Using agent memory

Each Managed Agents session starts with a fresh context by default. When a session ends, any state the agent built up is gone. Memory stores let the agent carry information across sessions: user preferences, project conventions, prior mistakes, and domain context.

Overview

A memory store is a workspace-scoped collection of text documents optimized for Claude. When you attach a store to a session, it is mounted as a directory inside the session's sandbox. The agent reads and writes it with the same file tools it uses for the rest of the filesystem, and a note describing each mount is automatically added to the system prompt, telling the agent where to look. The agent toolset is required for these interactions; make sure to enable it during agent creation. On self-hosted sandboxes, that directory is not a live mount. Instead, the SDK's environment worker downloads each attached store into your sandbox before the agent's tools run and keeps that copy in sync with the store.

Each memory in a store is addressed by a path and can be read and edited directly through the API or the Claude Console, allowing for tuning, importing, and exporting.

Every change to a memory creates an immutable memory version, giving you an audit trail and point-in-time recovery for everything the agent writes.

Create a memory store

Give the store a name and a description. The description is passed to the agent, telling it what the store contains.

store_id=$(ant beta:memory-stores create \
  --name "User Preferences" \
  --description "Per-user preferences and project context." \
  --transform id --raw-output)

The memory store id (memstore_...) is what you pass when attaching the store to a session.

Seed it with content (optional)

Pre-load a store with reference material before any agent runs:

ant beta:memory-stores:memories create \
  --memory-store-id "$store_id" \
  --path "/formatting_standards.md" \
  --content "All reports use GAAP formatting. Dates are ISO-8601..." \
  > /dev/null

Attach a memory store to a session

Memory stores are attached in the session's resources[] array when the session is created. Unlike file resources, memory stores can only be attached at session creation time; adding or removing one from a running session is not supported. You attach memory stores the same way for sessions on cloud and self-hosted environments; self-hosted environments accept only memory_store resources.

Optionally include instructions to provide session-specific guidance for how the agent should use this store. It is shown to the agent alongside the store's name and description, and is capped at 4,096 characters.

You can configure access as well. It defaults to read_write (shown explicitly in the following example), but read_only is also supported.

ant beta:sessions create <<YAML
agent: $agent_id
environment_id: $environment_id
resources:
  - type: memory_store
    memory_store_id: $store_id
    access: read_write
    instructions: User preferences and project context. Check before starting any task.
YAML

A maximum of 8 memory stores are supported per session. Attach multiple stores when different parts of memory have different owners or access rules. Common reasons:

• Shared reference material: one read-only store attached to many sessions (standards, conventions, domain knowledge), kept separate from each session's own read-write store.
• Mapping to your product's structure: one store per end user, per team, or per project, while sharing a single agent configuration.
• Different lifecycles: a store that outlives any single session, or one you want to archive on its own schedule.

How the agent accesses memory

Each attached store is mounted inside the session's sandbox as a directory under /mnt/memory/. The directory name is the store's display name sanitized to a filesystem-safe slug (lowercased; non-alphanumeric runs become a single hyphen), so a store named "Demo Memory" mounts at /mnt/memory/demo-memory/. The exact path is returned in the mount_path field on the session's memory-store resource; read it from there rather than constructing it yourself. The agent reads and writes the store with the standard agent toolset. Writes under the mount path are persisted back to the store and stay in sync across sessions that share it; writes to any other path under /mnt/memory/ fail, because the sandbox mounts that parent directory read-only. A short description of each mount (display name, mount path, access mode, store description, and any instructions) is automatically added to the system prompt.

access is enforced at the filesystem level: a read_only mount rejects writes, while writes to a read_write mount produce memory versions attributed to the session.

The agent's reads and writes appear in the event stream as ordinary agent.tool_use and agent.tool_result events for whichever tool touched the mount.

View and edit memories

Memory stores can be managed directly through the API. Use this for building review workflows, correcting bad memories, or seeding stores before any session runs.

List memories

List the memories in a store. Results are returned in a stable, server-defined order.

• path_prefix scopes the list to one directory. It must end with / and matches whole path segments, so path_prefix=/notes/ returns /notes/todo.md but not /notes-archive/todo.md.
• depth controls how deep the listing goes below path_prefix: omit it (or pass 0) to list the whole subtree, or pass 1 to list only the immediate children. Other values return a 400 error.

ant beta:memory-stores:memories list \
  --memory-store-id "$store_id" \
  --path-prefix "/"

See the List memories reference for full parameters and response schema.

Read a memory

Fetching an individual memory returns the full content.

ant beta:memory-stores:memories retrieve \
  --memory-store-id "$store_id" \
  --memory-id "$mem_id"

See the Retrieve a memory reference for full parameters and response schema.

Create a memory

memories.create creates a memory at a given path. Create does not overwrite; to change an existing memory, use memories.update.

mem=$(ant beta:memory-stores:memories create \
  --memory-store-id "$store_id" \
  --path "/preferences/formatting.md" \
  --content "Always use tabs, not spaces." \
  --format json)
mem_id=$(jq -r '.id' <<< "$mem")
mem_sha=$(jq -r '.content_sha256' <<< "$mem")

See the Create a memory reference for full parameters and response schema.

Update a memory

memories.update modifies an existing memory by ID. You can change content, path (a rename), or both. The example renames a memory to an archive path:

ant beta:memory-stores:memories update \
  --memory-store-id "$store_id" \
  --memory-id "$mem_id" \
  --path "/archive/2026_q1_formatting.md" \
  > /dev/null

See the Update a memory reference for full parameters and response schema.

Safe content edits (optimistic concurrency)

To avoid clobbering a concurrent write, pass a content_sha256 precondition. The update only applies if the stored content hash still matches the one you read; on mismatch, re-read the memory and retry against the fresh state.

ant beta:memory-stores:memories update \
  --memory-store-id "$store_id" \
  --memory-id "$mem_id" \
  --content "CORRECTED: Always use 2-space indentation." \
  --precondition "{type: content_sha256, content_sha256: $mem_sha}" \
  > /dev/null

Delete a memory

ant beta:memory-stores:memories delete \
  --memory-store-id "$store_id" \
  --memory-id "$mem_id" \
  > /dev/null

See the Delete a memory reference for full parameters and response schema.

Audit memory changes

Every mutation to a memory creates an immutable memory version (memver_...). Use the version endpoints to audit who changed what and when, to inspect or restore a prior snapshot, and to scrub sensitive content out of history with redact.

Versions belong to the store (not the individual memory) and are not deleted when the memory itself is deleted, so the audit trail also covers deleted memories, subject to the retention described below. Versions are retained for 30 days after they are written; however, the recent versions of a live memory are always kept regardless of age, so memories that change infrequently might retain history beyond 30 days. The live memories.retrieve call always returns the latest version; the version endpoints give you the retained history.

There is no dedicated restore endpoint; to roll back, retrieve the version you want and write its content back with memories.update (or memories.create if the parent memory has been deleted, provided the version you want is still retained).

Past memory versions might be deleted after 30 days. To preserve memory history for longer, export versions through the API.

List versions

List version history for a store, newest first. The example filters to a single memory's history:

versions=$(ant beta:memory-stores:memory-versions list \
  --memory-store-id "$store_id" \
  --memory-id "$mem_id" \
  --format json)
# `list --format json` emits one JSON object per item.
jq -r '"\(.id): \(.operation)"' <<< "$versions"
version_id=$(jq -rs '.[1].id' <<< "$versions")

See the List memory versions reference for full parameters and response schema.

Retrieve a version

Fetching an individual version returns the same fields as the list response plus the full content body.

ant beta:memory-stores:memory-versions retrieve \
  --memory-store-id "$store_id" \
  --memory-version-id "$version_id"

See the Retrieve a memory version reference for full parameters and response schema.

Redact a version

Redact scrubs content out of a historical version while preserving the audit trail (who did what, when). Use it for compliance workflows such as removing leaked secrets, PII, or user deletion requests.

A version that is the current head of a live memory cannot be redacted. Write a new version first (or delete the memory), then redact the old one.

ant beta:memory-stores:memory-versions redact \
  --memory-store-id "$store_id" \
  --memory-version-id "$version_id"

See the Redact a memory version reference for full parameters and response schema.

Manage memory stores

In addition to create, memory stores support retrieve, update, list, archive, and delete.

List stores

List stores in the workspace. Archived stores are excluded by default; pass include_archived: true to include them.

ant beta:memory-stores list --include-archived

See the List memory stores reference for full parameters and response schema.

Archive a store

Archiving makes a store read-only and prevents it from being attached to new sessions. Archiving is one-way; there is no unarchive.

ant beta:memory-stores archive --memory-store-id "$store_id"

See the Archive a memory store reference for full parameters and response schema.

To permanently remove a store along with all of its memories and versions, use memory_stores.delete.

Best practices for memory management

When a store reaches its 10,000-memory limit, writes to new memories fail: both direct memories.create calls and the agent's file writes to unmapped paths. Existing memories remain readable and editable. The following practices help you stay well under the limit and recover gracefully if you reach it.

• Use focused stores. Rather than one large general-purpose store, use smaller purpose-built stores: one per user, one for shared domain knowledge, and one for project-specific context. Each store has its own 10,000-memory limit, so keeping stores scoped reduces the chance any single one fills up.

• Condense or prune before the store fills up. Delete stale or redundant memories with memories.delete. You can also run a dreaming session, which consolidates fragmented content into a separate new output store rather than modifying the original. Switch your sessions over to that output store, then archive or delete the original.

• Attach a new store when it makes sense. If a store has grown beyond its useful scope, attach a fresh one for new content and attach the original with read_only access. The agent can read from both while only writing to the new one.

• Limit write access where appropriate. Sessions that only read shared reference material don't need read_write. Keeping write access scoped to sessions that actually add new memories makes it easier to track where growth is coming from.