diff --git a/.env.example b/.env.example
index 3e1fd45..65e9c86 100644
--- a/.env.example
+++ b/.env.example
@@ -1,5 +1,6 @@
 # --- Required: AI ---
-ANTHROPIC_API_KEY=sk-ant-...
+# From the Anthropic console. Leave unset and NL translation fails closed.
+ANTHROPIC_API_KEY=
 
 # --- Required: internal control-plane DB (audit log + agents + databases + encrypted creds) ---
 # Railway provisions this — set DATABASE_URL automatically.
@@ -15,14 +16,15 @@ VAULT_KEY=
 REDIS_URL=
 
 # --- Billing (Stripe) ---
-STRIPE_SECRET_KEY=sk_live_...
-STRIPE_WEBHOOK_SECRET=whsec_...
-STRIPE_PRICE_STARTER=price_...
-STRIPE_PRICE_PRO=price_...
-STRIPE_PRICE_ENTERPRISE=price_...
+# Paste from the Stripe dashboard. Checkout and webhooks fail closed when unset.
+STRIPE_SECRET_KEY=
+STRIPE_WEBHOOK_SECRET=
+STRIPE_PRICE_STARTER=
+STRIPE_PRICE_PRO=
+STRIPE_PRICE_ENTERPRISE=
 
 # --- Notifications ---
-SENDGRID_API_KEY=SG....
+SENDGRID_API_KEY=
 SENDGRID_FROM=alerts@queryshield.io
 # Product-specific Discord webhook — separate channel from other agentic-build products.
 QUERY_SHIELD_DISCORD_WEBHOOK_URL=
diff --git a/.gitignore b/.gitignore
index b1c6bc0..a5f16bb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,14 +1,43 @@
+# Python
 __pycache__/
 *.py[cod]
+*$py.class
 .pytest_cache/
+.mypy_cache/
+.ruff_cache/
+.coverage
+htmlcov/
+.tox/
+.nox/
+
+# Virtual environments
 .venv/
 venv/
+env/
+ENV/
+.direnv/
+
+# Secrets and local env (keep the committed template)
 .env
+.env.*
+!.env.example
+*.pem
+*.key
+
+# Local databases and SQLite sidecars (runtime artifacts, not fixtures)
 *.db
+*.db-journal
+*.db-wal
+*.db-shm
 *.sqlite
 *.sqlite3
-.idea/
-.vscode/
+*.sqlite-journal
+*.sqlite3-journal
+
+# Packaging and editor
 *.egg-info/
 build/
 dist/
+.idea/
+.vscode/
+.DS_Store
diff --git a/README.md b/README.md
index 19b5e65..c0f4651 100644
--- a/README.md
+++ b/README.md
@@ -24,12 +24,16 @@ Agents never see connection strings.
 ```bash
 pip install -r requirements.txt
 cp .env.example .env
-# Set ANTHROPIC_API_KEY, DATABASE_URL, VAULT_KEY (see below)
+# Set ANTHROPIC_API_KEY, DATABASE_URL, and VAULT_KEY in .env (see below).
+# Do not commit .env. QueryShield reads secrets from the environment only.
 
 python -m queryshield.start
 ```
 
-Generate a Fernet key for `VAULT_KEY` once and never lose it:
+Generate a Fernet key for `VAULT_KEY` once and never lose it. Credential
+encryption and session signing both require `VAULT_KEY` (or `SESSION_KEY`
+for cookies). If it is unset, those operations fail instead of using a
+built-in key:
 
 ```bash
 python -c "from cryptography.fernet import Fernet; print(Fernet.generate_key().decode())"
@@ -50,7 +54,7 @@ curl -X POST localhost:8000/v1/databases \
   -d '{
     "alias": "prod",
     "db_type": "postgresql",
-    "connection_string": "postgresql://reader:secret@db.acme.internal:5432/app",
+    "connection_string": "postgresql://READER:PASSWORD@db.example.internal:5432/app",
     "allowed_tables": ["users", "orders"]
   }'
 
diff --git a/queryshield/auth.py b/queryshield/auth.py
index c7cc943..00778a1 100644
--- a/queryshield/auth.py
+++ b/queryshield/auth.py
@@ -45,10 +45,12 @@
 # --- Session cookies ---------------------------------------------------
 
 def _session_key() -> bytes:
-    """Derive a stable HMAC key. Falls back to VAULT_KEY if SESSION_KEY unset."""
+    """Derive a stable HMAC key from SESSION_KEY, or from VAULT_KEY if unset."""
     s = get_settings()
-    key = getattr(s, "session_key", None) or s.vault_key or "dev-only-fallback-session-key"
-    return hashlib.sha256(key.encode("utf-8") if isinstance(key, str) else key).digest()
+    key = s.session_key or s.vault_key
+    if not isinstance(key, str) or not key.strip():
+        raise RuntimeError("SESSION_KEY or VAULT_KEY is not configured")
+    return hashlib.sha256(key.encode("utf-8")).digest()
 
 
 def issue_session(tenant_id: str) -> str:
diff --git a/queryshield/config.py b/queryshield/config.py
index 636bd7d..14b7a45 100644
--- a/queryshield/config.py
+++ b/queryshield/config.py
@@ -1,8 +1,9 @@
 """Centralized settings — one place for env-var reads.
 
 Pattern matches the rest of Brett's agentic-build projects: a singleton
-``Settings`` instance loaded once at import, with conservative defaults so
-local development works without a .env file.
+``Settings`` instance loaded once at import, with conservative defaults for
+non-secret settings so local development works without a .env file.
+Secrets have no built-in default and must come from the environment.
 """
 from __future__ import annotations
 
@@ -29,9 +30,9 @@ class Settings(BaseSettings):
     database_url: str = "sqlite:///queryshield_local.db"
 
     # Vault
-    vault_key: Optional[str] = None  # Fernet key (base64) — required in prod
-    # Optional: override session-cookie HMAC key. Defaults to a derived key
-    # off VAULT_KEY if unset. Rotating SESSION_KEY logs everyone out.
+    vault_key: Optional[str] = None  # Fernet key (base64). Required to encrypt credentials.
+    # Optional: override session-cookie HMAC key. Derived from VAULT_KEY when
+    # unset. There is no built-in fallback. Rotating SESSION_KEY logs everyone out.
     session_key: Optional[str] = None
 
     # Cache
diff --git a/queryshield/vault.py b/queryshield/vault.py
index 5208bf4..4ed2d52 100644
--- a/queryshield/vault.py
+++ b/queryshield/vault.py
@@ -32,11 +32,9 @@
 
 def _fernet() -> Fernet:
     key = get_settings().vault_key
-    if not key:
-        # In dev, fall back to a deterministic key so local boots work.
-        # In production the startup config check refuses to start without one.
-        key = "dev-only-vault-key-do-not-use-in-prod-dev-only-vault-key="
-    return Fernet(key.encode("utf-8") if isinstance(key, str) else key)
+    if not isinstance(key, str) or not key.strip():
+        raise RuntimeError("VAULT_KEY is not configured")
+    return Fernet(key.encode("utf-8"))
 
 
 def encrypt_connection(payload: dict) -> bytes:
diff --git a/queryshield/web.py b/queryshield/web.py
index d453653..7367a72 100644
--- a/queryshield/web.py
+++ b/queryshield/web.py
@@ -473,7 +473,7 @@ def replace(self, key, value="", *a, **kw):  # type: ignore[override]
                     <option value="sqlite">SQLite</option>
                 </select>
                 <label>Connection string (encrypted at rest)</label>
-                <input id="db-cs" type="text" placeholder="postgresql://reader:secret@host:5432/db">
+                <input id="db-cs" type="text" placeholder="postgresql://READER:PASSWORD@host:5432/db">
                 <p class="muted" style="margin-top: 8px;">Tip: use a <em>read-only</em> database role. QueryShield's safety check + RLS only run inside our service; defense in depth means the DB itself should refuse writes.</p>
                 <button class="btn secondary" onclick="registerDb()">Register</button>
                 <div id="db-result"></div>
diff --git a/queryshield_local.db-journal b/queryshield_local.db-journal
deleted file mode 100644
index bcb0bce..0000000
Binary files a/queryshield_local.db-journal and /dev/null differ
diff --git a/tests/conftest.py b/tests/conftest.py
index c632343..88044ca 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -14,6 +14,7 @@
 from pathlib import Path
 
 import pytest
+from cryptography.fernet import Fernet
 
 # Make sure the package under test is importable
 ROOT = Path(__file__).resolve().parent.parent
@@ -24,9 +25,10 @@
 # SQLAlchemy ENGINE at module import using the env-time DATABASE_URL.
 _TEST_TMP = tempfile.mkdtemp(prefix="queryshield-tests-")
 os.environ["DATABASE_URL"] = f"sqlite:///{_TEST_TMP}/control.db"
-os.environ["VAULT_KEY"] = "RIaPxXZl9MNm7ESjqpsnbsiBCDkfErP6Mum0lmGD-7w="  # fixed test key
+# Fresh key per process. Never a committed shared key, and never logged.
+os.environ["VAULT_KEY"] = Fernet.generate_key().decode()
 os.environ["ENVIRONMENT"] = "test"
-os.environ["ANTHROPIC_API_KEY"] = "sk-ant-test"
+os.environ["ANTHROPIC_API_KEY"] = "test-not-a-real-key"
 
 
 @pytest.fixture()
diff --git a/tests/test_hardening.py b/tests/test_hardening.py
index 995b6bf..b309f23 100644
--- a/tests/test_hardening.py
+++ b/tests/test_hardening.py
@@ -63,6 +63,26 @@ def test_register_db_with_private_host_returns_400(client) -> None:
 
 # --- Rate limit ---------------------------------------------------------
 
+def test_vault_requires_key(monkeypatch) -> None:
+    from queryshield.config import get_settings
+    from queryshield.vault import encrypt_connection
+
+    monkeypatch.setattr(get_settings(), "vault_key", None)
+    with pytest.raises(RuntimeError, match="VAULT_KEY is not configured"):
+        encrypt_connection({"type": "sqlite", "url": "sqlite:///x"})
+
+
+def test_session_requires_key(monkeypatch) -> None:
+    from queryshield.auth import issue_session
+    from queryshield.config import get_settings
+
+    settings = get_settings()
+    monkeypatch.setattr(settings, "vault_key", None)
+    monkeypatch.setattr(settings, "session_key", None)
+    with pytest.raises(RuntimeError, match="SESSION_KEY or VAULT_KEY is not configured"):
+        issue_session("tenant")
+
+
 def test_token_bucket_basic() -> None:
     _BUCKETS.clear()
     for _ in range(3):