diff --git a/dashboard/src/agentforge_dashboard/client.py b/dashboard/src/agentforge_dashboard/client.py
index 93f4980..cdaa2ab 100644
--- a/dashboard/src/agentforge_dashboard/client.py
+++ b/dashboard/src/agentforge_dashboard/client.py
@@ -66,6 +66,9 @@ class CoreClient:
     def _post(self, path: str, body: dict) -> Any:
         r = self._client.post(path, json=body)
         if r.status_code in {404, 409, 422}:
-            return {"error": r.json()}
+            # Clave deliberadamente distinta de "error": el cuerpo de un AgentExecution
+            # correcto ya trae error=None, así que las páginas no podrían distinguir
+            # "ejecución sin error" de "la API rechazó la petición" si reusáramos "error".
+            return {"api_error": r.json()}
         r.raise_for_status()
         return r.json()
diff --git a/dashboard/src/agentforge_dashboard/pages/2_▶️_Ejecutar.py b/dashboard/src/agentforge_dashboard/pages/2_▶️_Ejecutar.py
index b78ecc9..45b05e1 100644
--- a/dashboard/src/agentforge_dashboard/pages/2_▶️_Ejecutar.py
+++ b/dashboard/src/agentforge_dashboard/pages/2_▶️_Ejecutar.py
@@ -53,7 +53,9 @@ if st.button("🚀 Invocar agente", type="primary", disabled=not user_input):
     st.session_state["last_execution"] = result
 
 execution = st.session_state.get("last_execution")
-if execution and "error" not in execution:
+if execution and "api_error" in execution:
+    st.error(f"Error de la API: {execution['api_error']}")
+elif execution:
     st.divider()
     st.markdown(f"**trace_id:** `{execution['trace_id']}`")
     st.markdown(f"**Status:** `{execution['status']}`")
@@ -63,10 +65,10 @@ if execution and "error" not in execution:
             "Esta ejecución requiere aprobación humana. "
             "Ve a la página **Aprobaciones** para revisar y decidir."
         )
+    if execution.get("error"):
+        st.error(f"La ejecución terminó con error: `{execution['error']}`")
     if execution.get("final_output"):
         st.subheader("📦 Output final")
         st.json(execution["final_output"])
     render_violations(execution.get("violations", []))
     render_trace(execution.get("decision_path", []))
-elif execution and "error" in execution:
-    st.error(f"Error de la API: {execution['error']}")
diff --git a/dashboard/src/agentforge_dashboard/pages/3_🤝_Aprobaciones.py b/dashboard/src/agentforge_dashboard/pages/3_🤝_Aprobaciones.py
index 4698dd5..f316343 100644
--- a/dashboard/src/agentforge_dashboard/pages/3_🤝_Aprobaciones.py
+++ b/dashboard/src/agentforge_dashboard/pages/3_🤝_Aprobaciones.py
@@ -65,8 +65,8 @@ with col_a:
                 execution["trace_id"],
                 {"approved_action_ids": approved_ids, "comment": comment},
             )
-        if "error" in r:
-            st.error(r["error"])
+        if "api_error" in r:
+            st.error(r["api_error"])
         else:
             st.success(f"Status: {r['status']}")
             st.rerun()
@@ -75,8 +75,8 @@ with col_r:
     if st.button("❌ Rechazar ejecución", disabled=not reason):
         with st.spinner("Aplicando rechazo..."):
             r = client.reject(execution["trace_id"], {"reason": reason})
-        if "error" in r:
-            st.error(r["error"])
+        if "api_error" in r:
+            st.error(r["api_error"])
         else:
             st.success(f"Status: {r['status']}")
             st.rerun()
diff --git a/tests/unit/test_dashboard_client.py b/tests/unit/test_dashboard_client.py
new file mode 100644
index 0000000..f64fdd2
--- /dev/null
+++ b/tests/unit/test_dashboard_client.py
@@ -0,0 +1,59 @@
+"""Tests del CoreClient: cómo mapea respuestas HTTP del core a dicts.
+
+Importante para el dashboard: una ejecución correcta (``AgentExecution`` serializado)
+incluye SIEMPRE el campo ``error`` (``str | None``). El wrapper que el cliente añade
+ante un 4xx debe usar una clave distinta (``api_error``) para no colisionar con ese
+campo; si usara ``error``, las páginas no podrían distinguir "el agente terminó sin
+error" de "la API devolvió 404/409/422".
+"""
+
+from __future__ import annotations
+
+from collections.abc import Callable
+
+import httpx
+import pytest
+
+from agentforge_dashboard.client import CoreClient
+
+
+def _client_with(handler: Callable[[httpx.Request], httpx.Response]) -> CoreClient:
+    client = CoreClient(base_url="http://test")
+    client._client.close()
+    client._client = httpx.Client(base_url="http://test", transport=httpx.MockTransport(handler))
+    return client
+
+
+def test_post_2xx_devuelve_el_cuerpo_verbatim_incluido_error_none() -> None:
+    """Un AgentExecution con ``error=None`` se devuelve tal cual, sin envolver."""
+    execution = {
+        "trace_id": "11111111-1111-1111-1111-111111111111",
+        "status": "completed",
+        "error": None,
+        "violations": [],
+        "decision_path": [],
+    }
+
+    def handler(_: httpx.Request) -> httpx.Response:
+        return httpx.Response(200, json=execution)
+
+    result = _client_with(handler).invoke_agent("incident_analyzer", {"input": "x"})
+    assert result == execution
+    assert "api_error" not in result
+
+
+@pytest.mark.parametrize("status", [404, 409, 422])
+def test_post_4xx_envuelve_el_detalle_en_api_error(status: int) -> None:
+    def handler(_: httpx.Request) -> httpx.Response:
+        return httpx.Response(status, json={"detail": "boom"})
+
+    result = _client_with(handler).invoke_agent("incident_analyzer", {"input": "y"})
+    assert result == {"api_error": {"detail": "boom"}}
+
+
+def test_post_5xx_propaga_la_excepcion() -> None:
+    def handler(_: httpx.Request) -> httpx.Response:
+        return httpx.Response(500, json={"detail": "kaput"})
+
+    with pytest.raises(httpx.HTTPStatusError):
+        _client_with(handler).invoke_agent("incident_analyzer", {"input": "z"})