Procedural memory is the agent's how-to knowledge. Not facts, not episodes, skills. "How I usually handle this kind of task." "The recipe that worked last time." Agents that build up procedural memory get better at recurring tasks over time.
After a successful task, agent (or human) distills the solution into a reusable recipe:
{
"procedure_id": "deploy_staging",
"description": "How to deploy a branch to staging",
"steps": [
"Confirm branch is up to date with main",
"Run tests locally",
"Push to remote",
"Trigger staging deploy workflow",
"Verify at staging.example.com"
],
"constraints": "Don't deploy on Fridays after 3pm"
}
When agent starts a task matching an existing procedure, retrieve it and follow (or adapt). Much faster than reasoning from scratch.
A mature agent system has all four, layered.