Keep a disk heat finding open without a current reading

Patrol verifies a disk-high finding as recovered once the disk's
temperature cools to its alert clear value. A disk in standby, or one
whose host agent stopped reporting, has no current reading, and a
missing reading counted as cooled. A finding raised for a SATA disk at
56C would close as soon as the disk spun down, while its temperature
alert stayed open.

When a disk has no current reading and its last known reading is still
at or above the clear value, verification now reports the recovery as
unknown instead of proven. A disk last seen cool still recovers.

docs/release-control/v6/internal/subsystems/ai-runtime.md

@@ -315,7 +315,8 @@ configuration applies. A disk is hot from its trigger: a triage warning, a disk
 issue and an AI chat "needing attention" entry, as its temperature alert and
 Physical Disks Running Hot verdict are. A disk-high finding recovers at or
 below the clear value (under the trigger when there is no band below it), as
-the alert does. Scoped runs keep the provider, and a
+the alert does. With no current reading, a disk last seen hot leaves that
+verification unknown rather than recovered. Scoped runs keep the provider, and a
 provider set before Patrol starts is handed to it. Below the trigger Patrol flags nothing, so an NVMe at 63C stays
 quiet and a SATA disk at 56C is flagged. Proofs:
 `internal/ai/patrol_disk_temperature_test.go` and

internal/ai/patrol_disk_temperature_test.go

@@ -1,12 +1,15 @@
 package ai
 
 import (
+	"errors"
 	"strings"
 	"testing"
 	"time"
 
 	"github.com/rcourtman/pulse-go-rewrite/internal/models"
 	"github.com/rcourtman/pulse-go-rewrite/internal/unifiedresources"
+	"github.com/rcourtman/pulse-go-rewrite/pkg/aicontracts"
+	"github.com/rcourtman/pulse-go-rewrite/pkg/diskinventory"
 )
 
 // raisedNVMeThresholds is a user who raised the NVMe disk temperature trigger
@@ -226,3 +229,21 @@ func TestDiskHeatRecoversAtTheClearValue(t *testing.T) {
 		t.Fatalf("no-band limits %+v: want 70C hot and not cooled, 69C cooled", noBand)
 	}
 }
+
+// With no current reading (standby, a silent agent) a disk last seen hot has
+// not shown that it cooled, so heat recovery is unknown rather than proven.
+func TestDiskHeatRecoveryNeedsACurrentReading(t *testing.T) {
+	retained := &diskinventory.CollectionStatus{Temperature: diskinventory.Unavailable("smartctl", "disk is in standby")}
+	state := newPatrolRuntimeState(models.StateSnapshot{PhysicalDisks: []models.PhysicalDisk{
+		{ID: "sata-retained-hot", DevPath: "/dev/sda", Type: "sata", Health: "PASSED", Wearout: -1, Temperature: 56, Collection: retained},
+		{ID: "sata-retained-cool", DevPath: "/dev/sdb", Type: "sata", Health: "PASSED", Wearout: -1, Temperature: 40, Collection: retained},
+	}})
+
+	if _, err := verifyMetricRecoveredState(state, PatrolThresholds{}, "disk-high", "sata-retained-hot", "physical_disk"); !errors.Is(err, aicontracts.ErrVerificationUnknown) {
+		t.Fatalf("retained 56C: err = %v, want ErrVerificationUnknown", err)
+	}
+	recovered, err := verifyMetricRecoveredState(state, PatrolThresholds{}, "disk-high", "sata-retained-cool", "physical_disk")
+	if err != nil || !recovered {
+		t.Fatalf("retained 40C: recovered = %v, err = %v, want recovered", recovered, err)
+	}
+}

internal/ai/patrol_findings.go

@@ -2296,6 +2296,11 @@ func verifyMetricRecoveredState(snap patrolRuntimeState, thresholds PatrolThresh
 					if !disk.temperatureLimits.cooled(disk.temperature) {
 						return false, nil
 					}
+					// A disk last seen hot with no current reading has not
+					// shown that it cooled, so its recovery is unknown.
+					if disk.temperature <= 0 && !disk.temperatureLimits.cooled(disk.lastKnownTemperature) {
+						return false, fmt.Errorf("%w: no current temperature reading for %s", aicontracts.ErrVerificationUnknown, rid)
+					}
 					return true, nil
 				}
 				break
@@ -2317,10 +2322,13 @@ func verifyMetricRecoveredState(snap patrolRuntimeState, thresholds PatrolThresh
 }
 
 type patrolPhysicalDiskVerification struct {
-	health            string
-	wearout           int
-	temperature       int
-	temperatureLimits diskTemperatureLimits
+	health      string
+	wearout     int
+	temperature int
+	// lastKnownTemperature is a retained reading the current observation
+	// did not collect (a disk in standby, a silent agent).
+	lastKnownTemperature int
+	temperatureLimits    diskTemperatureLimits
 }
 
 type patrolPhysicalDiskVisitor func(identifiers []string, verification patrolPhysicalDiskVerification) bool
@@ -2464,10 +2472,11 @@ func patrolVisitPhysicalDiskVerification(snap patrolRuntimeState, visit patrolPh
 	rows := patrolPhysicalDiskRows(snap, nil)
 	for _, disk := range rows {
 		if !visit([]string{disk.id, disk.name, disk.devPath, disk.model}, patrolPhysicalDiskVerification{
-			health:            strings.TrimSpace(disk.health),
-			wearout:           disk.wearout,
-			temperature:       disk.temperature.Collected,
-			temperatureLimits: disk.temperatureLimits,
+			health:               strings.TrimSpace(disk.health),
+			wearout:              disk.wearout,
+			temperature:          disk.temperature.Collected,
+			lastKnownTemperature: disk.temperature.LastKnown,
+			temperatureLimits:    disk.temperatureLimits,
 		}) {
 			return true
 		}