Reverse Engineering Reveals Claude Code Quietly Shipped 'Pinned Memories'
imjustnewatai · x · 2026-07-25
By diffing three consecutive public binaries of Claude Code (2.1.217 to 2.1.219), a developer discovered that Anthropic quietly shipped an unannounced “pinned memories” system.
- Mechanism: By marking a project memory file with metadata.pinned: true, Claude will inject its contents into every future conversation for that project.
- Limits: It keeps up to 4 pinned files, newest first, with each capped at 200 lines or 25KB.
- Status: The feature is missing from the official changelog, and current docs still claim topic memory is read on demand. Rollout appears feature-gated and unconfirmed.
This gives Claude Code an always-on working set for critical project facts and preferences.
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