Project Context Files

rho scans for project-level instruction files and injects them into the system prompt. This lets projects tell the agent how to work with their codebase — without modifying rho itself.

Scan list

rho looks for the following files in the project root (sandbox root), in priority order:

The scan list can be overridden in config:

[context]
scan_list = ["AGENTS.md", "CLAUDE.md"]

Trust model

Project context files are a prompt injection vector — anyone with write access to the repository can modify them. rho addresses this with a trust store:

1. First encounter: rho prompts the user to review the file contents and confirm trust.
2. Trust stored: the SHA-256 hash of the accepted file is stored in ~/.rho/trusted_projects.toml.
3. Subsequent loads: if the hash matches, the file is loaded silently. If it changed since the last trust decision, rho prompts the user again.

This ensures:

• A malicious PR that silently modifies AGENTS.md will trigger a re-review prompt.
• Legitimate updates (new project instructions) are confirmed once, then loaded automatically.
• The user can always audit what's in trusted_projects.toml.

Prompt composition

Context files are appended to the system prompt after the base prompt, in scan-list order. The final system prompt structure is:

[base prompt]           ← prompts/base.md (or compact prompt)
[project context files] ← AGENTS.md, CLAUDE.md, etc.
[environment block]     ← working directory, shell info
[Rust tooling block]    ← cargo check/clippy/test guidance

In practice

The file you're reading right now (AGENTS.md) is a context file. It tells rho about the project layout, conventions, testing approach, and commit format. Without it, rho would still work — but it wouldn't know about cargo xtask ci, the conventional commit format, or the forbid(unsafe_code) lint.