fix(desktop): improve deeplink action routing and control surface

[JYZ-LESLIE]

/claim #1540

This is a focused desktop-side quality pass for the deeplink/Raycast control surface.

What changed

• fixes cap-desktop://action?... parsing by using the deeplink host (host_str) so action links are no longer rejected
• adds recording-control deeplink actions:
  • pause_recording
  • resume_recording
  • toggle_pause_recording
  • restart_recording
  • take_screenshot
  • set_microphone (with switch_microphone alias)
  • set_camera (with switch_camera alias)
  • refresh_raycast_device_cache
• extracts shared capture-target resolution so start/screenshot flows use the same mapping logic
• writes Raycast JSON artifacts:
  • raycast-device-cache.json
  • raycast-last-screenshot.json
• keeps runtime responsive by moving device enumeration into spawn_blocking and writing files with async FS APIs
• adds parser tests for action-host routing, nullable camera/mic payloads, capture payloads, and non-action deeplinks (cap-desktop://signin)

Notes

• SetCamera uses skip_camera_window=true so deeplink-triggered device changes do not force camera preview UI popups.

Validation

• Could not run cargo fmt / cargo test in this environment because Rust (cargo) is unavailable on the runner.
• Added focused parser unit coverage in deeplink_actions.rs for the changed payload surface.

Demo

• I cannot capture a desktop demo video from this headless environment. The PR includes deterministic parser tests and desktop-side action wiring only (no frontend-side behavior changes).

Greptile Summary

This PR fixes the long-standing url.domain() → url.host_str() bug that caused all cap-desktop://action?... deeplinks to be rejected, and wires up eight new recording-control actions (pause_recording, resume_recording, toggle_pause_recording, restart_recording, take_screenshot, set_microphone/switch_microphone, set_camera/switch_camera, refresh_raycast_device_cache) to their existing Rust backend handlers.

• The core URL-parsing fix is correct: host_str() is the right method for custom-scheme URLs and the NotAction guard now correctly passes through non-action links like cap-desktop://signin.
• refresh_raycast_device_cache properly offloads blocking device-enumeration calls into spawn_blocking, and writes the cache/screenshot-result artifacts via tokio::fs; parser unit tests cover all new variants including serde aliases and nullable payloads.
• capture_target_from_mode (shared by StartRecording and the new TakeScreenshot path) still calls list_displays() / list_windows() directly on the async runtime thread, inconsistent with the spawn_blocking discipline applied elsewhere in this PR.

Confidence Score: 4/5

Safe to merge; the URL-parsing fix and new action wiring are correct. The one issue (blocking OS calls in TakeScreenshot) mirrors a pre-existing pattern in StartRecording and will not cause data loss or crashes — it may only cause minor runtime latency on systems with many open windows.

The URL-parsing regression fix is well-scoped and correct. New actions delegate to existing, tested backend functions. The spawn_blocking discipline is applied in refresh_raycast_device_cache but not carried through to capture_target_from_mode, which is used by the new TakeScreenshot path — a quality inconsistency rather than a correctness problem.

apps/desktop/src-tauri/src/deeplink_actions.rs — specifically the TakeScreenshot arm and capture_target_from_mode

Important Files Changed

Filename

Overview

apps/desktop/src-tauri/src/deeplink_actions.rs

Adds 8 new recording-control deeplink actions, fixes action-host URL parsing (domain→host_str), extracts capture-target resolution into a shared helper, writes Raycast JSON artifacts, and adds parser tests. One inconsistency: capture_target_from_mode calls blocking OS APIs directly in the async executor for TakeScreenshot, while refresh_raycast_device_cache correctly wraps equivalent calls in spawn_blocking.

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
apps/desktop/src-tauri/src/deeplink_actions.rs:195-199
**Blocking OS calls on async thread in `TakeScreenshot`**

`capture_target_from_mode` calls `list_displays()` / `list_windows()` — synchronous system APIs — directly on the Tokio runtime thread. `refresh_raycast_device_cache` wraps the identical calls in `spawn_blocking` specifically to avoid stalling the runtime, but the same protection is missing here. On a system with many windows, `list_windows()` can take tens of milliseconds and will block the entire runtime thread for the duration.

_{Reviews (1): Last reviewed commit: "fix(desktop): improve deeplink action ro..." | Re-trigger Greptile}

Greptile also left 1 inline comment on this PR.

[JYZ-LESLIE]

Addressed the blocking thread by moving onto and updating call sites to await it (commit cf68ea5). Marked the review thread resolved; ready for maintainer re-review.

[JYZ-LESLIE]

Implemented the blocking-thread fix in commit cf68ea5: capture target lookup now runs in a blocking task and both call sites await it. The corresponding review thread has been resolved and this PR is ready for maintainer re-review.