diff --git a/SEO.md b/SEO.md
index c5f2690..f449404 100644
--- a/SEO.md
+++ b/SEO.md
@@ -75,6 +75,7 @@ that page's frontmatter, never here.
 | `docs/guides/run-on-postgres` | ctrlrun postgres | Use Postgres when workers on more than one host must share one store. |
 | `docs/guides/verify-in-ci` | verify agent safety configuration CI | `ctrlrun verify` runs the kernel's own failure scenarios against your policy. |
 | `docs/guides/export-to-opentelemetry` | opentelemetry AI agent actions | `OTelEventSink` turns every action into one OpenTelemetry span. |
+| `docs/guides/langchain-middleware` | langchain middleware tool call policy | CTRLRun checks every tool call your agent makes against a policy you write, before the call runs, and records what happened after. |
 | `docs/guides/langgraph-adapter` | langgraph interrupt human approval | `ctrlrun-langgraph` makes an `approve` decision surface as a LangGraph `interrupt()`. |
 | `docs/guides/openai-agents-adapter` | openai agents sdk tool approval | `ctrlrun-openai-agents` makes an `approve` decision stop the run with the SDK's own `ToolApprovalItem`. |
 | `docs/cookbook/index` | AI agent policy examples | Each recipe is a situation an agent is put in. |
diff --git a/docs.json b/docs.json
index aa438b0..ced1ba3 100644
--- a/docs.json
+++ b/docs.json
@@ -109,6 +109,7 @@
               "docs/guides/verify-in-ci",
               "docs/guides/export-to-opentelemetry",
               "docs/adapters",
+              "docs/guides/langchain-middleware",
               "docs/guides/langgraph-adapter",
               "docs/guides/openai-agents-adapter"
             ]
@@ -611,6 +612,11 @@
       "destination": "/docs/guides/export-to-opentelemetry",
       "permanent": true
     },
+    {
+      "source": "/guides/langchain-middleware",
+      "destination": "/docs/guides/langchain-middleware",
+      "permanent": true
+    },
     {
       "source": "/guides/langgraph-adapter",
       "destination": "/docs/guides/langgraph-adapter",
diff --git a/docs/adapters.md b/docs/adapters.md
index 0d4abe8..7f7c99e 100644
--- a/docs/adapters.md
+++ b/docs/adapters.md
@@ -26,6 +26,7 @@ rather than growing by one each time a framework is named.
 
 | Distribution | Framework | Shape | Reuses | Binding |
 |---|---|---|---|---|
+| `ctrlrun-langchain` | LangChain | the call itself is handed over | `AgentMiddleware.wrap_tool_call`, so `handler` **is** the executor | **prevention** |
 | `ctrlrun-langgraph` | LangGraph | resumed in place | `interrupt()` + `Command(resume=...)`, and the checkpointer | **prevention** |
 | `ctrlrun-openai-agents` | OpenAI Agents SDK | decided before invocation | the tool-approval interruption | **attribution** |
 
diff --git a/docs/guides/langchain-middleware.mdx b/docs/guides/langchain-middleware.mdx
new file mode 100644
index 0000000..924b40a
--- /dev/null
+++ b/docs/guides/langchain-middleware.mdx
@@ -0,0 +1,110 @@
+---
+title: "Use the LangChain middleware"
+description: "Gate every LangChain tool call with ctrlrun-langchain, through wrap_tool_call, so a refused call never runs and every decision leaves a receipt."
+---
+
+This guide provides a quick overview for getting started with the CTRLRun [middleware](https://docs.langchain.com/oss/langchain/middleware/overview). CTRLRun checks every tool call your agent makes against a policy you write, before the call runs, and records what happened after.
+
+## Overview
+
+### Details
+
+| Class | Package | Serializable | Downloads | Version |
+| :--- | :--- | :---: | :---: | :---: |
+| `CTRLRunMiddleware` | [`ctrlrun-langchain`](https://pypi.org/project/ctrlrun-langchain/) | beta/❌ | ![PyPI - Downloads](https://img.shields.io/pypi/dm/ctrlrun-langchain?style=flat-square&label=%20) | ![PyPI - Version](https://img.shields.io/pypi/v/ctrlrun-langchain?style=flat-square&label=%20) |
+
+### Features
+
+- **Policy-gated tool calls** — a refused call never reaches the tool, and the model is told which rule refused it
+- **Once stays once** — an effect key executes at most once, across processes sharing a store
+- **Unknown outcomes stay unknown** — a tool that raises leaves the effect unresolved rather than retried
+- **Human approval** — a policy decision of `approve` holds the call for a person
+- **A receipt for every decision** — requests, decisions and results, refusals included
+
+---
+
+## Setup
+
+No account and no API key. CTRLRun is a library, and the policy is a file in your repository.
+
+### Installation
+
+```bash
+pip install ctrlrun-langchain
+```
+
+### Write a policy
+
+`ctrlrun.yaml` says how much autonomy each tool gets. Unknown tools are denied; there is no default-allow.
+
+```yaml
+schema: ctrlrun.policy/v2
+actions:
+  lookup_order:
+    decision: allow
+  issue_refund:
+    effect: "refund:{payment_id}"
+    rules:
+      - when: { amount_gte: 0, amount_lte: 5000 }   # up to €50.00, autonomous
+        decision: allow
+      - when: { amount_gte: 0, amount_lte: 500000 } # up to €5,000.00, ask a human
+        decision: approve
+      - decision: deny
+```
+
+## Instantiation
+
+```python
+from langchain.agents import create_agent
+from ctrlrun import Control
+from ctrlrun_langchain import CTRLRunMiddleware
+
+control = Control.from_file("ctrlrun.yaml")
+
+agent = create_agent(
+    model="gpt-5.5",
+    tools=[lookup_order, issue_refund],
+    middleware=[CTRLRunMiddleware(control)],
+)
+```
+
+## Invocation
+
+```python
+import ctrlrun
+
+with ctrlrun.context(agent="support-agent"):
+    result = agent.invoke({"messages": [{"role": "user", "content": "refund order 4471"}]})
+```
+
+Every protected call needs a principal: who is acting is an authorization input, so a call without one is denied before the policy is consulted. `ctrlrun.context(...)` supplies it in development; in production an identity provider verifies a credential instead.
+
+## What the agent sees
+
+The middleware uses [`wrap_tool_call`](https://docs.langchain.com/oss/langchain/middleware/custom), so a refused call is short-circuited — the tool is never invoked, and the model receives a `ToolMessage` explaining why:
+
+```text
+issue_refund  amount=900000    CTRLRun refused this call: rule[2]. The tool did not run.
+rm_rf                          CTRLRun refused this call: unknown_action. The tool did not run.
+issue_refund  amount=1000      (the tool runs)
+issue_refund  amount=1000      CTRLRun refused this call: this effect is already committed
+```
+
+That last line is the property worth knowing about. Because `handler` is the executor, the effect is reserved before the tool runs and committed from what it returned. Two agents sharing a store cannot both execute the same effect key, and a tool that raises leaves the outcome `AMBIGUOUS` rather than `FAILED` — so the retry is refused until a person resolves it, instead of becoming a double charge.
+
+## Approvals
+
+Where the policy says `approve`, the call is held and the model is told how to release it:
+
+```text
+CTRLRun is holding this call for a human. Approve it with 'ctrlrun approve apr_...',
+then ask again. The tool did not run.
+```
+
+To have the human answered *inside* the run instead, use [`ctrlrun-langgraph`](https://pypi.org/project/ctrlrun-langgraph/), which routes the approval through LangGraph's `interrupt()` and re-presents the same proposal on resume.
+
+## Next
+
+- [Use the LangGraph adapter](/docs/guides/langgraph-adapter): approvals answered inside the run, through `interrupt()`.
+- [Adapters](/docs/adapters): the three ways in, and why this one is prevention.
+- [The middleware's README](https://github.com/CTRLRun/ctrlrun/blob/main/adapters/langchain/README.md) · [Get started](/docs/get-started/quickstart) · [Why](/docs/why).