Context Windows, Memory and the Limits of a Conversation

November 10, 2026

3 Minutes

A conversation with an AI tool can feel continuous even when the machinery behind it is changing what it keeps. That matters when you are working through a long brief, a script or a collection of documents.

The word memory is especially slippery. It can refer to information in the current input, a summary of previous messages or something a product stores and retrieves later. Those mechanisms have different limits.

What fits is not always what gets used well

A context window is the amount of information a model can accept for an operation, measured in tokens. Depending on the system, that budget may include instructions, conversation history, retrieved material and room for the response.

A large window is useful, but capacity alone does not establish reliable use of every detail. Anthropic's context engineering guidance discusses the need to select, organise and maintain useful context as an agent's work grows.

For a long project, I would ask a more practical question than the advertised maximum: can the tool find and correctly use the specific requirement I care about

Try placing an important qualification in different parts of a test document. Ask a question that depends on it. Compare the responses with the original text rather than assuming that a successful upload means a successful reading.

Different things called memory. Current context: Available for this operation. Summary: A condensed account. Stored record: Persisted by a product. Retrieval: Selected for a later task

Give the project a stable reference

Imagine a fictional website commission with three audiences, an approved budget boundary and a rule against inventing client testimonials. After many discussions, those facts may be surrounded by discarded ideas.

I would keep a short approved brief outside the conversation. It would record the current objective, audiences, required pages, factual claims, unresolved questions and decisions already made. Date the brief and distinguish approved material from proposals.

When a conversation is summarised, compare the summary with this brief. A summary that forgets “do not publish the client's name” can cause a much larger problem than a summary that forgets an early colour suggestion.

This is also a reason to retain original documents. A condensed record is convenient, but it may omit wording whose exact meaning matters. For an agreement or a quotation, return to the source instead of relying on a summary of a summary.

These are workflow recommendations. They do not establish how a particular service stores data or whether it uses conversations for training. Check that service's current settings and documentation separately.

Keep an approved project brief. Facts: What is established. Decisions: What is currently approved. Questions: What still needs an answer. Source files: The original evidence

Decide what belongs in the next step

A useful project brief should not grow until it becomes another unreadable archive. Keep the facts needed for the current task visible. Move discarded options into a separate record if you need to preserve them.

Before asking for a page description, provide the approved facts for that page, the intended reader and the output requirements. You do not need every previous discussion about the site's menu animation.

After receiving the description, ask which source statements support its factual claims. Then check the answer yourself. The point is to make omissions and additions easier to find.

For a continuing project, I would keep a small decision log: what changed, why it changed and which document now represents the approved version. When the task moves to another session or another tool, that log can travel with the source material.

The conversation is a place to work. It should not be the only place where the project exists.

Once you treat context as a limited resource that needs editing, you can stop hoping the tool remembers everything and start giving it the information that the next decision actually needs.