slice.