diff --git a/src/gateway/api/deps.py b/src/gateway/api/deps.py
index 264e12aa2..729c14e94 100644
--- a/src/gateway/api/deps.py
+++ b/src/gateway/api/deps.py
@@ -916,6 +916,17 @@ def get_model_provider_port(db: PortSessionDep, container: ContainerDep) -> Mode
     return container.resolve(ModelProviderPort, db)
 
 
+# ``get_db`` rather than ``PortSessionDep``: every management-plane caller here already
+# holds a session from ``get_db``, and naming the same dependency shares it instead of
+# opening a second one. Data-plane routes (chat/messages/responses) keep the port above.
+def get_model_provider_port_shared(
+    db: Annotated[AsyncSession, Depends(get_db)],
+    container: ContainerDep,
+) -> ModelProviderPort:
+    """Resolve the model-provider adapter, sharing the caller's own database session."""
+    return container.resolve(ModelProviderPort, db)
+
+
 # Deliberately ``get_db`` and not ``PortSessionDep``: every surface that
 # resolves this port (the OTLP receiver, the telemetry read and purge
 # endpoints, user deletion) is standalone-only and already holds a session from
@@ -1022,6 +1033,7 @@ def get_organization_guardrail_definition_service(
 IdentityProviderPortDep = Annotated[IdentityProviderPort, Depends(get_identity_provider_port)]
 McpServerPortDep = Annotated[McpServerPort, Depends(get_mcp_server_port)]
 ModelProviderPortDep = Annotated[ModelProviderPort, Depends(get_model_provider_port)]
+ModelProviderPortSharedDep = Annotated[ModelProviderPort, Depends(get_model_provider_port_shared)]
 
 
 def get_org_provider_model_service(
diff --git a/src/gateway/api/routes/catalog.py b/src/gateway/api/routes/catalog.py
index d0fa2786f..041bed127 100644
--- a/src/gateway/api/routes/catalog.py
+++ b/src/gateway/api/routes/catalog.py
@@ -38,6 +38,7 @@
 
 from gateway.api.deps import (
     ModelProviderPortDep,
+    ModelProviderPortSharedDep,
     get_config,
     get_db,
     get_session_identity,
@@ -661,7 +662,7 @@ async def list_catalog(
     config: Annotated[GatewayConfig, Depends(get_config)],
     caller: Annotated[CatalogCaller, Depends(verify_catalog_reader_or_public)],
     session_identity: Annotated[TenancyUser | None, Depends(get_session_identity)],
-    model_provider: ModelProviderPortDep,
+    model_provider: ModelProviderPortSharedDep,
     at_context: Annotated[
         int | None,
         Query(
@@ -724,7 +725,7 @@ async def get_catalog_model(
     config: Annotated[GatewayConfig, Depends(get_config)],
     caller: Annotated[CatalogCaller, Depends(verify_catalog_reader_or_public)],
     session_identity: Annotated[TenancyUser | None, Depends(get_session_identity)],
-    model_provider: ModelProviderPortDep,
+    model_provider: ModelProviderPortSharedDep,
 ) -> CatalogModelDetail:
     """One model and every offering of it this caller may use.
 
diff --git a/src/gateway/api/routes/models.py b/src/gateway/api/routes/models.py
index f2ae8a44e..e299d0883 100644
--- a/src/gateway/api/routes/models.py
+++ b/src/gateway/api/routes/models.py
@@ -8,7 +8,7 @@
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from gateway.api.deps import (
-    ModelProviderPortDep,
+    ModelProviderPortSharedDep,
     get_config,
     get_db,
     get_session_identity,
@@ -183,7 +183,7 @@ async def list_models(
     config: Annotated[GatewayConfig, Depends(get_config)],
     auth: Annotated[tuple[APIKey | None, bool], Depends(verify_catalog_reader)],
     session_identity: Annotated[TenancyUser | None, Depends(get_session_identity)],
-    model_provider: ModelProviderPortDep,
+    model_provider: ModelProviderPortSharedDep,
     provider: Annotated[str | None, Query(description="Filter models by provider name")] = None,
 ) -> ModelListResponse:
     """List all available models.
@@ -276,7 +276,7 @@ async def get_model(
     config: Annotated[GatewayConfig, Depends(get_config)],
     auth: Annotated[tuple[APIKey | None, bool], Depends(verify_catalog_reader)],
     session_identity: Annotated[TenancyUser | None, Depends(get_session_identity)],
-    model_provider: ModelProviderPortDep,
+    model_provider: ModelProviderPortSharedDep,
 ) -> ModelObject:
     """Get details for a specific model."""
     api_key, _is_master_key = auth
diff --git a/src/gateway/api/routes/organization_pricing.py b/src/gateway/api/routes/organization_pricing.py
index 4f4dc314d..f81fd74df 100644
--- a/src/gateway/api/routes/organization_pricing.py
+++ b/src/gateway/api/routes/organization_pricing.py
@@ -27,7 +27,7 @@
 from sqlalchemy.exc import IntegrityError, SQLAlchemyError
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from gateway.api.deps import CurrentIdentity, ModelProviderPortDep, get_config, get_db, verify_master_key
+from gateway.api.deps import CurrentIdentity, ModelProviderPortSharedDep, get_config, get_db, verify_master_key
 from gateway.core.config import GatewayConfig
 from gateway.models.money import as_float
 from gateway.models.pricing import OrganizationModelPricing
@@ -212,7 +212,7 @@ class OrganizationModelPricingsPublic(BaseModel):
 def get_organization_pricing_service(
     db: Annotated[AsyncSession, Depends(get_db)],
     config: Annotated[GatewayConfig, Depends(get_config)],
-    model_provider: ModelProviderPortDep,
+    model_provider: ModelProviderPortSharedDep,
 ) -> OrganizationPricingService:
     """Build the pricing service on the request's session, provider map, and hosted-credential port."""
     return OrganizationPricingService(db, config, model_provider=model_provider)
diff --git a/src/gateway/api/routes/organization_routing.py b/src/gateway/api/routes/organization_routing.py
index c6f43740c..08e7b24f4 100644
--- a/src/gateway/api/routes/organization_routing.py
+++ b/src/gateway/api/routes/organization_routing.py
@@ -61,7 +61,7 @@
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlmodel import col
 
-from gateway.api.deps import CurrentIdentity, ModelProviderPortDep, get_config, get_db, verify_master_key
+from gateway.api.deps import CurrentIdentity, ModelProviderPortSharedDep, get_config, get_db, verify_master_key
 from gateway.api.routes.aliases import (
     AliasRequest,
     AliasResponse,
@@ -298,7 +298,7 @@ async def set_organization_routing_policy(
     db: Annotated[AsyncSession, Depends(get_db)],
     config: Annotated[GatewayConfig, Depends(get_config)],
     current_identity: CurrentIdentity,
-    model_provider: ModelProviderPortDep,
+    model_provider: ModelProviderPortSharedDep,
 ) -> PolicyResponse:
     """Create or update a stored policy in one of the organization's workspaces.
 
@@ -380,7 +380,7 @@ async def set_organization_alias(
     db: Annotated[AsyncSession, Depends(get_db)],
     config: Annotated[GatewayConfig, Depends(get_config)],
     current_identity: CurrentIdentity,
-    model_provider: ModelProviderPortDep,
+    model_provider: ModelProviderPortSharedDep,
 ) -> AliasResponse:
     """Create or update a stored alias in one of the organization's workspaces.
 
diff --git a/src/gateway/api/routes/playground.py b/src/gateway/api/routes/playground.py
index 936476487..a8fd6e2df 100644
--- a/src/gateway/api/routes/playground.py
+++ b/src/gateway/api/routes/playground.py
@@ -66,7 +66,7 @@
     CurrentIdentity,
     FileServiceDep,
     McpServerPortDep,
-    ModelProviderPortDep,
+    ModelProviderPortSharedDep,
     WebSearchPolicyPortDep,
     get_config,
     get_db,
@@ -183,7 +183,7 @@ async def playground_chat_completions(
     files: FileServiceDep,
     config: Annotated[GatewayConfig, Depends(get_config)],
     log_writer: Annotated[LogWriter, Depends(get_log_writer)],
-    model_provider: ModelProviderPortDep,
+    model_provider: ModelProviderPortSharedDep,
     code_execution_port: CodeExecutionPortDep,
     mcp_server_port: McpServerPortDep,
     web_search_policy_port: WebSearchPolicyPortDep,
diff --git a/tests/unit/test_model_provider_port_management_route_session.py b/tests/unit/test_model_provider_port_management_route_session.py
new file mode 100644
index 000000000..78ec9118a
--- /dev/null
+++ b/tests/unit/test_model_provider_port_management_route_session.py
@@ -0,0 +1,62 @@
+"""Regression for otari#1266: a management-plane route's model-provider port must
+share the route's own database session, not open a second, independent one.
+"""
+
+from typing import Annotated, cast
+
+import pytest
+from fastapi import Depends, FastAPI
+from fastapi.testclient import TestClient
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from gateway.api.routes.organization_pricing import get_organization_pricing_service
+from gateway.core import database
+from gateway.core.config import GatewayConfig
+from gateway.ports.model_provider_port import ModelProviderPort
+from gateway.services.organization_pricing_service import OrganizationPricingService
+
+
+class _FakeSession:
+    """A distinguishable stand-in for ``AsyncSession``; only its identity matters here."""
+
+    async def __aenter__(self) -> "_FakeSession":
+        return self
+
+    async def __aexit__(self, *exc: object) -> None:
+        return None
+
+
+class _NullModelProviderPort:
+    """A do-nothing port; the stub container below only records which session built it."""
+
+
+class _RecordingContainer:
+    """Stands in for the composition-root container, recording ``resolve``'s session arg."""
+
+    def __init__(self) -> None:
+        self.resolved_with: list[AsyncSession | None] = []
+
+    def resolve(self, port: type[ModelProviderPort], session: AsyncSession | None) -> ModelProviderPort:
+        self.resolved_with.append(session)
+        return cast(ModelProviderPort, _NullModelProviderPort())
+
+
+def test_organization_pricing_service_shares_its_own_request_session(monkeypatch: pytest.MonkeyPatch) -> None:
+    # A fresh fake per call, so a route that opens two sessions is caught by identity.
+    monkeypatch.setattr(database, "_SessionLocal", lambda: _FakeSession())
+
+    container = _RecordingContainer()
+    app = FastAPI()
+    app.state.container = container
+    app.state.config = GatewayConfig(database_url="sqlite:///./test.db")
+
+    @app.get("/probe")
+    async def probe(
+        service: Annotated[OrganizationPricingService, Depends(get_organization_pricing_service)],
+    ) -> dict[str, bool]:
+        return {"shared": len(container.resolved_with) == 1 and container.resolved_with[0] is service.db}
+
+    response = TestClient(app).get("/probe")
+
+    assert response.status_code == 200
+    assert response.json() == {"shared": True}