Live Reload#

When enabled, Bialet injects a small polling script into every HTML response. The script checks for file changes once per second and reloads the page automatically — no browser extensions, no WebSocket server, no extra process.

Enabling#

Live reload is controlled by the BIALET_LIVE_RELOAD configuration key. Set it once in your development database:

bialet -r 'Config.enable("BIALET_LIVE_RELOAD")' .

Or directly:

bialet -r 'Config.set("BIALET_LIVE_RELOAD", "1")' .

Disable it:

bialet -r 'Config.disable("BIALET_LIVE_RELOAD")' .

Since configuration lives in the SQLite database, enabling it in dev has no effect on production — each environment has its own _db.sqlite3 and its own BIALET_CONFIG table.

To check if it’s currently active:

if (Config.bool("BIALET_LIVE_RELOAD")) {
  System.print("Live reload is on")
}

How It Works#

Script injection#

When live reload is enabled, Bialet appends a <script> tag to every HTML response, right before </body> (or at the end if no </body> is present). The script polls the /_livereload endpoint every second.

The `/_livereload` endpoint#

This is an internal route handled by the server before any Wren code runs. It returns a plain-text version number that updates whenever a file in the app directory changes.

GET /_livereload → 200 OK
Content-Type: text/plain

1746554321

When the browser sees a different version number from its last poll, it calls location.reload().

File watching#

Bialet uses inotify (on Linux) to watch the app directory for changes. When any file is created, modified, or deleted, the version number updates and the next poll picks it up.

The Wren VM also reloads automatically on .wren file changes — this is independent of live reload and happens regardless of the config setting.

Limitations#

Polling, not push. There’s a 1-second delay between saving a file and the browser reloading. For CSS-only changes, consider a tool that injects stylesheets directly.
No WebSocket. Bialet speaks HTTP/1.0 and runs in a single process. Polling is the simplest approach that works everywhere without adding dependencies.
Full page reload only. The script calls location.reload(). State in JavaScript variables or form inputs is lost.

⚠️ Pitfall: Enabling live reload on a production database injects the script into every page served to real users. The /_livereload endpoint becomes publicly accessible. Only enable it in development.

Live Reload

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