X_DOC_CAUSE_ECHOES_TITLE
Means
a row of this page states its title again as its typical cause
Typical cause
the row was written with no cause of its own — bun run new-error-code used to copy --title into the cell when none was given — so it says what failed twice and why it fails never, the half an agent reads to know what to look for
Fix
bun run scripts/doc-fixes.ts --json names each row and line; rewrite its Typical cause cell. A new code takes one as bun run new-error-code <CODE> … --cause '<what usually makes it happen>'