VFSForGit AGENTS.md

Agent instructions for VFS for Git, a system that lets Git work with very large repositories by managing files efficiently. They describe the repository layout, build-output locations, and the quick unit-test workflow.

In plain words
What is it for?
Use them to set up the expected clone structure, find build outputs, and run the short incremental unit-test loop.
Why use it?
They prevent confusion about where source and build files belong and show the recommended way to test small changes quickly.

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/microsoft/vfsforgit/agents-md
Clone the repo
git clone --depth 1 https://github.com/microsoft/VFSForGit

Made for: Codex, OpenCode.

Per session 2,444 This file is loaded in full into every session.
When invoked 2,444 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 $0.02444 $0.02444
Opus 5 $0.01222 $0.01222
Sonnet 5 $0.00489 $0.00489
Haiku 4.5 $0.00244 $0.00244

Measured 2d ago against content hash 45be71ef2b22, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

VFSForGit 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 · 208 lines

How it starts

The opening of the file, as written. The whole thing — 208 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent instructions for VFS for Git

This file is for AI coding assistants (GitHub Copilot, Claude Code, Cursor, OpenAI Codex, Gemini CLI, Aider, etc.). It captures project-specific knowledge that isn't obvious from a fresh git clone and which routinely trips up agents. See CONTRIBUTING.md for coding standards (StyleCop rules, error handling, exception logging) — do not duplicate those here.

Repository layout

The build scripts (scripts\Build.bat and friends) put build outputs one level up from the git working tree. The Readme documents the recommended clone-into-src\ convention, which matches the layout that gvfs clone creates for end users:

# Recommended (matches Readme.md and CI):
git clone https://github.com/microsoft/VFSForGit C:\Repos\VFSForGit\src
C:\Repos\VFSForGit\
├── src\                    ← git working tree (.git, GVFS.sln, all source)
├── out\                    ← build output (gitignored — it's outside the working tree)
└── packages\               ← NuGet cache

Cloning without the src\ suffix also works — outputs just land one level above wherever you cloned. The rest of this document and the project's own scripts (CI, Readme) use the src\ form, so commands assume it. The parent directory must be writable (cloning to C:\ itself won't work because the build can't create C:\out).

All commands below run from the enlistment root (the parent of src\):

cd C:\Repos\VFSForGit         # NOT C:\Repos\VFSForGit\src

This keeps src\... and out\... paths symmetric and matches what Build.bat does internally.

Build paths

scripts\Build.bat does a full installer build with NativeAOT publish plus Inno Setup. That's ~5 minutes minimum, and AOT has no incremental support — ilc relinks every executable on every dotnet publish. Do not use Build.bat for dev-loop iteration. Pick the right path for what you're doing.

Read the full file on GitHub · 208 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 · 208 lines · 2,444 tokens per session scan A 45be71ef2b22

Subscribe to this mod's changes

VFSForGit AGENTS.md is an instructions file published in the GitHub repository microsoft/VFSForGit (6,136 stars, last pushed 4d ago), licensed MIT. It adds 2,444 tokens to every session, about $0.0122 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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