prometeu-studio/discussion/workflow/plans/PLN-0105-wrap-pbs-frontend-as-explicit-provider.md

id	ticket	title	status	created	ref_decisions	tags
PLN-0105	multi-frontend-provider-contract	Wrap PBS frontend as explicit provider	open	2026-07-15	DEC-0040	compiler compiler-general studio frontend registry multi-frontend

Briefing

DEC-0040 requires PBS to become the only initial real provider behind the new FrontendProvider contract. This plan wraps existing PBS frontend behavior without changing PBS product behavior.

Domain owner: compiler/general, with implementation in compiler/pbs and composition impact in prometeu-app.

Objective

Create and register an explicit PBS provider through the application composition root.

Dependencies

• PLN-0104 must introduce FrontendProvider and provider lookup first.
• Accepted decision: DEC-0040.
• Existing PBS frontend phase/service implementation.
• Application composition root in prometeu-app.

Scope

• Add PBSFrontendProvider or equivalent concrete provider object.
• Make the provider return the existing PBS FrontendSpec.
• Make the provider return the existing PBS compiler-facing service or phase.
• Return no language service, or the existing PBS language-service adapter only if already present and compatible.
• Register PBS explicitly in prometeu-app/src/main/java/p/studio/AppContainer.java or the nearest current application composition point.
• Ensure PBS remains the only initial real provider.

Non-Goals

• Do not create another real frontend.
• Do not change PBS parsing, semantics, lowering, or runtime output.
• Do not migrate all common consumers in this plan.
• Do not introduce dynamic provider discovery.

Execution Method

1. Inspect PBS frontend module boundaries and locate the current FrontendSpec and FrontendPhaseService construction.
2. Add PBSFrontendProvider in the PBS frontend module or an existing integration package that can legally depend on PBS.
3. Implement specification() and compiler() by delegating to the existing PBS objects.
4. Implement languageService() as empty unless a current Studio-compatible PBS language service already exists.
5. Update AppContainer or the existing composition root to register the PBS provider explicitly with FrontendRegistryService.
6. Remove direct PBS registration paths that duplicate the provider registration if they become redundant.
7. Add tests proving only PBS is registered as the real provider in the default composition path.

Acceptance Criteria

• PBS is represented by a concrete provider object.
• Default application composition registers PBS explicitly as a provider.
• PBS remains functional through existing compile/build flows.
• No additional real frontend is introduced.
• No dynamic discovery mechanism is added.

Tests

• Provider test: PBSFrontendProvider.specification() returns the PBS language id.
• Provider test: PBSFrontendProvider.compiler() returns working compiler-facing behavior.
• Composition test: default registry contains PBS as the only real provider.
• Existing PBS compile/build tests continue to pass.

Affected Artifacts

• PBS frontend module under prometeu-compiler/frontends/prometeu-frontend-pbs/...
• prometeu-app/src/main/java/p/studio/AppContainer.java
• Registry or application composition tests.