Fix agent host SDK terminal tool rendering; disable custom terminal tool by default

[roblourens]

Two related changes for the agent host SDK terminal tool experience.

1. Normalize LF to CRLF in agent host terminal tool output

The detached xterm used to render terminal tool output (DetachedTerminalSnapshotMirror.render() in chatTerminalCommandMirror.ts) calls terminal.xterm.write(text), which treats input as a raw TTY stream. A lone \n is just LF (cursor moves down, column unchanged), so subsequent lines start at whatever column the previous line ended producing a staircase.on

Example SDK output:

394:\tsshConfigHost: hostAlias,\n541:\tconst expectedKey = config.sshConfigHost\n542:\t\t? `ssh:${config.sshConfigHost}`\n

Rendered as:

394:                    sshConfigHost: hostAlias,
                                                 541:   const expectedKey = config.sshConfigHost
                                                                                                  542:            ? `ssh:${config.sshConfigHost}`

Why the custom terminal tool didn't hit this

xterm's serialize addon, which emits proper VT with \r\n. The agent host SDK path in stateToProgressAdapter.getTerminalOutput() just passed the SDK's plain text through unchanged.

Fix

\r\n in the adapter boundary where SDK content is shaped intoterminalCommandOutput. This:getTerminalOutput()

• keeps the custom-tool path untouched (already VT-correct);
• is co-located with the other SDK conversions;
• is idempotent on already-CRLF input.

Added a regression test covering mixed \n / \r\n input and updated two existing assertions in agentHostChatContribution.test.ts that exercised the same path.

2. Disable agent host custom terminal tool by default

Changed the default of chat.agentHost.customTerminalTool.enabled from true to false, so Copilot SDK sessions use the SDK's default terminal behavior out of the box. Users who want the Agent Host terminal tool override can still opt in.

(Written by Copilot)

[Copilot]

Pull request overview

Fixes staircase rendering of multi-line terminal tool output for agent-host SDK terminal tools by normalizing \n to \r\n in the adapter that produces terminalCommandOutput.text, so the detached xterm (which treats input as raw TTY) advances both row and column.

Changes:

• Normalize lone LF to CRLF in getTerminalOutput at the SDK-to-protocol adapter boundary.
• Add a regression test covering mixed \n / \r\n inputs.

Show a summary per file

File	Description
src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/stateToProgressAdapter.ts	Replace \r?\n with \r\n in getTerminalOutput, with explanatory comment.
src/vs/workbench/contrib/chat/test/browser/agentSessions/stateToProgressAdapter.test.ts	New test asserting CRLF normalization in finalized terminal tool output.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 1