How to stop Ctrl+J from adding a new line in the Claude Code VS Code extension

In the Claude Code VS Code extension's prompt box, Ctrl+J inserts a new line, so a VS Code shortcut you bound to Ctrl+J doesn't fire there. Since v2.1.309 the extension reads Claude Code's keybindings.json, and unbinding the key there leaves Ctrl+J to VS Code and the OS.

1. Update the Claude Code extension to 2.1.309 or later in the Extensions view.
2. In keybindings.json in your Claude Code configuration directory, set "ctrl+j" to null in a Chat block. The directory is ~/.claude unless you moved it with CLAUDE_CONFIG_DIR. If the file doesn't exist, create it with exactly this content.

{
  "bindings": [
    {
      "context": "Chat",
      "bindings": {
        "ctrl+j": null
      }
    }
  ]
}

If the file exists, add the Chat block to the bindings array. If a Chat block is already there, add "ctrl+j": null to it, and if it already has a "ctrl+j" line, change only its value to null.

1. Save and press Ctrl+J in the prompt box. If it still adds a line, run Developer: Reload Window from the Command Palette. If that doesn't help, open Claude Code: Show Logs, find the warning that includes Ctrl+J in the chat input still inserts a newline, and fix the problem it reports.

Claude Code in the terminal reads the same file, so Ctrl+J stops adding a new line there too.