# ADR 008 — Complete Phase 0 Before Detailed Build Planning

**Status:** Accepted and completed

## Decision

The project completed repository research, validation, architecture selection, and critical prototypes before finalizing the detailed production implementation milestone plan.

## Context

Multiple candidate open-source projects implemented overlapping parts of the desired system. The correct build sequence depended on which codebase survived local validation.

## Alternatives Considered

- write full implementation plan immediately,
- begin coding against the first plausible project,
- perform a bounded Phase 0 and then finalize the build plan.

## Reason

The bounded Phase 0 prevented false assumptions from becoming production architecture. In particular, runtime testing discovered destructive AI-DnD Undo, an offline tokenizer fetch, remote fonts, Open Dungeon's lack of tests and destructive summary/history assumptions, and the relative-delta state-protocol failure mode.

## Completion Record

Phase 0 selected AI-DnD as the production base, validated the non-destructive head-cursor approach, selected explicit typed narrative-state events, established local-only hardening requirements, and produced the production `BUILD-MILESTONES.md`.

## Consequences

- the placeholder build plan has been replaced by a production milestone sequence,
- `SPECIFICATION.md` and `TECHNICAL-DESIGN.md` are the v1.0 planning baseline,
- production coding still requires explicit authorization and a milestone-specific prompt,
- the current review intentionally stops before preparing that prompt.