World Runtime supports four first-class extension seams for partner teams.

Adapter implementations must satisfy adapters.base.DomainAdapter:

• adapter_id (stable id, format recommendation: adapter-<slug>)
• domain_name (human-readable)
• entity_types and event_types (declared taxonomies)
• scenario_dir(repo_root)
• default_policy_path(repo_root)
• adapter_schema_paths(repo_root)

Contract boundaries:

• Adapter code may define domain taxonomies and fixtures.
• Adapter taxonomies extend the shared runtime vocabulary in docs/controlled-vocabulary-v1.md; they do not replace core runtime terms such as entity, event, proposal, policy, projection, or simulation.
• Adapter code may not bypass policy/approval enforcement in core/app_server.py.
• Adapter policy packs should validate against schemas/policy.schema.json.

Starter template:

• templates/adapter_starter/
• Scaffold command: python3 scripts/scaffold_extension.py adapter --name "My Domain" --output-dir tmp/my-domain-adapter

Connector plugins must satisfy core.connector_transports.TransportPlugin:

• provider string (stable provider id)
• send(payload, attempt, auth, options) -> dict

Contract boundaries:

• Plugin code receives payload/auth/options and returns provider response.
• Plugin code does not decide policy outcomes; policy decisions happen before transport execution.
• Plugin ids must be provider-scoped and referenced by outbound requests via transport_plugin.provider.

Starter template:

• templates/connector_plugin_starter/
• Scaffold command: python3 scripts/scaffold_extension.py connector-plugin --name "My Queue" --provider "my.queue" --output-dir tmp/my-queue-plugin

Policy packs are JSON documents validated by schemas/policy.schema.json.

Required fields:

• policy_id
• policy_name
• policy_type
• rules
• default_outcome
• created_at
• version

Policy compatibility boundary:

• Rule outcomes remain in the policy outcome set (allow, warn, require_approval, deny).
• Connector-specific scope fields (connector_ids, providers, sources, directions) are additive.

Simulation requests and stored simulation records follow schemas/simulation.schema.json.

Required fields:

• simulation_id
• simulation_type
• status
• created_at

Simulation compatibility boundary:

• Canonical event log writes stay outside simulation branch execution.
• Extension code can add inputs, assumptions, and hypothetical_events without mutating canonical state.

Use these commands before proposing extension bundles:

• make extension-contracts
• make adapters
• make connector-plugins
• make protocol-compat
• make public-api-compat