diff --git a/assistant/src/__tests__/guardian-principal-id-roundtrip.test.ts b/assistant/src/__tests__/guardian-principal-id-roundtrip.test.ts
new file mode 100644
index 00000000000..208a9bd1cbf
--- /dev/null
+++ b/assistant/src/__tests__/guardian-principal-id-roundtrip.test.ts
@@ -0,0 +1,193 @@
+import { mkdtempSync, rmSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+
+import { afterAll, beforeEach, describe, expect, mock, test } from 'bun:test';
+
+const testDir = mkdtempSync(join(tmpdir(), 'guardian-principal-id-roundtrip-test-'));
+
+mock.module('../util/platform.js', () => ({
+  getDataDir: () => testDir,
+  isMacOS: () => process.platform === 'darwin',
+  isLinux: () => process.platform === 'linux',
+  isWindows: () => process.platform === 'win32',
+  getSocketPath: () => join(testDir, 'test.sock'),
+  getPidPath: () => join(testDir, 'test.pid'),
+  getDbPath: () => join(testDir, 'test.db'),
+  getLogPath: () => join(testDir, 'test.log'),
+  ensureDataDir: () => {},
+}));
+
+mock.module('../util/logger.js', () => ({
+  getLogger: () =>
+    new Proxy({} as Record<string, unknown>, {
+      get: () => () => {},
+    }),
+}));
+
+import {
+  createCanonicalGuardianRequest,
+  getCanonicalGuardianRequest,
+  resolveCanonicalGuardianRequest,
+  updateCanonicalGuardianRequest,
+} from '../memory/canonical-guardian-store.js';
+import {
+  createBinding,
+  getActiveBinding,
+} from '../memory/guardian-bindings.js';
+import { getDb, initializeDb, resetDb } from '../memory/db.js';
+
+initializeDb();
+
+function resetTables(): void {
+  const db = getDb();
+  db.run('DELETE FROM canonical_guardian_deliveries');
+  db.run('DELETE FROM canonical_guardian_requests');
+  db.run('DELETE FROM channel_guardian_bindings');
+}
+
+describe('guardianPrincipalId roundtrip', () => {
+  beforeEach(() => {
+    resetTables();
+  });
+
+  afterAll(() => {
+    resetDb();
+    try {
+      rmSync(testDir, { recursive: true });
+    } catch {
+      // best-effort cleanup
+    }
+  });
+
+  // ── channel_guardian_bindings ────────────────────────────────────────
+
+  describe('channel_guardian_bindings', () => {
+    test('creates binding with guardianPrincipalId and reads it back', () => {
+      const binding = createBinding({
+        assistantId: 'self',
+        channel: 'telegram',
+        guardianExternalUserId: 'tg-user-123',
+        guardianDeliveryChatId: 'tg-chat-123',
+        guardianPrincipalId: 'principal-abc-def',
+      });
+
+      expect(binding.guardianPrincipalId).toBe('principal-abc-def');
+
+      const fetched = getActiveBinding('self', 'telegram');
+      expect(fetched).not.toBeNull();
+      expect(fetched!.guardianPrincipalId).toBe('principal-abc-def');
+    });
+
+    test('creates binding without guardianPrincipalId (defaults to null)', () => {
+      const binding = createBinding({
+        assistantId: 'self',
+        channel: 'sms',
+        guardianExternalUserId: 'sms-user-456',
+        guardianDeliveryChatId: 'sms-chat-456',
+      });
+
+      expect(binding.guardianPrincipalId).toBeNull();
+
+      const fetched = getActiveBinding('self', 'sms');
+      expect(fetched).not.toBeNull();
+      expect(fetched!.guardianPrincipalId).toBeNull();
+    });
+  });
+
+  // ── canonical_guardian_requests ──────────────────────────────────────
+
+  describe('canonical_guardian_requests', () => {
+    test('creates request with guardianPrincipalId and reads it back', () => {
+      const req = createCanonicalGuardianRequest({
+        kind: 'tool_approval',
+        sourceType: 'channel',
+        sourceChannel: 'telegram',
+        guardianExternalUserId: 'guardian-tg-1',
+        guardianPrincipalId: 'principal-123',
+      });
+
+      expect(req.guardianPrincipalId).toBe('principal-123');
+      expect(req.decidedByPrincipalId).toBeNull();
+
+      const fetched = getCanonicalGuardianRequest(req.id);
+      expect(fetched).not.toBeNull();
+      expect(fetched!.guardianPrincipalId).toBe('principal-123');
+      expect(fetched!.decidedByPrincipalId).toBeNull();
+    });
+
+    test('creates request without guardianPrincipalId (defaults to null)', () => {
+      const req = createCanonicalGuardianRequest({
+        kind: 'access_request',
+        sourceType: 'desktop',
+      });
+
+      expect(req.guardianPrincipalId).toBeNull();
+      expect(req.decidedByPrincipalId).toBeNull();
+    });
+
+    test('creates request with decidedByPrincipalId', () => {
+      const req = createCanonicalGuardianRequest({
+        kind: 'tool_approval',
+        sourceType: 'voice',
+        decidedByPrincipalId: 'decider-principal-1',
+      });
+
+      expect(req.decidedByPrincipalId).toBe('decider-principal-1');
+    });
+
+    test('updates decidedByPrincipalId via updateCanonicalGuardianRequest', () => {
+      const req = createCanonicalGuardianRequest({
+        kind: 'tool_approval',
+        sourceType: 'channel',
+      });
+
+      const updated = updateCanonicalGuardianRequest(req.id, {
+        status: 'approved',
+        decidedByPrincipalId: 'principal-decider-abc',
+        decidedByExternalUserId: 'ext-user-1',
+      });
+
+      expect(updated).not.toBeNull();
+      expect(updated!.decidedByPrincipalId).toBe('principal-decider-abc');
+      expect(updated!.decidedByExternalUserId).toBe('ext-user-1');
+      expect(updated!.status).toBe('approved');
+    });
+
+    test('resolveCanonicalGuardianRequest writes decidedByPrincipalId', () => {
+      const req = createCanonicalGuardianRequest({
+        kind: 'tool_approval',
+        sourceType: 'voice',
+        guardianPrincipalId: 'guardian-principal-xyz',
+      });
+
+      const resolved = resolveCanonicalGuardianRequest(req.id, 'pending', {
+        status: 'approved',
+        answerText: 'Approved',
+        decidedByExternalUserId: 'guardian-ext-1',
+        decidedByPrincipalId: 'guardian-principal-xyz',
+      });
+
+      expect(resolved).not.toBeNull();
+      expect(resolved!.status).toBe('approved');
+      expect(resolved!.decidedByPrincipalId).toBe('guardian-principal-xyz');
+      expect(resolved!.decidedByExternalUserId).toBe('guardian-ext-1');
+      expect(resolved!.guardianPrincipalId).toBe('guardian-principal-xyz');
+    });
+
+    test('resolve without decidedByPrincipalId leaves it null', () => {
+      const req = createCanonicalGuardianRequest({
+        kind: 'tool_approval',
+        sourceType: 'channel',
+      });
+
+      const resolved = resolveCanonicalGuardianRequest(req.id, 'pending', {
+        status: 'denied',
+        decidedByExternalUserId: 'guardian-ext-2',
+      });
+
+      expect(resolved).not.toBeNull();
+      expect(resolved!.decidedByPrincipalId).toBeNull();
+    });
+  });
+});
diff --git a/assistant/src/memory/canonical-guardian-store.ts b/assistant/src/memory/canonical-guardian-store.ts
index b2b388a3fe9..aaedd3b2d91 100644
--- a/assistant/src/memory/canonical-guardian-store.ts
+++ b/assistant/src/memory/canonical-guardian-store.ts
@@ -31,6 +31,7 @@ export interface CanonicalGuardianRequest {
   requesterExternalUserId: string | null;
   requesterChatId: string | null;
   guardianExternalUserId: string | null;
+  guardianPrincipalId: string | null;
   callSessionId: string | null;
   pendingQuestionId: string | null;
   questionText: string | null;
@@ -40,6 +41,7 @@ export interface CanonicalGuardianRequest {
   status: CanonicalRequestStatus;
   answerText: string | null;
   decidedByExternalUserId: string | null;
+  decidedByPrincipalId: string | null;
   followupState: string | null;
   expiresAt: string | null;
   createdAt: string;
@@ -117,6 +119,7 @@ function rowToRequest(row: typeof canonicalGuardianRequests.$inferSelect): Canon
     requesterExternalUserId: row.requesterExternalUserId,
     requesterChatId: row.requesterChatId,
     guardianExternalUserId: row.guardianExternalUserId,
+    guardianPrincipalId: row.guardianPrincipalId,
     callSessionId: row.callSessionId,
     pendingQuestionId: row.pendingQuestionId,
     questionText: row.questionText,
@@ -126,6 +129,7 @@ function rowToRequest(row: typeof canonicalGuardianRequests.$inferSelect): Canon
     status: row.status as CanonicalRequestStatus,
     answerText: row.answerText,
     decidedByExternalUserId: row.decidedByExternalUserId,
+    decidedByPrincipalId: row.decidedByPrincipalId,
     followupState: row.followupState,
     expiresAt: row.expiresAt,
     createdAt: row.createdAt,
@@ -160,6 +164,7 @@ export interface CreateCanonicalGuardianRequestParams {
   requesterExternalUserId?: string;
   requesterChatId?: string;
   guardianExternalUserId?: string;
+  guardianPrincipalId?: string;
   callSessionId?: string;
   pendingQuestionId?: string;
   questionText?: string;
@@ -169,6 +174,7 @@ export interface CreateCanonicalGuardianRequestParams {
   status?: CanonicalRequestStatus;
   answerText?: string;
   decidedByExternalUserId?: string;
+  decidedByPrincipalId?: string;
   followupState?: string;
   expiresAt?: string;
 }
@@ -187,6 +193,7 @@ export function createCanonicalGuardianRequest(params: CreateCanonicalGuardianRe
     requesterExternalUserId: params.requesterExternalUserId ?? null,
     requesterChatId: params.requesterChatId ?? null,
     guardianExternalUserId: params.guardianExternalUserId ?? null,
+    guardianPrincipalId: params.guardianPrincipalId ?? null,
     callSessionId: params.callSessionId ?? null,
     pendingQuestionId: params.pendingQuestionId ?? null,
     questionText: params.questionText ?? null,
@@ -196,6 +203,7 @@ export function createCanonicalGuardianRequest(params: CreateCanonicalGuardianRe
     status: params.status ?? ('pending' as const),
     answerText: params.answerText ?? null,
     decidedByExternalUserId: params.decidedByExternalUserId ?? null,
+    decidedByPrincipalId: params.decidedByPrincipalId ?? null,
     followupState: params.followupState ?? null,
     expiresAt: params.expiresAt ?? null,
     createdAt: now,
@@ -292,6 +300,7 @@ export interface UpdateCanonicalGuardianRequestParams {
   status?: CanonicalRequestStatus;
   answerText?: string;
   decidedByExternalUserId?: string;
+  decidedByPrincipalId?: string;
   followupState?: string | null;
   expiresAt?: string;
 }
@@ -307,6 +316,7 @@ export function updateCanonicalGuardianRequest(
   if (updates.status !== undefined) setValues.status = updates.status;
   if (updates.answerText !== undefined) setValues.answerText = updates.answerText;
   if (updates.decidedByExternalUserId !== undefined) setValues.decidedByExternalUserId = updates.decidedByExternalUserId;
+  if (updates.decidedByPrincipalId !== undefined) setValues.decidedByPrincipalId = updates.decidedByPrincipalId;
   if (updates.followupState !== undefined) setValues.followupState = updates.followupState;
   if (updates.expiresAt !== undefined) setValues.expiresAt = updates.expiresAt;
 
@@ -322,6 +332,7 @@ export interface ResolveDecision {
   status: CanonicalRequestStatus;
   answerText?: string;
   decidedByExternalUserId?: string;
+  decidedByPrincipalId?: string;
 }
 
 /**
@@ -343,6 +354,7 @@ export function resolveCanonicalGuardianRequest(
   };
   if (decision.answerText !== undefined) setValues.answerText = decision.answerText;
   if (decision.decidedByExternalUserId !== undefined) setValues.decidedByExternalUserId = decision.decidedByExternalUserId;
+  if (decision.decidedByPrincipalId !== undefined) setValues.decidedByPrincipalId = decision.decidedByPrincipalId;
 
   db.update(canonicalGuardianRequests)
     .set(setValues)
diff --git a/assistant/src/memory/db-init.ts b/assistant/src/memory/db-init.ts
index 9827e6d2684..f56487a1e04 100644
--- a/assistant/src/memory/db-init.ts
+++ b/assistant/src/memory/db-init.ts
@@ -37,6 +37,7 @@ import {
   migrateNotificationDeliveryThreadDecision,
   migrateReminderRoutingIntent,
   migrateSchemaIndexesAndColumns,
+  migrateGuardianPrincipalIdColumns,
   migrateVoiceInviteColumns,
   migrateVoiceInviteDisplayMetadata,
   recoverCrashedMigrations,
@@ -173,5 +174,8 @@ export function initializeDb(): void {
   // 28. Actor token records (hash-only actor token persistence)
   createActorTokenRecordsTable(database);
 
+  // 29. Guardian principal ID columns on channel_guardian_bindings and canonical_guardian_requests
+  migrateGuardianPrincipalIdColumns(database);
+
   validateMigrationState(database);
 }
diff --git a/assistant/src/memory/guardian-bindings.ts b/assistant/src/memory/guardian-bindings.ts
index 21b7e593cb9..3478ca637de 100644
--- a/assistant/src/memory/guardian-bindings.ts
+++ b/assistant/src/memory/guardian-bindings.ts
@@ -23,6 +23,7 @@ export interface GuardianBinding {
   channel: string;
   guardianExternalUserId: string;
   guardianDeliveryChatId: string;
+  guardianPrincipalId: string | null;
   status: BindingStatus;
   verifiedAt: number;
   verifiedVia: string;
@@ -42,6 +43,7 @@ function rowToBinding(row: typeof channelGuardianBindings.$inferSelect): Guardia
     channel: row.channel,
     guardianExternalUserId: row.guardianExternalUserId,
     guardianDeliveryChatId: row.guardianDeliveryChatId,
+    guardianPrincipalId: row.guardianPrincipalId,
     status: row.status as BindingStatus,
     verifiedAt: row.verifiedAt,
     verifiedVia: row.verifiedVia,
@@ -60,6 +62,7 @@ export function createBinding(params: {
   channel: string;
   guardianExternalUserId: string;
   guardianDeliveryChatId: string;
+  guardianPrincipalId?: string | null;
   verifiedVia?: string;
   metadataJson?: string | null;
 }): GuardianBinding {
@@ -73,6 +76,7 @@ export function createBinding(params: {
     channel: params.channel,
     guardianExternalUserId: params.guardianExternalUserId,
     guardianDeliveryChatId: params.guardianDeliveryChatId,
+    guardianPrincipalId: params.guardianPrincipalId ?? null,
     status: 'active' as const,
     verifiedAt: now,
     verifiedVia: params.verifiedVia ?? 'challenge',
diff --git a/assistant/src/memory/migrations/125-guardian-principal-id-columns.ts b/assistant/src/memory/migrations/125-guardian-principal-id-columns.ts
new file mode 100644
index 00000000000..962b6ccb0bc
--- /dev/null
+++ b/assistant/src/memory/migrations/125-guardian-principal-id-columns.ts
@@ -0,0 +1,19 @@
+import type { DrizzleDb } from '../db-connection.js';
+
+/**
+ * Add guardian_principal_id columns to channel_guardian_bindings and
+ * canonical_guardian_requests, plus decided_by_principal_id to
+ * canonical_guardian_requests.
+ *
+ * These nullable TEXT columns support the canonical identity binding
+ * cutover — linking guardian bindings and approval requests to a
+ * stable principal identity rather than relying solely on
+ * channel-specific external user IDs.
+ *
+ * Uses ALTER TABLE ADD COLUMN with try/catch for idempotency.
+ */
+export function migrateGuardianPrincipalIdColumns(database: DrizzleDb): void {
+  try { database.run(/*sql*/ `ALTER TABLE channel_guardian_bindings ADD COLUMN guardian_principal_id TEXT`); } catch { /* already exists */ }
+  try { database.run(/*sql*/ `ALTER TABLE canonical_guardian_requests ADD COLUMN guardian_principal_id TEXT`); } catch { /* already exists */ }
+  try { database.run(/*sql*/ `ALTER TABLE canonical_guardian_requests ADD COLUMN decided_by_principal_id TEXT`); } catch { /* already exists */ }
+}
diff --git a/assistant/src/memory/migrations/index.ts b/assistant/src/memory/migrations/index.ts
index a129e637662..876c7422a45 100644
--- a/assistant/src/memory/migrations/index.ts
+++ b/assistant/src/memory/migrations/index.ts
@@ -65,6 +65,7 @@ export { createCanonicalGuardianTables } from './121-canonical-guardian-requests
 export { migrateCanonicalGuardianRequesterChatId } from './122-canonical-guardian-requester-chat-id.js';
 export { migrateCanonicalGuardianDeliveriesDestinationIndex } from './123-canonical-guardian-deliveries-destination-index.js';
 export { migrateVoiceInviteDisplayMetadata } from './124-voice-invite-display-metadata.js';
+export { migrateGuardianPrincipalIdColumns } from './125-guardian-principal-id-columns.js';
 export {
   MIGRATION_REGISTRY,
   type MigrationRegistryEntry,
diff --git a/assistant/src/memory/schema.ts b/assistant/src/memory/schema.ts
index 9f1807c25f2..fc49980fea8 100644
--- a/assistant/src/memory/schema.ts
+++ b/assistant/src/memory/schema.ts
@@ -637,6 +637,7 @@ export const channelGuardianBindings = sqliteTable('channel_guardian_bindings',
   channel: text('channel').notNull(),
   guardianExternalUserId: text('guardian_external_user_id').notNull(),
   guardianDeliveryChatId: text('guardian_delivery_chat_id').notNull(),
+  guardianPrincipalId: text('guardian_principal_id'),
   status: text('status').notNull().default('active'),
   verifiedAt: integer('verified_at').notNull(),
   verifiedVia: text('verified_via').notNull().default('challenge'),
@@ -887,6 +888,7 @@ export const canonicalGuardianRequests = sqliteTable('canonical_guardian_request
   requesterExternalUserId: text('requester_external_user_id'),
   requesterChatId: text('requester_chat_id'),
   guardianExternalUserId: text('guardian_external_user_id'),
+  guardianPrincipalId: text('guardian_principal_id'),
   callSessionId: text('call_session_id'),
   pendingQuestionId: text('pending_question_id'),
   questionText: text('question_text'),
@@ -896,6 +898,7 @@ export const canonicalGuardianRequests = sqliteTable('canonical_guardian_request
   status: text('status').notNull().default('pending'),
   answerText: text('answer_text'),
   decidedByExternalUserId: text('decided_by_external_user_id'),
+  decidedByPrincipalId: text('decided_by_principal_id'),
   followupState: text('followup_state'),
   expiresAt: text('expires_at'),
   createdAt: text('created_at').notNull(),