new-increment

name	new-increment
description	Deliver one releasable increment from increments/<feature>.md — strict TDD by default (one test-lists/<feature>.md, unit tests). ATDD only when a real outer seam exists (API/UI/contract). One increment per invocation; RED before GREEN; all project verify steps green before done; commit then stop. Not for whole-feature planning (skills/new-feature).
allowed-tools	Read, Edit, MultiEdit, Bash, Grep, Glob

New increment (one slice)

Mission

Implement exactly one open line from increments/<feature-stem>.md.

Default: skills/tdd/SKILL.md only — unit (or narrow integration) tests, behaviors tracked in one test-lists/<feature-stem>.md (section per increment).

When a real outer seam exists: compose skills/atdd/SKILL.md at that boundary, then TDD inside. Never duplicate the same assertions in acceptance and unit layers.

Always: complete test strategy before first RED; run all applicable verify steps; leave the suite green; commit; mark the parent backlog line [x]; stop. Never start the next backlog line — even if the user asked for the whole feature (that is new-feature automatic mode).

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Workflow

Shared delivery rules: docs/delivery-process.md and docs/project-verification.md.

1. Lock scope to one [ ] backlog line; branch e.g. feat/<feature>-<increment-slug>.
2. Test strategy — test-strategy-selection.md: discover configured jobs; complete adopt/skip table before first RED (checklists/test-strategy.md). On greenfield, introduce mutation (and other warranted practices) when characterization says adopt and the introduce-tooling threshold is met — do not wait to be asked; teaching/kata may skip with an explicit reason.
3. Discover project verification for the language/module you will touch (§2; project-verification.md) — README, CI, scripts, Makefile, Sonar, mutation config; do not assume one command.
4. Choose layer — references/scoped-atdd-tdd.md (TDD-only vs ATDD+TDD; Gherkin only when Distill needs it).
5. Artifacts — references/artifact-policy.md: one feature test list; no per-increment markdown sprawl.
6. RED → GREEN → REFACTOR per behavior; one failing check at a time; re-run affected tests after every edit; run adopted practices (mutation, integration, contract, etc.) at slice boundary.
7. If construction/import/API changed, search and update all call sites in scope (§3).
8. Update parent increments/… to [x] with link to test list section (and acceptance section if used) — only after verification is fully green.
9. Cleanup redundant slice-only markdown if created by mistake.
10. Run all applicable project verify steps (tests, lint, format, typecheck, SonarQube, mutation job if adopted); none may be skipped because another already passed (§2). If any step is red → fix; do not stop as done.
11. Commit — ensure this increment’s work is committed (follow skills/tdd micro-commits + squash per cycle; leave a clean committed tip). Include commit SHAs in the return payload. AMPD agents: commit is part of done. Outside AMPD delivery workflows, follow the user’s git policy.
12. Return payload (§10) including test strategy table and verification table; stop — do not start the next increment.

Prep if needed: skills/legacy-testing (invalid harness), skills/refactoring, skills/spike — then resume.

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Definition of done

• One backlog line only; test strategy table completed before first RED (test-strategy-selection.md)
• All project verify steps for this scope passed (§2; project-verification.md) — including adopted practices (mutation, contract, integration, etc.)
• Hard green gate: no applicable verify step left red
• Work committed; no uncommitted slice leftovers presented as done
• RED observed before each production change (see scoped reference)
• Test list lines [x] only with passing checks referenced
• No duplicate acceptance + unit tests for the same behavior
• Change-surface complete if APIs/seams changed (§3)
• Parent increment line [x]
• No behavior from future increments
• Return payload delivered (§10); stopped (next line is new-feature’s decision)

Checklist: checklists/increment-done.md, checklists/test-strategy.md.

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Anti-patterns

• Implementing multiple backlog lines in one session (even under “automatic” feature mode)
• Stopping with failing tests or unverified adopted practices
• Leaving the increment uncommitted when claiming done
• acceptance-examples/ + unit tests with identical assertions (documentation theater)
• Per-increment test-lists/<slice>.md files (use one feature file)
• Marking [x] on markdown before tests exist or fail
• Writing full test files and full production in one step
• Skipping mutation on greenfield branchy domain with only “not configured” when the introduce-tooling threshold is met
• Forcing mutation tooling into teaching/kata slices or when setup clearly dominates the slice
• Batch message: “implementing increments 2–7”

See references/anti-patterns.md.

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Additional resources

• docs/delivery-process.md
• docs/test-strategy-selection.md
• references/scoped-atdd-tdd.md
• references/artifact-policy.md
• references/anti-patterns.md