Implement pre/post processing framework for multi-target workflows

[obie]

Summary

This PR implements issue #61 by adding support for pre-processing and post-processing phases to Roast workflows. This allows workflows that operate on multiple targets to:

• Execute setup tasks once before processing any targets
• Aggregate results from all workflow executions
• Generate comprehensive reports after all targets are processed

Changes

• Added pre_processing and post_processing arrays to workflow schema
• Updated ConfigurationLoader to extract pre/post processing steps
• Modified StepLoader to support phase-specific directories (pre_processing/, post_processing/)
• Enhanced WorkflowRunner to execute phases and collect workflow results
• Added comprehensive test coverage for the new functionality
• Created example workflow demonstrating the feature
• Updated README with documentation

Example Usage

name: test_improvement_workflow
tools: [read_file, update_files, cmd]

target: "$(find . -name '*_test.rb' -type f)"

pre_processing:
  - gather_baseline_metrics
  - setup_test_environment

steps:
  - analyze_test_file
  - improve_test_coverage
  - optimize_test_performance
  - validate_changes

post_processing:
  - aggregate_metrics
  - generate_summary_report
  - cleanup_environment

The post-processing steps have access to aggregated results from all workflow executions via {{ workflow_results }}.

Testing

• Added comprehensive unit tests for all new functionality
• Created example workflow with documentation
• All tests passing
• RuboCop clean

Closes #61

🤖 Generated with Claude Code

[Copilot]

Pull Request Overview

This PR implements a new pre-/post-processing framework for multi-target workflows, allowing one-time setup and teardown tasks as well as aggregated reporting across all targets.

• Add phase support in WorkflowExecutor and StepLoader to load phase-specific steps
• Introduce WorkflowExecutionContext to collect and expose pre-processing and per-target outputs
• Update configuration, base workflow, examples, and documentation to wire in pre/post processing steps

Reviewed Changes

Copilot reviewed 27 out of 27 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
lib/roast/workflow/workflow_executor.rb	Added phase keyword to initialize and pass to StepLoader
lib/roast/workflow/step_loader.rb	Lookup of steps under pre_processing/ and post_processing/ dirs
lib/roast/workflow/workflow_execution_context.rb	New class to manage and aggregate outputs across phases
lib/roast/workflow/configuration_loader.rb	Extract pre_processing and post_processing arrays
lib/roast/workflow/configuration.rb	Store new pre/post arrays on Configuration
lib/roast/workflow/base_workflow.rb	Inject pre_processing_data into workflow instances
examples/pre_post_processing/*	New example workflow and step prompts
README.md	Document the new pre/post-processing framework

Comments suppressed due to low confidence (1)

lib/roast/workflow/workflow_execution_context.rb:1

• Add unit tests for WorkflowExecutionContext, covering add_target_output, to_h, and generate_target_key behavior to ensure outputs are aggregated correctly.

# frozen_string_literal: true

[parruda]

In a future PR, we probably want to adopt the dev way here and have a key users can use to verify a requirement has been met and not need to run this command every time.