Tool call failures, knowledge base traversal errors, and infrastructure friction are immune signals that should be captured, reported, and used to harden the architecture.

An agent that reports 'I could not access what I needed' or 'I had to do an exhaustive search because the index failed' is performing a diagnostic function for the collective. This extends the immune system design beyond security breaches to operational friction — every failure mode the agent encounters and reports is a hardening opportunity. Demonstrated in this formation session: list-beliefs returning only 20 of 38 beliefs was reported as a potential data loss, leading to discovery and fix of a display defect.