Skip to main content

0029. Parent broadcast conformance stops before narrowing

Status: Accepted · 2026-08-12 · #269 Governed by: 0000, 0019

TL;DR Dynamic parent behavior shared by Socket.IO 4.7.5 and 4.8.3 is conformance, including direct parent broadcasts. Narrowed parent broadcasts remain outside that claim because the supported versions disagree; Smocket does not reproduce the 4.8.3 TypeError.

Decision​

Socket.IO 4.7.5 and 4.8.3 agree that a direct parent emit reaches the current concrete child namespaces, while each child keeps its own rooms, adapter, sockets, and lifecycle. Smocket will reproduce and publish that common behavior together with concrete-child routing.

The supported versions disagree after a parent broadcast is narrowed. In 4.7.5, parent.to(room).emit(...) routes across matching children. In 4.8.3, the released in-memory parent adapter throws a TypeError because its child collection is not wired into the narrowed broadcast adapter.

Smocket will not reproduce that TypeError: it is not common supported-version behavior and does not describe a useful delivery rule. Smocket also will not select the 4.7.5 result as conformance while 4.8.3 disagrees. Narrowed parent broadcasts therefore stay outside the published conformance claim until the supported real versions converge or a later decision intentionally selects a result.

This boundary is about the parent operation only. Room routing on every concrete child remains ordinary conformance. Under [0019], adding the common dynamic parent surface is a minor after v1 and a patch before v1.

Alternatives rejected​

  • Reproduce the 4.8.3 TypeError. One supported version does not throw, and encoding an adapter wiring defect would make the mock less useful without a stable fidelity source.
  • Select the 4.7.5 narrowed routing result now. It is coherent, but publishing it as conformance would overstate agreement across the supported versions.
  • Exclude all parent broadcasts. Direct parent broadcast behavior agrees and is observable, so excluding it would leave verified surface unimplemented.