refactor: remove PipelineHandler getter from pipelinesteps plugin

[intel352]

Summary

• Removes the PipelineHandler() getter from plugins/pipelinesteps/plugin.go — callers no longer reach inside the plugin to configure it
• Plugin now implements SetStepRegistry() and SetLogger() optional interfaces, which the engine's LoadPlugin() detects and calls automatically
• Plugin adds a WiringHook that injects dependencies into the handler and registers it as a named service (pipeline-workflow-handler)
• cmd/server/main.go discovers the handler via service registry lookup when needed (e.g., for wiring SetEventRecorder post-start)
• Engine's LoadPlugin() now supports stepRegistrySetter and slogLoggerSetter optional interfaces for all plugins

Closes #60

Test plan

• go build ./... passes
• go test ./... — all tests pass
• golangci-lint run — 0 issues (verified by pre-push hook)

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Refactors the pipelinesteps plugin integration so callers no longer access a concrete handler via a plugin-specific getter, and instead rely on engine-driven optional interface injection and service registry discovery.

Changes:

• Removed PipelineHandler() getter from plugins/pipelinesteps and added optional SetStepRegistry() / SetLogger() setters plus a wiring hook that registers the handler as a named service.
• Extended StdEngine.LoadPlugin() to inject step registry and (optionally) a *slog.Logger into plugins that implement the new setter interfaces.
• Updated server wiring and tests to discover the pipeline handler via the service registry rather than via direct plugin access.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
plugins/pipelinesteps/plugin.go	Removes handler getter; adds optional setters + wiring hook; registers handler under a constant service name
engine.go	Adds optional-interface injection for step registry and *slog.Logger during plugin load
cmd/server/main.go	Removes direct plugin handler wiring; wires EventRecorder via service-registry lookup post-start
engine_pipeline_test.go	Updates tests to locate the pipeline handler from the engine’s handler list
cmd/server/main_test.go	Adjusts tests for updated buildEngine signature
plugins/http/plugin_test.go	Formatting-only change

Comments suppressed due to low confidence (2)

plugins/pipelinesteps/plugin.go:145

• app.RegisterService errors are currently ignored. If registration fails (e.g., name collision), the PipelineWorkflowHandler won’t be discoverable via the service registry and post-start wiring (SetEventRecorder) will silently not happen. Return the error (or at least log it) so mis-wiring fails fast and is diagnosable.

				// Register the handler as a service so callers can discover it
				// (e.g. to wire SetEventRecorder post-start) without a plugin-specific getter.
				_ = app.RegisterService(PipelineHandlerServiceName, p.pipelineHandler)
				return nil

cmd/server/main.go:871

• If the pipeline handler service is missing from the registry or doesn’t implement SetEventRecorder, this branch becomes a silent no-op and pipeline execution events won’t be recorded without any signal. Consider adding a Debug/Warn log when the service isn’t found and when the type assertion fails, to make misconfiguration visible in production.

		if svc, ok := engine.GetApp().SvcRegistry()[pluginpipeline.PipelineHandlerServiceName]; ok {
			if ph, ok := svc.(eventRecorderSetter); ok {
				recorder := evstore.NewEventRecorderAdapter(app.stores.eventStore)
				ph.SetEventRecorder(recorder)
				logger.Info("Wired EventRecorder to PipelineWorkflowHandler")
			}
		}

[Copilot]

Pull request overview

Copilot reviewed 5 out of 6 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

plugins/pipelinesteps/plugin.go:145

• app.RegisterService returns an error (e.g., duplicate service name). Ignoring it here can silently break post-start wiring that relies on this service being present. Consider handling the error and returning it from the wiring hook (or at least logging it) so BuildFromConfig fails fast if the handler service cannot be registered.

				// Register the handler as a service so callers can discover it
				// (e.g. to wire SetEventRecorder post-start) without a plugin-specific getter.
				_ = app.RegisterService(PipelineHandlerServiceName, p.pipelineHandler)
				return nil