diff --git a/src/pkg/hub/quadrant_attach_rates_test.go b/src/pkg/hub/quadrant_attach_rates_test.go
new file mode 100644
index 000000000..d3b27bf09
--- /dev/null
+++ b/src/pkg/hub/quadrant_attach_rates_test.go
@@ -0,0 +1,155 @@
+package hub
+
+// Tests for the two evidence-normalisation helpers in quadrant_attach.go:
+// budgetSpendPerDay and mergeAcceptanceRate. Both feed the fleet quadrant
+// scorer, and both must return ok=false — "not a measurement" — rather than
+// a misleading zero whenever the underlying signal is absent or too thin.
+
+import (
+	"math"
+	"testing"
+	"time"
+)
+
+func i64ptr(v int64) *int64 { return &v }
+
+func TestBudgetSpendPerDay(t *testing.T) {
+	now := time.Date(2026, 8, 28, 12, 0, 0, 0, time.UTC)
+
+	cases := []struct {
+		name     string
+		spend    *int64
+		start    time.Time
+		wantRate float64
+		wantOK   bool
+	}{
+		{
+			name:  "nil spend is not a measurement",
+			spend: nil,
+			start: now.Add(-48 * time.Hour),
+		},
+		{
+			name:  "zero window start is not a measurement",
+			spend: i64ptr(1000),
+			start: time.Time{},
+		},
+		{
+			name:  "window younger than six hours is noise",
+			spend: i64ptr(1000),
+			start: now.Add(-minBudgetWindowElapsed + time.Minute),
+		},
+		{
+			name:  "window start in the future (clock skew) is rejected",
+			spend: i64ptr(1000),
+			start: now.Add(2 * time.Hour),
+		},
+		{
+			name:     "spend over two elapsed days halves to a daily rate",
+			spend:    i64ptr(1000),
+			start:    now.Add(-48 * time.Hour),
+			wantRate: 500,
+			wantOK:   true,
+		},
+		{
+			name:     "exactly the six-hour floor is accepted",
+			spend:    i64ptr(240),
+			start:    now.Add(-minBudgetWindowElapsed),
+			wantRate: 960, // 240 tokens in a quarter day
+			wantOK:   true,
+		},
+		{
+			name:     "zero spend over a valid window is a real zero rate",
+			spend:    i64ptr(0),
+			start:    now.Add(-24 * time.Hour),
+			wantRate: 0,
+			wantOK:   true,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			e := RegistryEntry{BudgetCurrentSpend: tc.spend, BudgetWindowStartsAt: tc.start}
+			rate, ok := budgetSpendPerDay(e, now)
+			if ok != tc.wantOK {
+				t.Fatalf("ok = %v, want %v", ok, tc.wantOK)
+			}
+			if !tc.wantOK {
+				if rate != 0 {
+					t.Fatalf("rate = %v, want 0 when not measurable", rate)
+				}
+				return
+			}
+			if math.Abs(rate-tc.wantRate) > 1e-9 {
+				t.Fatalf("rate = %v, want %v", rate, tc.wantRate)
+			}
+		})
+	}
+}
+
+func TestMergeAcceptanceRate(t *testing.T) {
+	ip := func(v int) *int { return &v }
+
+	cases := []struct {
+		name     string
+		merged   *int
+		rejected *int
+		wantRate float64
+		wantOK   bool
+	}{
+		{
+			name:     "nil merged count is not a measurement",
+			merged:   nil,
+			rejected: ip(3),
+		},
+		{
+			name:     "nil rejected count is not a measurement",
+			merged:   ip(3),
+			rejected: nil,
+		},
+		{
+			name:     "below the minimum PR floor is suppressed",
+			merged:   ip(1),
+			rejected: ip(1), // total 2 < minPRsForReworkRate
+		},
+		{
+			name:     "three merged one rejected reaches the floor at 0.75",
+			merged:   ip(3),
+			rejected: ip(1),
+			wantRate: 0.75,
+			wantOK:   true,
+		},
+		{
+			name:     "all rejected at the floor is a real zero",
+			merged:   ip(0),
+			rejected: ip(4),
+			wantRate: 0,
+			wantOK:   true,
+		},
+		{
+			name:     "all merged is a perfect rate",
+			merged:   ip(10),
+			rejected: ip(0),
+			wantRate: 1,
+			wantOK:   true,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			e := RegistryEntry{PRsMerged90d: tc.merged, PRsRejected90d: tc.rejected}
+			rate, ok := mergeAcceptanceRate(e)
+			if ok != tc.wantOK {
+				t.Fatalf("ok = %v, want %v", ok, tc.wantOK)
+			}
+			if !tc.wantOK {
+				if rate != 0 {
+					t.Fatalf("rate = %v, want 0 when not measurable", rate)
+				}
+				return
+			}
+			if math.Abs(rate-tc.wantRate) > 1e-9 {
+				t.Fatalf("rate = %v, want %v", rate, tc.wantRate)
+			}
+		})
+	}
+}