infrahub/transforms/README.md

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+# Infrahub Transforms
+
+Jinja2 transforms that query InfraHub and produce JSON configuration payloads for the EVPN-VXLAN fabric devices.
+
+Each transform follows the same pattern: a **GraphQL query** fetches intent data from InfraHub, and a **Jinja2 template** renders it into a structured JSON payload. Transforms are registered in `.infrahub.yml` at the repository root.
+
+## Available Transforms
+
+| Transform | Query | Scope |
+|-----------|-------|-------|
+| `vlan_yang_transform` | `vlan_intent` | VLAN definitions per device |
+| `interface_yang_transform` | `interface_intent` | Physical/logical interfaces, switchport config |
+| `vxlan_yang_transform` | `vxlan_intent` | VXLAN/VTEP tunnel config, VNI mappings |
+| `vrf_yang_transform` | `vrf_intent` | VRF instances, L3VNI, route targets |
+| `mlag_yang_transform` | `mlag_intent` | MLAG domain, peer-link, dual-primary detection |
+| `bgp_yang_transform` | `bgp_intent` | BGP process, peer groups, neighbors, address families |
+
+## Usage
+
+All transforms take a `device_name` parameter:
+
+```bash
+# Render a single transform
+infrahubctl render vlan_yang_transform device_name=leaf1
+infrahubctl render interface_yang_transform device_name=leaf1
+infrahubctl render vxlan_yang_transform device_name=leaf1
+infrahubctl render vrf_yang_transform device_name=leaf7
+infrahubctl render mlag_yang_transform device_name=leaf1
+infrahubctl render bgp_yang_transform device_name=spine1
+```
+
+Devices without applicable config return `[]` (e.g. `mlag_yang_transform` on a spine, `vxlan_yang_transform` on a non-VTEP device).
+
+## Directory Structure
+
+```
+infrahub/transforms/
+├── queries/          # GraphQL .gql files
+├── templates/        # Jinja2 .j2 files
+└── tests/            # Unit test fixtures (mock input + expected output)
+```
+
+## Adding a New Transform
+
+1. Create the GraphQL query in `queries/<name>_intent.gql`
+2. Create the Jinja2 template in `templates/<name>_yang.j2`
+3. Register both in `.infrahub.yml` (query + jinja2_transform)
+4. Add test fixtures in `tests/<name>_yang/`