feat(langchain): add Stagehand code-mode integration

Author: shrey150

.github/workflows/stagehand-codemode.yml

@@ -5,6 +5,7 @@ on:
     paths:
       - '.github/workflows/stagehand-codemode.yml'
       - 'examples/integrations/crewai/stagehand-codemode/**'
+      - 'examples/integrations/langchain/stagehand-codemode/**'
       - 'examples/integrations/mastra/stagehand-codemode/**'
       - 'examples/integrations/vercel/stagehand-codemode/**'
       - 'packages/stagehand-codemode/**'
@@ -14,6 +15,7 @@ on:
     paths:
       - '.github/workflows/stagehand-codemode.yml'
       - 'examples/integrations/crewai/stagehand-codemode/**'
+      - 'examples/integrations/langchain/stagehand-codemode/**'
       - 'examples/integrations/mastra/stagehand-codemode/**'
       - 'examples/integrations/vercel/stagehand-codemode/**'
       - 'packages/stagehand-codemode/**'
@@ -94,3 +96,25 @@ jobs:
       - run: pnpm --filter @browserbasehq/stagehand-codemode run build
       - run: python -m pip install -r examples/integrations/crewai/stagehand-codemode/requirements.txt
       - run: python examples/integrations/crewai/stagehand-codemode/smoke.py
+
+  deepagents:
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@v4
+      - uses: pnpm/action-setup@v4
+        with:
+          version: 10.9.0
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 24.x
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.12'
+          cache: pip
+          cache-dependency-path: examples/integrations/langchain/stagehand-codemode/requirements.txt
+
+      - run: pnpm install --no-frozen-lockfile
+      - run: pnpm --filter @browserbasehq/stagehand-codemode run build
+      - run: python -m pip install -r examples/integrations/langchain/stagehand-codemode/requirements.txt
+      - run: python examples/integrations/langchain/stagehand-codemode/smoke.py

examples/integrations/langchain/stagehand-codemode/README.md

@@ -0,0 +1,13 @@
+# LangChain Deep Agents + Stagehand code mode
+
+This binding launches the local MCP over stdio and keeps one explicit LangChain MCP session open
+around the complete Deep Agent invocation.
+
+Do not replace the explicit `client.session()` plus `load_mcp_tools(session)` flow with
+`client.get_tools()`. LangChain documents that `get_tools()` creates a new session for each tool
+call; for a stdio server, that means a new process and a new browser every time.
+
+The shared Stagehand V4 syntax skill is loaded as the Deep Agent's `system_prompt` and is also
+included in the MCP tool description.
+
+See [`agent.py`](./agent.py).

examples/integrations/langchain/stagehand-codemode/agent.py

@@ -0,0 +1,47 @@
+from __future__ import annotations
+
+import os
+from pathlib import Path
+from typing import Any
+
+from deepagents import create_deep_agent
+from langchain_mcp_adapters.client import MultiServerMCPClient
+from langchain_mcp_adapters.tools import load_mcp_tools
+
+
+REPOSITORY_ROOT = Path(__file__).resolve().parents[4]
+CLI_PATH = REPOSITORY_ROOT / "packages/stagehand-codemode/dist/cli.js"
+SKILL_PATH = REPOSITORY_ROOT / "packages/stagehand-codemode/STAGEHAND_CODEMODE_SKILL.md"
+STAGEHAND_CODEMODE_SKILL = SKILL_PATH.read_text().strip()
+
+
+async def run_stagehand_agent(prompt: str, model: str | Any = "openai:gpt-5-mini") -> dict[str, Any]:
+    client = MultiServerMCPClient(
+        {
+            "stagehand": {
+                "transport": "stdio",
+                "command": "node",
+                "args": [str(CLI_PATH)],
+                "env": dict(os.environ),
+            }
+        },
+        tool_name_prefix=False,
+        handle_tool_errors=True,
+    )
+
+    # An explicit session is required. client.get_tools() would start a fresh stdio
+    # process for each tool call and lose the browser between calls.
+    async with client.session("stagehand") as session:
+        tools = await load_mcp_tools(session)
+        code_tools = [tool for tool in tools if tool.name == "code_execute"]
+        if len(code_tools) != 1:
+            raise RuntimeError(f"Expected one code_execute tool, got {[tool.name for tool in tools]}")
+        agent = create_deep_agent(
+            model=model,
+            tools=code_tools,
+            system_prompt=STAGEHAND_CODEMODE_SKILL,
+        )
+        return await agent.ainvoke(
+            {"messages": [{"role": "user", "content": prompt}]},
+            config={"recursion_limit": 20},
+        )

examples/integrations/langchain/stagehand-codemode/requirements.txt

@@ -0,0 +1,4 @@
+deepagents>=0.7.1,<1
+langchain-mcp-adapters>=0.3.1,<1
+langchain-openai>=1.2.1,<2
+mcp>=1.24.0,<2

examples/integrations/langchain/stagehand-codemode/smoke.py

@@ -0,0 +1,30 @@
+from __future__ import annotations
+
+import asyncio
+
+from langchain_mcp_adapters.client import MultiServerMCPClient
+from langchain_mcp_adapters.tools import load_mcp_tools
+
+from agent import CLI_PATH, STAGEHAND_CODEMODE_SKILL
+
+
+async def main() -> None:
+    client = MultiServerMCPClient(
+        {
+            "stagehand": {
+                "transport": "stdio",
+                "command": "node",
+                "args": [str(CLI_PATH)],
+            }
+        }
+    )
+    async with client.session("stagehand") as session:
+        tools = await load_mcp_tools(session)
+        assert [tool.name for tool in tools] == ["code_execute"]
+        assert "Stagehand V4 code-mode syntax" in (tools[0].description or "")
+        assert "stagehand.extract" in STAGEHAND_CODEMODE_SKILL
+        print("Deep Agents persistent stdio discovery PASS: code_execute")
+
+
+if __name__ == "__main__":
+    asyncio.run(main())