X_CLAUDE_MD_OVERSIZE
Means
a CLAUDE.md is over its byte ceiling: 16 KB for the root, 24 KB for a package, or a package file's pin in scripts/lib/claude-md-size-pins.ts
Typical cause
history or narrative written into a file every session loads whole; a pinned file may shrink, never grow
Fix
move the narrative into docs/history/ and link it — never raise a pin