[log] There seems no way to set log level for "webview" target

[CrendKing]

Describe the bug

If I want to set log level for logging from the frontend, I can't simply .level_for(WEBVIEW_TARGET, level) on the builder. This is because the command sets the "location" as target for the record builder, which includes the function name, file name, timestamp and even line number of the call site. For example, webview:myFunction@http://localhost:5173/src/myFile.ts?t=1787480723620:47:4. I could set log level for this exact string, but it wouldn't be very useful. Also, once the Javascript is packed and minified for release build, everything after the webview: is garbage anyway, so dev would have to include identifiable name in the actual log message anyway. So I suggest just use webview as the target.

Reproduction

Literally just add logging in the frontend, like debug('my message'). Make the builder's default level lower than that, e.g. .level(log::LevelFilter::Info). That message will never be logged.

Expected behavior

Add .level_for(WEBVIEW_TARGET, level) to the builder to configure log level for webview target.

Full tauri info output

[✔] Environment
    - OS: Windows 10.0.26200 x86_64 (X64)
    ✔ WebView2: 151.0.4129.101
    ✔ MSVC: Visual Studio Build Tools 2026
    ✔ rustc: 1.98.0 (88d9e12ae 2026-08-18)
    ✔ cargo: 1.98.0 (797e8a9bc 2026-08-05)
    ✔ rustup: 1.29.0 (28d1352db 2026-03-05)
    ✔ Rust toolchain: stable-x86_64-pc-windows-msvc (default)
    - node: 26.7.0
    - npm: 11.19.0

[-] Packages
    - tauri 🦀: 2.11.5
    - tauri-build 🦀: 2.6.3
    - wry 🦀: 0.55.1, (outdated, latest: 0.56.1)
    - tao 🦀: 0.35.3, (outdated, latest: 0.37.0)
    - @tauri-apps/api  ⱼₛ: not installed!
    - @tauri-apps/cli  ⱼₛ: 2.11.4

[-] Plugins
    - tauri-plugin-log 🦀: 2.9.0
    - @tauri-apps/plugin-log  ⱼₛ: not installed!
    - tauri-plugin-single-instance 🦀: 2.4.3
    - @tauri-apps/plugin-single-instance  ⱼₛ: not installed!
    - tauri-plugin-fs 🦀: 2.5.1
    - @tauri-apps/plugin-fs  ⱼₛ: not installed!
    - tauri-plugin-clipboard-manager 🦀: 2.3.2
    - @tauri-apps/plugin-clipboard-manager  ⱼₛ: not installed!
    - tauri-plugin-opener 🦀: 2.5.4
    - @tauri-apps/plugin-opener  ⱼₛ: not installed!
    - tauri-plugin-window-state 🦀: 2.4.1
    - @tauri-apps/plugin-window-state  ⱼₛ: not installed!
    - tauri-plugin-dialog 🦀: 2.7.2
    - @tauri-apps/plugin-dialog  ⱼₛ: not installed!

[-] App
    - build-type: build
    - CSP: unset
    - frontendDist: ../dist
    - devUrl: http://localhost:5173/
    - framework: Svelte
    - bundler: Vite

Stack trace

Additional context

Alternatively, I think if you add one more colon after webview: in the current target, fern would consider webview as a component, thus also fix this issue. It seems the author made a typo back in PR #2021.

Workaround

The workaround seems to set the default log level for everything Trace, then only use filter() to simulate log level in our own code. Something like this:

Builder::default()
    .level(LevelFilter::Trace)
    .filter(|metadata: &Metadata| {
        if metadata.target().starts_with("webview:") {
            metadata.level() < Level::Debug
        } else {
            metadata.level() < Level::Info
        }
    })
    .build()
)