ADR-0057: Reserved publishers¶

Status: Accepted Date: 2026-10-12 Deciders: Alex Nodeland

Designs the values of ADR-0039's decision 4, which put reserved publishers on Workspaces, keyed by namespace, with per-type exceptions.

Context¶

Workspaces(emitted=[...]) reserves types to runs, but nothing reserves a type to one publisher (lattice #8, was reflexr #72). Any client allowed to publish could send an event that only a bridge or an integration should.

stackr RFC-0002 bridges artifactr's events into reflexr as artifactr:*, published as SourceActor(name="artifactr"), and rules act on them. One installs rules a person accepted in chat, so a forged artifactr:proposal_resolved must install nothing (phase 5). Until types can be reserved, those rules check the envelope's actor themselves.

ADR-0039 settled where the policy lives and its keys. It left three questions open: what a value names, whether emitted= folds into it, and where the check sits.

Decision¶

• Workspaces(publishers={key: [actor, ...]}). A key is a namespace ("artifactr") or a qualified type ("plans:plan_approved"). A type's entry replaces its namespace's, so an exception can widen or narrow it.
• A value is actors, compared by participant. SourceActor(name="artifactr") is the publisher source:artifactr. Every run of one rule's agent shares a participant (agent:<rule>), so a type can be reserved to a rule's runs. Full equality could never match one: each run has its own run_id.
• Anyone else is forbidden, runs included: "artifactr:proposal_resolved events are reserved to source:artifactr". A rule's agent that emits a bridged type is as much a forgery as a client that publishes one.
• A fixed check beneath authorize, beside the refusal of reflexr:*. publish asks authorize for reflexr:publish first, then checks the type. The hook decides who may publish at all, and the policy decides who may publish a type. grantr can't grant around it. It adds nothing to ACTIONS.
• Keys are checked at startup, as events=, emitted= and rules are. A type or namespace that isn't in the workspaces' registry, or reflexr's, raises ValueError.
• emitted= stays. It reserves a type to whatever a run caused, which is a handle's causation, not an actor's identity. Folding it in would need a "runs" value that is not an actor. The two compose: a type in both must be published by a run of a listed publisher.

Options considered¶

What a value names¶

Where the check sits¶

Folding emitted= in¶

Trade-off analysis¶

Reserving by participant lets one entry cover a source, a system component or a rule's runs, with typed actors as events= and emitted= take typed classes. Putting the check beneath the hook keeps the policy where ADR-0039 put it: the application's code, which alone resolves clients to actors. The cost ADR-0039 named remains. An application that forgets the bridge's entry leaves forging open, so relayr's wiring should pass it.

Consequences¶

• Easier: a bridge's namespace is reserved in one entry, and rules can trust an artifactr:* envelope's actor without checking it themselves.
• Easier: an integration's types, such as a webhook's, can be reserved to the source that receives it.
• Harder: an application must never resolve a client to a reserved source. This was true before. Now the library relies on it.
• Revisit: a library-exported entry, once relayr has one to export.

Action items¶

1. Workspaces(publishers=), checked at startup and in publish, with tests on handles and REST.
2. relayr's wiring passes publishers={"artifactr": [SourceActor(name="artifactr")]} (stackr RFC-0002, phases 3 and 5).
3. relayr's rules drop their own check of the envelope's actor (stackr RFC-0002, phase 5).