diff --git a/CLAUDE.md b/CLAUDE.md
index 28b1f2e..685bf32 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -57,6 +57,12 @@ Fall back to Grep/Glob/Read **only** when the graph doesn't cover what you need.
 - A local MariaDB is expected to already be running on `127.0.0.1:3306` with the `file_converter` DB and `convert_user` credentials seeded.
 - Known pre-existing failures unrelated to any fix: `test/cleanup.test.js` ("deletes an expired pending job...") and `test/jobs/jobRepository.test.js` ("finds expired jobs and allows deleting them") — both fail on `main` independent of other changes (looks like a clock/timezone mismatch around `expiresAt` comparisons, not yet root-caused). Don't assume a change caused these; verify against `main` first if they show up again.
 
+## Deployment (o2switch)
+
+- o2switch is shared hosting: no compiler toolchain, no root access. Any dependency with a native/binary component must ship as a precompiled binary — it cannot be built from source on the server.
+- `sharp` (libvips) and `puppeteer` (bundled Chromium) are the current binary dependencies in `package.json`. Install them so npm fetches the prebuilt binary for the target platform/arch rather than triggering a source build.
+- Before adding any new dependency with native bindings, confirm it publishes prebuilt binaries for o2switch's platform/arch — otherwise it will fail to install or run there.
+
 ## Database schema & migrations
 
 - `prisma/schema.prisma` is the source of truth for the `conversion_jobs` schema; `prisma/migrations/` is its version history. `db/schema.sql` no longer exists.