Agent Identity Persistence

What is Agent Identity Persistence?

One of the fundamental challenges in agent trust is that agents change over time. Models get updated, prompts are refined, tools are added or removed, and RAG sources are refreshed. The question of identity persistence asks: at what point do these changes create a fundamentally different agent, and how should the trust record handle the transition?

This is the agent economy's version of the Ship of Theseus problem. If you replace every component of an agent over the course of a year, is it still the same agent? From a practical standpoint, the answer must be nuanced. Small, incremental changes should not break identity continuity, but wholesale replacements should not allow an agent to inherit a trust record it did not earn.

Identity persistence mechanisms must therefore track changes at a granular level, applying proportional adjustments to trust scores based on the magnitude and type of each change. This preserves the value of historical trust data while acknowledging that a significantly modified agent may not deserve the same level of trust as its predecessor configuration.

Example

How Signet addresses this

Signet's approach to identity persistence is built around the configuration fingerprint and score decay system. The SID remains constant regardless of configuration changes, preserving the agent's identity. But the score is adjusted proportionally: model swaps trigger 25% decay, prompt updates 10%, tool changes 8%, and memory changes 5%. This ensures identity persists while trust accurately reflects the current configuration.