test(agent_session_endpoints): regression tests for required JWT secret

Asserts:
  * _get_signing_secret raises AgentJWTSecretNotConfiguredError when
    LITELLM_AGENT_JWT_SECRET is unset, even with LITELLM_MASTER_KEY set
    (no silent fallback).
  * is_agent_jwt_secret_configured returns False for unset / empty,
    True for any non-empty value.
  * mint_daemon_token and decode_daemon_token both surface the same
    error when the env var is missing.

Greptile P1 SECURITY regression coverage (validation #15).

tests/test_litellm/proxy/agent_session_endpoints/test_jwt_secret_required.py

@@ -0,0 +1,97 @@
+"""
+Validation #15 — daemon JWT secret is REQUIRED, no master-key fallback.
+
+The daemon JWT secret (``LITELLM_AGENT_JWT_SECRET``) MUST be a separate
+credential from the proxy master key. A prior version of
+``auth._get_signing_secret`` fell back to ``LITELLM_MASTER_KEY`` when
+the dedicated env var was unset — which conflated two distinct auth
+surfaces and meant a captured daemon JWT could be used to mint regular
+API keys with master-key authority.
+
+This test file enforces:
+  1. ``_get_signing_secret`` raises when ``LITELLM_AGENT_JWT_SECRET`` is
+     unset, even when ``LITELLM_MASTER_KEY`` IS set (no silent fallback).
+  2. ``is_agent_jwt_secret_configured()`` returns False in that case so
+     ``proxy_server.py`` knows to skip mounting the routers.
+  3. ``mint_daemon_token`` and ``decode_daemon_token`` both surface the
+     same error — every caller is gated by the env var.
+"""
+
+import pytest
+
+from litellm.proxy.agent_session_endpoints.auth import (
+    AgentJWTSecretNotConfiguredError,
+    _get_signing_secret,
+    decode_daemon_token,
+    is_agent_jwt_secret_configured,
+    mint_daemon_token,
+)
+
+
+def test_signing_secret_raises_without_dedicated_env_var(monkeypatch):
+    """The dedicated env var is the ONLY source of the secret.
+
+    Setting LITELLM_MASTER_KEY (and clearing LITELLM_AGENT_JWT_SECRET)
+    must NOT silently provide a fallback.
+    """
+    monkeypatch.delenv("LITELLM_AGENT_JWT_SECRET", raising=False)
+    monkeypatch.setenv("LITELLM_MASTER_KEY", "sk-master-key-which-must-not-be-used")
+
+    with pytest.raises(AgentJWTSecretNotConfiguredError):
+        _get_signing_secret()
+
+
+def test_is_agent_jwt_secret_configured_reports_unset(monkeypatch):
+    """Used at startup to decide whether to mount the routers.
+
+    Returns False when the env var is unset, even if the master key is
+    set — preventing the proxy from silently exposing an
+    auth-conflated /v2/agents surface.
+    """
+    monkeypatch.delenv("LITELLM_AGENT_JWT_SECRET", raising=False)
+    monkeypatch.setenv("LITELLM_MASTER_KEY", "sk-1234")
+    assert is_agent_jwt_secret_configured() is False
+
+
+def test_is_agent_jwt_secret_configured_reports_set(monkeypatch):
+    monkeypatch.setenv("LITELLM_AGENT_JWT_SECRET", "dedicated-jwt-secret-value")
+    assert is_agent_jwt_secret_configured() is True
+
+
+def test_is_agent_jwt_secret_configured_rejects_empty_string(monkeypatch):
+    """Empty string should be treated as unset — same as ``os.environ.get`` semantics."""
+    monkeypatch.setenv("LITELLM_AGENT_JWT_SECRET", "")
+    assert is_agent_jwt_secret_configured() is False
+
+
+def test_mint_token_raises_without_dedicated_env_var(monkeypatch):
+    monkeypatch.delenv("LITELLM_AGENT_JWT_SECRET", raising=False)
+    monkeypatch.setenv("LITELLM_MASTER_KEY", "sk-1234")
+    with pytest.raises(AgentJWTSecretNotConfiguredError):
+        mint_daemon_token(
+            session_id="sess_abc",
+            agent_id="agt_abc",
+            expires_at_epoch=10**10,
+        )
+
+
+def test_decode_token_raises_without_dedicated_env_var(monkeypatch):
+    """Even decoding (which the daemon-auth dependency calls on every
+    request) must refuse to operate without the dedicated secret."""
+    monkeypatch.delenv("LITELLM_AGENT_JWT_SECRET", raising=False)
+    monkeypatch.setenv("LITELLM_MASTER_KEY", "sk-1234")
+    with pytest.raises(AgentJWTSecretNotConfiguredError):
+        decode_daemon_token("any-token-bytes")
+
+
+def test_proxy_server_skips_mounting_when_secret_missing(monkeypatch):
+    """End-to-end: simulate the startup check ``proxy_server.py`` runs.
+
+    When the env var is unset, ``is_agent_jwt_secret_configured`` returns
+    False — and that is the function ``proxy_server.py`` inspects to
+    decide whether to mount the routers.
+    """
+    monkeypatch.delenv("LITELLM_AGENT_JWT_SECRET", raising=False)
+    # No master key fallback even when LITELLM_MASTER_KEY is set.
+    monkeypatch.setenv("LITELLM_MASTER_KEY", "sk-1234")
+    assert is_agent_jwt_secret_configured() is False