Long CLAUDE.md files can be cut to their start and marked start-only

What

CLAUDE.md is a memory file of standing instructions that Claude Code reads into a conversation. New code shows only the start of a CLAUDE.md file when it is too long. Each case sits behind its own gate, a switch Anthropic turns on remotely. Nothing has been read about either gate, so it is not known whether either one is on.

• Top-level CLAUDE.md files: in non-interactive sessions that are not diskless, files larger than a size that depends on the model are cut. A non-interactive session is one run from a script with no person typing. Each cut file is marked startOnly, and Claude Code's record of what it has read from that file is marked start-only. This needs the tengu_velvet_possum gate, a tool that can read files, and no tool that can edit them. Before, these instructions were never cut.
• Nested CLAUDE.md files (ones in subfolders): when such a file is cut, Claude Code's record of what it has read is marked start-only, but only under the tengu_quizzical_mango gate.
• Repeat announcements: Claude Code now compares a nested file against a list of its earlier announcements instead of a single one. It recognises an earlier cut version of the same file, so the file is not announced again. Before, the cut text was built in place with an 'Only the start of this file is shown' note.

Why

Very long memory files may reach scripted, headless runs only in part. The start-only marker shows Claude Code it has seen just the beginning of the file. Fewer repeat announcements mean a long nested CLAUDE.md is not added to the conversation again and again.