ADR-0010: Generated boundaries and typed connectors

Context

Generic executors, service locators, provider factories, and handwritten adapters create parallel interpretations of pipeline semantics and conceal external-boundary behaviour.

Decision

Prefer compiler-generated/framework boundaries over application glue. pipeline.yaml is the primary semantic contract; annotations and Java signatures support discovery and local execution but do not independently own flow shape. Invalid step shapes, type links, mapper pairs, connector declarations, placement, and generated-boundary requirements fail at build time whenever possible.

Connectors are versioned typed external-boundary products. Binding selects a configured provider identity; an operation selects one capability; invocation input carries dynamic business data. Operation configuration cannot encode branching or become a second pipeline language. Dynamic selection remains constrained to compiler-authorized typed identities and preserves Query/Command semantics.

This decision governs connector SPI and providers under framework/connectors, compiler generation in framework/deployment, and generated metadata under META-INF/pipeline/.

Rationale

One generated model makes boundary behaviour discoverable to runtime, replay, telemetry, security, and validation tooling.

Consequences

• Mapper selection is pair-accurate and deterministic.
• Extend the SPI only for a reusable semantic capability with a stable lifecycle.
• One application's policy stays application code unless a real framework gap is proven.