Another possibly reasonable option would be to create a (configurable) whitelist of commands that are considered safe, and keep running the pipeline automatical

Another possibly reasonable option would be to create a (configurable) whitelist of commands that are considered safe, and keep running the pipeline automatically as long as it only contains whitelisted commands. Any time a non-whitelisted command is introduced, stop auto-running and require Ctrl+Enter or something, until the command once again consists of only whitelisted commands. This would save you, for example, if you had a custom command called "gr" which was short for "get rid of current directory" (obviously chosen as a pathological example since it's a prefix of grep). As you type the word "grep", auto-running is paused because "g", "gr", and "gre" are not whitelisted, and then once "grep" is fully typed, it recognizes that "grep" is on the whitelist and resumes auto-running. And it never ran the dangerous "gr" command.