fix: preserve path, query, and fragment in proxy URLs (#7668)

CHANGELOG.md

@@ -22,6 +22,11 @@ Code v99.99.999
 
 ## Unreleased
 
+### Fixed
+
+- Preserve the original path, query parameters, and fragment when rewriting
+  localhost URLs through the port proxy (#7668).
+
 ## [4.137.0](https://github.com/coder/code-server/releases/tag/v4.137.0) - 2026-09-11
 
 Code v1.137.0

patches/proxy-uri.diff

@@ -13,12 +13,18 @@ This has e2e tests.
 For the `asExternalUri` changes, you'll need to test manually by:
 1. running code-server with the test extension
 2. Command Palette > code-server: asExternalUri test
-3. input a url like http://localhost:3000
-4. it should show a notification and show output as <code-server>/proxy/3000
+3. input a url like http://localhost:3000/my/path?token=abc#section
+4. it should show a notification and show output as
+   <code-server>/proxy/3000/my/path?token%3Dabc#section
 
 Do the same thing but set `VSCODE_PROXY_URI: "https://{{port}}-main-workspace-name-user-name.coder.com"`
 and the output should replace `{{port}}` with port used in input url.
 
+The rewritten URI must preserve the original path, query, and fragment (see
+#7668). Append the original path to the proxy path using URI components so
+encoded characters are not decoded or encoded twice. This also works with
+proxy templates that do not have a trailing slash.
+
 This also enables the forwared ports view panel by default.
 
 Lastly, it adds a tunnelProvider so that ports are forwarded using code-server's
@@ -104,7 +110,7 @@ Index: code-server/lib/vscode/src/vs/code/browser/workbench/workbench.ts
  import type { IURLCallbackProvider } from '../../../workbench/services/url/browser/urlService.js';
  import { create } from '../../../workbench/workbench.web.main.internal.js';
 
-@@ -612,6 +613,39 @@ class WorkspaceProvider implements IWork
+@@ -612,6 +613,44 @@ class WorkspaceProvider implements IWork
  		settingsSyncOptions: config.settingsSyncOptions ? { enabled: config.settingsSyncOptions.enabled, } : undefined,
  		workspaceProvider: WorkspaceProvider.create(config),
  		urlCallbackProvider: new LocalStorageURLCallbackProvider(config.callbackRoute),
@@ -116,7 +122,12 @@ Index: code-server/lib/vscode/src/vs/code/browser/workbench/workbench.ts
 +					const renderedTemplate = config.productConfiguration.proxyEndpointTemplate
 +						.replace('{{port}}', localhostMatch.port.toString())
 +						.replace('{{host}}', window.location.host)
-+					resolvedUri = URI.parse(new URL(renderedTemplate, window.location.href).toString())
++					const proxyUri = URI.parse(new URL(renderedTemplate, window.location.href).toString())
++					resolvedUri = proxyUri.with({
++						path: proxyUri.path.replace(/\/$/, '') + uri.path,
++						query: uri.query,
++						fragment: uri.fragment,
++					})
 +				} else {
 +					throw new Error(`Failed to resolve external URI: ${uri.toString()}. Could not determine base url because productConfiguration missing.`)
 +				}

test/e2e/extensions.test.ts

@@ -15,6 +15,56 @@ function runTestExtensionTests() {
     const normalizedAddress = address.replace(/\/+$/, "")
     await expect(codeServerPage.page.getByText(`Info: proxyUri: ${normalizedAddress}/proxy/{{port}}/`)).toBeVisible()
   })
+
+  runExternalUriTests()
+}
+
+function runExternalUriTests(proxyEndpointTemplate?: string) {
+  const cases = [
+    {
+      name: "path",
+      input: "http://127.0.0.1:1234/my/path",
+      suffix: "/my/path",
+    },
+    {
+      name: "query and fragment",
+      input: "http://localhost:1234/my/path?token=abc&mode=preview#section",
+      suffix: "/my/path?token%3Dabc%26mode%3Dpreview#section",
+    },
+    {
+      name: "encoded components",
+      input: "http://0.0.0.0:1234/my%20path/%23file?token=a%20b#my%20section",
+      suffix: "/my%20path/%23file?token%3Da%20b#my%20section",
+    },
+    {
+      name: "root path",
+      input: "http://127.0.0.1:1234/",
+      suffix: "/",
+    },
+  ]
+
+  for (const { name, input, suffix } of cases) {
+    test(`asExternalUri should preserve ${name}`, async ({ codeServerPage }) => {
+      const address = await getMaybeProxiedCodeServer(codeServerPage)
+      const normalizedAddress = address.replace(/\/+$/, "")
+      const proxyBase = proxyEndpointTemplate
+        ? new URL(proxyEndpointTemplate.replace("{{port}}", "1234"), `${normalizedAddress}/`).toString()
+        : `${normalizedAddress}/proxy/1234/`
+
+      await codeServerPage.waitForTestExtensionLoaded()
+      await codeServerPage.executeCommandViaMenus("code-server: asExternalUri test")
+
+      const inputBox = codeServerPage.page.locator(".quick-input-widget input")
+      await inputBox.fill(input)
+      await inputBox.press("Enter")
+
+      // The test extension displays URI.toString(), which also encodes query delimiters.
+      const output = `${proxyBase.replace(/\/$/, "")}${suffix}`
+      await expect(
+        codeServerPage.page.getByText(`Info: input: ${input} output: ${output}`, { exact: true }),
+      ).toBeVisible()
+    })
+  }
 }
 
 const flags = ["--disable-workspace-trust", "--extensions-dir", path.join(__dirname, "./extensions")]
@@ -23,6 +73,17 @@ describe("Extensions", flags, {}, () => {
   runTestExtensionTests()
 })
 
+for (const proxyEndpointTemplate of ["./proxy/{{port}}", "https://{{port}}-workspace.example.com"]) {
+  describe(
+    `Extensions with VSCODE_PROXY_URI=${proxyEndpointTemplate}`,
+    flags,
+    { VSCODE_PROXY_URI: proxyEndpointTemplate },
+    () => {
+      runExternalUriTests(proxyEndpointTemplate)
+    },
+  )
+}
+
 if (process.env.USE_PROXY !== "1") {
   describe("Extensions with --cert", [...flags, "--cert"], {}, () => {
     runTestExtensionTests()