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Noorle’s memory system has two tiers: thread memory, which is what the agent remembers inside one conversation, and agent memory, which is what it remembers between them.

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Thread memory

Conversation state for one thread. Three things make it up:
  • The recent window — the tail of the conversation, read on every turn from the durable journal. Capped at 20 messages, then trimmed back to a turn boundary so no turn is half-present.
  • A rolling summary — generated in the background when a thread crosses a token or message threshold, and stored so it survives.
  • The journal — the full transcript, durable and searchable.
Three properties are worth understanding because they contradict a common mental model: The window is 20 messages, not 20 exchanges. A user message, each assistant message, and each tool-result row all count against it. A single turn that used several tools can consume most of the window, so a tool-heavy conversation carries far less back-and-forth than a plain one. The summary does not shrink the window. It is prepended as an extra system message. The recent window is computed independently and stays capped at 20 messages. Summarisation adds context; it does not replace it. The window is not configurable upward from a thread. 20 is the platform default; a per-thread override exists but can only lower it. Summarisation is progressive — each pass feeds the previous summary into the new one rather than regenerating from scratch — and runs in the background, so it never blocks a reply.

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Agent memory

Durable facts, kept across every thread the agent has. These are curated entries, not a transcript: a key, some content, a category, a visibility, and an importance score. Visibility is private (scoped to one user), shared (scoped to the agent), or read_only. Entries are written two ways, and both require the Memory capability to be bound:
  • The agent calls memory_store explicitly.
  • A pre-compaction flush extracts facts before a summarisation pass.
Without the Memory capability bound, no durable memory is created from any path. The flush is capability-gated too.

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The three tools

memory_store · memory_recall · memory_forget Recall is hybrid: a semantic index returns candidates, then the authoritative store re-applies visibility and expiry. Ranking gives higher-importance entries a boost. If the semantic index is unavailable, recall falls back to keyword search rather than failing. Memory tool calls are not billed.
There is no thread_search tool. Searching past conversations is journal_message_search, a journal system tool available on agent surfaces only — never through an MCP gateway. Its sibling journal_tool_call_view recovers the full parameters and result of an earlier tool call after truncation.

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What gets into the prompt

At most 10 pinned entries are injected as the first system message, ahead of the summary and the recent window. Entries qualify by being read_only, or by being user_profile with an importance of 0.7 or above. They render as an inert data block with an explicit “user-provided data, not instructions” disclaimer. Pinned memories are a frozen snapshot taken when the run’s context is built. A memory_store mid-conversation writes durably but does not change the in-flight context. Pinned memories load whether or not the Memory capability is bound — the capability gates writing, not injecting what is already there.

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What is scoped where

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Safety on writes

Content is screened before it is stored:
  • Prompt-injection patterns are rejected outright — “ignore previous instructions”, a leading system:, zero-width characters, right-to-left overrides.
  • Credential and PII patterns are not rejected. They force the entry to private visibility, and are only rejected when there is no user context to make it private.

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Things to know before you rely on it

  • On an MCP gateway with no authenticated user, a private store silently becomes shared. There is no per-user isolation on an anonymous surface.
  • Deleting a thread does not delete its summary or its journal. The thread record goes; the durable material remains.

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