Replace the config push mechanism that broadcast the full config
blob on a 'state' class pub/sub queue with a lightweight notify
signal containing only the version number and affected config
types. Processors fetch the full config via request/response from
the config service when notified.
This eliminates the need for the pub/sub 'state' queue class and
stateful pub/sub services entirely. The config push queue moves
from 'state' to 'flow' class — a simple transient signal rather
than a retained message. This solves the RabbitMQ
late-subscriber problem where restarting processes never received
the current config because their fresh queue had no historical
messages.
Key changes:
- ConfigPush schema: config dict replaced with types list
- Subscribe-then-fetch startup with retry: processors subscribe
to notify queue, fetch config via request/response, then
process buffered notifies with version comparison to avoid race
conditions
- register_config_handler() accepts optional types parameter so
handlers only fire when their config types change
- Short-lived config request/response clients to avoid subscriber
contention on non-persistent response topics
- Config service passes affected types through put/delete/flow
operations
- Gateway ConfigReceiver rewritten with same notify pattern and
retry loop
Tests updated
New tests:
- register_config_handler: without types, with types, multiple
types, multiple handlers
- on_config_notify: old/same version skipped, irrelevant types
skipped (version still updated), relevant type triggers fetch,
handler without types always called, mixed handler filtering,
empty types invokes all, fetch failure handled gracefully
- fetch_config: returns config+version, raises on error response,
stops client even on exception
- fetch_and_apply_config: applies to all handlers on startup,
retries on failure
Adds a RabbitMQ backend as an alternative to Pulsar, selectable via
PUBSUB_BACKEND=rabbitmq. Both backends implement the same PubSubBackend
protocol — no application code changes needed to switch.
RabbitMQ topology:
- Single topic exchange per topicspace (e.g. 'tg')
- Routing key derived from queue class and topic name
- Shared consumers: named queue bound to exchange (competing, round-robin)
- Exclusive consumers: anonymous auto-delete queue (broadcast, each gets
every message). Used by Subscriber and config push consumer.
- Thread-local producer connections (pika is not thread-safe)
- Push-based consumption via basic_consume with process_data_events
for heartbeat processing
Consumer model changes:
- Consumer class creates one backend consumer per concurrent task
(required for pika thread safety, harmless for Pulsar)
- Consumer class accepts consumer_type parameter
- Subscriber passes consumer_type='exclusive' for broadcast semantics
- Config push consumer uses consumer_type='exclusive' so every
processor instance receives config updates
- handle_one_from_queue receives consumer as parameter for correct
per-connection ack/nack
LibrarianClient:
- New shared client class replacing duplicated librarian request-response
code across 6+ services (chunking, decoders, RAG, etc.)
- Uses stream-document instead of get-document-content for fetching
document content in 1MB chunks (avoids broker message size limits)
- Standalone object (self.librarian = LibrarianClient(...)) not a mixin
- get-document-content marked deprecated in schema and OpenAPI spec
Serialisation:
- Extracted dataclass_to_dict/dict_to_dataclass to shared
serialization.py (used by both Pulsar and RabbitMQ backends)
Librarian queues:
- Changed from flow class (persistent) back to request/response class
now that stream-document eliminates large single messages
- API upload chunk size reduced from 5MB to 3MB to stay under broker
limits after base64 encoding
Factory and CLI:
- get_pubsub() handles 'rabbitmq' backend with RabbitMQ connection params
- add_pubsub_args() includes RabbitMQ options (host, port, credentials)
- add_pubsub_args(standalone=True) defaults to localhost for CLI tools
- init_trustgraph skips Pulsar admin setup for non-Pulsar backends
- tg-dump-queues and tg-monitor-prompts use backend abstraction
- BaseClient and ConfigClient accept generic pubsub config
Remove Pulsar-specific concepts from application code so that
the pub/sub backend is swappable via configuration.
Rename translators:
- to_pulsar/from_pulsar → decode/encode across all translator
classes, dispatch handlers, and tests (55+ files)
- from_response_with_completion → encode_with_completion
- Remove pulsar.schema.Record from translator base class
Queue naming (CLASS:TOPICSPACE:TOPIC):
- Replace topic() helper with queue() using new format:
flow:tg:name, request:tg:name, response:tg:name, state:tg:name
- Queue class implies persistence/TTL (no QoS in names)
- Update Pulsar backend map_topic() to parse new format
- Librarian queues use flow class (persistent, for chunking)
- Config push uses state class (persistent, last-value)
- Remove 15 dead topic imports from schema files
- Update init_trustgraph.py namespace: config → state
Confine Pulsar to pulsar_backend.py:
- Delete legacy PulsarClient class from pubsub.py
- Move add_args to add_pubsub_args() with standalone flag
for CLI tools (defaults to localhost)
- PulsarBackendConsumer.receive() catches _pulsar.Timeout,
raises standard TimeoutError
- Remove Pulsar imports from: async_processor, flow_processor,
log_level, all 11 client files, 4 storage writers, gateway
service, gateway config receiver
- Remove log_level/LoggerLevel from client API
- Rewrite tg-monitor-prompts to use backend abstraction
- Update tg-dump-queues to use add_pubsub_args
Also: pubsub-abstraction.md tech spec covering problem statement,
design goals, as-is requirements, candidate broker assessment,
approach, and implementation order.
