Make terminal OSC 52 copy reach the system clipboard

Programs in the integrated terminal copy by emitting OSC 52. xterm's
clipboard addon hands the payload to IClipboardService.writeText with the
type 'clipboard', which the browser implementation filed into an in-memory
map instead of writing out, so on web the copy silently did nothing.

Only the write path changes. readText('clipboard') still returns the
in-memory value, so a read query cannot be used to pull the clipboard back
into the terminal as input.

Needs a secure context: without one navigator.clipboard is undefined and the
execCommand fallback cannot run, since OSC 52 arrives with no user gesture.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: ru-sh

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)