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Co-authored-by: Fu-Jie <33599649+Fu-Jie@users.noreply.github.com>

docs/plugins/pipes/index.md

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+# Pipe Plugins
+
+Pipe plugins create custom model integrations or transform LLM responses. They appear as selectable models in the OpenWebUI interface.
+
+## What are Pipes?
+
+Pipes allow you to:
+
+- :material-api: Connect to external AI APIs (Gemini, Claude, etc.)
+- :material-robot: Create custom model wrappers
+- :material-cog-transfer: Transform requests and responses
+- :material-middleware: Implement middleware logic
+
+---
+
+## Available Pipe Plugins
+
+<div class="grid cards" markdown>
+
+-   :material-google:{ .lg .middle } **Gemini Manifold**
+
+    ---
+
+    Integration pipeline for Google's Gemini models with full streaming support.
+
+    **Version:** 1.0.0
+
+    [:octicons-arrow-right-24: Documentation](gemini-manifold.md)
+
+</div>
+
+---
+
+## How Pipes Work
+
+```mermaid
+graph LR
+    A[User selects Pipe as Model] --> B[Pipe receives request]
+    B --> C[Transform/Route request]
+    C --> D[External API / Custom Logic]
+    D --> E[Return response]
+    E --> F[Display to User]
+```
+
+### The `pipes` Method
+
+Defines what models this pipe provides:
+
+```python
+def pipes(self):
+    return [
+        {"id": "my-model", "name": "My Custom Model"},
+        {"id": "my-model-fast", "name": "My Custom Model (Fast)"}
+    ]
+```
+
+### The `pipe` Method
+
+Handles the actual request processing:
+
+```python
+def pipe(self, body: dict) -> Generator:
+    # Process the request
+    messages = body.get("messages", [])
+    
+    # Call external API or custom logic
+    response = call_external_api(messages)
+    
+    # Return response (can be streaming)
+    return response
+```
+
+---
+
+## Quick Installation
+
+1. Download the desired pipe `.py` file
+2. Navigate to **Admin Panel** → **Settings** → **Functions**
+3. Upload the file and configure API keys
+4. The pipe will appear as a selectable model
+
+---
+
+## Development Template
+
+```python
+"""
+title: My Custom Pipe
+author: Your Name
+version: 1.0.0
+description: Description of your pipe plugin
+"""
+
+from pydantic import BaseModel, Field
+from typing import Generator, Iterator, Union
+
+class Pipe:
+    class Valves(BaseModel):
+        API_KEY: str = Field(
+            default="",
+            description="API key for the external service"
+        )
+        API_URL: str = Field(
+            default="https://api.example.com",
+            description="API endpoint URL"
+        )
+    
+    def __init__(self):
+        self.valves = self.Valves()
+    
+    def pipes(self) -> list[dict]:
+        """Define available models."""
+        return [
+            {"id": "my-model", "name": "My Custom Model"},
+        ]
+    
+    def pipe(
+        self,
+        body: dict
+    ) -> Union[str, Generator, Iterator]:
+        """Process the request and return response."""
+        messages = body.get("messages", [])
+        model = body.get("model", "")
+        
+        # Your logic here
+        # Can return:
+        # - str: Single response
+        # - Generator/Iterator: Streaming response
+        
+        return "Response from custom pipe"
+```
+
+For more details, check our [Plugin Development Guide](../../development/plugin-guide.md).