Leading whitespace before slash commands is no longer stripped — command text sent as message instead

Version: Claude Code v2.1.119, Opus 4.7 (1M context), Claude Max

Summary

Lines starting with whitespace followed by a slash command (e.g. /plugin uninstall foo) are no longer recognized as slash commands. They're being sent to the model as regular chat messages. Previously, Claude Code stripped leading whitespace before matching against /, so commands pasted from external sources or copied with indentation still worked as commands. This is a regression — observed on 2026-04-24.

Reproduction

1. Start a Claude Code CLI session.
2. At the prompt, type or paste: ␣␣/plugin (two spaces followed by /plugin).
3. Observe: the message is sent to the model instead of opening the /plugin UI.

Expected behavior

Leading whitespace before a slash-command token is stripped; the command is recognized and invoked by Claude Code itself.

Actual behavior

The leading whitespace prevents slash-command recognition; the text is sent to the model as a chat message. The model's response (something like "I can't invoke slash commands for you — type that line at the prompt") is just a downstream effect of the command not being intercepted by the CLI at all.

Example transcript

❯   /plugin uninstall standard-tooling@standard-tooling-marketplace

⏺ I'll wait — that's a command you're running, not a request for me. Let me know when you want me to do something.

❯   /plugin uninstall standard-tooling@standard-tooling-marketplace

⏺ /plugin is a built-in Claude Code command you run yourself in the CLI — I can't invoke it for you. Type that line at the prompt (not in a message to me) and Claude Code will uninstall the plugin.

Impact

Copy-paste workflows that include indentation (run books, step-by-step guides in markdown, previous transcripts where the command appeared in a bulleted or indented block) now silently send the command as a message instead of executing it. Wasted round-trips and confusion about whether the command was accepted.

Regression

This worked historically — pasting commands with leading whitespace from research-run transcripts was routine. The behavior change is recent.

Workaround

Manually remove leading whitespace before / before pressing Enter.