The most expensive class of agent error is recommending a function that doesn't exist. Users follow the recommendation, hit the wall, and distrust the tool for the rest of the session. The defence is simple: verify before recommending.
Whenever you're about to type a function name and your confidence isn't backed by a recent grep.
LLM training data is a snapshot. Real codebases drift. Memory is ephemeral. The only authoritative source for "does this symbol exist" is the working tree (and, for recently-removed symbols, git history).
The frontmatter steps are the canonical verification ladder: grep,
then git log -S, then suspect rename, then admit defeat. Each rung
adds confidence; reaching the bottom rung without a hit is itself the
answer.
The frontmatter pitfalls are the recurring failure modes. The
"rephrasing to sound more authoritative" antipattern is especially
damaging — it converts a low-confidence guess into high-confidence
output without adding any evidence.