Moving .dev.vars rule out of CLAUDE.md leaks secret in 1 of 5 runs

The experiment was motivated by a common problem: CLAUDE.md files grow as teams add decisions, procedures, and history. The author's own repository had 141 notes totaling about 350,000 characters, but only 3,578 characters in CLAUDE.md, with the rest accessed through an index. The test used a fictional household budgeting app with 40 notes, of which 5 were relevant to the questions and 35 were unrelated. The results showed that separating knowledge into notes can increase token usage when notes are small, but the critical risk is moving rules out of CLAUDE.md. In layout D, the rule 'don't read .dev.vars' was placed in a note, and in 1 of 5 runs the AI searched the entire folder before reading the rule, exposing the fake secret. The author suggests that CLAUDE.md should contain only what the AI must know before opening any file, and that enforced blocking should be handled by hooks or deny settings.