diff --git a/.env.example b/.env.example
new file mode 100644
index 0000000..7b9110f
--- /dev/null
+++ b/.env.example
@@ -0,0 +1,15 @@
+# Denya OneCare — runtime environment template (HARDENING.md P0.1/P1.1)
+# Copy to .env and fill in real values. NEVER commit .env.
+# Generate the secret with: openssl rand -hex 32
+
+# ── Required ─────────────────────────────────────────────
+SECRET_KEY=
+DATABASE_URL=sqlite+aiosqlite:///./data/denya_onecare.db
+# Explicit origin allow-list — "*" is rejected at startup (P0.2)
+CORS_ORIGINS=http://localhost:8000
+
+# ── Optional (WhatsApp; needed before wiring Meta) ───────
+WHATSAPP_PHONE_NUMBER_ID=
+WHATSAPP_ACCESS_TOKEN=
+WHATSAPP_VERIFY_TOKEN=
+META_GRAPH_BASE=https://graph.facebook.com/v18.0
diff --git a/app/core/config.py b/app/core/config.py
index 78b2e17..5a8cc51 100644
--- a/app/core/config.py
+++ b/app/core/config.py
@@ -23,7 +23,7 @@ class Settings(BaseSettings):
     DATABASE_URL: str = "sqlite+aiosqlite:///./denya_onecare.db"
 
     # ── Auth ─────────────────────────────────────────────────────────
-    SECRET_KEY: str = "change-me-in-production-use-a-real-secret"
+    SECRET_KEY: str = ""
     ALGORITHM: str = "HS256"
     ACCESS_TOKEN_EXPIRE_MINUTES: int = 60  # Phase 1: raised 30 -> 60 for fewer re-logins
     REFRESH_TOKEN_EXPIRE_MINUTES: int = 60 * 24 * 7  # 7 days
@@ -42,3 +42,21 @@ class Settings(BaseSettings):
 
 
 settings = Settings()
+
+# ── Fail-closed secret validation (HARDENING.md P0.1) ─────────────────
+# Refuse to boot without a real SECRET_KEY. Devs must create a local .env
+# (see .env.example); production injects it via docker-compose env_file.
+_KNOWN_PLACEHOLDER_SECRETS = {
+    "",
+    "change-me-in-production",
+    "change-me-in-production-use-a-real-secret",
+    "changeme",
+    "secret",
+}
+
+if settings.SECRET_KEY in _KNOWN_PLACEHOLDER_SECRETS or len(settings.SECRET_KEY) < 32:
+    raise RuntimeError(
+        "SECRET_KEY is missing, a known placeholder, or shorter than 32 chars. "
+        "Generate one with: openssl rand -hex 32 — and set it in .env "
+        "(dev) or the runtime environment (prod). Refusing to start."
+    )
diff --git a/app/main.py b/app/main.py
index d45289d..18800e7 100644
--- a/app/main.py
+++ b/app/main.py
@@ -83,10 +83,17 @@ app = FastAPI(
     lifespan=lifespan,
 )
 
-# ── CORS ─────────────────────────────────────────────────────────────
+# ── CORS (HARDENING.md P0.2 — explicit origin allow-list, never "*") ──
+_origins = [o.strip() for o in settings.CORS_ORIGINS.split(",") if o.strip()]
+if "*" in _origins or not _origins:
+    raise RuntimeError(
+        "CORS_ORIGINS must be an explicit comma-separated origin allow-list "
+        "(e.g. 'https://denya.sysloggh.net,http://localhost:8000'). "
+        "'*' with allow_credentials=True is invalid and unsafe. Refusing to start."
+    )
 app.add_middleware(
     CORSMiddleware,
-    allow_origins=settings.CORS_ORIGINS.split(",") if settings.CORS_ORIGINS != "*" else ["*"],
+    allow_origins=_origins,
     allow_credentials=True,
     allow_methods=["*"],
     allow_headers=["*"],
diff --git a/app/schemas/auth.py b/app/schemas/auth.py
index 3febf54..ac55166 100644
--- a/app/schemas/auth.py
+++ b/app/schemas/auth.py
@@ -10,7 +10,10 @@ class RegisterRequest(BaseModel):
     password: str
     full_name: str
     phone: str | None = None
-    role: str = "CS Rep"
+    # HARDENING.md P0.3: role is NOT client-controllable. Self-registration
+    # always creates the least-privilege role; privileged roles are assigned
+    # by an admin directly in the DB (or a future admin-gated endpoint).
+    role: str = "CS Rep"  # kept for backward compat; ignored by the service
 
 
 class LoginRequest(BaseModel):
diff --git a/app/services/auth.py b/app/services/auth.py
index 9bed864..fd82810 100644
--- a/app/services/auth.py
+++ b/app/services/auth.py
@@ -16,9 +16,18 @@ from app.core.security import (
 from app.models.user import User
 from app.schemas.auth import RegisterRequest
 
+# HARDENING.md P0.3 — least-privilege default for self-registered users.
+_SELF_REGISTER_ROLE = "CS Rep"
+
 
 async def register(db: AsyncSession, body: RegisterRequest) -> User:
-    """Create a new user.  Raises 409 if email already exists."""
+    """Create a new user.  Raises 409 if email already exists.
+
+    HARDENING.md P0.3: unauthenticated self-registration must never mint a
+    privileged role. The client-supplied ``role`` field is IGNORED — new
+    self-registered users always land on the least-privilege role.
+    Admins assign elevated roles directly (DB seed / admin endpoint).
+    """
     result = await db.execute(select(User).where(User.email == body.email))
     if result.scalar_one_or_none():
         raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail="Email already registered")
@@ -28,7 +37,7 @@ async def register(db: AsyncSession, body: RegisterRequest) -> User:
         password_hash=hash_password(body.password),
         full_name=body.full_name,
         phone=body.phone,
-        role=body.role,
+        role=_SELF_REGISTER_ROLE,
     )
     db.add(user)
     await db.flush()
diff --git a/docker-compose.yml b/docker-compose.yml
index 1fe37ba..bfacdba 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -4,10 +4,9 @@ services:
     container_name: denya-onecare
     ports:
       - "8000:8000"
+    env_file:
+      - .env            # git-ignored; see .env.example for required keys
     environment:
-      - DATABASE_URL=sqlite+aiosqlite:///./data/denya_onecare.db
-      - SECRET_KEY=change-me-in-production
-      - CORS_ORIGINS=*
       - DEBUG=false
     volumes:
       - app-data:/app/data
diff --git a/tests/conftest.py b/tests/conftest.py
index 23c8bd1..b8fbdf6 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -12,6 +12,10 @@ import tempfile
 
 _TMP_DIR = tempfile.mkdtemp(prefix="denya-test-")
 os.environ["DATABASE_URL"] = f"sqlite+aiosqlite:///{_TMP_DIR}/test.db"
+# HARDENING.md P0.1/P0.2: the app now fails closed without a real SECRET_KEY
+# and an explicit CORS allow-list — tests must satisfy both.
+os.environ.setdefault("SECRET_KEY", "test-secret-key-not-for-production-0123456789abcdef")
+os.environ.setdefault("CORS_ORIGINS", "http://test")
 
 import pytest_asyncio  # noqa: E402  (DATABASE_URL must be set before app imports)
 from httpx import ASGITransport, AsyncClient  # noqa: E402
diff --git a/tests/test_p0_hardening.py b/tests/test_p0_hardening.py
new file mode 100644
index 0000000..71d3b0c
--- /dev/null
+++ b/tests/test_p0_hardening.py
@@ -0,0 +1,132 @@
+"""P0 hardening regression tests (HARDENING.md P0.1 / P0.2 / P0.3).
+
+Covers:
+- P0.3: self-registration CANNOT mint a privileged role (role field ignored)
+- P0.3: duplicate email still 409s
+- P0.1: app fails to import/boot with placeholder or missing SECRET_KEY
+- P0.2: app fails to boot with CORS_ORIGINS="*"
+"""
+
+from __future__ import annotations
+
+import os
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+from httpx import ASGITransport, AsyncClient
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+
+pytestmark = pytest.mark.asyncio
+
+
+
+# ── P0.3: registration role-escalation ────────────────────────────────
+
+async def test_register_cannot_mint_admin_role(client: AsyncClient):
+    """A raw unauthenticated register call must NOT be able to mint Admin/*."""
+    resp = await client.post(
+        "/api/auth/register",
+        json={
+            "email": "attacker@example.com",
+            "password": "Sup3rSecret!",
+            "full_name": "Attacker",
+            "role": "Admin/Jerome",
+        },
+    )
+    assert resp.status_code == 201, resp.text
+    created = resp.json()
+    assert created["role"] == "CS Rep", (
+        f"self-registration minted privileged role: {created['role']}"
+    )
+
+
+async def test_register_role_wahab_also_blocked(client: AsyncClient):
+    resp = await client.post(
+        "/api/auth/register",
+        json={
+            "email": "attacker2@example.com",
+            "password": "Sup3rSecret!",
+            "full_name": "Attacker Two",
+            "role": "Admin/Wahab",
+        },
+    )
+    assert resp.status_code == 201
+    assert resp.json()["role"] == "CS Rep"
+
+
+async def test_register_duplicate_email_conflict(client: AsyncClient):
+    payload = {
+        "email": "dupe@example.com",
+        "password": "Sup3rSecret!",
+        "full_name": "Dupe",
+    }
+    r1 = await client.post("/api/auth/register", json=payload)
+    assert r1.status_code == 201
+    r2 = await client.post("/api/auth/register", json=payload)
+    assert r2.status_code == 409
+
+
+# ── P0.1 / P0.2: fail-closed boot validation ──────────────────────────
+
+def _boot_with_env(env_overrides: dict[str, str]) -> subprocess.CompletedProcess:
+    """Try importing app.main in a subprocess with the given env; the import
+    must fail (non-zero) when fail-closed validation trips."""
+    env = os.environ.copy()
+    env["DATABASE_URL"] = "sqlite+aiosqlite:///:memory:"
+    env.pop("SECRET_KEY", None)
+    env.pop("CORS_ORIGINS", None)
+    env.update(env_overrides)
+    script = (
+        "import sys; sys.path.insert(0, ''); "
+        "import app.main"  # noqa
+    )
+    return subprocess.run(
+        [sys.executable, "-c", script],
+        cwd=str(REPO_ROOT),
+        env=env,
+        capture_output=True,
+        text=True,
+        timeout=60,
+    )
+
+
+def test_boot_fails_with_placeholder_secret():
+    result = _boot_with_env({"SECRET_KEY": "change-me-in-production"})
+    assert result.returncode != 0, "app booted with placeholder SECRET_KEY!"
+    assert "SECRET_KEY" in result.stderr
+
+
+def test_boot_fails_with_short_secret():
+    result = _boot_with_env({"SECRET_KEY": "tooshort"})
+    assert result.returncode != 0, "app booted with a <32-char SECRET_KEY!"
+    assert "SECRET_KEY" in result.stderr
+
+
+def test_boot_fails_without_secret():
+    result = _boot_with_env({"SECRET_KEY": ""})
+    assert result.returncode != 0, "app booted without a SECRET_KEY!"
+    assert "SECRET_KEY" in result.stderr
+
+
+def test_boot_fails_with_wildcard_cors():
+    result = _boot_with_env(
+        {
+            "SECRET_KEY": "test-secret-key-not-for-production-0123456789abcdef",
+            "CORS_ORIGINS": "*",
+        }
+    )
+    assert result.returncode != 0, "app booted with CORS_ORIGINS=* !"
+    assert "CORS_ORIGINS" in result.stderr
+
+
+def test_boot_succeeds_with_valid_env():
+    result = _boot_with_env(
+        {
+            "SECRET_KEY": "test-secret-key-not-for-production-0123456789abcdef",
+            "CORS_ORIGINS": "http://test",
+        }
+    )
+    assert result.returncode == 0, result.stderr