diff --git a/src/main/java/com/clearfolio/viewer/analytics/KpiSnapshotLedger.java b/src/main/java/com/clearfolio/viewer/analytics/KpiSnapshotLedger.java
index f5cbde5d..6793afe4 100644
--- a/src/main/java/com/clearfolio/viewer/analytics/KpiSnapshotLedger.java
+++ b/src/main/java/com/clearfolio/viewer/analytics/KpiSnapshotLedger.java
@@ -213,7 +213,11 @@ private static int integer(String field) {
 
     private static double rate(String field) {
         try {
-            return Double.parseDouble(field);
+            double parsed = Double.parseDouble(field);
+            if (!Double.isFinite(parsed) || parsed < 0.0 || parsed > 1.0) {
+                throw invalidLine();
+            }
+            return parsed;
         } catch (NumberFormatException ex) {
             throw invalidLine(ex);
         }
@@ -224,7 +228,11 @@ private static Long nullableLong(String field) {
             return null;
         }
         try {
-            return Long.parseLong(field);
+            long parsed = Long.parseLong(field);
+            if (parsed < 0L) {
+                throw invalidLine();
+            }
+            return parsed;
         } catch (NumberFormatException ex) {
             throw invalidLine(ex);
         }
diff --git a/src/test/java/com/clearfolio/viewer/analytics/KpiSnapshotLedgerTest.java b/src/test/java/com/clearfolio/viewer/analytics/KpiSnapshotLedgerTest.java
index d42349fd..61b64962 100644
--- a/src/test/java/com/clearfolio/viewer/analytics/KpiSnapshotLedgerTest.java
+++ b/src/test/java/com/clearfolio/viewer/analytics/KpiSnapshotLedgerTest.java
@@ -86,6 +86,23 @@ void rejectsInvalidPersistedLedgerLines() throws Exception {
         assertInvalidLedger(snapshotLine().replace(encoded("tenant-a"), "!"));
     }
 
+    @Test
+    void rejectsNonFiniteOrOutOfRangePersistedKpiEvidence() throws Exception {
+        assertInvalidLedger(snapshotLine().replace("\t0.5\t", "\tNaN\t"));
+        assertInvalidLedger(snapshotLine().replace("\t0.5\t", "\tInfinity\t"));
+        assertInvalidLedger(snapshotLine().replace("\t0.5\t", "\t-Infinity\t"));
+        assertInvalidLedger(snapshotLine().replace("\t0.5\t", "\t-0.01\t"));
+        assertInvalidLedger(snapshotLine().replace("\t0.5\t", "\t1.01\t"));
+        assertInvalidLedger(snapshotLine().replace("\t123", "\t-1"));
+    }
+
+    @Test
+    void acceptsInclusiveKpiNumericBoundaries() throws Exception {
+        assertValidLedger(snapshotLine().replace("\t0.5\t", "\t0.0\t"), 0.0, 123L);
+        assertValidLedger(snapshotLine().replace("\t0.5\t", "\t1.0\t"), 1.0, 123L);
+        assertValidLedger(snapshotLine().replace("\t123", "\t0"), 0.5, 0L);
+    }
+
     @Test
     void reportsLoadAndWriteFailures() throws Exception {
         Path directory = tempDir.resolve("directory-ledger");
@@ -107,7 +124,24 @@ private void assertInvalidLedger(String line) throws Exception {
                 StandardCharsets.UTF_8
         );
 
-        assertThrows(IllegalStateException.class, () -> new KpiSnapshotLedger(ledgerPath, CLOCK));
+        IllegalStateException error = assertThrows(
+                IllegalStateException.class,
+                () -> new KpiSnapshotLedger(ledgerPath, CLOCK)
+        );
+        assertEquals("kpi snapshot ledger contains an invalid line", error.getMessage());
+    }
+
+    private void assertValidLedger(String line, double expectedRate, Long expectedP95) throws Exception {
+        Path ledgerPath = Files.writeString(
+                tempDir.resolve(UUID.randomUUID() + ".log"),
+                line + System.lineSeparator(),
+                StandardCharsets.UTF_8
+        );
+
+        KpiSnapshotLedger ledger = new KpiSnapshotLedger(ledgerPath, CLOCK);
+        var snapshot = ledger.snapshotsFor("tenant-a").getFirst();
+        assertEquals(expectedRate, snapshot.conversionSuccessRate());
+        assertEquals(expectedP95, snapshot.p95TimeToPreviewMs());
     }
 
     private static TenantContext context(String tenantId) {