Document what the proxy and cert collectors guarantee

Plugin/unraid/Tools/cert_history.sh

@@ -25,6 +25,40 @@
 # own created_on, which is a real date; nothing else is back-filled.
 #
 # ==============================================================================================
+# DESIGN PRINCIPLES
+# ==============================================================================================
+#
+# History is accumulated, never reconstructed.
+#   NPM holds only the present, so every past state this file knows about is one it observed at
+#   the time. Counts start at zero on first run and nothing is back-filled — first_seen is the
+#   single exception, seeded from NPM's own created_on because that is a real recorded date
+#   rather than an inference.
+#
+# A domain is retired on strikes, not on a single bad pass.
+#   A pass fails for a domain when it is absent from NPM's list or its expiry is already in the
+#   past — and NPM's list can come back short for reasons that have nothing to do with the
+#   certificate, such as an API hiccup or a restart mid-pass. CERT_HISTORY_STRIKES consecutive
+#   failures are required before a domain is retired, and it stays in the store afterwards, so
+#   one bad read can neither erase months of history nor hide a genuine expiry.
+#
+# The wrapper holds no logic.
+#   The work sits next to the NPM client it needs, because token handling lives in
+#   include/auth.php and a bash reimplementation would be a second copy of the thing most worth
+#   having only one of. Flags are forwarded verbatim.
+#
+# ==============================================================================================
+# OPERATIONAL SAFEGUARDS
+# ==============================================================================================
+#
+# The store is replaced atomically: temp file, verified, then renamed over the original. A pass
+# that fails partway leaves the previous history intact rather than a truncated file — this is
+# the only record of what these certificates did, and there is no second copy to restore from.
+#
+# --dry-run reports every change it would make and writes nothing. --status only reads.
+#
+# Read-only against NPM. Certificates are observed; nothing here renews, deletes or edits one.
+#
+# ==============================================================================================
 # RUNTIME MODES
 # ==============================================================================================
 #

Plugin/unraid/Tools/npm_access_stats.sh

@@ -22,6 +22,42 @@
 # passes are not counted. Running daily keeps that to whatever NPM rotates in a day.
 #
 # ==============================================================================================
+# DESIGN PRINCIPLES
+# ==============================================================================================
+#
+# Incremental by byte offset, never a re-read.
+#   475 MB across 41 files cannot be parsed on a page load, and re-parsing what was already
+#   counted would make each pass slower than the last. Each run records where it stopped and
+#   resumes there, so cost tracks new traffic rather than total traffic.
+#
+# A rotated log is detected, not assumed.
+#   A file smaller than the offset already recorded for it means NPM rotated it beneath us, so
+#   that file's offset restarts at zero and a rotation is counted. The totals are cumulative and
+#   are never reset by it — what rotated out between two passes is simply not counted, which is
+#   why this runs often enough to keep that gap to whatever NPM rotates in a day.
+#
+# Varaverk's own probes are excluded.
+#   uptime_probe.sh requests every proxied host every minute under Varaverk-Uptime/1.0. Counting
+#   those would make the monitor the busiest client of everything it monitors.
+#
+# ==============================================================================================
+# OPERATIONAL SAFEGUARDS
+# ==============================================================================================
+#
+# Read-only against NPM. Access logs are read and never rotated, truncated or removed — that is
+# NPM's business, and a stats collector that deleted its own inputs would be unrecoverable.
+#
+# --dry-run parses and reports without writing the store or advancing any offset, so a dry run
+# leaves the next real pass with exactly the same work to do.
+#
+# --reset forgets offsets and totals deliberately. It starts from the current end of each log,
+# so it discards history rather than double-counting it.
+#
+# The store is replaced atomically: written to a temp file, re-read and parsed to prove it is
+# valid JSON, then renamed over the original. A pass that dies midway — or produces something
+# unparseable — leaves the previous document untouched rather than a truncated one.
+#
+# ==============================================================================================
 # RUNTIME MODES
 # ==============================================================================================
 #

Plugin/unraid/Tools/uptime_probe.sh

@@ -25,6 +25,39 @@
 # that, this monitor becomes fifty thousand requests a day in the logs it reports on.
 #
 # ==============================================================================================
+# DESIGN PRINCIPLES
+# ==============================================================================================
+#
+# Probe what is served, not what was visited.
+#   The domain list comes from NPM's own proxy hosts, so a host nobody has requested is measured
+#   exactly like a busy one. Deriving the list from traffic would leave the quietest hosts — the
+#   ones most likely to be broken without anyone noticing — permanently unmonitored.
+#
+# The probe is excluded from the statistics it feeds.
+#   Every request carries Varaverk-Uptime/1.0, which npm_access_stats.sh filters out. Without
+#   that the monitor would be the largest single source of traffic in the logs it reports on,
+#   and every access figure would be measuring this script.
+#
+# The wrapper holds no logic.
+#   Flags are forwarded verbatim and nothing is interpreted here. Two places that both know what
+#   --dry-run means is two places that can disagree about it.
+#
+# ==============================================================================================
+# OPERATIONAL SAFEGUARDS
+# ==============================================================================================
+#
+# UPTIME_PROBE_ENABLED gates the whole run. Off means no probes and no writes.
+#
+# Bounded per domain by UPTIME_PROBE_TIMEOUT, so an unresponsive host costs one timeout rather
+# than stalling the pass — the probes run in parallel, so one slow domain never delays the rest.
+#
+# --dry-run probes and reports without writing. --status and --events read stored history and
+# probe nothing, so neither can alter what it is describing.
+#
+# Read-only against NPM. The domain list is read; no proxy host, certificate or setting is
+# touched by anything in this path.
+#
+# ==============================================================================================
 # RUNTIME MODES
 # ==============================================================================================
 #