Memory

Memory stores curated facts across conversations. It is separate from session history: a session preserves a transcript, while memory keeps a small set of facts intended to remain useful beyond one transcript.

Built-in stores

The built-in provider uses two files:

$HERMES_HOME/memories/
├── MEMORY.md    # Agent notes, environment facts, and conventions
└── USER.md      # User preferences and profile information

Enable the prompt surfaces in $HERMES_HOME/config.yaml:

memory:
  memory_enabled: true
  user_profile_enabled: true
  memory_char_limit: 2200
  user_char_limit: 1375

Then expose the write/read tool to the model:

agent = AIAgent(..., enabled_toolsets=["memory"])

skip_memory=True disables memory loading for an agent regardless of the shared configuration. The batch runner sets this deliberately so one dataset item cannot contaminate another.

Cache-stable snapshots

Memory and user-profile text are bounded and frozen into the conversation's system-prompt snapshot. A memory tool call can update the files, but it does not mutate the already cached prompt prefix halfway through a conversation. A later conversation sees the updated snapshot.

External providers

The retained plugin surface includes Mem0 and ByteRover integrations. The built-in provider remains available, and at most one external memory provider can be active at a time. Provider initialization, prefetch, turn sync, tool calls, session transitions, and shutdown use async contracts.

Mem0's packaged SDK is optional (mem0 install extra); self-hosted HTTP modes can use the base async HTTP client. Availability still depends on external credentials and services.

Privacy and tenancy

Memory is application state, not a model-provider privacy boundary. Do not store credentials or sensitive material that the model should not receive. Isolate HERMES_HOME, memory provider namespaces, and session databases between untrusted tenants. See Security.