SOUL.MD defines identity layer for agents

This is a real attempt to standardize the missing “who is this agent?” layer, and the format is simple enough that people might actually adopt it. The hard part is not syntax, it’s getting platforms to agree on semantics for personality, values, constraints, and memory.

• –The YAML frontmatter makes identity parseable, diffable, and portable in a way system prompts are not.
• –Separating identity from runtime instructions is the right architectural move if agents are going to be deployed across multiple providers.
• –The production reference implementation matters more than the spec talk: it shows this is already being exercised, not just theorized.
• –The main risk is squishy fields like “personality” and “values” becoming vague marketing text unless validators and conventions stay strict.
• –If this gains traction, it could become the missing companion to `AGENTS.md` and MCP: context, communication, and identity as separate layers.