diff --git a/src/main/java/com/clearfolio/viewer/model/ConversionJob.java b/src/main/java/com/clearfolio/viewer/model/ConversionJob.java
index c5b553ba..1a9cb7a5 100644
--- a/src/main/java/com/clearfolio/viewer/model/ConversionJob.java
+++ b/src/main/java/com/clearfolio/viewer/model/ConversionJob.java
@@ -82,7 +82,12 @@ public ConversionJob(
     }
 
     /**
-     * Creates a conversion job with tenant and subject ownership metadata.
+     * Creates a conversion job with explicit tenant and subject ownership metadata.
+     *
+     * <p>This authority-bearing constructor fails closed when tenant or subject
+     * claims are absent or control-corrupted. Development callers that
+     * intentionally use demo authority must use one of the convenience
+     * constructors that supplies the demo identities explicitly.</p>
      *
      * @param jobId job identifier
      * @param tenantId tenant isolation boundary
@@ -104,8 +109,8 @@ public ConversionJob(
             int maxAttempts
     ) {
         this.jobId = jobId;
-        this.tenantId = normalizeOrDefault(tenantId, DEFAULT_TENANT_ID);
-        this.subjectId = normalizeOrDefault(subjectId, DEFAULT_SUBJECT_ID);
+        this.tenantId = requireAuthority(tenantId, "tenantId");
+        this.subjectId = requireAuthority(subjectId, "subjectId");
         this.originalFileName = sanitize(originalFileName);
         this.contentType = sanitize(contentType);
         this.contentHash = contentHash;
@@ -125,6 +130,27 @@ private String sanitize(String value) {
         return value.replace("\u0000", "");
     }
 
+    private String requireAuthority(String value, String fieldName) {
+        if (value == null) {
+            throw new IllegalArgumentException(fieldName + " must not be blank");
+        }
+        if (value.codePoints().anyMatch(ConversionJob::isDisallowedAuthorityCharacter)) {
+            throw new IllegalArgumentException(fieldName + " must not contain control characters");
+        }
+        String normalized = value.strip();
+        if (normalized.isBlank()) {
+            throw new IllegalArgumentException(fieldName + " must not be blank");
+        }
+        return normalized;
+    }
+
+    private static boolean isDisallowedAuthorityCharacter(int codePoint) {
+        int characterType = Character.getType(codePoint);
+        return Character.isISOControl(codePoint)
+                || characterType == Character.LINE_SEPARATOR
+                || characterType == Character.PARAGRAPH_SEPARATOR;
+    }
+
     private String normalizeOrDefault(String value, String fallback) {
         String sanitized = sanitize(value);
         if (sanitized == null || sanitized.isBlank()) {
diff --git a/src/test/java/com/clearfolio/viewer/model/ConversionJobTenantAuthorityTest.java b/src/test/java/com/clearfolio/viewer/model/ConversionJobTenantAuthorityTest.java
new file mode 100644
index 00000000..cce4ab1b
--- /dev/null
+++ b/src/test/java/com/clearfolio/viewer/model/ConversionJobTenantAuthorityTest.java
@@ -0,0 +1,135 @@
+package com.clearfolio.viewer.model;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.util.List;
+import java.util.UUID;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Proves that the tenant-aware conversion-job constructor never manufactures
+ * or normalizes unsafe production authority when explicit claims are absent or
+ * control-corrupted.
+ */
+class ConversionJobTenantAuthorityTest {
+
+    @Test
+    void explicitConstructorRejectsMissingTenantAuthority() {
+        IllegalArgumentException exception = assertThrows(
+                IllegalArgumentException.class,
+                () -> new ConversionJob(
+                        UUID.randomUUID(),
+                        null,
+                        "subject-a",
+                        "report.pdf",
+                        "application/pdf",
+                        "hash",
+                        10L,
+                        3
+                )
+        );
+
+        assertEquals("tenantId must not be blank", exception.getMessage());
+    }
+
+    @Test
+    void explicitConstructorRejectsBlankTenantAuthorityAfterSanitization() {
+        IllegalArgumentException exception = assertThrows(
+                IllegalArgumentException.class,
+                () -> new ConversionJob(
+                        UUID.randomUUID(),
+                        " \u0000 ",
+                        "subject-a",
+                        "report.pdf",
+                        "application/pdf",
+                        "hash",
+                        10L,
+                        3
+                )
+        );
+
+        assertEquals("tenantId must not contain control characters", exception.getMessage());
+    }
+
+    @Test
+    void explicitConstructorRejectsControlCorruptedTenantAuthority() {
+        for (String tenantId : List.of("tenant\u0000-a", "tenant\n-a", "tenant\u001B-a")) {
+            IllegalArgumentException exception = assertThrows(
+                    IllegalArgumentException.class,
+                    () -> new ConversionJob(
+                            UUID.randomUUID(),
+                            tenantId,
+                            "subject-a",
+                            "report.pdf",
+                            "application/pdf",
+                            "hash",
+                            10L,
+                            3
+                    )
+            );
+
+            assertEquals("tenantId must not contain control characters", exception.getMessage());
+        }
+    }
+
+    @Test
+    void explicitConstructorRejectsMissingSubjectAuthority() {
+        IllegalArgumentException exception = assertThrows(
+                IllegalArgumentException.class,
+                () -> new ConversionJob(
+                        UUID.randomUUID(),
+                        "tenant-a",
+                        null,
+                        "report.pdf",
+                        "application/pdf",
+                        "hash",
+                        10L,
+                        3
+                )
+        );
+
+        assertEquals("subjectId must not be blank", exception.getMessage());
+    }
+
+    @Test
+    void explicitConstructorRejectsBlankSubjectAuthorityAfterSanitization() {
+        IllegalArgumentException exception = assertThrows(
+                IllegalArgumentException.class,
+                () -> new ConversionJob(
+                        UUID.randomUUID(),
+                        "tenant-a",
+                        " \u0000 ",
+                        "report.pdf",
+                        "application/pdf",
+                        "hash",
+                        10L,
+                        3
+                )
+        );
+
+        assertEquals("subjectId must not contain control characters", exception.getMessage());
+    }
+
+    @Test
+    void explicitConstructorRejectsControlCorruptedSubjectAuthority() {
+        for (String subjectId : List.of("subject\u0000-a", "subject\t-a", "subject\u007F-a")) {
+            IllegalArgumentException exception = assertThrows(
+                    IllegalArgumentException.class,
+                    () -> new ConversionJob(
+                            UUID.randomUUID(),
+                            "tenant-a",
+                            subjectId,
+                            "report.pdf",
+                            "application/pdf",
+                            "hash",
+                            10L,
+                            3
+                    )
+            );
+
+            assertEquals("subjectId must not contain control characters", exception.getMessage());
+        }
+    }
+}
diff --git a/src/test/java/com/clearfolio/viewer/model/ConversionJobTest.java b/src/test/java/com/clearfolio/viewer/model/ConversionJobTest.java
index dafeb708..44d2ecd1 100644
--- a/src/test/java/com/clearfolio/viewer/model/ConversionJobTest.java
+++ b/src/test/java/com/clearfolio/viewer/model/ConversionJobTest.java
@@ -55,6 +55,8 @@ void constructorSetsDefaultDemoTenantMetadata() {
         assertEquals(TenantContext.DEMO_TENANT_ID, job.getTenantId());
         assertEquals(TenantContext.DEMO_SUBJECT_ID, job.getSubjectId());
         assertTrue(job.belongsToTenant(TenantContext.DEMO_TENANT_ID));
+        assertFalse(job.belongsToTenant(null));
+        assertFalse(job.belongsToTenant(" \u0000 "));
     }
 
     @Test
@@ -76,24 +78,6 @@ void constructorAcceptsExplicitTenantMetadata() {
         assertFalse(job.belongsToTenant("tenant-b"));
     }
 
-    @Test
-    void constructorFallsBackToDemoMetadataForBlankTenantClaims() {
-        ConversionJob job = new ConversionJob(
-                UUID.randomUUID(),
-                " \u0000 ",
-                null,
-                "report.docx",
-                "application/octet-stream",
-                "hash",
-                10L,
-                3
-        );
-
-        assertEquals(TenantContext.DEMO_TENANT_ID, job.getTenantId());
-        assertEquals(TenantContext.DEMO_SUBJECT_ID, job.getSubjectId());
-        assertFalse(job.belongsToTenant(null));
-    }
-
     @Test
     void clampsMaxAttemptsToOneWhenZeroIsConfigured() {
         ConversionJob job = new ConversionJob(