fix: Ignore pathless layout routes when matching actions (#4376)

* fix: Ignore pathless layout routes when matching actions

* Add changeset

* Add comment

* Remove deuped function

.changeset/stupid-games-build.md

@@ -0,0 +1,6 @@
+---
+"@remix-run/react": patch
+"@remix-run/server-runtime": patch
+---
+
+Ignore pathless layout routes in action matches

integration/form-test.ts

@@ -400,6 +400,47 @@ test.describe("Forms", () => {
             )
           }
         `,
+
+        "app/routes/pathless-layout-parent.jsx": js`
+          import { json } from '@remix-run/server-runtime'
+          import { Form, Outlet, useActionData } from '@remix-run/react'
+
+          export async function action({ request }) {
+            return json({ submitted: true });
+          }
+          export default function () {
+            let data = useActionData();
+            return (
+              <>
+                <Form method="post">
+                  <h1>Pathless Layout Parent</h1>
+                  <button type="submit">Submit</button>
+                </Form>
+                <Outlet />
+                <p>{data?.submitted === true ? 'Submitted - Yes' : 'Submitted - No'}</p>
+              </>
+            );
+          }
+        `,
+
+        "app/routes/pathless-layout-parent/__pathless.jsx": js`
+          import { Outlet } from '@remix-run/react';
+
+          export default function () {
+            return (
+              <>
+                <h2>Pathless Layout</h2>
+                <Outlet />
+              </>
+            );
+          }
+        `,
+
+        "app/routes/pathless-layout-parent/__pathless/index.jsx": js`
+          export default function () {
+            return <h3>Pathless Layout Index</h3>
+          }
+        `,
       },
     });
 
@@ -942,4 +983,24 @@ test.describe("Forms", () => {
       );
     }
   });
+
+  test("pathless layout routes are ignored in form actions", async ({
+    page,
+  }) => {
+    let app = new PlaywrightFixture(appFixture, page);
+    await app.goto("/pathless-layout-parent");
+    let html = await app.getHtml();
+    expect(html).toMatch("Pathless Layout Parent");
+    expect(html).toMatch("Pathless Layout ");
+    expect(html).toMatch("Pathless Layout Index");
+
+    let el = getElement(html, `form`);
+    expect(el.attr("action")).toMatch("/pathless-layout-parent");
+
+    expect(await app.getHtml()).toMatch("Submitted - No");
+    // This submission should ignore the index route and the pathless layout
+    // route above it and hit the action in routes/pathless-layout-parent.jsx
+    await app.clickSubmitButton("/pathless-layout-parent");
+    expect(await app.getHtml()).toMatch("Submitted - Yes");
+  });
 });

packages/remix-react/transition.ts

@@ -590,7 +590,7 @@ export function createTransitionManager(init: TransitionManagerInit) {
         invariant(matches, "No matches found");
         if (fetchControllers.has(key)) abortFetcher(key);
 
-        let match = getFetcherRequestMatch(
+        let match = getRequestMatch(
           new URL(href, window.location.href),
           matches
         );
@@ -644,17 +644,28 @@ export function createTransitionManager(init: TransitionManagerInit) {
     return false;
   }
 
-  function getFetcherRequestMatch(
-    url: URL,
-    matches: RouteMatch<ClientRoute>[]
-  ) {
+  // Return the correct single match for a route (used for submission
+  // navigations and  and fetchers)
+  // - ?index should try to match the leaf index route
+  // - otherwise it should match the deepest "path contributing" match, which
+  //   ignores index and pathless routes
+  function getRequestMatch(url: URL, matches: ClientMatch[]) {
     let match = matches.slice(-1)[0];
 
-    if (!isIndexRequestUrl(url) && match.route.index) {
-      return matches.slice(-2)[0];
+    if (isIndexRequestUrl(url) && match.route.index) {
+      return match;
     }
 
-    return match;
+    return getPathContributingMatches(matches).slice(-1)[0];
+  }
+
+  // Filter index and pathless routes when looking for submission targets
+  function getPathContributingMatches(matches: ClientMatch[]) {
+    return matches.filter(
+      (match, index) =>
+        index === 0 ||
+        (!match.route.index && match.route.path && match.route.path.length > 0)
+    );
   }
 
   async function handleActionFetchSubmission(
@@ -1071,14 +1082,10 @@ export function createTransitionManager(init: TransitionManagerInit) {
     // to run on layout/index routes.  We do not want to mutate the eventual
     // matches used for revalidation
     let actionMatches = matches;
-    if (
-      !isIndexRequestUrl(createUrl(submission.action)) &&
-      actionMatches[matches.length - 1].route.index
-    ) {
-      actionMatches = actionMatches.slice(0, -1);
-    }
-
-    let leafMatch = actionMatches.slice(-1)[0];
+    let leafMatch = getRequestMatch(
+      createUrl(submission.action),
+      actionMatches
+    );
     let result = await callAction(submission, leafMatch, controller.signal);
 
     if (controller.signal.aborted) {

packages/remix-server-runtime/server.ts

@@ -708,11 +708,19 @@ function isIndexRequestUrl(url: URL) {
 function getRequestMatch(url: URL, matches: RouteMatch<ServerRoute>[]) {
   let match = matches.slice(-1)[0];
 
-  if (!isIndexRequestUrl(url) && match.route.id.endsWith("/index")) {
-    return matches.slice(-2)[0];
+  if (isIndexRequestUrl(url) && match.route.id.endsWith("/index")) {
+    return match;
   }
 
-  return match;
+  return getPathContributingMatches(matches).slice(-1)[0];
+}
+
+function getPathContributingMatches(matches: RouteMatch<ServerRoute>[]) {
+  return matches.filter(
+    (match, index) =>
+      index === 0 ||
+      (!match.route.index && match.route.path && match.route.path.length > 0)
+  );
 }
 
 function getDeepestRouteIdWithBoundary(