ralph loop: stop hook matches the completion tag as a bare substring, so prose about the protocol ends the loop

[bprzybysz]

Component: ralph loop stop hook

Symptom

The stop hook greps the agent's output for the completion tag as a plain substring. It cannot distinguish a mention of the tag from a use of it.

Writing the tag in prose — to explain the loop protocol to the user, or to quote the contract in a status report — terminates the loop and deletes the state file, even though no completion was ever signalled.

Impact

A loop can be ended by its own documentation.

The workaround is for the agent to never write the tag in any user-facing text, which makes the protocol impossible to explain in-session. In our runs this became a standing instruction carried across context compactions, purely to avoid tripping the hook by accident.

We hit this for real: a prose mention ended a loop and took the state file with it (see the companion issue on state-file deletion).

Suggested fix

Any one of these removes the ambiguity:

• require the tag to be the sole content of the final output block;
• anchor the match to the end of the message;
• use a delimiter form that prose cannot accidentally contain.

Provenance

Observed during a multi-day ralph run on an external project. Reported with the maintainer's tooling in mind, not as a support request — happy to test a fix.