diff --git a/core/src/agentforge_core/api/agents.py b/core/src/agentforge_core/api/agents.py
new file mode 100644
index 0000000..e57bbde
--- /dev/null
+++ b/core/src/agentforge_core/api/agents.py
@@ -0,0 +1,5 @@
+"""Router stub de /agents — se implementa en una task posterior."""
+
+from fastapi import APIRouter
+
+router = APIRouter()
diff --git a/core/src/agentforge_core/api/executions.py b/core/src/agentforge_core/api/executions.py
new file mode 100644
index 0000000..87a2df3
--- /dev/null
+++ b/core/src/agentforge_core/api/executions.py
@@ -0,0 +1,5 @@
+"""Router stub de /executions — se implementa en una task posterior."""
+
+from fastapi import APIRouter
+
+router = APIRouter()
diff --git a/core/src/agentforge_core/api/middlewares.py b/core/src/agentforge_core/api/middlewares.py
new file mode 100644
index 0000000..c88cd4b
--- /dev/null
+++ b/core/src/agentforge_core/api/middlewares.py
@@ -0,0 +1,27 @@
+"""Middleware de propagación de `trace_id` en cada request HTTP."""
+
+from __future__ import annotations
+
+from uuid import uuid4
+
+from starlette.middleware.base import BaseHTTPMiddleware, RequestResponseEndpoint
+from starlette.requests import Request
+from starlette.responses import Response
+
+from agentforge_core.observability.logging import bind_trace_id, clear_trace_id
+
+
+class TraceIdMiddleware(BaseHTTPMiddleware):
+    """Lee o genera `X-Trace-Id`, lo bind-ea al contexto de structlog y lo devuelve en la respuesta."""
+
+    async def dispatch(
+        self, request: Request, call_next: RequestResponseEndpoint
+    ) -> Response:
+        trace_id = request.headers.get("X-Trace-Id") or str(uuid4())
+        bind_trace_id(trace_id)
+        try:
+            response = await call_next(request)
+            response.headers["X-Trace-Id"] = trace_id
+            return response
+        finally:
+            clear_trace_id()
diff --git a/core/src/agentforge_core/api/policies.py b/core/src/agentforge_core/api/policies.py
new file mode 100644
index 0000000..a307683
--- /dev/null
+++ b/core/src/agentforge_core/api/policies.py
@@ -0,0 +1,5 @@
+"""Router stub de /policies — se implementa en una task posterior."""
+
+from fastapi import APIRouter
+
+router = APIRouter()
diff --git a/core/src/agentforge_core/api/violations.py b/core/src/agentforge_core/api/violations.py
new file mode 100644
index 0000000..e38b5be
--- /dev/null
+++ b/core/src/agentforge_core/api/violations.py
@@ -0,0 +1,5 @@
+"""Router stub de /violations — se implementa en una task posterior."""
+
+from fastapi import APIRouter
+
+router = APIRouter()
diff --git a/core/src/agentforge_core/main.py b/core/src/agentforge_core/main.py
new file mode 100644
index 0000000..018d575
--- /dev/null
+++ b/core/src/agentforge_core/main.py
@@ -0,0 +1,36 @@
+"""Composición raíz de la aplicación FastAPI (agentforge-core)."""
+
+from __future__ import annotations
+
+from fastapi import FastAPI
+
+from agentforge_core.api.middlewares import TraceIdMiddleware
+from agentforge_core.config import Settings
+from agentforge_core.observability.logging import configure_logging
+
+
+def create_app() -> FastAPI:
+    """Construye la app: logging, middleware de trace_id, /health y routers."""
+    settings = Settings()
+    configure_logging(level=settings.log_level)
+    app = FastAPI(
+        title="AgentForge Core",
+        version="0.1.0",
+        description="Plataforma de gobernanza de agentes IA — API REST.",
+    )
+    app.add_middleware(TraceIdMiddleware)
+
+    @app.get("/health", tags=["meta"])
+    async def health() -> dict[str, str]:
+        return {"status": "ok"}
+
+    from agentforge_core.api import agents, executions, policies, violations
+
+    app.include_router(agents.router, prefix="/agents", tags=["agents"])
+    app.include_router(executions.router, prefix="/executions", tags=["executions"])
+    app.include_router(policies.router, prefix="/policies", tags=["policies"])
+    app.include_router(violations.router, prefix="/violations", tags=["violations"])
+    return app
+
+
+app = create_app()
diff --git a/tests/unit/test_health.py b/tests/unit/test_health.py
new file mode 100644
index 0000000..4124b41
--- /dev/null
+++ b/tests/unit/test_health.py
@@ -0,0 +1,24 @@
+"""Tests del endpoint /health y del TraceIdMiddleware."""
+
+from fastapi.testclient import TestClient
+
+from agentforge_core.main import create_app
+
+
+def test_health_responde_ok() -> None:
+    client = TestClient(create_app())
+    r = client.get("/health")
+    assert r.status_code == 200
+    assert r.json() == {"status": "ok"}
+
+
+def test_trace_id_header_se_devuelve_generado() -> None:
+    client = TestClient(create_app())
+    r = client.get("/health")
+    assert r.headers.get("x-trace-id")
+
+
+def test_trace_id_header_se_propaga_si_viene_en_la_request() -> None:
+    client = TestClient(create_app())
+    r = client.get("/health", headers={"X-Trace-Id": "fixed-123"})
+    assert r.headers["x-trace-id"] == "fixed-123"