realtime.signals

Chirpsignal()— the declare-once / bind-many live-value primitive.

A signal is a server-owned named value, declared once, that fans out over a single shared SSE connection to every template binding that listens for it. {{ signal('balance') }} in the topbar and {{ signal('balance') }}in a modal both swap together from one update on the wire — a cardinality plain OOB cannot express. Htmx 2 uses a named event; htmx 4 uses one targeted partial whose data-chirp-signalselector matches every sink.

This module is the framework substrate behind the public@app.signal/ @app.derived / app.emit surface and the signal() / signal_block() /signal_connect()template globals. It is intentionally a thin layer over existing transport:

• The private signal update remains client-neutral until the SSE response boundary chooses the frozen htmx 2 or htmx 4 dialect.

• ReactiveBusprovides the free-threaded (threading.Lock + per-subscriber asyncio.Queue + call_soon_threadsafe

  • bounded back-pressure) fan-out. Here the bus scope is the signal name.

  Free-threading (3.14t):SignalSpec / DerivedSpecare frozen/slots; the registry's mutable maps + value cache are guarded by a singlethreading.Lock (mirroring OOBRegistry). Cross-thread emits ride the bus'scall_soon_threadsafedelivery path, so a sync-mode producer can app.emit(...)safely.