Use AGENTS.md for project instructions

AGENTS.md is an emerging open standard for providing project-level instructions to AI agents, backed by OpenAI, Google, Cursor, Sourcegraph, and others. Everruns ships it as the default file for its built-in agent instructions capability, which re-reads configured files on every turn.

Enable the capability

curl -X PATCH http://localhost:9300/api/v1/agents/$AGENT_ID \
  -H "Content-Type: application/json" \
  -d '{
    "capabilities": [
      { "ref": "agent_instructions" },
      { "ref": "session_file_system" }
    ]
  }'

session_file_system isn’t required, but pairing it with agent_instructions lets the agent edit AGENTS.md itself.

To also read another instruction file, configure files on the capability:

curl -X PATCH http://localhost:9300/api/v1/agents/$AGENT_ID \
  -H "Content-Type: application/json" \
  -d '{
    "capabilities": [
      {
        "ref": "agent_instructions",
        "config": {
          "files": ["AGENTS.md", "CLAUDE.md"]
        }
      },
      { "ref": "session_file_system" }
    ]
  }'

Write the file

Drop a plain Markdown file at AGENTS.md in the session workspace root for repo-wide rules. Add nested files (for example docs/AGENTS.md) for subdirectory-scoped rules — deeper files override shallower ones on conflict, and sibling subtrees never see each other’s files:

## Project: Acme API

REST API built with Rust + Axum. PostgreSQL for storage.

## Style

- snake_case for variables and functions
- PascalCase for types
- Keep functions under 50 lines

## Build & Test

    cargo build
    cargo test --all-features
    cargo clippy -- -D warnings

## Architecture

- `src/api/` — HTTP handlers
- `src/domain/` — Business logic
- `src/db/` — Database queries

## Commits

Use conventional commits: `feat(scope): description`

There are no required sections. Write whatever a new contributor would need to know.

How it lands in the prompt

Every turn the model sees, top-to-bottom:

System prompt: harness safety instructions, tool guidance, role.
Conversation context: your resolved AGENTS.md hierarchy, broadest scope first.
Conversation history and your message.

Project files never enter the system prompt — system instructions always win on conflict, and your explicit message wins over project files.

Limits and dynamics

Content is capped at 32 KiB (32,768 bytes) per file (excess truncated with a warning), plus a 128 KiB total budget per turn across the hierarchy.
Configured files are resolved from the filesystem root down to the working directory on every turn. Edits during a session apply on the next turn, no restart needed.
If a configured file doesn’t exist, the agent operates normally without it.

Other tools’ instruction files

Everruns reads AGENTS.md by default at every hierarchy level. Add other file names to files when an agent should also resolve CLAUDE.md, .cursorrules, or .github/copilot-instructions.md per level.