diff --git a/packages/server/src/db/migrations/014_organizations_not_null.sql b/packages/server/src/db/migrations/014_organizations_not_null.sql
new file mode 100644
index 0000000..08562ea
--- /dev/null
+++ b/packages/server/src/db/migrations/014_organizations_not_null.sql
@@ -0,0 +1,27 @@
+-- NOT NULL backstop for the organization tenant FKs. Migration 013 added
+-- organization_id as nullable so the backfill and the app writers could be rolled out
+-- incrementally; now that every writer (admin routes, create-admin, create-project) sets
+-- it, we close the gap at the DB level so a tenant-less project or admin can never exist.
+
+-- Catch any stragglers first: rows an older image may have created after 013 but before
+-- the org-aware writers shipped. Bucket them into a 'Default' org (create it if needed)
+-- so the constraint can be applied cleanly. In an in-order deploy there are none.
+DO $$
+DECLARE
+  default_org UUID;
+BEGIN
+  IF EXISTS (SELECT 1 FROM admin_users WHERE organization_id IS NULL)
+     OR EXISTS (SELECT 1 FROM projects WHERE organization_id IS NULL) THEN
+    SELECT id INTO default_org FROM organizations WHERE name = 'Default' LIMIT 1;
+    IF default_org IS NULL THEN
+      INSERT INTO organizations (name, slug) VALUES ('Default', 'default')
+        ON CONFLICT (slug) DO UPDATE SET name = EXCLUDED.name
+        RETURNING id INTO default_org;
+    END IF;
+    UPDATE admin_users SET organization_id = default_org WHERE organization_id IS NULL;
+    UPDATE projects    SET organization_id = default_org WHERE organization_id IS NULL;
+  END IF;
+END $$;
+
+ALTER TABLE admin_users ALTER COLUMN organization_id SET NOT NULL;
+ALTER TABLE projects    ALTER COLUMN organization_id SET NOT NULL;
diff --git a/packages/server/src/lib/organizations.ts b/packages/server/src/lib/organizations.ts
new file mode 100644
index 0000000..0f3d357
--- /dev/null
+++ b/packages/server/src/lib/organizations.ts
@@ -0,0 +1,16 @@
+import { db } from '../db/client.js';
+
+// Find an organization by name, or create it. Used by the bootstrap CLIs (create-admin,
+// create-project) to attach the first admin/project to a tenant: a fresh self-host install
+// has no org until the first bootstrap, so these scripts provision one. Multi-tenant hosts
+// pass a distinct name per customer. Idempotent on name (re-running returns the same org).
+export async function findOrCreateOrgByName(name: string): Promise<string> {
+  const existing = await db<{ id: string }[]>`
+    SELECT id FROM organizations WHERE name = ${name} LIMIT 1
+  `;
+  if (existing[0]) return existing[0].id;
+  const [org] = await db<{ id: string }[]>`
+    INSERT INTO organizations (name) VALUES (${name}) RETURNING id
+  `;
+  return org!.id;
+}
diff --git a/packages/server/src/pipeline/retention.integration.test.ts b/packages/server/src/pipeline/retention.integration.test.ts
index 6402952..4361250 100644
--- a/packages/server/src/pipeline/retention.integration.test.ts
+++ b/packages/server/src/pipeline/retention.integration.test.ts
@@ -3,13 +3,16 @@ import { migrate } from '../db/migrate.js';
 import { db } from '../db/client.js';
 import { sweepRetention } from './retention.js';
 import { hashApiKey } from '../middleware/api-key.js';
+import { createTestOrg, deleteTestOrg } from '../test-support/org.js';
 
 // Gated on DATABASE_URL like the other integration suites (runs in CI, skips locally
 // without a DB). See events.integration.test.ts for the rationale.
 const hasDb = Boolean(process.env['DATABASE_URL']);
 const API_KEY = 'retention-test-key';
+const ORG = 'Retention IT Org';
 
 let projectId: string; // retention_days = 30
+let orgId: string;
 
 async function seedIdentity(project: string, ageDays: number): Promise<string> {
   const id = `ret-${ageDays}d-${crypto.randomUUID()}`;
@@ -24,9 +27,11 @@ beforeAll(async () => {
   if (!hasDb) return;
   await migrate();
   await db`DELETE FROM projects WHERE api_key_hash IN (${hashApiKey(API_KEY)}, ${hashApiKey(`${API_KEY}-keep`)})`;
+  await deleteTestOrg(ORG);
+  orgId = await createTestOrg(ORG);
   const [proj] = await db<{ id: string }[]>`
-    INSERT INTO projects (api_key_hash, name, retention_days)
-    VALUES (${hashApiKey(API_KEY)}, 'Retention Test', 30) RETURNING id
+    INSERT INTO projects (api_key_hash, name, retention_days, organization_id)
+    VALUES (${hashApiKey(API_KEY)}, 'Retention Test', 30, ${orgId}) RETURNING id
   `;
   projectId = proj!.id;
 });
@@ -34,6 +39,7 @@ beforeAll(async () => {
 afterAll(async () => {
   if (!hasDb) return;
   await db`DELETE FROM projects WHERE api_key_hash IN (${hashApiKey(API_KEY)}, ${hashApiKey(`${API_KEY}-keep`)})`;
+  await deleteTestOrg(ORG);
   await db.end();
 });
 
@@ -55,8 +61,8 @@ describe.skipIf(!hasDb)('sweepRetention', () => {
 
   it('skips projects with null retention_days (keep forever)', async () => {
     const [keepProj] = await db<{ id: string }[]>`
-      INSERT INTO projects (api_key_hash, name)
-      VALUES (${hashApiKey(`${API_KEY}-keep`)}, 'Keep Forever') RETURNING id
+      INSERT INTO projects (api_key_hash, name, organization_id)
+      VALUES (${hashApiKey(`${API_KEY}-keep`)}, 'Keep Forever', ${orgId}) RETURNING id
     `;
     const ancient = await seedIdentity(keepProj!.id, 999);
 
diff --git a/packages/server/src/risk/assess.integration.test.ts b/packages/server/src/risk/assess.integration.test.ts
index 2d26292..0cc2fe9 100644
--- a/packages/server/src/risk/assess.integration.test.ts
+++ b/packages/server/src/risk/assess.integration.test.ts
@@ -3,6 +3,7 @@ import { migrate } from '../db/migrate.js';
 import { db } from '../db/client.js';
 import { hashApiKey } from '../middleware/api-key.js';
 import { assessRisk } from './assess.js';
+import { createTestOrg, deleteTestOrg } from '../test-support/org.js';
 
 // Regression coverage for the risk_assessments.flags encoding bug: the insert used
 // `${JSON.stringify(flags)}::jsonb`, which postgres.js double-encodes into a JSON
@@ -11,6 +12,7 @@ import { assessRisk } from './assess.js';
 // ARRAY. Gated on DATABASE_URL.
 const hasDb = Boolean(process.env['DATABASE_URL']);
 const API_KEY = 'assess-integration-key';
+const ORG = 'Assess IT Org';
 const ID = 'assessit-identity-1';
 
 let projectId: string;
@@ -20,8 +22,10 @@ beforeAll(async () => {
   if (!hasDb) return;
   await migrate();
   await db`DELETE FROM projects WHERE api_key_hash = ${hashApiKey(API_KEY)}`;
+  await deleteTestOrg(ORG);
+  const org = await createTestOrg(ORG);
   const [proj] = await db<{ id: string }[]>`
-    INSERT INTO projects (api_key_hash, name) VALUES (${hashApiKey(API_KEY)}, 'Assess Integration') RETURNING id
+    INSERT INTO projects (api_key_hash, name, organization_id) VALUES (${hashApiKey(API_KEY)}, 'Assess Integration', ${org}) RETURNING id
   `;
   projectId = proj!.id;
   await db`
@@ -39,6 +43,7 @@ beforeAll(async () => {
 afterAll(async () => {
   if (!hasDb) return;
   await db`DELETE FROM projects WHERE api_key_hash = ${hashApiKey(API_KEY)}`;
+  await deleteTestOrg(ORG);
   await db.end();
 });
 
diff --git a/packages/server/src/routes/events.integration.test.ts b/packages/server/src/routes/events.integration.test.ts
index 3ff4ddd..dbdb0df 100644
--- a/packages/server/src/routes/events.integration.test.ts
+++ b/packages/server/src/routes/events.integration.test.ts
@@ -9,6 +9,7 @@ import { resolveSnapshot } from '../pipeline/resolve.js';
 import { createQueueConnection, INGEST_QUEUE_NAME } from '../queue/ingest.js';
 import type { IngestJobData } from '../queue/ingest.js';
 import { hashApiKey } from '../middleware/api-key.js';
+import { createTestOrg, deleteTestOrg } from '../test-support/org.js';
 
 // Integration tests hit a real Postgres + Redis. They run in CI (which provides
 // DATABASE_URL/REDIS_URL via service containers) and locally when those env vars
@@ -17,6 +18,7 @@ import { hashApiKey } from '../middleware/api-key.js';
 const hasDb = Boolean(process.env['DATABASE_URL']);
 
 const API_KEY = 'integration-test-key';
+const ORG = 'Events IT Org';
 
 // A rich, stable signal set: identical re-submissions resolve to the same identity
 // with high confidence (canvas/audio/fonts/hardware dominate the weighting).
@@ -80,8 +82,10 @@ beforeAll(async () => {
   await migrate();
   await redis.flushdb();
   await db`DELETE FROM projects WHERE api_key_hash = ${hashApiKey(API_KEY)}`; // cascades to identities/snapshots/links
+  await deleteTestOrg(ORG);
+  const org = await createTestOrg(ORG);
   const [proj] = await db<{ id: string }[]>`
-    INSERT INTO projects (api_key_hash, name) VALUES (${hashApiKey(API_KEY)}, 'Integration Test') RETURNING id
+    INSERT INTO projects (api_key_hash, name, organization_id) VALUES (${hashApiKey(API_KEY)}, 'Integration Test', ${org}) RETURNING id
   `;
   projectId = proj!.id;
 });
@@ -89,6 +93,7 @@ beforeAll(async () => {
 afterAll(async () => {
   if (!hasDb) return;
   await db`DELETE FROM projects WHERE api_key_hash = ${hashApiKey(API_KEY)}`;
+  await deleteTestOrg(ORG);
   await redis.quit();
   await db.end();
 });
diff --git a/packages/server/src/routes/events.resolution.integration.test.ts b/packages/server/src/routes/events.resolution.integration.test.ts
index fb19013..79eb511 100644
--- a/packages/server/src/routes/events.resolution.integration.test.ts
+++ b/packages/server/src/routes/events.resolution.integration.test.ts
@@ -5,6 +5,7 @@ import { db } from '../db/client.js';
 import { redis } from '../db/redis.js';
 import { resolveSnapshot } from '../pipeline/resolve.js';
 import { hashApiKey } from '../middleware/api-key.js';
+import { createTestOrg, deleteTestOrg } from '../test-support/org.js';
 
 // Integration coverage for the *resolution decisions* — new-vs-returning boundary,
 // ambiguous match, and cluster linking — that the happy-path suite doesn't reach.
@@ -14,6 +15,7 @@ import { hashApiKey } from '../middleware/api-key.js';
 // skips locally without a DB).
 const hasDb = Boolean(process.env['DATABASE_URL']);
 const API_KEY = 'integration-resolution-key';
+const ORG = 'Resolution IT Org';
 
 // Base device: 4 stable (weight 0.9) + 5 moderate (0.55) signals.
 const C = {
@@ -89,8 +91,10 @@ beforeAll(async () => {
   await migrate();
   await redis.flushdb();
   await db`DELETE FROM projects WHERE api_key_hash = ${hashApiKey(API_KEY)}`;
+  await deleteTestOrg(ORG);
+  const org = await createTestOrg(ORG);
   const [proj] = await db<{ id: string }[]>`
-    INSERT INTO projects (api_key_hash, name) VALUES (${hashApiKey(API_KEY)}, 'Resolution Integration') RETURNING id
+    INSERT INTO projects (api_key_hash, name, organization_id) VALUES (${hashApiKey(API_KEY)}, 'Resolution Integration', ${org}) RETURNING id
   `;
   projectId = proj!.id;
 });
@@ -98,6 +102,7 @@ beforeAll(async () => {
 afterAll(async () => {
   if (!hasDb) return;
   await db`DELETE FROM projects WHERE api_key_hash = ${hashApiKey(API_KEY)}`;
+  await deleteTestOrg(ORG);
   await redis.quit();
   await db.end();
 });
diff --git a/packages/server/src/routes/queries.integration.test.ts b/packages/server/src/routes/queries.integration.test.ts
index f76450f..8ba610b 100644
--- a/packages/server/src/routes/queries.integration.test.ts
+++ b/packages/server/src/routes/queries.integration.test.ts
@@ -5,12 +5,14 @@ import { migrate } from '../db/migrate.js';
 import { db } from '../db/client.js';
 import { redis } from '../db/redis.js';
 import { hashApiKey } from '../middleware/api-key.js';
+import { createTestOrg, deleteTestOrg } from '../test-support/org.js';
 
 // Integration coverage for the read/query API (the GET routes + /v1/resolve), which
 // the OpenAPI spec documents and the SDK/Observatory consume. Seeds a small graph and
 // asserts status + response shape. Gated on DATABASE_URL like the other suites.
 const hasDb = Boolean(process.env['DATABASE_URL']);
 const API_KEY = 'queries-integration-key';
+const ORG = 'Queries IT Org';
 
 const app = createApp();
 let projectId: string;
@@ -28,8 +30,10 @@ beforeAll(async () => {
   await migrate();
   await redis.flushdb();
   await db`DELETE FROM projects WHERE api_key_hash = ${hashApiKey(API_KEY)}`;
+  await deleteTestOrg(ORG);
+  const org = await createTestOrg(ORG);
   const [proj] = await db<{ id: string }[]>`
-    INSERT INTO projects (api_key_hash, name) VALUES (${hashApiKey(API_KEY)}, 'Queries Integration') RETURNING id
+    INSERT INTO projects (api_key_hash, name, organization_id) VALUES (${hashApiKey(API_KEY)}, 'Queries Integration', ${org}) RETURNING id
   `;
   projectId = proj!.id;
 
@@ -82,6 +86,7 @@ beforeAll(async () => {
 afterAll(async () => {
   if (!hasDb) return;
   await db`DELETE FROM projects WHERE api_key_hash = ${hashApiKey(API_KEY)}`;
+  await deleteTestOrg(ORG);
   await redis.quit();
   await db.end();
 });
diff --git a/packages/server/src/scripts/create-admin.ts b/packages/server/src/scripts/create-admin.ts
index b7c708b..b5e1039 100644
--- a/packages/server/src/scripts/create-admin.ts
+++ b/packages/server/src/scripts/create-admin.ts
@@ -1,32 +1,38 @@
 import { db } from '../db/client.js';
 import { hashPassword } from '../admin/password.js';
+import { findOrCreateOrgByName } from '../lib/organizations.js';
 
 // Bootstrap an admin user. This is the install owner: CLI-created admins are always
-// 'owner' (full access — manages projects and, going forward, other admins). Member
+// 'owner' (full access — manages projects and other admins WITHIN their org). Member
 // accounts are provisioned from the Observatory, not here. Password is hashed with
 // bcrypt before it touches the DB.
 //
-//   tsx src/scripts/create-admin.ts <email> <password>          (dev)
-//   docker compose exec scent-server node dist/scripts/create-admin.js <email> <pw>
+//   tsx src/scripts/create-admin.ts <email> <password> [orgName]   (dev)
+//   docker compose exec scent-server node dist/scripts/create-admin.js <email> <pw> [org]
 //
-// Re-running for an existing email resets the password but leaves the role untouched.
+// The optional org name (default 'Default') attaches the admin to a tenant, creating it
+// if needed — this is how a fresh install gets its first org + owner, and how an operator
+// adds a second tenant on a hosted box. Re-running for an existing email resets the
+// password but leaves the role and org untouched.
 async function main(): Promise<void> {
   const email = process.argv[2]?.trim().toLowerCase();
   const password = process.argv[3];
+  const orgName = process.argv[4]?.trim() || 'Default';
   if (!email || !password) {
-    console.error('Usage: create-admin <email> <password>');
+    console.error('Usage: create-admin <email> <password> [orgName]');
     process.exit(1);
   }
 
   const passwordHash = await hashPassword(password);
+  const organizationId = await findOrCreateOrgByName(orgName);
   const [user] = await db<{ id: string }[]>`
-    INSERT INTO admin_users (email, password_hash, role)
-    VALUES (${email}, ${passwordHash}, 'owner')
+    INSERT INTO admin_users (email, password_hash, role, organization_id)
+    VALUES (${email}, ${passwordHash}, 'owner', ${organizationId})
     ON CONFLICT (email) DO UPDATE SET password_hash = EXCLUDED.password_hash
     RETURNING id
   `;
 
-  console.error(`Admin user ready: ${email} (id: ${user?.id})`);
+  console.error(`Admin user ready: ${email} (id: ${user?.id}, org: ${orgName})`);
   await db.end();
 }
 
diff --git a/packages/server/src/scripts/create-project.ts b/packages/server/src/scripts/create-project.ts
index a15bb24..e501541 100644
--- a/packages/server/src/scripts/create-project.ts
+++ b/packages/server/src/scripts/create-project.ts
@@ -1,30 +1,36 @@
 import { db } from '../db/client.js';
 import { mintApiKey } from '../lib/api-key.js';
+import { findOrCreateOrgByName } from '../lib/organizations.js';
 
 // Create a project and mint its API key. Only the key's hash is stored; the
 // plaintext is printed once here and cannot be recovered later.
 //
-//   tsx src/scripts/create-project.ts "Project Name"          (dev)
-//   node dist/scripts/create-project.js "Project Name"        (in the image)
+//   tsx src/scripts/create-project.ts "Project Name" [orgName]   (dev)
+//   node dist/scripts/create-project.js "Project Name" [org]     (in the image)
 //   docker compose exec scent-server node dist/scripts/create-project.js "Prod"
+//
+// The optional org name (default 'Default') attaches the project to a tenant, creating
+// it if needed — every project belongs to an organization (migration 013).
 async function main(): Promise<void> {
   const name = process.argv[2];
+  const orgName = process.argv[3]?.trim() || 'Default';
   if (!name) {
-    console.error('Usage: create-project "<project name>"');
+    console.error('Usage: create-project "<project name>" [orgName]');
     process.exit(1);
   }
 
   const { apiKey, keyHash, keyPrefix } = mintApiKey();
+  const organizationId = await findOrCreateOrgByName(orgName);
 
   const [project] = await db<{ id: string }[]>`
-    INSERT INTO projects (api_key_hash, name, key_prefix)
-    VALUES (${keyHash}, ${name}, ${keyPrefix})
+    INSERT INTO projects (api_key_hash, name, key_prefix, organization_id)
+    VALUES (${keyHash}, ${name}, ${keyPrefix}, ${organizationId})
     RETURNING id
   `;
 
   // The key is shown exactly once. Print to stdout; everything else to stderr so
   // `... | tail` style capture of just the key works.
-  console.error(`Created project "${name}" (id: ${project?.id})`);
+  console.error(`Created project "${name}" (id: ${project?.id}, org: ${orgName})`);
   console.error('API key (store it now — it is not recoverable):');
   console.log(apiKey);