Make a starved discovery cycle say so, in the log and on /api/health.

For about a year the production RELAYS list did not include the relay carrying
the kind 38000/38172 archive. Every backfill read about thirty events, wrote them
faithfully, reported ok=true, and the nightly build republished an index of eight
mints. Nothing measured the difference between "the cycle completed" and "the
cycle read anything", so nothing went red.

Three signals now do:

  - Per-relay attribution. queryRelays() replaces pool.querySync(), which merges
    every relay into one deduplicated array and throws away who sent what. It
    keeps one subscription per relay over the pool's existing sockets and shares
    a single alreadyHaveEvent across them, so an event five relays carry is still
    verified once; receivedEvent fires before that check, which is what makes the
    per-relay count mean "what this relay contributed". The deadline moved out of
    each Subscription's own EOSE timer so `eose` means a frame arrived rather than
    something timed out.

  - A WARN naming any relay that will not connect, on every cycle, and any relay
    that connected and sent nothing, on backfills only. An incremental cycle is
    supposed to come back empty.

  - BACKFILL_MIN_EVENTS, default 200. Under it, ERROR discovery starvation
    suspected and a flag health reports as discovery_starved, forcing 503. Sticky
    across incremental cycles so an hourly cycle finding four events cannot clear
    what a backfill diagnosed; stored in the database so a restart cannot either.

A fresh database is starved until its first backfill lands. That is intended: it
holds the build's health gate rather than publishing a site made from nothing.

Verified against the live relay set — 1528 events, five relays connected, EOSE on
all five, health 200 — and against an unreachable list, which produces the two
WARN lines, the ERROR, and 503.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.env.example

@@ -96,6 +96,19 @@ SEO_PRODUCT_JSONLD=1
 # so reviews the old site published to snort/primal were invisible to it.
 RELAYS=wss://relay.cashumints.space,wss://nos.lol,wss://relay.azzamo.net,wss://relay.snort.social,wss://relay.primal.net
 
+# How many events a backfill has to read before it counts as having read anything.
+#
+# A backfill asks every relay above for the whole history of four kinds; on a working
+# relay list that is thousands of events. Under this floor, discovery logs
+# `ERROR discovery starvation suspected` and /api/health answers 503 with
+# `discovery_starved: true` until the next backfill clears it.
+#
+# This exists because a RELAYS list missing the relay that carries the announcement
+# archive returned about thirty events per backfill for a year, reported ok=true every
+# time, and left the index at eight mints with every health signal green. Lower it only
+# for a private or test relay that genuinely holds less; 1 disables the check.
+#BACKFILL_MIN_EVENTS=200
+
 # Profile relays for the BUILD (kind 0, prerendered reviewer names on the home
 # page). A wider pool than RELAYS on purpose: relay.cashumints.space holds no kind
 # 0 at all and snort/primal hold almost none, so the two aggregators below are what