bonnard-design-guide

A set of design rules for building a semantic layer: a clear, user-friendly description of business data on top of database tables. It helps AI agents and people find and understand the right metrics.

In plain words
What is it for?
Use it when building data views, describing metrics, or fixing poor agent answers. It recommends starting with common questions and designing views around the people who ask them.
Why use it?
It prevents a data model from simply copying the database structure, which can make common business questions difficult to answer accurately.

Cursor rule

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/bonnard-data/bonnard-cli/bonnard-design-guide
Clone the repo
git clone --depth 1 https://github.com/bonnard-data/bonnard-cli
Per session 29 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,133 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00029 $0.02133
Opus 5 $0.00015 $0.01066
Sonnet 5 $0.00006 $0.00427
Haiku 4.5 $0.00003 $0.00213

Measured yesterday against content hash 539f40ad0bd0, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

bonnard-design-guide scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

src/templates/cursor/rules/bonnard-design-guide.mdc · 234 lines

How it starts

The opening of the file, as written. The whole thing — 234 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Semantic Layer Design Guide

This guide covers design decisions that determine whether your semantic layer works for end users and AI agents. It complements the setup guides (bonnard-get-started, bonnard-metabase-migrate) which cover mechanics.

Read this before building views, or revisit it when agents return wrong answers or users can't find the right metrics.

Principle 1: Start from Questions, Not Tables

The natural instinct is: look at tables, build cubes, expose everything. This produces a semantic layer that mirrors your warehouse schema — technically correct but useless to anyone who doesn't already know the schema.

Instead, start from what people ask:

  1. Collect the 10-20 most common questions your team asks about data
  2. For each question, identify which tables/columns are needed to answer it
  3. Group questions by audience (who asks them)
  4. Build views that answer those question groups

If you have a BI tool (Metabase, Looker, Tableau), your top dashboards by view count are the best source of real questions. If not, ask each team: "What 3 numbers do you check every week?"

Why this matters: A semantic layer built from questions produces focused, audience-scoped views. One built from tables produces generic views that agents struggle to choose between. Governance policies control which views each user or role can access, so build as many views as your audiences need — but make each one purposeful with clear descriptions.

Principle 2: Views Are for Audiences, Not Tables

A common mistake is creating one view per cube (table). This produces views like orders_view, users_view, invoices_view — which is just the warehouse schema with extra steps.

Views should represent how a team thinks about data:

BAD (model-centric):                 GOOD (audience-centric):
views/                               views/
  orders_view.yaml       (1 cube)      management.yaml      (revenue + users)
  users_view.yaml        (1 cube)      sales.yaml           (opportunities + invoices)
  invoices_view.yaml     (1 cube)      product.yaml         (users + funnel + contracts)
  opportunities_view.yaml (1 cube)     partners.yaml        (partners + billing)

Read the full file on GitHub · 234 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 234 lines · 29 tokens per session scan A 539f40ad0bd0

Subscribe to this mod's changes

bonnard-design-guide is a cursor rule published in the GitHub repository bonnard-data/bonnard-cli (50 stars, last pushed 2mo ago), licensed MIT. It adds 29 tokens to every session and 2,133 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.