Phase 3 foundation (docs §3): env-filtered, proximity-first config
inheritance down the group tree.
- Migration 0048: `vars` (polymorphic group|app owner via two nullable FKs
+ CHECK exactly-one, env scope, JSONB value, explicit tombstone) +
`apps.environment` (the env marker the resolver filters on — 'an
environment is an app').
- config_resolver: a shared chain-walk CTE (mirrors effective_app_role) that
walks app → ancestor groups, env-filters in SQL, plus a pure Rust
resolution pass implementing the §3 semantics SQL can't — per-key
proximity-first, @E-over-* within a level, map deep-merge, tombstone
suppression, and provenance for --explain.
Verified: 8 unit tests (incl. the §3.2 proximity-beats-env-specificity call,
deep-merge, tombstone, boundary) + the candidate-fetch CTE against live
Postgres (env-filter drops a non-matching @production value; nearer level
shadows farther).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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