From 8953d2b3f1d596a2418ab78d369b956a52ee229f Mon Sep 17 00:00:00 2001
From: TZZheng <tzzheng1996@gmail.com>
Date: Sun, 12 Jul 2026 15:49:23 -0500
Subject: [PATCH] fix(mcp): expand placeholders for HTTP connections (#761)

---
 src/lingtai/agent.py         |  7 ++++
 tests/test_mcp_capability.py | 71 ++++++++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+)

diff --git a/src/lingtai/agent.py b/src/lingtai/agent.py
index 6ab2e21f..87c0d587 100644
--- a/src/lingtai/agent.py
+++ b/src/lingtai/agent.py
@@ -965,6 +965,13 @@ def connect_mcp_http(
         """
         from .services.mcp import HTTPMCPClient
 
+        url = self._expand_agent_placeholders(url)
+        if headers:
+            headers = {
+                name: self._expand_agent_placeholders(value)
+                for name, value in headers.items()
+            }
+
         client = HTTPMCPClient(url=url, headers=headers)
         client.start()
 
diff --git a/tests/test_mcp_capability.py b/tests/test_mcp_capability.py
index 41b53007..f6e54085 100644
--- a/tests/test_mcp_capability.py
+++ b/tests/test_mcp_capability.py
@@ -185,6 +185,77 @@ def test_expand_agent_placeholders_scopes_workbench_root(tmp_path):
     assert agent._expand_agent_placeholders(None) is None
 
 
+class _FakeConnectionClient:
+    """Capture transport inputs without opening a subprocess or connection."""
+
+    instances = []
+
+    def __init__(self, **kwargs):
+        self.kwargs = kwargs
+        self.started = False
+        type(self).instances.append(self)
+
+    def start(self):
+        self.started = True
+
+    def list_tools(self):
+        return []
+
+
+def test_connect_mcp_http_expands_url_and_header_values(tmp_path, monkeypatch):
+    from lingtai.services import mcp
+
+    class FakeHTTPMCPClient(_FakeConnectionClient):
+        instances = []
+
+    monkeypatch.setattr(mcp, "HTTPMCPClient", FakeHTTPMCPClient)
+    agent, workdir = _mk_agent(tmp_path)
+
+    agent.connect_mcp_http(
+        "https://example.test/agents/{agent_id}/mcp",
+        {
+            "X-Agent-Dir": "{agent_dir}",
+            "X-{agent_id}": "unchanged",
+            "X-Literal": "no-placeholders",
+        },
+    )
+
+    client = FakeHTTPMCPClient.instances[-1]
+    assert client.started
+    assert client.kwargs == {
+        "url": "https://example.test/agents/agent/mcp",
+        "headers": {
+            "X-Agent-Dir": str(workdir),
+            "X-{agent_id}": "unchanged",
+            "X-Literal": "no-placeholders",
+        },
+    }
+
+
+def test_connect_mcp_stdio_placeholder_expansion_is_unchanged(tmp_path, monkeypatch):
+    from lingtai.services import mcp
+
+    class FakeMCPClient(_FakeConnectionClient):
+        instances = []
+
+    monkeypatch.setattr(mcp, "MCPClient", FakeMCPClient)
+    agent, workdir = _mk_agent(tmp_path)
+
+    agent.connect_mcp(
+        "bin/{agent_id}",
+        args=["--root", "{agent_dir}", "literal"],
+        env={"AGENT": "{agent_id}", "LITERAL": "unchanged"},
+    )
+
+    client = FakeMCPClient.instances[-1]
+    assert client.started
+    assert client.kwargs == {
+        "command": "bin/agent",
+        "args": ["--root", str(workdir), "literal"],
+        "env": {"AGENT": "agent", "LITERAL": "unchanged"},
+    }
+
+
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