feat: default to rerun-web and auto-open browser on startup (browser …

[Nabla7]

…does better memory management that OS so until rerun memory leak is fixed this is better)

• Changed GlobalConfig.viewer_backend default from rerun-native to rerun-web
• WebsocketVisModule now opens dashboard in browser automatically on start
• Requested by Jeff

[greptile-apps]

Greptile Summary

This PR changes the default visualization backend from rerun-native to rerun-web and adds automatic browser opening on module startup. The changes are minimal and focused, affecting the default configuration and WebSocket visualization server initialization.

Key Changes:

• Changed GlobalConfig.viewer_backend default from "rerun-native" to "rerun-web"
• Added automatic browser tab opening via webbrowser.open_new_tab() when the WebSocket module starts
• Implemented thread-safe browser opening using a global lock to prevent multiple browser windows from opening when multiple module instances exist
• Updated log message from "Command Center" to "Dashboard" to reflect the new default landing page

Documentation Update Required:

• The documentation in docs/VIEWER_BACKENDS.md at line 10 still states "Rerun native viewer (default)" but should be updated to reflect that rerun-web is now the default

Confidence Score: 4/5

• This PR is safe to merge with one caveat: documentation needs to be updated to reflect the new default backend
• The code changes are minimal, focused, and well-implemented. The browser opening logic uses proper thread-safe synchronization with a lock and flag to prevent race conditions. However, the score is 4 instead of 5 because the documentation in docs/VIEWER_BACKENDS.md still references the old default ("Rerun native viewer (default)") and should be updated to reflect that rerun-web is now the default. This is a documentation inconsistency rather than a code issue, but important for user clarity.
• Documentation files (specifically docs/VIEWER_BACKENDS.md) need to be updated to reflect the new default viewer backend

Important Files Changed

Filename	Overview
dimos/core/global_config.py	Changed viewer_backend default from rerun-native to rerun-web on line 36. This is a straightforward configuration change with no implementation concerns. The change aligns with the PR goal to use the browser-based viewer by default for better memory management.
dimos/web/websocket_vis/websocket_vis_module.py	Added automatic browser opening on module start (lines 29, 62-63, 160-170). Uses a global lock and flag to ensure the browser is opened only once across multiple instances. The implementation is functional but the documentation at line 10 of VIEWER_BACKENDS.md stating "Rerun native viewer (default)" should be updated to reflect the new default.

Sequence Diagram

sequenceDiagram
    participant App as Application
    participant WebsocketVis as WebsocketVisModule.start()
    participant Lock as _browser_open_lock
    participant Browser as webbrowser
    
    App->>WebsocketVis: start()
    WebsocketVis->>WebsocketVis: Create server & broadcast loop
    WebsocketVis->>Lock: Acquire _browser_open_lock
    Lock-->>WebsocketVis: Lock acquired
    
    alt _browser_opened == False
        WebsocketVis->>Browser: open_new_tab(url)
        Browser-->>Browser: Open browser tab at http://localhost:port/
        WebsocketVis->>WebsocketVis: Set _browser_opened = True
    else _browser_opened == True
        WebsocketVis->>WebsocketVis: Skip browser opening (already opened)
    end
    
    WebsocketVis->>Lock: Release _browser_open_lock
    Lock-->>WebsocketVis: Lock released
    WebsocketVis->>WebsocketVis: Subscribe to LCM messages
    WebsocketVis-->>App: start() returns

Loading