diff --git a/backend/tests/test_auth_es256.py b/backend/tests/test_auth_es256.py
new file mode 100644
index 0000000..8e0567f
--- /dev/null
+++ b/backend/tests/test_auth_es256.py
@@ -0,0 +1,123 @@
+"""
+TDD scaffold for Phase 7.3: ES256 algorithm upgrade, startup token rotation,
+and remember_me session TTL — all stubs xfail strict=True until promoted.
+"""
+from __future__ import annotations
+
+import base64
+import hashlib
+import json
+import time
+import uuid
+from datetime import datetime, timedelta, timezone
+
+import pytest
+import pytest_asyncio
+
+
+# ── ES256 key fixture ────────────────────────────────────────────────────────
+
+
+@pytest.fixture(autouse=True)
+def es256_keys(monkeypatch):
+    """Generate a throw-away P-256 keypair and monkeypatch it into settings.
+
+    raising=False: settings fields do not exist until Plan 02 adds them;
+    this fixture must not error before that.
+    """
+    from cryptography.hazmat.primitives.asymmetric import ec
+    from cryptography.hazmat.primitives import serialization
+
+    private_key = ec.generate_private_key(ec.SECP256R1())
+    private_pem = private_key.private_bytes(
+        encoding=serialization.Encoding.PEM,
+        format=serialization.PrivateFormat.PKCS8,
+        encryption_algorithm=serialization.NoEncryption(),
+    )
+    public_pem = private_key.public_key().public_bytes(
+        encoding=serialization.Encoding.PEM,
+        format=serialization.PublicFormat.SubjectPublicKeyInfo,
+    )
+    private_b64 = base64.b64encode(private_pem).decode()
+    public_b64 = base64.b64encode(public_pem).decode()
+
+    import config
+    monkeypatch.setattr(config.settings, "jwt_private_key", private_b64, raising=False)
+    monkeypatch.setattr(config.settings, "jwt_public_key", public_b64, raising=False)
+
+
+# ── ES256-01: access token algorithm ─────────────────────────────────────────
+
+
+@pytest.mark.xfail(strict=True, reason="ES256-01: not yet implemented")
+def test_access_token_uses_es256():
+    pytest.xfail("not yet implemented")
+
+
+# ── ES256-02: HS256 token rejected ───────────────────────────────────────────
+
+
+@pytest.mark.xfail(strict=True, reason="ES256-02: not yet implemented")
+def test_hs256_token_rejected():
+    pytest.xfail("not yet implemented")
+
+
+# ── ES256-03: password-reset token algorithm ──────────────────────────────────
+
+
+@pytest.mark.xfail(strict=True, reason="ES256-03: not yet implemented")
+def test_reset_token_uses_es256():
+    pytest.xfail("not yet implemented")
+
+
+# ── ES256-04: startup rotation revokes tokens ─────────────────────────────────
+
+
+@pytest.mark.xfail(strict=True, reason="ES256-04: not yet implemented")
+@pytest.mark.asyncio
+async def test_startup_rotation_revokes_tokens(db_session):
+    pytest.xfail("not yet implemented")
+
+
+# ── ES256-05: startup rotation is idempotent ─────────────────────────────────
+
+
+@pytest.mark.xfail(strict=True, reason="ES256-05: not yet implemented")
+@pytest.mark.asyncio
+async def test_startup_rotation_idempotent(db_session):
+    pytest.xfail("not yet implemented")
+
+
+# ── RM-01: default TTL is 16 hours ───────────────────────────────────────────
+
+
+@pytest.mark.xfail(strict=True, reason="RM-01: not yet implemented")
+@pytest.mark.asyncio
+async def test_default_ttl_16_hours(async_client, db_session, auth_user):
+    pytest.xfail("not yet implemented")
+
+
+# ── RM-02: remember_me TTL is 30 days ────────────────────────────────────────
+
+
+@pytest.mark.xfail(strict=True, reason="RM-02: not yet implemented")
+@pytest.mark.asyncio
+async def test_remember_me_ttl_30_days(async_client, db_session, auth_user):
+    pytest.xfail("not yet implemented")
+
+
+# ── RM-03: cookie Max-Age values ─────────────────────────────────────────────
+
+
+@pytest.mark.xfail(strict=True, reason="RM-03: not yet implemented")
+@pytest.mark.asyncio
+async def test_remember_me_cookie_max_age(async_client, auth_user):
+    pytest.xfail("not yet implemented")
+
+
+# ── CFG-01 satellite: settings has jwt key fields ────────────────────────────
+
+
+@pytest.mark.xfail(strict=True, reason="CFG-01: not yet implemented")
+def test_settings_has_jwt_keys():
+    pytest.xfail("not yet implemented")
diff --git a/backend/tests/test_task1_models_config.py b/backend/tests/test_task1_models_config.py
index c833ff0..2144ec8 100644
--- a/backend/tests/test_task1_models_config.py
+++ b/backend/tests/test_task1_models_config.py
@@ -29,6 +29,10 @@ def test_settings_has_jwt_config():
     assert settings.access_token_expire_minutes == 15
     assert hasattr(settings, "refresh_token_expire_days")
     assert settings.refresh_token_expire_days == 30
+    assert hasattr(settings, "refresh_token_expire_hours")
+    assert settings.refresh_token_expire_hours == 16
+    assert hasattr(settings, "jwt_private_key")
+    assert hasattr(settings, "jwt_public_key")
 
 
 def test_settings_has_smtp_config():