generated from coulomb/repo-seed
Headless, API-first, agent-optimized native engine = canonical-mode shard backend. Thesis: a page-store kernel with a typed-extension runtime; everything beyond the c2-minimum is a typed extension activated per shard, and the shard's §A capability profile is DERIVED from its active extensions (configuration->capability->conformance). 9 engine invariants (engine-is-one-shard, small kernel, per-shard activation, profile-from-extensions, headless/agent-first, reuse-not-reinvent, typed+verified). Kernel (4 concepts), typed-extension model (typed hooks + deterministic composition + feature-control activation), T2 featureset/conflict-mediation realized, engine-as-shard, agent-first API surface, module sketch, reuse (consumes feature-control/authorization; G1 framework proposal), traceability, decisions/open, stability note. Marks T5 done. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>