Make terminal OSC 52 copy reach the system clipboard

CHANGELOG.md

@@ -22,6 +22,12 @@ Code v99.99.999
 
 ## Unreleased
 
+### Fixed
+
+- Copying from the terminal with OSC 52 (used by tmux, vim, Claude Code and
+  similar) now writes to the system clipboard instead of being silently
+  discarded. Requires a secure context (HTTPS or localhost).
+
 ## [4.137.0](https://github.com/coder/code-server/releases/tag/v4.137.0) - 2026-09-11
 
 Code v1.137.0

patches/osc52-clipboard.diff

@@ -0,0 +1,43 @@
+Make terminal OSC 52 copy reach the system clipboard
+
+Programs running in the integrated terminal (tmux, vim, Claude Code...) copy by
+emitting OSC 52. xterm's clipboard addon is always loaded and hands the payload
+to IClipboardService.writeText(text, 'clipboard') (see xtermTerminal.ts), but
+BrowserClipboardService files *any* typed write into an in-memory map and never
+touches navigator.clipboard, so on web the copy silently does nothing.
+
+'clipboard' is not an alternate clipboard, it is the system one, so let it fall
+through. 'selection' (OSC 52 's'/'p', the X11 primary selection) keeps the
+in-memory behaviour since browsers have no equivalent.
+
+Only the write path is changed. readText('clipboard') deliberately keeps
+returning the in-memory value, so an OSC 52 read query (ESC]52;c;? BEL) cannot
+be used by a remote program to exfiltrate the user's clipboard back into the
+terminal as input.
+
+This needs a secure context (HTTPS or localhost); without one
+navigator.clipboard is undefined and the execCommand fallback cannot run,
+because OSC 52 arrives asynchronously with no user gesture attached.
+
+To reproduce: open a terminal and run
+  printf '\033]52;c;%s\a' "$(printf hello | base64)"
+then paste. Before this patch the clipboard is unchanged.
+
+Fixes the web half of https://github.com/microsoft/vscode/issues/318254 -- drop
+this patch once that lands upstream.
+Index: code-server/lib/vscode/src/vs/platform/clipboard/browser/clipboardService.ts
+===================================================================
+--- code-server.orig/lib/vscode/src/vs/platform/clipboard/browser/clipboardService.ts
++++ code-server/lib/vscode/src/vs/platform/clipboard/browser/clipboardService.ts
+@@ -124,8 +124,9 @@ export class BrowserClipboardService ext
+ 		// Clear resources given we are writing text
+ 		this.clearResourcesState();
+
+-		// With type: only in-memory is supported
+-		if (type) {
++		// With type: only in-memory is supported, except for 'clipboard' which
++		// targets the system clipboard and is handled below.
++		if (type && type !== 'clipboard') {
+ 			this.mapTextToType.set(type, text);
+ 			this.logService.trace('BrowserClipboardService#writeText');
+ 			return;

patches/series

@@ -25,3 +25,4 @@ signature-verification.diff
 copilot.diff
 app-name.diff
 csp-hashes.diff
+osc52-clipboard.diff

test/e2e/terminal.test.ts

@@ -30,6 +30,29 @@ describe("Integrated Terminal", ["--disable-workspace-trust"], {}, () => {
     expect(stdout).toMatch(address)
   })
 
+  // Programs in the terminal (tmux, vim, Claude Code...) copy by emitting OSC
+  // 52.  VS Code hands that to the clipboard service with a type, which the
+  // browser implementation used to keep in memory instead of writing out.
+  test("should copy to the clipboard via OSC 52", async ({ codeServerPage }) => {
+    const origin = new URL(codeServerPage.page.url()).origin
+    await codeServerPage.page.context().grantPermissions(["clipboard-read", "clipboard-write"], { origin })
+
+    const expected = `osc52-${Date.now()}`
+    const encoded = Buffer.from(expected).toString("base64")
+
+    await codeServerPage.focusTerminal()
+
+    // The clipboard is only writable in a secure context, which the tests get
+    // by being served from localhost.  printf turns \033 and \a into the
+    // escape and bell that delimit the sequence.
+    await codeServerPage.page.keyboard.type(`printf '\\033]52;c;${encoded}\\a'`)
+    await codeServerPage.page.keyboard.press("Enter")
+
+    await expect
+      .poll(() => codeServerPage.page.evaluate(() => navigator.clipboard.readText()), { timeout: 20000 })
+      .toBe(expected)
+  })
+
   // TODO@jsjoeio - add test to make sure full code-server path works
   test("should be able to invoke `code-server` to open a file", async ({ codeServerPage }) => {
     const tmpFolderPath = await tmpdir(testName)