# Phase 86: Schema Tree Doc Boundary - Context

**Gathered:** 2026-04-11
**Status:** Implemented and verified
**Mode:** Second implementation phase for `v1.51`

<domain>
## Phase Boundary

Continue `v1.51` by documenting the root-versus-runtime schema-tree boundary
so future contract additions do not drift silently.

</domain>

<decisions>
## Implementation Decisions

### Locked decisions

- publish one README in each schema tree rather than burying the rule in code
- update `docs/architecture.md` so the boundary is visible from the main design
  doc
- keep the wording explicit enough for tests to guard against future ambiguity

</decisions>

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*Phase: 86-schema-tree-doc-boundary*
*Context captured on 2026-04-11 after Phase 86 implementation and verification*
