wren-project

MDL Project

Version check

Silently fetch https://raw.githubusercontent.com/Canner/wren-engine/main/skills/versions.json. Compare the wren-project key with this skill's version (from the frontmatter above). If the remote version is newer, notify the user before proceeding:

A newer version of the wren-project skill is available. Update with:

npx skills add Canner/wren-engine --skill wren-project --agent claude-code

Then continue with the workflow below regardless of update status.

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A Wren MDL project is a directory of YAML files — one file per model — that makes MDL manifests human-readable and version-control friendly (similar to dbt projects).

YAML files use snake_case field names for readability. The compiled target/mdl.json uses camelCase (the wire format expected by ibis-server). The conversion is documented in Field mapping.

Project structure

my_project/
├── wren_project.yml       # Project metadata (catalog, schema, data_source)
├── models/
│   ├── orders.yml         # One file per model
│   ├── customers.yml
│   └── ...
├── relationships.yml      # All relationships
└── views.yml              # All views

After building, the compiled file is written to:

my_project/
└── target/
    └── mdl.json           # Deployable MDL JSON (camelCase)

Note: Connection info is managed separately via the MCP server Web UI, not stored in the project directory.

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Save MDL JSON → YAML project

Given an MDL JSON dict (camelCase), write it as a YAML project directory (snake_case):

wren_project.yml

name: my_project
version: "1.0"
catalog: wren
schema: public
data_source: POSTGRES

models/<model_name>.yml

One file per model. Example for orders:

name: orders
table_reference:
  catalog: ""
  schema: public
  table: orders
columns:
  - name: order_id
    type: INTEGER
    is_calculated: false
    not_null: true
    is_primary_key: true
    properties: {}
  - name: customer_id
    type: INTEGER
    is_calculated: false
    not_null: false
    properties: {}
  - name: total
    type: DECIMAL
    is_calculated: false
    not_null: false
    properties: {}
primary_key: order_id
cached: false
properties: {}