Instructions for Agent Chat and Quick Chat

Instructions are rules Copilot should keep following, such as your writing style, folder conventions, preferred formats, and safety boundaries.

Agent Chat and Quick Chat use different instruction systems:

Agent Chat reads AGENTS.md files that are shared across opencode, Claude, and Codex.
Quick Chat uses selectable system prompt files.

Changing one does not change the other.

Choose the right instruction tool

Use	Best for
Vault `AGENTS.md`	Rules every Agent Chat in a vault should follow
Project `AGENTS.md`	More specific rules for one Project
Skill	A reusable workflow with instructions and supporting files
Copilot command	A short saved prompt or template you want to run again
Quick Chat system prompt	A role, tone, or response style for a Quick Chat conversation
One-off prompt	A request that matters only for the current turn

Keep stable conventions in AGENTS.md. Use a Skill when an agent needs a repeatable process. Use a Copilot command for a short reusable prompt.

Vault instructions for Agent Chat

Vault-wide instructions live in AGENTS.md at the root of your vault. They apply to new Agent Chats with opencode, Claude, and Codex.

Open Settings → Copilot → Basic → Custom instructions and edit Custom vault instructions. Copilot saves the text to the vault-root file as you type. Select Open AGENTS.md to edit the same file as a normal note.

Good instructions are short and concrete:

- Keep meeting notes under Meetings/.
- Use YYYY-MM-DD dates.
- Preserve existing frontmatter unless I ask you to change it.
- Ask before deleting a note.

Start a new Agent Chat after changing AGENTS.md so the selected backend reads the latest version.

Project instructions

Each Project can add its own AGENTS.md inside the Project folder. Open the Project info menu and select AGENTS.md, or use Edit project → Project instructions.

A Project chat follows both files:

The vault-root AGENTS.md provides general rules.
The Project AGENTS.md provides more specific rules and takes precedence when the two conflict.

Use Project instructions for details that should not affect the rest of the vault, such as a client’s tone, deliverable format, source folders, or output location.

Claude compatibility

Claude Code normally reads CLAUDE.md. To keep AGENTS.md as the shared source of truth, Copilot adds this import to the related CLAUDE.md:

@AGENTS.md

If CLAUDE.md already contains Claude-specific instructions, Copilot preserves them and adds the import. You do not need to copy shared rules into both files.

System prompts for Quick Chat

Quick Chat system prompts are Markdown files under:

<Copilot folder>/system-prompts/

Create a .md file in that folder. The filename becomes the prompt name, and the file body contains the instructions. Copilot refreshes the prompt list when you create, edit, rename, or delete a file.

In Quick Chat, open Chat Settings and choose a System Prompt. Select None (use built-in prompt) to return to Copilot’s default.

The selected system prompt applies only to Quick Chat. It is not sent to opencode, Claude, or Codex. Agent Chat reads AGENTS.md instead.

Examples and next steps

Start with the AGENTS.md examples, then keep only rules that reflect how you actually work. Long procedures are easier to maintain as Skills.