fix(router-plugin): don't prepend ./ to absolute paths in imports

Fixed an issue where absolute paths (used internally by bundlers like Vite
and Rspack) were incorrectly having './' prepended, creating invalid import
paths like './/home/workspace/...'.

The fix now checks if a path is absolute before adding the './' prefix:
- Unix absolute paths (starting with '/')
- Windows absolute paths (starting with drive letter like 'C:')
- Already relative paths (starting with './' or '../')

These are all left unchanged, while bare relative paths get './' prepended
for proper ES module resolution.

This maintains the correct behavior for both:
- User-facing relative imports (need './' for bundlers)
- Internal absolute paths (used by bundler virtual file systems)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: KyleAMathews

packages/router-plugin/src/core/code-splitter/compilers.ts

@@ -81,9 +81,13 @@ function addSplitSearchParamToFilename(
 ) {
   const [bareFilename] = filename.split('?')
 
-  // Ensure relative import specifier for proper bundler resolution
+  // Don't modify absolute paths - they're used internally by bundlers
+  // Only ensure relative import specifier for relative paths
   const relativeFilename =
-    bareFilename!.startsWith('./') || bareFilename!.startsWith('../')
+    bareFilename!.startsWith('/') || // Unix absolute path
+    /^[a-zA-Z]:/.test(bareFilename!) || // Windows absolute path (C:\ or C:/)
+    bareFilename!.startsWith('./') ||
+    bareFilename!.startsWith('../')
       ? bareFilename!
       : `./${bareFilename!}`
 
@@ -96,8 +100,13 @@ function addSplitSearchParamToFilename(
 
 function removeSplitSearchParamFromFilename(filename: string) {
   const [bareFilename] = filename.split('?')
-  // Ensure relative import specifier for proper bundler resolution
-  return bareFilename!.startsWith('./') || bareFilename!.startsWith('../')
+
+  // Don't modify absolute paths - they're used internally by bundlers
+  // Only ensure relative import specifier for relative paths
+  return bareFilename!.startsWith('/') || // Unix absolute path
+    /^[a-zA-Z]:/.test(bareFilename!) || // Windows absolute path (C:\ or C:/)
+    bareFilename!.startsWith('./') ||
+    bareFilename!.startsWith('../')
     ? bareFilename!
     : `./${bareFilename!}`
 }

packages/router-plugin/tests/add-hmr/snapshots/react/[email protected]

@@ -1,4 +1,4 @@
-const $$splitComponentImporter = () => import('arrow-function.tsx?tsr-split=component');
+const $$splitComponentImporter = () => import('./arrow-function.tsx?tsr-split=component');
 import { lazyRouteComponent } from '@tanstack/react-router';
 import * as React from 'react';
 import { createFileRoute } from '@tanstack/react-router';

packages/router-plugin/tests/add-hmr/snapshots/react/[email protected]

@@ -1,4 +1,4 @@
-const $$splitComponentImporter = () => import('arrow-function.tsx?tsr-split=component');
+const $$splitComponentImporter = () => import('./arrow-function.tsx?tsr-split=component');
 import { lazyRouteComponent } from '@tanstack/react-router';
 import * as React from 'react';
 import { createFileRoute } from '@tanstack/react-router';

packages/router-plugin/tests/add-hmr/snapshots/react/[email protected]

@@ -1,4 +1,4 @@
-const $$splitComponentImporter = () => import('function-declaration.tsx?tsr-split=component');
+const $$splitComponentImporter = () => import('./function-declaration.tsx?tsr-split=component');
 import { lazyRouteComponent } from '@tanstack/react-router';
 import * as React from 'react';
 import { createFileRoute } from '@tanstack/react-router';

packages/router-plugin/tests/add-hmr/snapshots/react/[email protected]

@@ -1,4 +1,4 @@
-const $$splitComponentImporter = () => import('function-declaration.tsx?tsr-split=component');
+const $$splitComponentImporter = () => import('./function-declaration.tsx?tsr-split=component');
 import { lazyRouteComponent } from '@tanstack/react-router';
 import * as React from 'react';
 import { createFileRoute } from '@tanstack/react-router';

packages/router-plugin/tests/add-hmr/snapshots/solid/[email protected]

@@ -1,4 +1,4 @@
-const $$splitComponentImporter = () => import('arrow-function.tsx?tsr-split=component');
+const $$splitComponentImporter = () => import('./arrow-function.tsx?tsr-split=component');
 import { lazyRouteComponent } from '@tanstack/solid-router';
 import { createFileRoute } from '@tanstack/solid-router';
 import { fetchPosts } from '../posts';

packages/router-plugin/tests/add-hmr/snapshots/solid/[email protected]

@@ -1,4 +1,4 @@
-const $$splitComponentImporter = () => import('arrow-function.tsx?tsr-split=component');
+const $$splitComponentImporter = () => import('./arrow-function.tsx?tsr-split=component');
 import { lazyRouteComponent } from '@tanstack/solid-router';
 import { createFileRoute } from '@tanstack/solid-router';
 import { fetchPosts } from '../posts';