Use native WKWebView evaluateJavaScript on macOS#13
Use native WKWebView evaluateJavaScript on macOS#13bituq wants to merge 3 commits intohypothesi:mainfrom
Conversation
The existing eval + IPC callback approach fails on macOS because scripts injected via Tauri's window.eval() can't communicate back to Rust through invoke() or event.emit(). The eval succeeds (no error from Rust's side) but the injected JS never reaches the IPC message handlers, causing a 5-second timeout on every call. This adds a macOS-specific code path that uses WKWebView's native evaluateJavaScript:completionHandler: API (via with_webview and objc2-web-kit) to get script results directly from the completion handler. This completely bypasses the eval->IPC->event pipeline. The existing eval + event listener approach is kept as a fallback for non-macOS platforms. Fixes hypothesi#12
|
@yokuze Could you please review this PR? Otherwise this mcp server is unusable on MacOS. |
Hey, could you accept my request on discord, my user is "swezp." |
|
Confirming that I was also having this issue and this change does fix it. Please merge! |
Thank you both for the bug report. Curious: Are you also on 15? |
yokuze
left a comment
yokuze
left a comment
There was a problem hiding this comment.
This looks good, but the Rust linting is failing in CI.
Could you run
cargo clippy --fix
and
cargo fmt
And then fixup the original commits + force-push?
Thanks!
|
@yokuze no, i'm on macOS 26.3 |
Ok,thank you. That's odd. I'd re-tested the methods the issue ticket mentioned on macOS 26 and they succeeded. If either of you happen to have a payload that can reproduce the issue, that'd be valuable to have for future test cases. If you leave the example payload(s) as a comment on this PR I will include them in a follow-up PR for regression testing. Either way, after the formatting fixes are pushed to this branch, I'll merge. Thanks |
4 participants
Fixes #12
Problem
On macOS, all JS execution tools (
webview_execute_js,webview_dom_snapshot,webview_interact,read_logs) time out after 5 seconds. Screenshots and window listing work fine since they use native APIs.The current approach injects a script via
window.eval(), and the script sends results back throughwindow.__TAURI__.event.emit()orinvoke(). The eval succeeds (Rust gets no error), but the injected JS never reaches the IPC message handlers. The result never comes back, so it times out.Fix
On macOS, use
WKWebView.evaluateJavaScript:completionHandler:directly (viawith_webview+ objc2-web-kit), same pattern the screenshot code already uses. The completion handler gives us the result directly without needing any IPC roundtrip.The existing eval + event listener approach stays as a fallback for other platforms.
Testing
Tested on macOS 15 (Darwin 25.3.0) with Tauri 2.10.3. Before the fix, every JS execution call timed out. After,
webview_execute_js,webview_dom_snapshot, andwebview_interactall work.