Windows: Cannot select .cap directory when importing recording into Studio timeline

[honsontran]

Description

When editing a recording in Studio Mode, I try to import another existing
.cap recording into the current project.

Cap displays a prompt asking me to select a .cap directory. However, on
Windows, the file picker appears to be configured to select a .cap file
rather than a directory.

Because a .cap project is a directory whose folder name ends in .cap,
Windows will not let me select it.

Steps to reproduce

1. Open an existing .cap recording in Studio Mode.
2. Choose the option to import/add another Cap recording.
3. Navigate to another valid Recording.cap directory.
4. Attempt to select the directory.

Actual behavior

The Windows file picker expects a .cap file and does not allow the
.cap directory to be selected.

Expected behavior

The picker should operate in directory-selection mode and allow selecting
a folder whose name ends in .cap.

[linear]

CAP-759

[tembo]

The issue is in apps/desktop/src/routes/editor/ClipsSidebar.tsx in the pickCapRecording function:

const pickCapRecording = async () => {
    const recordingsPath = await join(await appDataDir(), "recordings");
    const path = await open({
        defaultPath: recordingsPath,
        filters: [{ name: "Cap Recording", extensions: ["cap"] }],
        multiple: false,
    });
    if (typeof path === "string") await importRecordingPath(path);
};

The dialog uses a file filter with extensions: ["cap"], which works on macOS because .cap directories are treated as bundles/packages and appear as selectable "files" in the picker. On Windows, .cap is a regular directory, so the file picker cannot select it.

The fix should use directory: true on Windows instead of file filters. The Tauri dialog open() function supports a directory option that switches to folder selection mode. After selection, the code should validate that the selected folder ends with .cap and contains a recording-meta.json file (this validation already exists in the Rust backend at apps/desktop/src-tauri/src/import.rs#L160-L162 via is_cap_project_path).

A platform-conditional approach could look like:

import { platform } from "@tauri-apps/plugin-os";

const pickCapRecording = async () => {
    const recordingsPath = await join(await appDataDir(), "recordings");
    const currentPlatform = platform();
    
    const path = await open({
        defaultPath: recordingsPath,
        // macOS treats .cap folders as bundles, so file filter works
        // Windows needs directory mode since .cap is a regular folder
        ...(currentPlatform === "windows" 
            ? { directory: true }
            : { filters: [{ name: "Cap Recording", extensions: ["cap"] }] }
        ),
        multiple: false,
    });
    if (typeof path === "string") await importRecordingPath(path);
};

The backend already handles validation in add_existing_recording_to_editor which checks is_cap_project_path(&source_path) - it verifies the path is a directory containing recording-meta.json.