Restructure response envelopes architecture: split ADR from spec, add Value.Cast composability, document implementation gaps
- Split monolithic 680-line response-envelopes.md into focused ADR-005
(decisions/005-response-envelopes.md, 152 lines) and specification
(response-envelopes.md, 441 lines)
- ADR-005: consolidate 10 inline ADRs into coherent decision record with
rationale for data+meta envelope shape, handler responsibility shift,
string discriminant detection, and composability analysis
- Spec: types, factory functions, integration points, constraints, migration
checklist, and open questions
- Add MCP outputSchema extraction (2025-06-18+ spec) with FromSchema
conversion and<Value.Cast()> normalization for structuredContent
- Add current-source-vs-spec implementation gap tables to registry, call,
mcp adapter, and openapi adapter integration points
- Update adapters.md: from_mcp outputSchema extraction, structuredContent
handling, isError non-throw behavior, Value.Cast() for data normalization
- Add open questions: serving directionality, JSON.stringify in MCP content,
outputSchema extraction completeness, respond() visibility
- Note: existing call-protocol.md and api-surface.md describe pre-envelope
behavior; this spec supersedes them until updated per migration checklist