lance-duckdb AGENTS.md

Repository instructions for a DuckDB extension that lets DuckDB query Lance datasets, including vector and full-text searches. DuckDB is a database for analytics, while Lance is a data format for machine-learning data.

In plain words
What is it for?
Use them when documenting, implementing, reviewing, testing, or changing compatibility in the lance-duckdb extension.
Why use it?
They explain which upstream DuckDB and Lance rules take priority and how the C++ and Rust parts must work together.

Instructions file for CodexOpenCode

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 instructions/lance-format/lance-duckdb/agents-md
Clone the repo
git clone --depth 1 https://github.com/lance-format/lance-duckdb

Made for: Codex, OpenCode.

Per session 1,672 This file is loaded in full into every session.
When invoked 1,672 The same file — it is already loaded in full.
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 $0.01672 $0.01672
Opus 5 $0.00836 $0.00836
Sonnet 5 $0.00334 $0.00334
Haiku 4.5 $0.00167 $0.00167

Measured 2d ago against content hash e5c687fc3d5b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

lance-duckdb AGENTS.md 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 2d ago.

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.

AGENTS.md · 150 lines

How it starts

The opening of the file, as written. The whole thing — 150 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md

Project Overview

This repository contains a DuckDB extension for querying Lance format datasets (including scan, vector search, and full-text search). The DuckDB integration is implemented in C++ (under src/) and links a Rust static library (lance_duckdb_ffi) that uses the Lance Rust crate and exports data via the Arrow C Data Interface.

Documentation Language

All documentation in this repository (including README.md and files under docs/) must be written in English.

Constraint Hierarchy (Highest Priority)

For any planning, implementation, review, or refactor work in this repository:

  • The only hard constraints are upstream DuckDB requirements and upstream Lance requirements.
  • If any repository-local guidance conflicts with DuckDB or Lance behavior/contracts, follow DuckDB/Lance.
  • Any decision made inside lance-duckdb (APIs/ABIs, FFI boundaries, internal formats, module boundaries, naming, testing conventions, or implementation strategies) is mutable and may be changed when a better design is found.
  • Treat repository-local rules in this document as default guidance, not immutable policy.

Deliverable & Compatibility Policy

This project is delivered as a fully self-contained DuckDB extension artifact (statically linked in our distribution). Low-level APIs/ABIs/formats in this repository (C++/Rust FFI boundaries, internal encodings, file/IPC formats, etc.) are strictly internal implementation details:

  • They are not intended to be directly consumed by end users.
  • There are no external downstream users that depend on them.
  • Prioritize first principles and the most direct correct design; do not optimize for migrations or compatibility unless explicitly requested.
  • Compatibility commitments are driven by DuckDB/Lance behavior, not by historical repository-local decisions.
  • User-facing contracts should be defined at the SQL surface.

Public Surface Policy (SQL-First)

Expose user-facing capabilities primarily through SQL, not internal helper functions.

Read the full file on GitHub · 150 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. 2d ago First seen · 150 lines · 1,672 tokens per session scan A e5c687fc3d5b

Subscribe to this mod's changes

lance-duckdb AGENTS.md is an instructions file published in the GitHub repository lance-format/lance-duckdb (125 stars, last pushed 25d ago), licensed Apache-2.0. It adds 1,672 tokens to every session, about $0.0084 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.

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