diff --git a/AGENTS.md b/AGENTS.md
index db5dfc7e..02362764 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -28,6 +28,7 @@ The repo uses Mergify stacks for PR management. The `mergify-cli` is installed v
 
 ### Gotchas
 
+- **`@flatbread/proof` requires `CURSOR_RIPGREP_PATH`.** The proof package uses `@cursor/sdk` which expects a bundled ripgrep. In Cloud Agent VMs, set `export CURSOR_RIPGREP_PATH=/usr/bin/rg` to use the system ripgrep (included in the update script).
 - **Native build scripts are approved in `pnpm-workspace.yaml`.** The `onlyBuiltDependencies` list allows esbuild, sharp, @swc/core, etc. to run their postinstall scripts automatically during `pnpm install`.
 - **Vitest packages run in watch mode by default.** Always use `vitest run` (not bare `vitest`) to get a single run and exit.
 - **`flatbread` CLI is not on PATH.** Use `npx flatbread` when running from a shell. The `pnpm play` script from the root handles this automatically.