Preserve output channel visibility on restart

[Pradeep Ramola (pradeep-ramola)]

Summary

Preserves a language client's output channel visibility across LanguageClient.restart().

If the output channel is already visible before restart, the client shows it again after restart succeeds using show(true) so focus is preserved. If the output channel is hidden or has not been created, restart behavior is unchanged.

The visibility detector matches VS Code log output resources by normalized log-channel resource suffix instead of using a broad substring match. This avoids treating another visible output channel as a match when, for example, the extension id contains the channel name, and it handles channel names that VS Code sanitizes in log file names.

This moves the behavior requested in microsoft/vscode-eslint#2206 into the shared LSP client library so other clients can benefit from it too.

Validation

• npm run compile:client
• npm run compile:client-node-tests
• npm run lint --prefix client
• npm run lint --prefix client-node-tests
• npm run test --prefix client-node-tests (208 passing)

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[Copilot]

🟡 Changes recommended

Output-channel matching is unreliable, and the tests bypass that detection logic.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Preserves a language client’s output-channel visibility across successful restarts.

Changes:

• Detects whether the output channel is visible before stopping.
• Restores visible channels without stealing focus.
• Adds restart sequencing tests.

File summaries

File	Description
client/src/node/main.ts	Captures and restores visibility around restart.
client/src/common/client.ts	Implements visibility detection and restoration.
client-node-tests/src/integration.test.ts	Adds restart behavior tests.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 2
• Review effort level: Balanced

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[Dirk Bäumer (dbaeumer)]

Pradeep Ramola (@pradeep-ramola) can you have a look at the copilot comments.

[Pradeep Ramola (pradeep-ramola)]

Addressed the Copilot review comments in 77348094.

What changed:

• Replaced the substring-based output-channel visibility check with a normalized log resource suffix match. This uses the same invalid filename character removal VS Code applies when creating log output channel resources.
• Added a protected getVisibleTextEditors() wrapper so tests can exercise the real isOutputChannelVisible() detector without overriding it.
• Expanded restart/detector coverage for a matching visible output document, a hidden channel with another visible output document whose extension id contains the channel name, and a sanitized channel name such as C/C++.

Validated locally with:

• npm run compile:client
• npm run compile:client-node-tests
• npm run lint --prefix client
• npm run lint --prefix client-node-tests
• npm run test --prefix client-node-tests (207 passing)

[Pradeep Ramola (pradeep-ramola)]

Resolved the merge conflict with current main in 892c8683.

The conflict was in client-node-tests/src/integration.test.ts; I kept both the restart coverage from this PR and the upstream socket transport test added on main.

Validation after resolving conflicts:

• npm run compile:client
• npm run compile:client-node-tests
• npm run lint --prefix client
• npm run lint --prefix client-node-tests
• npm run test --prefix client-node-tests (208 passing)