# Implementation Plan: Quick HP Input

**Branch**: `011-quick-hp-input` | **Date**: 2026-03-05 | **Spec**: [spec.md](./spec.md)
**Input**: Feature specification from `/specs/011-quick-hp-input/spec.md`

## Summary

Add an always-visible inline quick HP input per combatant that allows the game master to type a damage or healing number and immediately apply it as a delta to current HP. The domain layer already provides `adjustHp(encounter, combatantId, delta)` with full clamping logic, so no domain or application changes are needed. This is a UI-only feature: a new `QuickHpInput` component in the web adapter layer with damage/heal mode toggle, keyboard-driven workflow, and clear visual distinction between modes.

## Technical Context

**Language/Version**: TypeScript 5.8 (strict mode, verbatimModuleSyntax)
**Primary Dependencies**: React 19, Vite 6, Tailwind CSS v4, shadcn/ui-style components, Lucide React (icons)
**Storage**: N/A (no storage changes -- existing localStorage persistence handles HP via `adjustHpUseCase`)
**Testing**: Vitest (domain pure-function tests); UI component tested via existing patterns
**Target Platform**: Browser (single-user, local-first)
**Project Type**: Web application (monorepo: packages/domain, packages/application, apps/web)
**Performance Goals**: N/A (single-user, instant local state updates)
**Constraints**: Must follow layered architecture (domain -> application -> adapters); UI-only changes in apps/web
**Scale/Scope**: Single combatant row component enhancement

## Constitution Check

*GATE: Must pass before Phase 0 research. Re-check after Phase 1 design.*

| Principle | Status | Notes |
|-----------|--------|-------|
| I. Deterministic Domain Core | PASS | No domain changes. Existing `adjustHp` is a pure function. |
| II. Layered Architecture | PASS | All changes are in the adapter layer (apps/web). Domain and application layers unchanged. |
| III. Agent Boundary | N/A | No agent features involved. |
| IV. Clarification-First | PASS | Clarifications completed in spec (visibility model, direct entry coexistence). |
| V. Escalation Gates | PASS | All requirements are in the spec. |
| VI. MVP Baseline Language | PASS | Exclusions use "MVP baseline does not include" phrasing. |
| VII. No Gameplay Rules | PASS | No gameplay mechanics in constitution. |

## Project Structure

### Documentation (this feature)

```text
specs/011-quick-hp-input/
├── spec.md
├── plan.md              # This file
├── research.md          # Phase 0 output
├── data-model.md        # Phase 1 output
├── quickstart.md        # Phase 1 output
└── tasks.md             # Phase 2 output (via /speckit.tasks)
```

### Source Code (repository root)

```text
apps/web/src/
├── components/
│   ├── combatant-row.tsx          # Modified: integrate QuickHpInput
│   ├── quick-hp-input.tsx         # NEW: inline damage/heal input component
│   └── ui/
│       ├── button.tsx             # Existing (may use for toggle)
│       └── input.tsx              # Existing (base input styling)
├── hooks/
│   └── use-encounter.ts           # Unchanged (adjustHp already exposed)
└── App.tsx                        # Unchanged (props already passed through)

packages/domain/src/
├── adjust-hp.ts                   # Unchanged (already supports +/- deltas)
├── set-hp.ts                      # Unchanged
├── types.ts                       # Unchanged
└── __tests__/
    └── adjust-hp.test.ts          # Unchanged (domain logic covered)

packages/application/src/
├── adjust-hp-use-case.ts          # Unchanged
└── ports.ts                       # Unchanged
```

**Structure Decision**: UI-only change. Single new component (`quick-hp-input.tsx`) added to the existing component directory. `combatant-row.tsx` modified to integrate it alongside the existing direct HP entry. No new directories needed.

## Complexity Tracking

No violations to justify. All changes are within the existing adapter layer, using established patterns.