Break handler↔module concrete-type dependency via shared interfaces package

[Copilot]

• Explore codebase: handlers/pipeline.go, module/pipeline_executor.go, module/pipeline_step_registry.go, engine.go
• Create interfaces/pipeline.go — define EventRecorder, PipelineRunner, StepRegistryProvider interfaces
• Update module/pipeline_executor.go — alias EventRecorder to interfaces.EventRecorder; add SetLogger/SetEventRecorder/Run methods to Pipeline
• Update handlers/pipeline.go — replace *module.Pipeline/*module.StepRegistry/module.EventRecorder with interfaces.*; inject logger/recorder at configuration time (not per-execution) to avoid hot-path mutations
• Update engine.go — update PipelineAdder interface to use interfaces.PipelineRunner
• Add mockPipelineRunner, mockEventRecorder, TestPipelineHandler_MockRunner, TestPipelineHandler_InjectionAtConfigTime tests
• Fix test comment to "without depending on concrete module types"
• Build, lint, and run affected tests — all pass

Original prompt

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This section details on the original issue you should resolve

<issue_title>Bidirectional handler↔module dependency in handlers/pipeline.go</issue_title>
<issue_description>## Problem
The handlers package directly imports and holds concrete types from the module package (*module.Pipeline, *module.StepRegistry). This creates a bidirectional dependency and means handlers cannot be tested without instantiating real module types.

Fix Direction

Define PipelineRunner and StepRegistry interfaces in a shared package (e.g. workflow/interfaces or as part of the plugin contract). Have handlers depend on these interfaces; module implements them. This breaks the import cycle and enables proper unit testing of handlers with mocks.

Context

See docs/DEFERRED_ISSUES.md — Architecture section.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Bidirectional handler↔module dependency in handlers/pipeline.go #63

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[Copilot]

Pull request overview

This PR decouples handlers from module concrete types by introducing a neutral interfaces package for shared contracts, enabling handler unit testing with mocks and reducing cross-package coupling.

Changes:

• Added interfaces package defining PipelineRunner, EventRecorder, and StepRegistryProvider.
• Updated module.Pipeline to implement interfaces.PipelineRunner (type alias for EventRecorder, plus SetLogger, SetEventRecorder, Run).
• Updated handlers/pipeline.go and engine.go to use interfaces.PipelineRunner, plus a new mock-based handler test.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
module/pipeline_executor.go	Aliases EventRecorder to shared interface and adds PipelineRunner methods (SetLogger, SetEventRecorder, Run).
interfaces/pipeline.go	Introduces shared interfaces to break handler↔module concrete-type dependency.
handlers/pipeline.go	Removes module dependency by storing/running pipelines via interfaces.PipelineRunner.
engine.go	Updates PipelineAdder signature to accept interfaces.PipelineRunner.
handlers/pipeline_test.go	Adds a mock PipelineRunner and verifies handler execution works with mocks.

[intel352]

@copilot apply changes based on the comments in this thread