feat: extract opencode_xdg.ts helper module

[jeonghun-jj-lee]

Closes #560

What

Extracts XDG path resolution into a standalone helper module (packages/extension/src/opencode_xdg.ts) with two pure functions:

• opencodeConfigDir() — returns $XDG_CONFIG_HOME/opencode or ~/.config/opencode
• opencodeDataDir() — returns $XDG_DATA_HOME/opencode or ~/.local/share/opencode

Why

Centralizes XDG logic currently inlined in chat_bridge.ts (and future consumers) into a single, tested module with no side effects.

Testing

4 vitest cases covering both env-set and env-unset branches for each function, with os.homedir() mocked to a predictable path.

Summary by CodeRabbit

• New Features

  • Added support for resolving OpenCode configuration and data directories using XDG environment settings.
  • Added sensible home-directory fallbacks when custom XDG locations are not configured.

• Tests

  • Added coverage for custom directory settings and default path resolution.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: e8dc128c-775b-4719-8086-d005d67c28e1

📥 Commits

Reviewing files that changed from the base of the PR and between d8dff37 and 631b399.

📒 Files selected for processing (2)

• packages/extension/src/opencode_xdg.ts
• packages/extension/test/opencode_xdg.test.ts

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📝 Walkthrough

Walkthrough

Added pure helpers that resolve OpenCode configuration and data directories from XDG environment variables, with home-directory fallbacks. Added tests for custom, unset, and empty environment values.

Changes

OpenCode XDG resolution

Layer / File(s)	Summary
Directory resolution and validation packages/extension/src/opencode_xdg.ts, packages/extension/test/opencode_xdg.test.ts	Added opencodeConfigDir() and opencodeDataDir() with XDG overrides and default paths. Tests cover custom, unset, and empty environment values, plus mocked home-directory resolution.

Estimated code review effort: 2 (Simple) | ~10 minutes

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 560-extract-opencode-xdg

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