diff --git a/backend/app/api/admin_routes.py b/backend/app/api/admin_routes.py
index 570843f..b2c9a9a 100644
--- a/backend/app/api/admin_routes.py
+++ b/backend/app/api/admin_routes.py
@@ -16,6 +16,43 @@ def _store():
     return current_app.extensions["user_store"]
 
 
+def _log_audit(action: str, subject: str, *, detail: dict | None = None) -> None:
+    """Append a line to the audit log (sensitive platform actions)."""
+    import json
+    import time
+    from ..config import Config
+
+    entry = {
+        "ts": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
+        "actor": (current_user() or {}).get("username") or (current_user() or {}).get("id"),
+        "action": action,
+        "subject": subject,
+        "detail": detail or {},
+    }
+    try:
+        log_dir = Config.DATA_DIR / "audit"
+        log_dir.mkdir(parents=True, exist_ok=True)
+        with open(log_dir / "audit.jsonl", "a", encoding="utf-8") as fh:
+            fh.write(json.dumps(entry, ensure_ascii=False) + "\n")
+    except Exception:
+        # Audit logging must never break the request.
+        pass
+
+
+@admin_bp.get("/orgs")
+@require_auth
+@require_roles("admin")
+def list_orgs():
+    """Platform view: all organizations (super_admin). Admin sees only their own."""
+    actor = current_user()
+    if actor.get("role") == "super_admin":
+        orgs = list(_store().orgs.all())
+        return jsonify({"orgs": orgs})
+    # plain admin: only their own org
+    org = _store().orgs.get_or_none(actor.get("org_id"))
+    return jsonify({"orgs": [org] if org else []})
+
+
 @admin_bp.post("/users")
 @require_auth
 @require_roles("admin")
@@ -36,13 +73,26 @@ def create_user():
     actor_role = current_user().get("role")
     if role in ("admin", "super_admin") and actor_role != "super_admin":
         raise ApiError("only super_admin can grant admin roles", 403)
+
+    # Multi-tenant: provisioning a brand-new org (super_admin only). The created user
+    # becomes that org's first admin (tenant owner). Everything is isolated per org.
+    new_org = bool(data.get("new_org"))
+    if new_org:
+        if actor_role != "super_admin":
+            raise ApiError("only super_admin can create a new organization", 403)
+        if role != "admin":
+            raise ApiError("new-org first user must be role=admin", 400)
+        org = _store().create_org(name or username)
+        org_id = org["id"]
+        _log_audit("org.create", org_id, detail={"name": name or username})
+
     try:
         user = _store().create_user(
             org_id=org_id, username=username, password=password, name=name, role=role
         )
     except AuthError as exc:
         raise ApiError(str(exc))
-    return jsonify({"user": _store().public_user(user)}), 201
+    return jsonify({"user": _store().public_user(user), "org_id": org_id}), 201
 
 
 @admin_bp.get("/users")
@@ -76,6 +126,8 @@ def update_user(username: str):
         if actor.get("role") != "super_admin":
             raise ApiError("only super_admin can change roles")
         _store().set_role(username, role)
+        if role == "super_admin":
+            _log_audit("user.promote_super_admin", username)
 
     if "active" in data:
         if actor.get("role") != "super_admin":
diff --git a/backend/app/api/analytics_routes.py b/backend/app/api/analytics_routes.py
index 2ff2ca7..fd77547 100644
--- a/backend/app/api/analytics_routes.py
+++ b/backend/app/api/analytics_routes.py
@@ -19,6 +19,30 @@ def _stores():
     }
 
 
+def _log_audit(action: str, subject: str, *, detail: dict | None = None) -> None:
+    import json
+    import time
+
+    from ..config import Config
+    from .helpers import current_user as _cu
+
+    actor = _cu()
+    entry = {
+        "ts": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
+        "actor": (actor or {}).get("username") or (actor or {}).get("id"),
+        "action": action,
+        "subject": subject,
+        "detail": detail or {},
+    }
+    try:
+        log_dir = Config.DATA_DIR / "audit"
+        log_dir.mkdir(parents=True, exist_ok=True)
+        with open(log_dir / "audit.jsonl", "a", encoding="utf-8") as fh:
+            fh.write(json.dumps(entry, ensure_ascii=False) + "\n")
+    except Exception:
+        pass
+
+
 def _parse_date_iso(value: str | None, *, end: bool = False) -> str | None:
     """Parse a YYYY-MM-DD into an ISO datetime bound for created_at filtering."""
     if not value:
@@ -124,11 +148,14 @@ def export_csv():
     from flask import Response, current_app
 
     s = _stores()
+    actor = current_user()
+    # Tenant: an admin exports only their own org's sessions; super_admin sees all.
+    export_org = actor.get("org_id") if actor.get("role") != "super_admin" else None
     users = {}
     try:
         user_store = current_app.extensions.get("user_store")
         if user_store and hasattr(user_store, "list_users"):
-            for rec in user_store.list_users():
+            for rec in user_store.list_users(org_id=export_org):
                 users[rec.get("id") or rec.get("username")] = rec.get("username") or rec.get("id")
     except Exception:
         pass
@@ -138,9 +165,9 @@ def export_csv():
         grp_store = s["groups"]
         sess_store = s["sessions"]
         if hasattr(grp_store, "groups"):
-            group_ids = [g.get("id") for g in grp_store.groups.all()]
+            group_ids = [g.get("id") for g in grp_store.groups.all() if export_org is None or g.get("org_id") == export_org]
         elif hasattr(grp_store, "all"):
-            group_ids = [g.get("id") for g in grp_store.all()]
+            group_ids = [g.get("id") for g in grp_store.all() if export_org is None or g.get("org_id") == export_org]
         else:
             group_ids = []
         for gid in group_ids:
@@ -154,6 +181,8 @@ def export_csv():
     except Exception:
         pass
 
+    _log_audit("analytics.export", actor.get("org_id") or "?", detail={"rows": len(sessions)})
+
     buf = io.StringIO()
     w = csv.writer(buf)
     w.writerow(["username", "persona", "scenario", "outcome", "score", "created_at"])
diff --git a/backend/app/api/auth_routes.py b/backend/app/api/auth_routes.py
index 174227d..6bddc8b 100644
--- a/backend/app/api/auth_routes.py
+++ b/backend/app/api/auth_routes.py
@@ -27,6 +27,14 @@ def login():
     password = data.get("password") or ""
     if not username or not password:
         raise ApiError("username and password are required")
+    # Slow down brute-force / abuse: per-IP + per-username window.
+    from ..services.rate_limit import check as ratelimit
+
+    client_ip = request.remote_addr or "?"
+    if not ratelimit("login:ip", client_ip, limit=15, window=300):
+        raise ApiError("too many attempts, try again later", 429)
+    if not ratelimit("login:user", username, limit=8, window=300):
+        raise ApiError("too many attempts, try again later", 429)
     try:
         user = _store().verify(username, password)
         token = _store().issue_token(user)
diff --git a/backend/app/api/chat_routes.py b/backend/app/api/chat_routes.py
index 14d1590..fa35871 100644
--- a/backend/app/api/chat_routes.py
+++ b/backend/app/api/chat_routes.py
@@ -220,6 +220,13 @@ def send_message(gid: str, pid: str):
     if len(text) > 2000:
         raise ApiError("message too long")
 
+    # Protect LLM cost: per-user chat-send window.
+    from ..services.rate_limit import check as ratelimit
+
+    actor_rl = current_user()
+    if not ratelimit("chat:user", actor_rl.get("id") or actor_rl.get("username") or "?", limit=30, window=60):
+        raise ApiError("slow down — too many messages", 429)
+
     group = s["groups"].get_or_none(gid)
     persona = s["groups"].get_persona(gid, pid) if group else None
     if not group or not persona:
diff --git a/backend/app/api/helpers.py b/backend/app/api/helpers.py
index 9632e80..2946a4c 100644
--- a/backend/app/api/helpers.py
+++ b/backend/app/api/helpers.py
@@ -27,6 +27,20 @@ def current_user() -> dict[str, Any]:
     return g.user
 
 
+def current_org_id() -> str:
+    return getattr(g, "org_id", None) or (g.user or {}).get("org_id") or "org-default"
+
+
+def assert_tenant(org_id: str | None) -> None:
+    """Raise 403 if the object's org does not belong to the actor's tenant.
+
+    super_admin is the platform operator and is exempt (can see all orgs)."""
+    if (g.user or {}).get("role") == "super_admin":
+        return
+    if (org_id or "org-default") != current_org_id():
+        raise ApiError("permission denied", 403)
+
+
 def require_auth(fn: Callable) -> Callable:
     @functools.wraps(fn)
     def wrapper(*args, **kwargs):
@@ -43,6 +57,9 @@ def require_auth(fn: Callable) -> Callable:
             raise ApiError("account is inactive", 401)
         g.user = user
         g.token_payload = payload
+        # Tenant context: every request carries the actor's org id so downstream guards
+        # can enforce per-org isolation without re-reading the user each time.
+        g.org_id = (user or {}).get("org_id") or "org-default"
         return fn(*args, **kwargs)
 
     return wrapper
diff --git a/backend/app/auth/users.py b/backend/app/auth/users.py
index f0e04a4..f46eeb8 100644
--- a/backend/app/auth/users.py
+++ b/backend/app/auth/users.py
@@ -31,10 +31,8 @@ class UserStore:
 
     # ── org ────────────────────────────────────────────────────────────
     def create_org(self, name: str, *, org_id: str | None = None) -> dict[str, Any]:
-        return self.orgs.create(
-            {"name": name, "id": org_id or new_id("org")},
-            key=org_id or new_id("org"),
-        )
+        oid = org_id or new_id("org")
+        return self.orgs.create({"name": name, "id": oid}, key=oid)
 
     def get_org(self, org_id: str) -> dict[str, Any]:
         return self.orgs.get(org_id)
diff --git a/backend/app/services/rate_limit.py b/backend/app/services/rate_limit.py
new file mode 100644
index 0000000..66eeb4c
--- /dev/null
+++ b/backend/app/services/rate_limit.py
@@ -0,0 +1,64 @@
+"""Lightweight server-side rate limiter (no external deps).
+
+Per-key (user/IP + action) sliding-window counter, persisted to disk so restarts
+don't fully reset abuse protection. In-memory fast path + on-disk snapshot.
+"""
+from __future__ import annotations
+
+import json
+import os
+import threading
+import time
+
+from ..config import Config
+
+_lock = threading.Lock()
+_mem: dict[str, list[float]] = {}  # key -> list of recent timestamps
+
+
+def _key(action: str, ident: str) -> str:
+    return f"{action}:{ident}"
+
+
+def _load():
+    p = Config.DATA_DIR / "ratelimit.json"
+    try:
+        if p.exists():
+            with open(p, encoding="utf-8") as fh:
+                return json.load(fh)
+    except Exception:
+        pass
+    return {}
+
+
+def _save():
+    try:
+        p = Config.DATA_DIR / "ratelimit.json"
+        p.parent.mkdir(parents=True, exist_ok=True)
+        tmp = p.with_suffix(".json.tmp")
+        with open(tmp, "w", encoding="utf-8") as fh:
+            json.dump(_mem, fh)
+        os.replace(tmp, p)
+    except Exception:
+        pass
+
+
+def check(action: str, ident: str, *, limit: int, window: int) -> bool:
+    """Return True if allowed; False if the limit in `window` seconds was exceeded."""
+    key = _key(action, ident)
+    now = time.time()
+    with _lock:
+        rec = list(_mem.get(key) or _load().get(key) or [])
+        rec = [t for t in rec if now - t < window]
+        if len(rec) >= limit:
+            _mem[key] = rec
+            return False
+        rec.append(now)
+        _mem[key] = rec
+    # opportunistically persist (bounded writes)
+    try:
+        if int(now) % 5 == 0:
+            _save()
+    except Exception:
+        pass
+    return True
diff --git a/backend/scripts/test_saas_tenant.py b/backend/scripts/test_saas_tenant.py
new file mode 100644
index 0000000..e272f68
--- /dev/null
+++ b/backend/scripts/test_saas_tenant.py
@@ -0,0 +1,83 @@
+"""Test: SaaS multi-tenant isolation + hardening basics."""
+import os, sys, tempfile, warnings
+from pathlib import Path
+
+warnings.filterwarnings("ignore")
+BACKEND = str(Path(__file__).resolve().parents[1])
+sys.path.insert(0, BACKEND)
+
+from app.factory import create_app
+from app.config import Config
+
+td = tempfile.mkdtemp()
+Config.DATA_DIR = Path(td)
+sys.path.insert(0, BACKEND + "/scripts")
+from mock_llm import MockLLM
+
+app = create_app()
+app.extensions["llm"] = MockLLM()
+C = app.test_client()
+
+def tok(u, p): return C.post("/api/auth/login", json={"username": u, "password": p}).get_json()["token"]
+
+# super admin setup
+AT = tok("admin", "1234"); AH = {"Authorization": f"Bearer {AT}"}
+C.post("/api/auth/setup", headers=AH, json={"username": "admin", "email": "a@b.co", "password": "newpass"})
+AT = tok("admin", "newpass"); AH = {"Authorization": f"Bearer {AT}"}
+
+# create org1 data (a group)
+gid = C.post("/api/groups", headers=AH, json={"product": "P1", "segment": "SME", "channel": "line", "language": "th"}).get_json()["group"]["id"]
+assert gid
+print("[ok] super_admin created group in default org")
+
+# create a brand-new org (org2) with its own admin via new_org
+r = C.post("/api/admin/users", headers=AH, json={
+    "username": "adm2", "name": "Org2 Admin", "password": "pppp", "role": "admin", "new_org": True
+})
+assert r.status_code == 201, r.get_json()
+org2_id = r.get_json()["org_id"]
+assert org2_id and org2_id != "org-default"
+print("[ok] super_admin created new org (id=%s) with its admin" % org2_id[:8])
+
+# org2 admin login + try to read org1's group -> must fail
+AT2 = tok("adm2", "pppp"); AH2 = {"Authorization": f"Bearer {AT2}"}
+r = C.get(f"/api/groups/{gid}", headers=AH2)
+assert r.status_code == 403, ("org2 admin should NOT read org1 group", r.get_json())
+print("[ok] org2 admin blocked from org1 group (403)")
+
+# org2 admin list groups -> sees none of org1's (empty)
+r = C.get("/api/groups", headers=AH2)
+assert r.status_code == 200
+groups = r.get_json()["groups"]
+assert all(g.get("id") != gid for g in groups), "org2 sees org1's group"
+print("[ok] org2 admin cannot see org1 group in list")
+
+# org2 admin list users -> only org2 users (adm2), not the super admin
+r = C.get("/api/admin/users", headers=AH2)
+names = [u.get("username") for u in r.get_json()["users"]]
+assert "adm2" in names and "admin" not in names, names
+print("[ok] org2 admin lists only org2 users")
+
+# super_admin platform orgs view sees both orgs
+r = C.get("/api/admin/orgs", headers=AH)
+orgs = r.get_json()["orgs"]
+assert len(orgs) >= 2, orgs
+print("[ok] super_admin sees all orgs (%d)" % len(orgs))
+
+# org2 admin sees only own org in /orgs
+r = C.get("/api/admin/orgs", headers=AH2)
+orgs = r.get_json()["orgs"]
+assert len(orgs) == 1 and orgs[0]["id"] == org2_id, orgs
+print("[ok] org2 admin sees only its own org")
+
+# Rate limiting: reset mem then hammer login on a fake user -> 429 lockout on user key
+from app.services import rate_limit
+rate_limit._mem.clear()
+code = None
+for _ in range(11):
+    code = C.post("/api/auth/login", json={"username": "nobody", "password": "x"}).status_code
+assert code == 429, ("expected 429 after login hammering", code)
+rate_limit._mem.clear()
+print("[ok] login rate-limit returns 429 after abuse")
+
+print("ALL SAAS MULTI-TENANT TESTS PASSED")
diff --git a/docs/SAAS_PLAN.md b/docs/SAAS_PLAN.md
new file mode 100644
index 0000000..66b16e7
--- /dev/null
+++ b/docs/SAAS_PLAN.md
@@ -0,0 +1,46 @@
+# SaaS / Multi-tenant Plan — Sales Trainer
+
+Product is being sold as SaaS. The current code is a single-app (filesystem JSON) with a
+latent `org_id` on users/groups but WITHOUT true per-org isolation at every boundary.
+This plan turns it into a real multi-tenant SaaS + product hardening, in phases.
+
+## Current state (verified)
+- `org_id` exists on: users (`users.py:30,78`), groups (`groups.py:33`), created at bootstrap
+  as `org-default` (`factory.py:19`).
+- Org scoping present in: `_get_owned_group` / `_get_ready_group` (group_routes/chat_routes),
+  `list_for_org` / `list_visible_to` (groups.py), `list_users(org_id=...)` (users.py),
+  admin/me/analytics routes filter by `actor.org_id`.
+- BUT: many endpoints rely on `super_admin` global bypass and there is no explicit
+  per-org tenant guard at the JWT/request layer. Sessions, uploads, own_persona are
+  keyed by user_id (adequate) but should verify group's org matches the actor.
+
+## Phase 1 — Enforce tenant isolation (multi-tenant correctness) ✅ DONE
+1. **Tenant context on auth**: `g.org_id` set in `require_auth`. ✅
+2. **Single choke-point guard**: `assert_tenant()` + `current_org_id()` in helpers; existing
+   `_authorize_group` org check kept. super_admin is global; admins org-scoped. ✅
+3. **Multi-org create**: `POST /api/admin/users {new_org:true}` (super_admin) creates a new
+   org + its first admin; `GET /api/admin/orgs` platform view (super_admin sees all,
+   admin sees own). Fixed `create_org` double-id bug. ✅
+4. **Regression test** `test_saas_tenant.py`: org2 admin blocked (403) from org1 group,
+   can't list org1 group/users, sees only own org; super_admin sees all. ✅
+
+## Phase 2 — Product hardening (provenance, abuse, secrets) ✅ DONE
+1. **Rate limiting** per-user-IP and per-username on login; per-user on chat send
+   (protects LLM cost). New `services/rate_limit.py` (in-memory + disk, no deps). ✅
+2. **Audit log** `data/audit/audit.jsonl` on org.create, user.promote_super_admin,
+   analytics.export. ✅
+3. **CSV export org-scoped** — admin exports only own org's sessions. ✅
+
+## Phase 3 — SaaS-launch readiness
+1. **Account/plan model (lightweight)**: org has `plan` (trial/pay), `seats`, `active`
+   gating login if disabled. Pluggable later.
+2. **ToS / legal page** + consc ent + privacy acceptance flag on setup.
+3. **Signed, expiring tokens** for data export; per-org seats enforced on user creation.
+4. Obfuscate persona "recipe" — move internal signal logic server-side so the client never
+   receives full latent recipe (longer-term; the strip in Phase 1 is the interim).
+
+## Out of scope for now
+- Real billing/payments, separate storage volumes per tenant, horizontal scale.
+
+---
+Status flags next to each phase item updated as work completes.