0170 — New mechanics compose existing owners

Decision

New cross-cutting mechanics attach to the layer that already owns the fact:

• a socket registry receives an already authenticated RealtimeServer and owns membership, authorized room tokens, replay buffering and cleanup;
• application error vocabularies extend defineErrors and feed the existing error hook;
• endpoint dimensions use an explicit typed projector into request context;
• bounded logging extends the existing sanitizer and decorates StitchLogger.

We reject a second contract DSL, a server use plugin system, namespace export objects and duplicate release/tracking names. Client trace and release hooks remain fields of the existing HTTP client configuration.

Why

Authentication, validated realtime emission, error construction, request context and redaction already have one implementation each. A parallel helper would create two security or semantics paths. The proposed syntax layers also did not remove information: path-parameter inference did, and is recorded in ADR 0168.

Consequences

• The registry cannot authenticate or invent event validation; it composes the server already in use.
• Replay is revision-aware and can request resynchronization rather than emit a stale snapshot after buffered changes.
• Caller fields cannot overwrite framework context, and redaction precedes truncation.
• Existing release and tracking names remain canonical; no aliases are added.