diff --git a/AGENTS.md b/AGENTS.md
index 900d07f..abc88ae 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -12,4 +12,4 @@ Services / commands (see `package.json` scripts):
 Gotchas:
 - Browser tests need the Playwright chromium browser **and** its system libraries. The update script runs `npx playwright install chromium`, but the OS libraries (`--with-deps`, needs sudo) are part of the base image, not the update script.
 - There is no lint script. `npx tsc --noEmit -p tsconfig.json` reports **pre-existing** errors in `__tests__/*.typespec.tsx` and a few spec files; it is not wired into `build` (which uses `vite-plugin-dts`) or CI. Rely on `npm run build` + `npx vitest run` as the quality gates.
-- `data0` (the reactive core) resolves from the npm-installed package unless a sibling `../data0/src` checkout exists (see `vite.config.ts`); no sibling checkout is present here.
+- `data0` (the reactive core) resolves from the npm-installed package unless a sibling `../data0/src` checkout exists (see the alias logic in `vitest.config.ts`). In this workspace the sibling `../data0` repo **is** checked out, so the test suite compiles `data0` from `../data0/src` — no separate `data0` install is required for axii's tests. The production build (`vite.prod.config.ts`) still externalizes `data0` and pulls its bundled types from the npm-installed copy in `node_modules`.