Three post-E1/E2/E3-merge items:
1. Schema amendment A-1 (architect P0-a, non-breaking clarification):
input.schema and output.schema are REQUIRED for all atom kinds. The
shared kei-atom-discovery parses them as Option<PathBuf> only to allow
tolerant skip-on-missing (stderr warn), not to permit absent schemas.
Resolves Stream C / Stream D enforcement asymmetry documented in
critic finding #6.
2. Cross-stream integration test (architect P0-b): tests/substrate_integration.sh
builds release binaries, scaffolds a test atom corpus, runs
schema-lint + list-atoms + atoms-discover + invoke; asserts all four
streams agree on the same atom corpus and exit codes honour the
locked §Runtime contract. Previously missing — only manual smoke
checks existed.
3. Fix regression introduced by E1's jsonschema 0.18 upgrade:
"relative URL without a base" on compile when schema declared a
relative $id like "kei-task/atoms/schemas/create-input.json".
validate.rs now synthesises an absolute file:// $id from the
canonicalised schema path before compile. Internal $refs still
resolve relative to the schema file; LocalFileResolver still confines
to the schema's parent dir. Integration test catches this.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
