Blank asset numbers, contested device claims, and honest toner forecasting

plugins/printers/api/asset_routes.py

@@ -1963,6 +1963,17 @@ def update_printer(printer_id: int):
 
     asset = printer.asset
 
+    # An UPDATE may not blank the asset number. Create validates it and the
+    # column is NOT NULL, but the conflict check below only runs when the value
+    # DIFFERS, and '' never collides with anything - so a payload carrying an
+    # empty assetnumber wrote it straight through. A form that loaded blank
+    # (a failed reference load, a partial fetch) then saved the blank over a
+    # real record.
+    if 'assetnumber' in data and not (data['assetnumber'] or '').strip():
+        return error_response(
+            ErrorCodes.VALIDATION_ERROR,
+            'assetnumber cannot be empty')
+
     # Check for conflicting assetnumber
     if 'assetnumber' in data and data['assetnumber'] != asset.assetnumber:
         if Asset.query.filter_by(assetnumber=data['assetnumber']).first():

plugins/printers/frontend/views/TonerForecast.vue

@@ -90,7 +90,7 @@
                 <th class="collevel">Level</th>
                 <th>Runs out</th>
                 <th>Rate</th>
-                <th>Changed</th>
+                <th title="Cartridge changes detected, over the days of history behind this row">Replacements</th>
               </tr>
             </thead>
             <tbody>
@@ -123,11 +123,20 @@
                   <span class="days" :class="c.band">{{ daysText(c) }}</span>
                 </td>
                 <td class="muted small">
-                  {{ c.burnrateperday != null ? c.burnrateperday + '%/day' : '-' }}
+                  <template v-if="c.burnrateperday != null">
+                    {{ c.burnrateperday }}%/day<!--
+                    --><span v-if="c.rateunstable" class="unstable"
+                             title="This cartridge's usage has varied a lot between readings - a burst then a lull, or the reverse. The estimate is the best available, not a measurement.">~</span>
+                  </template>
+                  <template v-else>-</template>
                 </td>
                 <td class="muted small">
-                  {{ c.replacements || 0 }}
-                  <span v-if="c.basisdays">/ {{ c.basisdays }}d</span>
+                  <!-- "2 / 90d" read as a date, a ratio, or a version to
+                       everyone who saw it. Say the unit. -->
+                  <template v-if="c.basisdays">
+                    {{ c.replacements || 0 }} in {{ c.basisdays }}d
+                  </template>
+                  <template v-else>{{ c.replacements || 0 }}</template>
                 </td>
               </tr>
             </tbody>
@@ -424,6 +433,10 @@ onMounted(load)
 .days.empty { color: var(--danger); }
 .days.soon { color: var(--warning); }
 .small { font-size: 0.8rem; }
+
+/* Marks a rate the intervals do not agree on. Deliberately quiet - it qualifies
+   the number beside it rather than competing with the urgency bands. */
+.unstable { margin-left: 2px; font-weight: 600; cursor: help; }
 .empty-state { padding: 2rem; text-align: center; }
 .footnote { margin-top: 1rem; font-size: 0.85rem; }
 </style>

plugins/printers/services/supply_history.py

@@ -20,6 +20,19 @@ from datetime import datetime, timezone
 # new cartridge rather than noise.
 REPLACEMENT_RISE = 10
 
+# A replacement must also LAND high. A fresh cartridge reads near full, so a
+# rise that stops mid-range is a gauge bouncing, not a swap. Without this the
+# count was any +10 between readings, and the two common noise shapes both
+# scored: a supply reading 0 or near-0 while it was out of the machine, then the
+# real level again (0 -> 60 counts as +60), and a coarse gauge ticking back up
+# after a reseat or a power cycle. That is how one cartridge claimed five
+# changes in ninety days.
+#
+# A site that fits PART-USED cartridges will under-count with this rule. That is
+# the right way round: a missed swap widens the run and slows the estimate,
+# while a phantom swap resets the run and throws the estimate away entirely.
+NEW_CARTRIDGE_LEVEL = 80
+
 # Below this many readings a slope is arithmetic, not evidence. Two points
 # through a coarse gauge can "prove" any rate at all.
 MIN_POINTS_FOR_ESTIMATE = 4
@@ -29,6 +42,12 @@ MIN_POINTS_FOR_ESTIMATE = 4
 # says "never", which is worse than saying nothing.
 MIN_DROP_FOR_ESTIMATE = 2
 
+# How far the fastest and slowest intervals may differ before a single rate
+# stops being a fair summary. A cartridge that ran at 10 percent/day for two
+# days and 0.2 percent/day since is not described by any one number, and a
+# precise-looking figure invites more trust than it has earned.
+RATE_SPREAD_FACTOR = 5
+
 # At or below this, the cartridge is done and the arithmetic stops being the
 # useful answer. A supply sitting at 1% that drains a tenth of a point a day
 # computes to ten days; a printer at 1% is out of toner as far as anyone
@@ -58,18 +77,65 @@ def normalise(points):
             continue
         out.append((datetime.fromtimestamp(seconds, tz=timezone.utc), level))
     out.sort(key=lambda p: p[0])
+    return drop_spikes(out)
+
+
+def drop_spikes(points, rise=REPLACEMENT_RISE):
+    """Remove one-reading dips that RECOVER to where they came from.
+
+    A single reading far below both neighbours, then a recovery, is a big
+    upward step that scores as a cartridge change. That is how a cartridge
+    claimed five changes in ninety days.
+
+    NOT a Zabbix timeout: an item that does not answer records nothing, it does
+    not write a zero. The dip is a value the device really reported - a supply
+    pulled out to be shaken and reseated, a door open mid-poll, or a site whose
+    preprocessing maps the Printer MIB's "unknown" sentinels (-1/-2/-3, which
+    cannot land in the unsigned history table) onto 0.
+
+    The filter keys on SHAPE rather than cause, which is why it holds for all of
+    them: a level that comes back to where it was did not get a new cartridge.
+
+    Only a dip that comes BACK to roughly its previous level is removed. A
+    genuine near-empty reading before a swap (30, 5, 100) does not recover - it
+    jumps to full - so it is kept, and the swap after it still counts.
+    """
+    if len(points) < 3:
+        return points
+    out = [points[0]]
+    for index in range(1, len(points) - 1):
+        previous = points[index - 1][1]
+        current = points[index][1]
+        following = points[index + 1][1]
+        dipped = (previous - current) >= rise and (following - current) >= rise
+        recovered = abs(following - previous) <= rise
+        if dipped and recovered:
+            continue
+        out.append(points[index])
+    out.append(points[-1])
     return out
 
 
-def find_replacements(points, rise=REPLACEMENT_RISE):
+def _is_replacement(previous, current, rise=REPLACEMENT_RISE,
+                    newlevel=NEW_CARTRIDGE_LEVEL):
+    """One definition of "a cartridge was changed", used by every caller.
+
+    The rise must be big enough to clear gauge noise AND land near full, which
+    is what a new cartridge reads. Both conditions, because either alone admits
+    a shape that is not a swap.
+    """
+    return (current - previous) >= rise and current >= newlevel
+
+
+def find_replacements(points, rise=REPLACEMENT_RISE,
+                      newlevel=NEW_CARTRIDGE_LEVEL):
     """Timestamps where the level jumped up - one per cartridge change.
 
-    Returns [] for a series that only falls. A rise smaller than `rise` is
-    treated as noise, not a replacement.
+    Returns [] for a series that only falls.
     """
     replacements = []
     for (_, previous), (when, current) in zip(points, points[1:]):
-        if current - previous >= rise:
+        if _is_replacement(previous, current, rise, newlevel):
             replacements.append(when)
     return replacements
 
@@ -84,28 +150,78 @@ def current_run(points, rise=REPLACEMENT_RISE):
         return []
     start = 0
     for index in range(1, len(points)):
-        if points[index][1] - points[index - 1][1] >= rise:
+        if _is_replacement(points[index - 1][1], points[index][1], rise):
             start = index
     return points[start:]
 
 
+def interval_rates(points):
+    """Percent-per-day for each consecutive pair, falling intervals only.
+
+    A rise inside a run is gauge noise (a swap would have ended the run), and
+    a flat interval is real information - a cartridge that did not move - so it
+    stays in at zero.
+    """
+    rates = []
+    for (whenprev, prev), (when, current) in zip(points, points[1:]):
+        days = (when - whenprev).total_seconds() / 86400
+        if days <= 0:
+            continue
+        drop = prev - current
+        if drop < 0:
+            continue
+        rates.append(drop / days)
+    return rates
+
+
+def _median(values):
+    ordered = sorted(values)
+    count = len(ordered)
+    if not count:
+        return None
+    middle = count // 2
+    if count % 2:
+        return ordered[middle]
+    return (ordered[middle - 1] + ordered[middle]) / 2
+
+
 def burn_rate(points):
     """Percent consumed per day over these readings, or None.
 
+    THE MEDIAN OF THE PER-INTERVAL RATES, not the slope between the first and
+    last reading. Two endpoints cannot tell "steady" from "burst then stopped":
+    a cartridge that lost 20 percent in two days and then barely moved for a
+    month reads as 0.83 percent/day forever after, so the report keeps promising
+    it will run out long after printing slowed. The burst is one interval among
+    many to a median, and one of two points to a secant.
+
     None means "no honest estimate": too few readings, no elapsed time, or a
     drop too small to distinguish from a gauge that has not moved yet.
     """
     if len(points) < MIN_POINTS_FOR_ESTIMATE:
         return None
-    first_when, first_level = points[0]
-    last_when, last_level = points[-1]
-    days = (last_when - first_when).total_seconds() / 86400
-    if days <= 0:
+    total_days = (points[-1][0] - points[0][0]).total_seconds() / 86400
+    if total_days <= 0:
         return None
-    drop = first_level - last_level
-    if drop < MIN_DROP_FOR_ESTIMATE:
+    # The overall drop still gates the estimate: a gauge sitting on one plateau
+    # has not proved anything yet, whatever the intervals say.
+    if points[0][1] - points[-1][1] < MIN_DROP_FOR_ESTIMATE:
         return None
-    return drop / days
+    rate = _median(interval_rates(points))
+    if not rate:
+        # Every interval flat or rising, yet the run dropped overall - the
+        # movement is all in intervals the median discarded. Fall back to the
+        # whole-run slope rather than reporting nothing.
+        return (points[0][1] - points[-1][1]) / total_days
+    return rate
+
+
+def rate_is_unstable(points, factor=RATE_SPREAD_FACTOR):
+    """True when the intervals disagree enough that one number oversells it."""
+    rates = [r for r in interval_rates(points) if r > 0]
+    if len(rates) < 2:
+        return False
+    return max(rates) >= min(rates) * factor
 
 
 def analyse(points, rise=REPLACEMENT_RISE, currentlevel=None):
@@ -131,6 +247,7 @@ def analyse(points, rise=REPLACEMENT_RISE, currentlevel=None):
     points = normalise(points)
     result = {
         'currentlevel': currentlevel, 'daysleft': None, 'burnrateperday': None,
+        'rateunstable': False,
         'reason': None, 'replacements': 0, 'lastreplaced': None,
         'basisdays': 0, 'points': [],
     }
@@ -182,6 +299,9 @@ def analyse(points, rise=REPLACEMENT_RISE, currentlevel=None):
 
     result['burnrateperday'] = round(rate, 2)
     result['daysleft'] = max(0, int(level / rate))
+    # Say so when the intervals disagree wildly. The number is still the best
+    # estimate available; the flag stops it reading as a measurement.
+    result['rateunstable'] = rate_is_unstable(run)
     return result