Click-to-source sends empty source= and hangs because setDisabledAfterClick(true) runs before reading highlightState.dataSource

[samkuehn]

TanStack Devtools version

@tanstack/devtools-vite: 0.7.0 @tanstack/react-devtools: 0.10.5

Framework/Library version

react: 19.2.6

Describe the bug and the steps to reproduce it

When using the inspect hotkey (Shift+Alt+Cmd) to click a component, the request to `/__tsd/open-source?source=` is

sent with an empty source parameter, even though the clicked element has a valid data-tsd-source
attribute. The dev server then hangs the request indefinitely, so the editor never opens.

This is fully reproducible in any React app using @tanstack/react-devtools@0.10.x (which pulls in
@tanstack/devtools@0.12.2) + @tanstack/devtools-vite@0.7.0. I am seeing it across multiple projects with
similar stacks.

Versions

• @tanstack/devtools@0.12.2
• @tanstack/react-devtools@0.10.5
• @tanstack/devtools-vite@0.7.0
• vite@8.0.14, react@19.2.6, Solid (bundled via devtools)

Reproduction

1. Add @tanstack/devtools-vite to a Vite + React project with a configured editor.
2. Mount <TanStackDevtools> in the app.
3. Hold Shift+Alt+Cmd and click any rendered component.
4. Observed: Network panel shows GET /__tsd/open-source?source= (empty value), status pending forever.
   Editor never opens.
5. Expected: URL should include the clicked element's data-tsd-source, server should respond 200, editor
   should open.

I verified the clicked element has a well-formed data-tsd-source attribute (matching /^\/.+:\d+:\d+$/). On the
page tested there were 1869 such elements, 0 empty, 0 malformed.

Root cause

packages/devtools/src/.../LGFFJRYV.js (the inspect overlay component) registers this click handler:

createEventListener(document, "click", (e) => {
  if (!highlightState.element) return;
  window.getSelection()?.removeAllRanges();
  e.preventDefault();
  e.stopPropagation();
  setDisabledAfterClick(true);   // <-- step 1
  if (settings().sourceAction === "copy-path") {
    navigator.clipboard.writeText(highlightState.dataSource).catch(() => {});
    return;
  }
  const baseUrl = new URL(import.meta.env?.BASE_URL ?? "/", location.origin);
  const url = new URL(
    `__tsd/open-source?source=${encodeURIComponent(highlightState.dataSource)}`,  // <-- step 2
    baseUrl
  );
  fetch(url).catch(() => {});
});

setDisabledAfterClick(true) flips this memo:

const isActive = createMemo(
  () => isHighlightingKeysHeld() && !disabledAfterClick()
);

…which makes isActive() false, which synchronously re-runs the highlight createEffect:

createEffect(() => {
  if (!isActive()) {
    resetHighlight();   // <-- sets element=null, dataSource=""
    return;
  }
  ...
});

By the time the next line in the click handler reads highlightState.dataSource, it is "". The constructed URL
is /__tsd/open-source?source= and is sent.

Compounding server-side bug

In @tanstack/devtools-vite (utils.js), the middleware does:

if (req.url?.includes("__tsd/open-source")) {
  const source = new URLSearchParams(req.url.split("?")[1]).get("source");
  if (!source) return;                       // <-- leaves the response hanging
  const parsed = parseOpenSourceParam(source);
  if (!parsed) return;                       // <-- same
  ...
}

Both early returns omit both res.end() and next(), so the connection sits open until the browser times out.
This is why users see "pending" rather than a quick failure.

Evidence

Captured at click time on a component whose data-tsd-source attribute is
/src/routes/tournaments/$tournament_id/leaderboard.tsx:55:7:

{
  "url": "http://localhost:5173/__tsd/open-source?source=",
  "rawSource": "",
  "stack": "...at HTMLDocument.<anonymous> (LGFFJRYV-DaE8v0zr.js:6195:3)"
}

reqid=101 GET http://localhost:5173/__tsd/open-source?source= [pending] in the Network panel.

The clicked element under the cursor at the same instant:

{ tag: "H1", src: "/src/routes/tournaments/$tournament_id/leaderboard.tsx:55:7" }

Suggested fix

Client (packages/devtools/.../LGFFJRYV.js): capture dataSource before mutating signals.

 createEventListener(document, "click", (e) => {
   if (!highlightState.element) return;
+  const source = highlightState.dataSource;   // capture before any setSignal
   window.getSelection()?.removeAllRanges();
   e.preventDefault();
   e.stopPropagation();
-  setDisabledAfterClick(true);
   if (settings().sourceAction === "copy-path") {
-    navigator.clipboard.writeText(highlightState.dataSource).catch(() => {});
+    navigator.clipboard.writeText(source).catch(() => {});
+    setDisabledAfterClick(true);
     return;
   }
   const baseUrl = new URL(import.meta.env?.BASE_URL ?? "/", location.origin);
-  const url = new URL(`__tsd/open-source?source=${encodeURIComponent(highlightState.dataSource)}`, baseUrl);
+  const url = new URL(`__tsd/open-source?source=${encodeURIComponent(source)}`, baseUrl);
   fetch(url).catch(() => {});
+  setDisabledAfterClick(true);
 });

Wrapping the signal write in batch(() => setDisabledAfterClick(true)) would not help here — the read happens
after the write, so the value is already reset by the time we read.

Server (packages/devtools-vite/src/utils.ts): defensively end the response on bad input instead of leaving
the socket open.

 if (req.url?.includes("__tsd/open-source")) {
   const source = new URLSearchParams(req.url.split("?")[1]).get("source");
-  if (!source) return;
+  if (!source) { res.statusCode = 400; res.end(); return; }
   const parsed = parseOpenSourceParam(source);
-  if (!parsed) return;
+  if (!parsed) { res.statusCode = 400; res.end(); return; }
   ...
 }

Workaround for users until fixed

Add this to your client entry (e.g., src/main.tsx) in dev only:

if (import.meta.env.DEV) {
  let lastSource: string | null = null;
  document.addEventListener('click', (e) => {
    if (e.shiftKey && e.altKey && (e.metaKey || e.ctrlKey)) {
      const t = document.elementFromPoint(e.clientX, e.clientY);
      const el = t?.closest?.('[data-tsd-source]') as HTMLElement | null;
      if (el) lastSource = el.getAttribute('data-tsd-source');
    }
  }, true); // capture phase: runs before the buggy handler
  const orig = window.fetch;
  window.fetch = function(input, init) {
    const url = typeof input === 'string' ? input
      : input instanceof URL ? input.href
      : (input as Request).url;
    if (typeof url === 'string' && url.endsWith('/__tsd/open-source?source=') && lastSource) {
      const fixed = url + encodeURIComponent(lastSource);
      lastSource = null;
      return orig.call(this, fixed, init);
    }
    return orig.call(this, input, init);
  };
}

Your Minimal, Reproducible Example - (Sandbox Highly Recommended)

A minimal sandbox isn't practical for this bug.

Screenshots or Videos (Optional)

No response

Do you intend to try to help solve this bug with your own PR?

Maybe, I'll investigate and start debugging

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• I understand that if my bug cannot be reliable reproduced in a debuggable environment, it will probably not be fixed and this issue may even be closed.