# Implementation Plan: Clear Encounter

**Branch**: `023-clear-encounter` | **Date**: 2026-03-09 | **Spec**: [spec.md](./spec.md)
**Input**: Feature specification from `/specs/023-clear-encounter/spec.md`

## Summary

Add a "Clear Encounter" action that removes all combatants and resets round/turn counters with a single confirmed click. Implementation follows the existing domain → application → adapter pattern with a new `clearEncounter` pure function, a use case orchestrator, and a clear button in the TurnNavigation component gated by `window.confirm()`.

## Technical Context

**Language/Version**: TypeScript 5.8 (strict mode, verbatimModuleSyntax)
**Primary Dependencies**: React 19, Tailwind CSS v4, Lucide React (icons)
**Storage**: Browser localStorage (existing adapter, updated to handle empty encounters)
**Testing**: Vitest
**Target Platform**: Web browser (single-page app)
**Project Type**: Web application (monorepo: domain/application/web)
**Performance Goals**: N/A (single synchronous state reset)
**Constraints**: Local-first, single-user MVP
**Scale/Scope**: Single encounter tracker screen

## Constitution Check

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

| Principle | Status | Notes |
|-----------|--------|-------|
| I. Deterministic Domain Core | PASS | `clearEncounter` is a pure function — same input always produces same output. No I/O, randomness, or clocks. |
| II. Layered Architecture | PASS | Domain function → Application use case → React adapter. No layer violations. |
| III. Agent Boundary | N/A | No agent layer involvement. |
| IV. Clarification-First | PASS | No non-trivial assumptions — feature is straightforward. Confirmation UI (browser confirm) is a reasonable default documented in research. |
| V. Escalation Gates | PASS | All work is within spec scope. |
| VI. MVP Baseline Language | PASS | Spec uses "MVP baseline does not include" for undo and encounter history. |
| VII. No Gameplay Rules | PASS | No gameplay mechanics in the plan. |

**Post-Phase 1 re-check**: All gates still pass. The empty encounter bypass of `createEncounter()` is consistent with existing behavior (remove-combatant already produces empty combatant lists). No new layer violations introduced.

## Project Structure

### Documentation (this feature)

```text
specs/023-clear-encounter/
├── 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 (/speckit.tasks command)
```

### Source Code (repository root)

```text
packages/domain/src/
├── clear-encounter.ts           # New: pure clearEncounter function
├── events.ts                    # Modified: add EncounterCleared event
├── index.ts                     # Modified: export clearEncounter + event
└── __tests__/
    └── clear-encounter.test.ts  # New: domain function tests

packages/application/src/
├── clear-encounter-use-case.ts  # New: use case orchestrator
└── index.ts                     # Modified: export use case

apps/web/src/
├── hooks/
│   └── use-encounter.ts         # Modified: add clearEncounter callback
├── persistence/
│   └── encounter-storage.ts     # Modified: handle empty encounter in load
├── components/
│   └── turn-navigation.tsx      # Modified: add clear button
└── App.tsx                      # Modified: wire clearEncounter prop
```

**Structure Decision**: Follows existing monorepo layout with strict domain → application → web layering. No new packages or directories needed. Three new files, six modified files.