Add implementation plan for embedding Copilot CLI binaries

[Copilot]

Developers currently must manually install GitHub Copilot CLI (0.0.409+) and manage PATH configuration. This PR documents a plan to optionally bundle platform-specific CLI binaries with the SDK.

Plan Document

Created docs/CLI_EMBEDDING_PLAN.md (705 lines) covering:

• 4 implementation approaches with trade-off analysis
• Recommended: Multi-module Maven project with platform-specific artifacts
  • copilot-sdk-cli-windows-x64, -linux-x64, -linux-arm, -macos-intel, -macos-arm
  • ~25 MB per platform, users include only what they need
  • Follows JavaFX's Maven classifier pattern
• 8-week implementation roadmap: infrastructure → runtime discovery → binary acquisition → testing → docs → release
• Technical details: platform detection, binary extraction, version sync, security

Usage (proposed)

<!-- Core SDK (unchanged) -->
<dependency>
    <groupId>io.github.copilot-community-sdk</groupId>
    <artifactId>copilot-sdk</artifactId>
    <version>1.0.10</version>
</dependency>

<!-- Optional: bundle CLI for your platform -->
<dependency>
    <groupId>io.github.copilot-community-sdk</groupId>
    <artifactId>copilot-sdk-cli-linux-x64</artifactId>
    <version>1.0.10</version>
    <scope>runtime</scope>
</dependency>

Runtime: SDK detects platform → extracts bundled CLI to temp → falls back to PATH if not found.

Research

• JavaFX: Maven classifiers for platform-specific natives, property-based selection
• .NET SDK: RID-based bundling in runtimes/{rid}/native/, encountered distro-specific mapping issues
• CLI distribution: 5 platforms available, 20-30 MB per binary

Next Steps

1. Confirm CLI redistribution rights with GitHub
2. RFC issue for community feedback
3. Review Maven Central policies for binary artifacts
4. Phase 1 implementation if approved

Documentation

• Added link in README Quick Links
• Documented in CHANGELOG under Unreleased

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Draft a plan with ideas on how to embed GitHub Copilot CLI</issue_title>
<issue_description>When a developer adds a dependency to Copilot SDK for Java, we should also consider adding an option for developers to bundle the Copilot CLI. This is challenging because Java is cross-platform. JavaFX has native dependencies per OS platform available on Maven Central, and the way they do is probably the way we should do here.

Draft a plan with ideas to execute this.</issue_description>

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

• Fixes Draft a plan with ideas on how to embed GitHub Copilot CLI #139

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