Memory Write

Overview

The Memory Write node persists arbitrary JSON values into the platform's memory system under a named namespace and key. If an entry with the same memory_id + key combination already exists it is overwritten (upsert semantics). Session-scoped entries can optionally carry a TTL after which they are automatically evicted. This node is commonly used to checkpoint conversation history, cache computed results, or accumulate state across the nodes of a multi-turn workflow.

Configuration

Field	Type	Required	Default	Description
memory_id	string	Yes	—	Namespace that groups related memory entries. Supports {{expression}} template syntax (e.g. "user:{{run.userId}}:ctx").
key	string	Yes	—	Unique key within the namespace under which the value is stored.
value	any	No	—	Static JSON value to write. If omitted, the node reads the value from the value input port at runtime.
type	string	No	"session"	Memory tier to write to. One of "session" (run-scoped) or "long_term" (persisted across runs).
ttl_seconds	integer	No	—	Time-to-live in seconds. Only applicable when type is "session". The entry is automatically evicted after this duration. Omit for no expiry within the session.
merge	boolean	No	false	When true and the existing value is an object, the incoming value is deep-merged rather than replaced. Arrays are always replaced.

Inputs

Port	Type	Description
value	any	Value to write. Overrides config.value when provided at runtime. Accepts any JSON-serialisable type.
memory_id	string	Optional runtime override for the memory_id config field.
key	string	Optional runtime override for the storage key.

Outputs

Port	Type	Description
output	object	Confirmation object with memory_id (string), key (string), type (string), and written_at (ISO-8601 timestamp).

Example

{
  "nodeType": "memory_write",
  "config": {
    "memory_id": "user:{{run.userId}}:conversation",
    "key": "history",
    "type": "long_term",
    "merge": false
  }
}

{
  "nodeType": "memory_write",
  "config": {
    "memory_id": "session:{{run.sessionId}}:cache",
    "key": "search_results",
    "type": "session",
    "ttl_seconds": 300
  }
}

Notes

• ttl_seconds is only honoured for "session" type entries; setting it on a "long_term" entry has no effect and generates a build-time warning.
• Using merge: true is safe only when the stored value is a flat or shallow object; deep merges on large or cyclic structures can produce unexpected results.
• The output port confirmation object is useful for audit trails; connect it to a kv_store_write or webhook_sender node if you need to log every write.
• To implement a rolling conversation window, read the history with memory_read, append the new message in a json_transform node, then write the result back with this node.