diff --git a/src/api/auth/identity-mapping-plan.ts b/src/api/auth/identity-mapping-plan.ts
index c473e2fc..9a2d281a 100644
--- a/src/api/auth/identity-mapping-plan.ts
+++ b/src/api/auth/identity-mapping-plan.ts
@@ -1,23 +1,28 @@
 import { createHash } from 'node:crypto';
+import { identityEndpointSchema } from '@treeseed/sdk/identity';
 
 export interface IdentityMapping { userId: string; issuer: string; subject: string }
 export interface IdentityMappingInventory {
   users: Array<{ id: string; status: string }>;
   mappings: IdentityMapping[];
+  workloads: Array<{ id: string; issuer: string; subject: string }>;
 }
 
 /** Read-only migration planning. Inputs must come from an authenticated import,
  * never from email matching. Applying requires a coordinated database restore point. */
 export function planIdentityMappings(inventory: IdentityMappingInventory, requested: IdentityMapping[]) {
   const normalize = (mapping: IdentityMapping): IdentityMapping => {
-    const url = new URL(mapping.issuer);
-    if (url.protocol !== 'https:' || url.username || url.password || url.search || url.hash ||
-        !mapping.subject.trim() || !mapping.userId.trim()) throw new Error('Invalid explicit identity mapping');
+    identityEndpointSchema.parse(mapping.issuer);
+    if (typeof mapping.userId !== 'string' || !/^[A-Za-z0-9][A-Za-z0-9._:-]{0,255}$/u.test(mapping.userId)
+      || typeof mapping.subject !== 'string' || !/^[\x21-\x7e]{1,255}$/u.test(mapping.subject))
+      throw new Error('Invalid explicit identity mapping');
     // OIDC issuer identifiers are exact strings; do not normalize trailing slashes.
     return { userId: mapping.userId, issuer: mapping.issuer, subject: mapping.subject };
   };
   const key = (mapping: IdentityMapping) => JSON.stringify([mapping.issuer, mapping.subject]);
   const desired = requested.map(normalize).sort((a, b) => key(a).localeCompare(key(b), 'en'));
+  const workloadIds = new Set(inventory.workloads.map(value => value.id));
+  const workloadSubjects = new Set(inventory.workloads.map(value => JSON.stringify([value.issuer, value.subject])));
   const existing = new Map<string, string>();
   for (const mapping of inventory.mappings) {
     const previous = existing.get(key(mapping));
@@ -28,6 +33,7 @@ export function planIdentityMappings(inventory: IdentityMappingInventory, reques
   const operations = desired.map(mapping => {
     if (seen.has(key(mapping))) throw new Error('Duplicate requested identity');
     seen.add(key(mapping));
+    if (workloadIds.has(mapping.userId) || workloadSubjects.has(key(mapping))) throw new Error('Human mapping conflicts with workload identity');
     const users = inventory.users.filter(user => user.id === mapping.userId);
     if (users.length !== 1 || users[0].status !== 'active') throw new Error('Mapping requires one active existing user');
     const owner = existing.get(key(mapping));
@@ -38,6 +44,8 @@ export function planIdentityMappings(inventory: IdentityMappingInventory, reques
   const observed = {
     users: [...inventory.users].sort((a, b) => a.id.localeCompare(b.id, 'en')),
     mappings: [...inventory.mappings].sort((a, b) => key(a).localeCompare(key(b), 'en')),
+    workloads: [...inventory.workloads].sort((a, b) => a.id.localeCompare(b.id, 'en')),
   };
-  return { inventoryDigest: createHash('sha256').update(JSON.stringify(observed)).digest('hex'), operations };
+  return { inventoryDigest: createHash('sha256').update(JSON.stringify(observed)).digest('hex'),
+    requestDigest: createHash('sha256').update(JSON.stringify(desired)).digest('hex'), operations };
 }
diff --git a/src/api/auth/identity-mapping-transaction.ts b/src/api/auth/identity-mapping-transaction.ts
index fbd95586..ab334cd1 100644
--- a/src/api/auth/identity-mapping-transaction.ts
+++ b/src/api/auth/identity-mapping-transaction.ts
@@ -7,17 +7,19 @@ interface MappingDatabase { transaction<T>(run: (client: PoolClient) => Promise<
 /** Internal migration primitive, not an account-linking endpoint. The orchestrator
  * must authorize the import and establish a coordinated restore point first. */
 export async function applyIdentityMappings(database: MappingDatabase, input: {
-  requested: IdentityMapping[]; inventoryDigest: string;
+  requested: IdentityMapping[]; inventoryDigest: string; requestDigest: string;
 }) {
   return database.transaction(async client => {
-    // Lock both inventory tables, including against legacy inserts/updates. Keep
+    // Lock human and workload inventory, including legacy inserts/updates. Keep
     // this maintenance transaction short; no network calls while locks are held.
     await client.query("SET LOCAL lock_timeout = '5s'");
-    await client.query('LOCK TABLE users, user_identities IN SHARE ROW EXCLUSIVE MODE');
+    await client.query('LOCK TABLE users, user_identities, identity_workloads IN SHARE ROW EXCLUSIVE MODE');
     const users = await client.query('SELECT id, status FROM users');
     const mappings = await client.query('SELECT user_id AS "userId", provider AS issuer, provider_subject AS subject FROM user_identities');
-    const plan = planIdentityMappings({ users: users.rows, mappings: mappings.rows }, input.requested);
-    if (plan.inventoryDigest !== input.inventoryDigest) throw new Error('Identity inventory changed; create a new mapping plan');
+    const workloads = await client.query('SELECT id,issuer,subject FROM identity_workloads');
+    const plan = planIdentityMappings({ users: users.rows, mappings: mappings.rows, workloads: workloads.rows }, input.requested);
+    if (plan.inventoryDigest !== input.inventoryDigest || plan.requestDigest !== input.requestDigest)
+      throw new Error('Identity inventory or request changed; create a new mapping plan');
     const now = new Date().toISOString();
     for (const mapping of plan.operations) {
       if (mapping.action === 'noop') continue;
diff --git a/tests/unit/control-plane/accounts/identity-mapping-plan.test.ts b/tests/unit/control-plane/accounts/identity-mapping-plan.test.ts
index 90a2d686..4fcfb15b 100644
--- a/tests/unit/control-plane/accounts/identity-mapping-plan.test.ts
+++ b/tests/unit/control-plane/accounts/identity-mapping-plan.test.ts
@@ -2,7 +2,7 @@ import { describe, expect, it } from 'vitest';
 import { planIdentityMappings } from '../../../../src/api/auth/identity-mapping-plan.ts';
 
 const mapping = { userId: 'existing-user', issuer: 'https://identity.example.test/realms/local', subject: 'imported-subject' };
-const inventory = { users: [{ id: mapping.userId, status: 'active' }], mappings: [] };
+const inventory = { users: [{ id: mapping.userId, status: 'active' }], mappings: [], workloads: [] };
 describe('explicit identity migration planning', () => {
   it('preserves user IDs and does not mutate the inventory', () => {
     expect(planIdentityMappings(inventory, [mapping]).operations).toEqual([{ ...mapping, action: 'bind' }]);
@@ -16,8 +16,8 @@ describe('explicit identity migration planning', () => {
     expect(() => planIdentityMappings(inventory, [mapping, mapping])).toThrow('Duplicate');
   });
   it('rejects absent and disabled users instead of creating accounts', () => {
-    expect(() => planIdentityMappings({ users: [], mappings: [] }, [mapping])).toThrow('active existing user');
-    expect(() => planIdentityMappings({ users: [{ id: mapping.userId, status: 'disabled' }], mappings: [] }, [mapping])).toThrow('active existing user');
+    expect(() => planIdentityMappings({ ...inventory, users: [] }, [mapping])).toThrow('active existing user');
+    expect(() => planIdentityMappings({ ...inventory, users: [{ id: mapping.userId, status: 'disabled' }] }, [mapping])).toThrow('active existing user');
   });
   it('rejects unsafe issuers and empty subjects', () => {
     for (const issuer of ['http://identity.test', 'https://user:password@identity.test', 'https://identity.test/?q=1', 'https://identity.test/#fragment']) {
@@ -27,8 +27,23 @@ describe('explicit identity migration planning', () => {
   });
   it('binds the plan to account status and preserves exact issuer distinctions', () => {
     const before = planIdentityMappings(inventory, []);
-    const after = planIdentityMappings({ users: [{ id: mapping.userId, status: 'disabled' }], mappings: [] }, []);
+    const after = planIdentityMappings({ ...inventory, users: [{ id: mapping.userId, status: 'disabled' }] }, []);
     expect(before.inventoryDigest).not.toBe(after.inventoryDigest);
     expect(planIdentityMappings({ ...inventory, mappings: [mapping] }, [{ ...mapping, issuer: `${mapping.issuer}/` }]).operations[0].action).toBe('bind');
   });
+  it('rejects workload subjects and principal IDs without treating them as human accounts', () => {
+    for (const workload of [{ id: 'service', issuer: mapping.issuer, subject: mapping.subject },
+      { id: mapping.userId, issuer: mapping.issuer, subject: 'service-subject' }]) {
+      expect(() => planIdentityMappings({ ...inventory, workloads: [workload] }, [mapping])).toThrow('workload identity');
+    }
+  });
+  it('binds exact requests and all workload inventory while retaining valid opaque subjects', () => {
+    const before = planIdentityMappings(inventory, [mapping]);
+    const changed = planIdentityMappings(inventory, [{ ...mapping, subject: 'other|subject' }]);
+    expect(changed.requestDigest).not.toBe(before.requestDigest);
+    expect(changed.inventoryDigest).toBe(before.inventoryDigest);
+    expect(planIdentityMappings({ ...inventory, workloads: [{ id: 'service', issuer: mapping.issuer, subject: 'other' }] }, [mapping]).inventoryDigest).not.toBe(before.inventoryDigest);
+    for (const subject of ['x'.repeat(256), 'bad\nsubject', 'with space'])
+      expect(() => planIdentityMappings(inventory, [{ ...mapping, subject }])).toThrow();
+  });
 });
diff --git a/tests/unit/control-plane/accounts/identity-mapping-postgres.test.ts b/tests/unit/control-plane/accounts/identity-mapping-postgres.test.ts
index c841c6b5..81991c56 100644
--- a/tests/unit/control-plane/accounts/identity-mapping-postgres.test.ts
+++ b/tests/unit/control-plane/accounts/identity-mapping-postgres.test.ts
@@ -1,4 +1,5 @@
 import { randomUUID } from 'node:crypto';
+import { readFileSync } from 'node:fs';
 import pg from 'pg';
 import { describe, expect, it } from 'vitest';
 import { AUTH_SCHEMA_SQL } from '../../../../src/api/auth/postgres-store.ts';
@@ -19,6 +20,7 @@ describe.skipIf(!url)('transactional identity mapping in real PostgreSQL', () =>
       connection.pathname = `/${name}`;
       pool = new pg.Pool({ connectionString: connection.href });
       for (const sql of AUTH_SCHEMA_SQL.slice(0, 3)) await pool.query(sql);
+      await pool.query(readFileSync('drizzle/control-plane/0020_identity_workloads.sql', 'utf8'));
       await pool.query("INSERT INTO users(id,status,created_at,updated_at) VALUES ('preserved','active','now','now')");
       const database = { transaction: async <T>(run: (client: pg.PoolClient) => Promise<T>) => {
         const client = await pool!.connect();
@@ -27,19 +29,24 @@ describe.skipIf(!url)('transactional identity mapping in real PostgreSQL', () =>
         finally { client.release(); }
       } };
       const inventory = async () => ({ users: (await pool!.query('SELECT id,status FROM users')).rows,
-        mappings: (await pool!.query('SELECT user_id AS "userId",provider AS issuer,provider_subject AS subject FROM user_identities')).rows });
+        mappings: (await pool!.query('SELECT user_id AS "userId",provider AS issuer,provider_subject AS subject FROM user_identities')).rows,
+        workloads: (await pool!.query('SELECT id,issuer,subject FROM identity_workloads')).rows });
       const mapping = { userId: 'preserved', issuer: 'https://identity.example.test', subject: 'first' };
       const initial = planIdentityMappings(await inventory(), [mapping]);
       await pool.query("UPDATE users SET status='disabled'");
-      await expect(applyIdentityMappings(database, { requested: [], inventoryDigest: initial.inventoryDigest })).rejects.toThrow('inventory changed');
+      await expect(applyIdentityMappings(database, { requested: [], ...initial })).rejects.toThrow('inventory or request changed');
       await pool.query("UPDATE users SET status='active'");
-      await applyIdentityMappings(database, { requested: [mapping], inventoryDigest: initial.inventoryDigest });
+      await expect(applyIdentityMappings(database, { requested: [{ ...mapping, subject: 'changed' }], ...initial })).rejects.toThrow('inventory or request changed');
+      await pool.query(`INSERT INTO identity_workloads(id,issuer,subject,client_id,display_name,status) VALUES ('service',$1,$2,'client','Service','revoked')`, [mapping.issuer,mapping.subject]);
+      await expect(applyIdentityMappings(database, { requested: [mapping], ...initial })).rejects.toThrow('workload identity');
+      await pool.query("DELETE FROM identity_workloads WHERE id='service'");
+      await applyIdentityMappings(database, { requested: [mapping], ...initial });
       const replay = planIdentityMappings(await inventory(), [mapping]);
-      expect((await applyIdentityMappings(database, { requested: [mapping], inventoryDigest: replay.inventoryDigest })).operations[0].action).toBe('noop');
+      expect((await applyIdentityMappings(database, { requested: [mapping], ...replay })).operations[0].action).toBe('noop');
       await pool.query("ALTER TABLE user_identities ADD CONSTRAINT reject_test_subject CHECK (provider_subject <> 'z-rejected')");
       const requested = [{ ...mapping, subject: 'a-inserted' }, { ...mapping, subject: 'z-rejected' }];
       const batch = planIdentityMappings(await inventory(), requested);
-      await expect(applyIdentityMappings(database, { requested, inventoryDigest: batch.inventoryDigest })).rejects.toThrow();
+      await expect(applyIdentityMappings(database, { requested, ...batch })).rejects.toThrow();
       expect((await inventory()).mappings).toEqual([mapping]);
       expect((await inventory()).users).toEqual([{ id: 'preserved', status: 'active' }]);
     } finally {