Fix disposed store error in DetachedTerminalSnapshotMirror

[Copilot]

DetachedTerminalSnapshotMirror can be disposed while async operations (attach(), render()) are in flight. Subsequent access to terminal.xterm.buffer triggers xterm's internal lazy registration, causing "Trying to add a disposable to a DisposableStore that has already been disposed of" errors.

Changes

• Constructor: Dispose terminal immediately if store is already disposed when promise resolves
• attach(): Early return after awaiting terminal if disposed
• render(): Early return after _getTerminal() and after terminal.xterm.write() if disposed

// Before: No disposal check after async
const terminal = await this._getTerminal();
this._computeMaxColumnWidth(terminal); // Throws if disposed

// After: Guard async continuations
const terminal = await this._getTerminal();
if (this._store.isDisposed) {
    return undefined;
}
this._computeMaxColumnWidth(terminal);

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• redirector.gvt1.com
  • Triggering command: /proc/self/exe /proc/self/exe --type=utility --utility-sub-type=network.mojom.NetworkService --lang=en-US --service-sandbox-type=none --no-sandbox --crashpad-handler-pid=6781 --enable-crash-reporter=7406e0f2-c70e-45b3-a85a-795a433530b7,no_channel --user-data-dir=/tmp/vscode-tests-1768928301321 --shared-files=v8_context_snapshot_data:100 --field-trial-handle=3,i,12506016518474805750,15792222962786304686,262144 --enable-features=PdfUseShowSaveFilePicker --disable-features=LocalNetworkAccessChecks,ScreenAIOCREnabled,SpareRendererForSitePerProcess,TraceSiteInstanceGetProcessCreation --variations-seed-version --trace-process-track-uuid=3190708989122997041 (dns block)
  • Triggering command: .build/electron/code-oss .build/electron/code-oss test/unit/electron/index.js --crash-reporter-directory=/home/REDACTED/work/vscode/vscode/.build/crashes --runGlob **/chatTerminalCommandMirror.test.js (dns block)
  • Triggering command: /proc/self/exe /proc/self/exe --type=utility --utility-sub-type=network.mojom.NetworkService --lang=en-US --service-sandbox-type=none --no-sandbox --crashpad-handler-pid=8480 --enable-crash-reporter=7406e0f2-c70e-45b3-a85a-795a433530b7,no_channel --user-data-dir=/tmp/vscode-tests-1768928654352 --shared-files=v8_context_snapshot_data:100 --field-trial-handle=3,i,14289129642060378853,1945214153318072413,262144 --enable-features=PdfUseShowSaveFilePicker --disable-features=LocalNetworkAccessChecks,ScreenAIOCREnabled,SpareRendererForSitePerProcess,TraceSiteInstanceGetProcessCreation --variations-seed-version --trace-process-track-uuid=3190708989122997041 d tsgo --project .ldd ommandMirror.tes/home/REDACTED/.cache/ms-playwright/webkit-2215/minibrowser-wpe/sys/lib/libsoup-3.0.so.0.7.4 odules/npm/node_modules/@npmcli/run-script/lib/node-gyp-bin/ldd ldd (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>Trying to add a disposable to a DisposableStore that has already been disposed of</issue_title>
<issue_description>On latest main and still running into these

xtermTerminal.ts:110 Error: Trying to add a disposable to a DisposableStore that has already been disposed of. The added object will be leaked!
    at g.add (xterm.js:1:367549)
    at u._register (xterm.js:1:368195)
    at get buffer (xterm.js:1:500912)
    at get buffer (xtermTerminal.ts:110:33)
    at DetachedTerminalSnapshotMirror._computeMaxColumnWidth (chatTerminalCommandMirror.ts:638:53)
    at DetachedTerminalSnapshotMirror.render (chatTerminalCommandMirror.ts:632:44)
    at async ChatTerminalToolOutputSection._renderSnapshotOutput (chatTerminalToolProgressPart.ts:1050:18)
    at async ChatTerminalToolOutputSection._updateTerminalContent (chatTerminalToolProgressPart.ts:997:4)
    at async ChatTerminalToolOutputSection.toggle (chatTerminalToolProgressPart.ts:878:3)
    at async ChatTerminalToolProgressPart._toggleOutput (chatTerminalToolProgressPart.ts:666:21)
```</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes Trying to add a disposable to a DisposableStore that has already been disposed of #288638

---

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[Copilot]

Pull request overview

This PR fixes a race condition where DetachedTerminalSnapshotMirror can be disposed while async operations are in flight, causing "Trying to add a disposable to a DisposableStore that has already been disposed of" errors when accessing terminal.xterm.buffer.

Changes:

• Added disposal checks after async operations in constructor, attach(), and render() methods
• Added test-output.json to .gitignore to exclude test artifacts

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/vs/workbench/contrib/terminal/browser/chatTerminalCommandMirror.ts	Added disposal checks in DetachedTerminalSnapshotMirror after awaiting terminal to prevent accessing disposed terminal buffers
.gitignore	Excluded test-output.json test artifact from version control

[Copilot]

The disposal check guards added to prevent the "Trying to add a disposable to a DisposableStore that has already been disposed of" error are not covered by tests. Consider adding a test case that simulates the disposal race condition by disposing the DetachedTerminalSnapshotMirror while async operations (attach() or render()) are in flight, to ensure the disposal checks work as intended and prevent the error.