nx_emitted_substrate.nx

nx_emitted_substrate.nx -- Phase 5 (Reproduce) substrate emission. Closes the ecosystem evolution lifecycle: a mature substrate (Phase 4 seed-ready) emits a SIGNED expected-blob-set that downstream devices consume in Phase 2 (Network) via nx_substrate_manifest_ingest. Per NISHI_ECOSYSTEM_EVOLUTION_ROADMAP.md Phase 5: Mature -> nx_emitted_substrate_sign(record, operator_priv) -> transport (sneakernet / USB / serial / HTTPS / spore) -> Downstream receiver verifies sig + populates its nx_substrate_manifest from the record -> Ingests blobs via nx_substrate_manifest_ingest until is_complete The record is the DECLARATION; the bytes-on-wire transport is transport-agnostic (the same record content goes over any medium). Bytes-identical canonical serialization means the signature works across any transport. Defends against: - Adversary in the middle who replaces an expected hash -> signature verification fails (downstream refuses ingest) - Adversary who substitutes the emitter's identity -> install_hash mismatch caught when downstream cross-checks against the operator's known good install_hashes - Stale spore replay -> ts_emit_us in canonical bytes; if paired with a freshness window, replays caught V1 scope: - Up to NX_EMIT_MAX_EXPECTED = 16 expected hashes inline - Single Ed25519 signature (threshold queued for SA-7) - Canonical serialization same shape as nx_install_plan (magic tag + LE i64 fields + length-prefixed hash array) - Round-trip from record into a fresh NxSubstrateManifest Deferred: - Larger N>16 (composes with Merkle root rather than flat set) - Multi-signature (threshold / N-of-M peers must co-sign) - Post-quantum migration (Ed25519 -> ML-DSA queued)