diff --git a/agent/agent_runtime_helpers.py b/agent/agent_runtime_helpers.py
index bf4d31b4f4d..1cde73419a4 100644
--- a/agent/agent_runtime_helpers.py
+++ b/agent/agent_runtime_helpers.py
@@ -1208,7 +1208,42 @@ def restore_primary_runtime(agent) -> bool:
             api_mode=rt.get("compressor_api_mode", ""),
         )
 
-        # ── Re-select from the credential pool if one is available ──
+        # ── Rebind and re-select the primary credential pool ──
+        # A cross-provider fallback attaches the fallback provider's pool. The
+        # runtime fields above restore the primary, but leaving that pool in
+        # place makes the next primary 401/429 hit the provider-mismatch guard
+        # and disables credential rotation. Reload the primary pool first; if
+        # auth storage is temporarily unreadable, clear the mismatched pool.
+        primary_provider = str(rt.get("provider") or "").strip().lower()
+        pool = getattr(agent, "_credential_pool", None)
+        pool_provider = str(getattr(pool, "provider", "") or "").strip().lower()
+        pool_matches_primary = pool_provider == primary_provider
+        if (
+            primary_provider == "custom"
+            and pool_provider.startswith("custom:")
+        ):
+            try:
+                from agent.credential_pool import get_custom_provider_pool_key
+
+                primary_key = (
+                    get_custom_provider_pool_key(str(rt.get("base_url") or "")) or ""
+                ).strip().lower()
+                pool_matches_primary = bool(primary_key) and primary_key == pool_provider
+            except Exception:
+                pool_matches_primary = False
+        if pool is not None and pool_provider and not pool_matches_primary:
+            agent._credential_pool = None
+            try:
+                from agent.credential_pool import load_pool
+
+                agent._credential_pool = load_pool(primary_provider)
+            except Exception as exc:
+                logger.warning(
+                    "Restore could not reload primary credential pool for %s: %s",
+                    primary_provider,
+                    exc,
+                )
+
         # The snapshot's api_key was captured at construction time.  Across
         # turns the pool may have rotated (token revocation, billing/rate-limit
         # exhaustion, cooldown), leaving the snapshot key stale.  Restoring it
@@ -1222,7 +1257,6 @@ def restore_primary_runtime(agent) -> bool:
             entry = pool.select()
             if entry is not None:
                 entry_provider = str(getattr(entry, "provider", "") or "").strip().lower()
-                primary_provider = str(rt.get("provider") or "").strip().lower()
                 entry_matches_primary = entry_provider == primary_provider
                 # Custom endpoints all carry the generic ``custom`` provider on
                 # the agent while the pool entry is keyed ``custom:<name>`` (see
@@ -1858,6 +1892,9 @@ def switch_model(agent, new_model, new_provider, api_key='', base_url='', api_mo
         old_norm = (old_provider or "").strip().lower()
         new_norm = (new_provider or "").strip().lower()
         if old_norm != new_norm or getattr(agent, "_credential_pool", None) is None:
+            # A pool bound to the old provider is worse than no pool: the
+            # recovery guard rejects it and every later 401/429 skips rotation.
+            agent._credential_pool = None
             try:
                 from agent.credential_pool import load_pool
                 agent._credential_pool = load_pool(new_provider)
diff --git a/tests/run_agent/test_primary_runtime_restore.py b/tests/run_agent/test_primary_runtime_restore.py
index d1ac56dca6b..0d732277e97 100644
--- a/tests/run_agent/test_primary_runtime_restore.py
+++ b/tests/run_agent/test_primary_runtime_restore.py
@@ -286,15 +286,47 @@ class TestRestorePrimaryRuntime:
         agent._credential_pool = _DeepseekPool()
         agent._swap_credential = MagicMock()
 
-        with patch("run_agent.OpenAI", return_value=MagicMock()):
+        primary_pool = MagicMock()
+        primary_pool.provider = primary_provider
+        primary_pool.has_available.return_value = False
+        with (
+            patch("run_agent.OpenAI", return_value=MagicMock()),
+            patch("agent.credential_pool.load_pool", return_value=primary_pool) as load_pool,
+        ):
             result = agent._restore_primary_runtime()
 
         assert result is True
         assert agent.provider == primary_provider
         assert agent.base_url == primary_base_url
         assert "deepseek" not in str(agent.base_url)
+        assert agent._credential_pool is primary_pool
+        load_pool.assert_called_once_with(primary_provider)
         agent._swap_credential.assert_not_called()
 
+    def test_restore_clears_fallback_pool_when_primary_pool_reload_fails(self):
+        """A fallback pool must never remain attached to the restored primary."""
+        agent = _make_agent(
+            provider="openai-api",
+            base_url="https://api.openai.com/v1",
+        )
+        agent._fallback_activated = True
+        fallback_pool = MagicMock()
+        fallback_pool.provider = "deepseek"
+        agent._credential_pool = fallback_pool
+
+        with (
+            patch("run_agent.OpenAI", return_value=MagicMock()),
+            patch(
+                "agent.credential_pool.load_pool",
+                side_effect=RuntimeError("auth store unavailable"),
+            ),
+        ):
+            result = agent._restore_primary_runtime()
+
+        assert result is True
+        assert agent.provider == "openai-api"
+        assert agent._credential_pool is None
+
     def test_restore_swaps_matching_custom_pool_entry(self):
         """Custom primary + custom:<name> entry whose base_url resolves to the
         SAME custom key must swap (legitimate same-endpoint rotation)."""
diff --git a/tests/run_agent/test_switch_model_pool_reload_52727.py b/tests/run_agent/test_switch_model_pool_reload_52727.py
index a1dba807f9f..e1ef7d651c0 100644
--- a/tests/run_agent/test_switch_model_pool_reload_52727.py
+++ b/tests/run_agent/test_switch_model_pool_reload_52727.py
@@ -213,6 +213,7 @@ class TestSwitchModelReloadsCredentialPool:
             )
 
         # The switch itself completed (provider/model updated) even though
-        # the pool reload failed.
+        # the pool reload failed, without retaining the old provider's pool.
         assert agent.provider == "groq"
-        assert agent.model == "llama-3.3-70b"
\ No newline at end of file
+        assert agent.model == "llama-3.3-70b"
+        assert agent._credential_pool is None