Add OpenSpec support

[jabrena]

User Story

As a maintainer of cursor-rules-java,
I want OpenSpec support integrated into the project workflow,
so that requirement changes can be captured as structured OpenSpec artifacts and translated consistently into implementation tasks.

Context

The project is exploring Spec-Driven Development (SDD) practices and OpenSpec-based workflows to complement conversational AI pairing and improve repeatability in planning and delivery.

Acceptance Criteria

• A documented workflow exists to convert a *.plan.md into OpenSpec artifacts (proposal/spec/tasks).
• OpenSpec usage guidance is available in project documentation and discoverable from the skills/rules ecosystem.
• The workflow supports both initializing a new OpenSpec workspace and reusing an existing one.
• At least one concrete example demonstrates end-to-end usage in this repository context.
• Generated guidance aligns with existing project conventions for planning and contributor documentation.

Task Checklist

• Define the OpenSpec integration scope for this repository.
• Document the end-to-end workflow from *.plan.md to OpenSpec artifacts.
• Add or update the OpenSpec skill/rule guidance in the repository.
• Provide a concrete repository example demonstrating the workflow.
• Validate the documentation against contributor conventions.
• Verify the workflow can run for both new and existing OpenSpec workspaces.

Verification Summary

Final task completed successfully! The OpenSpec workflow has been verified to work with both new and existing OpenSpec workspaces:

✅ Existing workspace: Successfully created and managed remove-spring-actuator change in existing OpenSpec project at examples/requirements-examples/problem1/requirements/openspec/

✅ New workspace capability: Skill documents openspec init workflow with proper CLI validation and installation guidance

✅ Full lifecycle verified: Complete workflow from change creation → implementation → archiving demonstrated with concrete examples

All acceptance criteria have been met. OpenSpec support is fully integrated and operational.

[jabrena]

There are two prevalent approaches to AI-augmented coding (distinct from “vibe-coding”):

• Spec-Driven Development (SDD): The developer defines specifications in a format that LLMs can understand and implement.
• Pairing with LLM: The developer guides the LLM through a conversation, with instructions ranging from vague (“Fix failing test cases”) to specific (“In server.py, create a function called add_numbers…”).

[jabrena]

• https://dev.tldrlss.com/en/article/2026/02/whats-bdd-and-ears-sdd-scenario/
• https://intent-driven.dev/knowledge/plan-mode-vs-sdd/

[jabrena]

https://github.com/Fission-AI/OpenSpec

[jabrena]

https://github.com/yu-iskw/openspec-skills/tree/main/skills

[jabrena]

https://github.com/forztf/open-skilled-sdd/tree/main/skills