The Context Window Is a Budget

Fri, 02 Oct 2026 09:00:00 +0100

You are halfway through a refactor. Pi has read forty files, run the test suite twice, and rewritten the same module three times because each attempt turned out to conflict with the last. The session is still on disk, but the request has grown too large. If Pi compacts it, older messages are represented by a summary rather than sent in full.

Most people meet this as a mood: Pi got worse at the task. It is easier to reason about as a budget. Each request consumes a varying number of tokens within the model’s context window, across components you can inspect and, in several cases, change.

Changing What Pi Knows

Fri, 02 Oct 2026 09:00:00 +0100

The guard works. Pi asks before a force push, run_checks runs the project’s own tests, and the failing-test tool answers with structured data.

What still goes wrong is quieter. Pi reviews a diff using npm test instead of run_checks, despite the tool being declared to the model. The tool description makes it available; it does not guarantee selection. A reminder placed only in conversation history can also disappear from the request after compaction, leaving the model without that guidance on a later turn.

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The Context Window Is a Budget

Changing What Pi Knows