docs: describe Cloud Agent local development constraints

Record the Node 24 PATH override, host Postgres and Redis startup, and the capped dev server so later agents do not boot the uncapped Next.js heap on this VM.

Author: cursoragent

CLAUDE.md

@@ -149,3 +149,11 @@ bun run apps/sim/scripts/check-block-registry.ts origin/staging
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 Author a `packages/db` schema change or migration with the `db-migrate` skill. CI also runs `bun run check:migrations` (it diffs against a base ref, `origin/staging` by default, so it is not in `check:audits`; run it when you touch `packages/db/migrations/**`), checks that `drizzle-kit generate` in `packages/db` produces no new migration, and runs a non-blocking `bun audit`. When an audit fails, its output and its script's header say what the rule protects; fix the code, never the check. Ratchet baselines (`scripts/*baseline.json`) only shrink: regenerate one with `--update` after removing violations; it refuses to admit new debt. The one exception is `check:tool-registry-boundary`, whose module-count baseline is re-recorded with `--update-baseline` when growth is deliberate (see its skill).
+
+## Cursor Cloud specific instructions
+
+The Cloud Agent VM already has Bun 1.4.2 on `/usr/local/bin` and Node.js 24 at `/usr/local/lib/nodejs/bin`. Prepend that Node directory to `PATH` before any `node` or native rebuild. The default `PATH` finds `/exec-daemon/node` first, and that binary is Node 22. App engines and `isolated-vm` need Node 24.
+
+Postgres 17 (pgvector, `btree_gin`, `pg_trgm`) listens on `127.0.0.1:5432`. Redis listens on `127.0.0.1:6379`. systemd is not available in this VM, so start them with `sudo pg_ctlcluster 17 main start` and `sudo redis-server /etc/redis/redis.conf --daemonize yes --supervised no`. The local database URL is `postgresql://postgres:postgres@127.0.0.1:5432/simstudio`.
+
+`apps/sim/.env`, `apps/realtime/.env`, and `packages/db/.env` are generated at install and gitignored. Keep the shared secrets identical across the app and realtime files. Run the product with `bun run dev:full:capped` (Next.js on port 3000, Socket.IO on port 3002). Uncapped `bun run dev:full` lets the Next.js heap grow to about 8GB and the 16GB VM OOM-kills the dev server. Email verification stays off when no mail provider is configured, so local signup reaches `/home` directly. Docker is not required for this loop.