Add interactive MCP workflow app for status, overview, and control

[Copilot]

This updates the Specrail MCP workflow surface from a passive payload viewer to an interactive MCP App. Hosts can now render workflow state, feature/outcome overview, test readiness, delegation prompts, and guided control actions from a single ui://specrail/workflow app.

• MCP App contract

  • Upgrades ui://specrail/workflow to an MCP Apps resource with text/html;profile=mcp-app
  • Advertises io.modelcontextprotocol/ui server capability
  • Adds UI resource metadata so hosts can treat the workflow panel as a first-class app surface

• Workflow app UI

  • Replaces the placeholder JSON panel with a control center for:
    • current workflow status and blockers
    • feature/outcome overview board
    • outcome test review details
    • delegation payloads
    • quick workflow controls for refresh, resume, activate, implement, verify, and advance
  • Preserves delegated prompts in-app instead of dropping them on refresh

• Tool integration

  • Attaches _meta.ui.resourceUri to the key workflow tools so hosts can render results into the workflow app consistently
  • Uses existing structured workflow actions and overview payloads as the control model rather than introducing a parallel UI-only state machine

• Bridge hardening

  • Adds MCP app handshake/display-mode support
  • Reports dynamic size to the host
  • Tightens message handling around trusted parent/host origin tracking for iframe bridge traffic

• Docs and contract coverage

  • Updates MCP server coverage to assert the new app MIME type, extension capability, and tool UI metadata
  • Refreshes plugin docs to describe the workflow app as an interactive MCP surface

Example of the updated MCP app wiring:

{
  "name": "specrail_status",
  "_meta": {
    "ui": {
      "resourceUri": "ui://specrail/workflow",
      "visibility": ["model", "app"]
    }
  }
}

[SamMRoberts]

@copilot can you share screenshots of the new workflow MCP App UI?

[Copilot]

@copilot can you share screenshots of the new workflow MCP App UI?

Shared one of the workflow MCP App screenshots below from commit 3876a61.

If you want, I can follow up with a second shot showing the active/delegation state as well.