Reference

What the 17 URN evaluators check

src/control/compatibility.ts was rewritten on top of a new pure-function module src/control/constraint-sets.ts.

• OR-of-AND semantics. A receiver is compatible iff ∃ constraint_set such that ∀ URN-constraints inside are satisfied (BCP-004-01 v1.0.0).
• 17 URN evaluators. Format: media_type, grain_rate, frame_width, frame_height, interlace_mode, colorspace, transfer_characteristic, color_sampling, component_depth, channel_count, sample_rate, sample_depth, event_type. Transport: packet_time, max_packet_time, packet_transmission_mode, st2110_21_sender_type.
• Meta URNs honoured. meta:enabled=false sets are skipped. meta:preference resolves ties and surfaces in matched_preference.
• Rationals. grain_rate, sample_rate use {numerator, denominator}; equality via float comparison after reduction.
• Vendor extensions skipped silently. Phase 3 doesn't fail on urn:x-acme:cap:*; it skips them — vendors retain control over their own constraint URNs.
• Sender parameter merging precedence: IS-11 constraints_active → SDP fmtp (authoritative for TP=2110TPN/TPNL/TPW, packet_time, PM=2110GPM/BPM) → Flow JSON (authoritative for media_type, frame_*, colorspace, grain_rate, interlace_mode) → NmosSource.channels.length → channel_count for audio.
• Back-compat. Receivers without constraint_sets fall back to the original v1 format/transport/media_type behavior. All 7 pre-existing compatibility tests still pass.
• New issue code: constraint_set_no_match (error) with per-set failure detail in the message.

How batch_connect atomic mode unwinds

1. Before any mutation, the handler captures each receiver's prior subscription.sender_id via getConnectionStatus(). The snapshot is persisted to the audit journal as a record with kind: 'batch_snapshot'.
2. If snapshot capture fails for any receiver, the batch aborts before mutation. Atomicity is preserved.
3. On mid-batch failure, the restore loop iterates over 'ok' items in reverse:
   • prior_sender_id === null → disconnect → status rolled_back.
   • prior_sender_id !== null → reconnect to prior sender → status restored.
   • Compatibility error during restore → restore_failed_compat (likely the prior sender was removed mid-batch).
   • Other restore error → restore_failed.
4. New tool aurora_replay_snapshot(snapshot_id, dry_run?) lets an operator replay a captured snapshot manually — useful after an Aurora crash.
5. aurora_audit_recent accepts a kind filter to find snapshots.
6. Dry-run batches return the snapshot in the response but do not journal it.
7. AuditRecord.kind is optional and defaults to 'route' on read for backward compatibility with pre-Phase-3 journal files on disk.

What's read-only, why, and what's in Phase 4

SofieEmberPlusProvider wraps emberplus-connection@0.3.1 (NRK Sofie, MIT-licensed, field-tested against Lawo Ruby/R3lay/MxGUI). It implements the same EmberTreeProvider interface as InProcessEmberTreeProvider, so swapping providers is a single-file change.

• Transitive git-URL dependency. emberplus-connection pulls asn1 from evs-broadcast/node-asn1 via GitHub URL rather than npm. Mitigations: .npmrc ignore-scripts=true neutralizes install-script risk, pnpm-lock.yaml pins the commit SHA, dep-guard pre-commit hook validates other dependencies as usual. Recommended Phase 4 follow-up: in-house s101/BER stack (~1500–2000 LOC) replacing the package entirely.
• Vendor SemanticHintRules are best-effort starters. Derived from public docs + the Sofie production codebase, not from live device captures. Production tuning needs at least one bench capture per vendor. Default rulesets ship for Lawo, Calrec, Studer, Grass Valley, and a generic fallback.
• Writes are feature-flagged off. Phase 3 ships read-only Ember+ support. Matrix writes require protocol-specific verification semantics (Lawo surface arbitration overrides Ember+ writes silently; GV NP0017 has User-ID Lock/Protect/Release that must be acquired before any GV write). These land in Phase 4.
• Multi-source matrix handling planned, not implemented. When real Ember+ matrices report nToOne or nToN types, the spec'd plan is to synthesise a primary-source NMOS receiver and expose the full source set in an aurora_additional_sources[] extension.