A window that opens before a counter existed reports that counter as though
it had been measured throughout. The reader cannot tell "zero because
nothing happened" from "zero because nobody was counting yet", and — worse
— cannot tell a partial count from a complete one. That middle case yields
a plausible FRACTION rather than an obvious zero, which is what makes it
dangerous.
It is not hypothetical. A 7-day window opened while the ranked rule
surfacing recorders were four days old produced an apparent 64% write loss,
which survived a code review, four ruled-out alternative causes and a
five-step milestone before an identity check falsified it in one read.
Every counter block now carries `complete_from` and `covers_window`.
THE GRAIN IS THE SOURCE. retrieval_logs accumulates for months, so a
per-table earliest row says months for every source it holds — including an
arm added days ago whose counter means something else entirely. The old
source would vouch for the young one, which is the exact reading this
prevents.
A SECTION TAKES ITS LATEST CONTRIBUTOR, NOT ITS EARLIEST. A figure summing
several sources is complete only once every one of them was being written,
so "*" is a max. Using min would reproduce the original error in miniature.
`covers_window` is null, never false, when nothing was ever recorded: "no
measurement" is not "partial measurement" — the null convention #3497
established for `suppression`, one level up.
Also corrects a stale claim in the tool docstring: it still taught readers
that write_path_rule "has never once declined to fire" (#3311). That was
the arm writing its retrieval_logs row only on calls that found something;
#3497 fixed it, and the arm declines the large majority of its calls.
_complete_from takes the caller's session rather than opening its own,
departing from the services canon (#2860) because it runs inside an
existing block; to be recorded against the ledger once it ingests.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011cPyzNnegXHr5iRMzzy5KJ
bvandeusenandClaude Opus 5
21a5831479