Context windows and forgotten instructions

Learning outcome: Separate available context from reliable use of that context.

A context window is the model input and output capacity for a request, measured in tokens. A chat product may also retrieve memories, compress earlier turns or supply tool results. These features differ from the model remembering an entire history without limits. Information being present does not guarantee it will be used correctly.

Treat a long project as a maintained brief. Keep the current goal, agreed decisions, source versions and unresolved questions together. When a rule changes, identify the old rule as superseded. Do not simply append another contradictory instruction and hope recency will solve the conflict. Check that a handover preserves the facts needed for the next task.

Worked example

An imaginary event starts at 09:00 in an early draft and 10:00 in the approved brief. The assistant produces both times in different sections. The repair is to identify the approved brief, remove the obsolete instruction from the active brief and check every reference to the start time. A longer context setting alone would not settle which source has authority.

Try it yourself

Write a five-line handover for an event whose start time changed. Include the approved time, superseded time, decision owner, unresolved venue question and next action.

You can do this exercise on paper. If using an assistant, keep to the fictional material and an approved tool.

Check your understanding

Both an old and a new deadline appear in the context. What should you establish first?

1. Which deadline makes the answer shorter
2. Which version is authoritative
3. Which deadline appears more often

Workbook

Download the course workbook to record your answer and compare it after the knowledge check.

Further reading

• Hugging Face: tokenizers
• Hugging Face: LLM course