diff --git a/agent/credential_pool.py b/agent/credential_pool.py
index 7f27873a7fb88..12463809834b6 100644
--- a/agent/credential_pool.py
+++ b/agent/credential_pool.py
@@ -140,6 +140,9 @@ def from_dict(cls, provider: str, payload: Dict[str, Any]) -> "PooledCredential"
         data.setdefault("priority", 0)
         data.setdefault("source", SOURCE_MANUAL)
         data.setdefault("access_token", "")
+        for ts_key in ("last_status_at", "last_error_reset_at"):
+            if ts_key in data and data[ts_key] is not None:
+                data[ts_key] = _parse_absolute_timestamp(data[ts_key])
         return cls(provider=provider, **data)
 
     def to_dict(self) -> Dict[str, Any]:
@@ -277,8 +280,10 @@ def _exhausted_until(entry: PooledCredential) -> Optional[float]:
     reset_at = _parse_absolute_timestamp(getattr(entry, "last_error_reset_at", None))
     if reset_at is not None:
         return reset_at
-    if entry.last_status_at:
-        return entry.last_status_at + _exhausted_ttl(entry.last_error_code)
+    if entry.last_status_at is not None:
+        ts = _parse_absolute_timestamp(entry.last_status_at)
+        if ts is not None:
+            return ts + _exhausted_ttl(entry.last_error_code)
     return None
 
 
diff --git a/scripts/release.py b/scripts/release.py
index c388116cff6fa..685673d4255ee 100755
--- a/scripts/release.py
+++ b/scripts/release.py
@@ -648,6 +648,7 @@
     "juan.ovalle@mistral.ai": "jjovalle99",
     "julien.talbot@ergonomia.re": "Julientalbot",
     "kagura.chen28@gmail.com": "kagura-agent",
+    "kagura.agent.ai@gmail.com": "kagura-agent",
     "1342088860@qq.com": "youngDoo",
     "kamil@gwozdz.me": "kamil-gwozdz",
     "skmishra1991@gmail.com": "bugkill3r",
diff --git a/tests/agent/test_credential_pool.py b/tests/agent/test_credential_pool.py
index 299567a9a6ff9..c0c7a4b0db6d0 100644
--- a/tests/agent/test_credential_pool.py
+++ b/tests/agent/test_credential_pool.py
@@ -286,6 +286,57 @@ def test_exhausted_401_entry_resets_after_five_minutes(tmp_path, monkeypatch):
     assert entry.last_status == "ok"
 
 
+def test_iso_string_last_status_at_does_not_crash_exhausted_until(tmp_path, monkeypatch):
+    """Regression: ISO-8601 last_status_at from disk should not cause TypeError.
+
+    See https://github.com/NousResearch/hermes-agent/issues/25516
+    """
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path / "hermes"))
+    _write_auth_store(
+        tmp_path,
+        {
+            "version": 1,
+            "credential_pool": {
+                "openai": [
+                    {
+                        "id": "cred-1",
+                        "label": "primary",
+                        "auth_type": "api_key",
+                        "priority": 0,
+                        "source": "manual",
+                        "access_token": "***",
+                        "last_status": "exhausted",
+                        "last_status_at": "2026-05-11T08:23:20.891066+00:00",
+                        "last_error_code": 429,
+                    },
+                    {
+                        "id": "cred-2",
+                        "label": "secondary",
+                        "auth_type": "api_key",
+                        "priority": 1,
+                        "source": "manual",
+                        "access_token": "***",
+                        "last_status": "ok",
+                        "last_status_at": None,
+                        "last_error_code": None,
+                    },
+                ]
+            },
+        },
+    )
+
+    from agent.credential_pool import load_pool
+
+    pool = load_pool("openai")
+    # Should not raise TypeError: can't add str and int
+    entry = pool.select()
+
+    assert entry is not None
+    # ISO timestamp from May 2026 is long expired; cred-1 should be usable again
+    assert entry.id == "cred-1"
+    assert entry.last_status == "ok"
+
+
 def test_explicit_reset_timestamp_overrides_default_429_ttl(tmp_path, monkeypatch):
     monkeypatch.setenv("HERMES_HOME", str(tmp_path / "hermes"))
     # Prevent auto-seeding from Codex CLI tokens on the host