Board: add toki:// OpenCode launcher via right-click Copy for LLM (Linux first, Windows next)

[ponbac]

Summary

Add a custom protocol launcher (toki://) so users can right-click Copy for LLM on board cards and choose Open in OpenCode.

Flow:

1. Fetch existing format-for-llm markdown.
2. Copy markdown to clipboard.
3. Open toki://open?tool=opencode&mode=clipboard&v=1&workItemId=<id>.
4. Local protocol handler launches a new terminal and opens OpenCode interactive with prefilled prompt from clipboard.

Agreed Product Decisions

• Scheme: toki:// (not ecosearch://)
• Payload transport: clipboard-based
• Card UX:
  • Left click on Copy button stays unchanged (copy markdown)
  • Right click on Copy button opens shadcn/radix context menu
  • Context menu options (v1): OpenCode only
• OpenCode run mode: interactive TUI with prefilled prompt
• Prompt source: existing GET /work-items/format-for-llm
• Platform scope:
  • Linux first
  • Windows support added immediately after Linux in same initiative
• Setup UX: in-app simple guided setup with copyable commands

Scope

Frontend

• Add shadcn/radix Context Menu integration for CopyWorkItem.
• Right-click menu item: Open in OpenCode.
• Launch sequence for that action:
  • fetch markdown from formatForLlm
  • copy to clipboard
  • navigate to toki://...
• Add URL builder helper for strict protocol contract:
  • action: open
  • allowlisted params: tool=opencode, mode=clipboard, v=1, optional workItemId
• Add error toasts for:
  • format fetch failure
  • clipboard failure
  • protocol launch fallback guidance (if setup missing)

In-app Guided Setup

Provide an in-app setup dialog with copyable command steps and validation guidance.

Linux (phase 1)

1. Install/verify OpenCode CLI.
2. Create local toki handler script.
3. Create .desktop entry registering x-scheme-handler/toki.
4. Run xdg-mime registration command.
5. Provide test command (xdg-open 'toki://open?...').

Windows (phase 2, same issue)

1. Add Windows setup instructions in the same in-app wizard section.
2. Register toki:// in Windows Registry.
3. Add local launcher script/exe entrypoint for protocol args.
4. Launch terminal and run OpenCode interactive with clipboard prompt.
5. Provide verification steps for protocol registration + launch.

Local Handler Behavior

• Accept URL arg and strictly parse toki://open.
• Validate allowlisted tool/mode/v.
• Read clipboard text with platform-specific fallback chain.
• Spawn a terminal emulator and run OpenCode interactive prefilled prompt.
• Fail with clear terminal-visible errors when dependencies are missing.

Acceptance Criteria

1. Left-click Copy behavior remains unchanged.
2. Right-click Copy opens context menu with Open in OpenCode.
3. Linux setup path works end-to-end and launches OpenCode with prompt content.
4. Windows setup path works end-to-end and launches OpenCode with prompt content.
5. Setup dialog can be re-opened and includes copyable steps for both OSes.
6. No backend API changes required for v1/v2 of this feature.

Notes

OpenCode CLI reference: https://opencode.ai/docs/cli/