Skip redundant Vercel builds with an Ignored Build Step

AGENTS.md

@@ -25,6 +25,15 @@ Verify a deploy the way Vercel does, not the way CI does:
 `cd packages/<app> && CI=1 pnpm install && ./node_modules/.bin/next build`.
 A green `pnpm install --frozen-lockfile` at the repo root does not exercise this path.
 
+Because `rootDirectory` is set, Vercel reads `vercel.json` from `packages/<app>/`, not
+the repo root. Each package's `vercel.json` wires `scripts/vercel-ignore.sh` as the
+Ignored Build Step: it skips Preview builds of `main`/`testnet` (each is production for
+one project and a wasted Preview on the others) and skips any build where nothing under
+the package or the workspace manifests changed since the last successful deployment.
+Every retained deployment holds a ~23 MB function bundle, and Vercel keeps the last 20
+production + 20 preview deployments per project regardless of retention policy, so
+deployment count is what drives Functions Storage.
+
 ## Maintaining this file
 
 Keep this file for knowledge useful to almost every future agent session in this project.

packages/app-sol/vercel.json

@@ -0,0 +1,4 @@
+{
+  "$schema": "https://openapi.vercel.sh/vercel.json",
+  "ignoreCommand": "bash \"$(git rev-parse --show-toplevel)/scripts/vercel-ignore.sh\" packages/app-sol"
+}

packages/app/vercel.json

@@ -0,0 +1,4 @@
+{
+  "$schema": "https://openapi.vercel.sh/vercel.json",
+  "ignoreCommand": "bash \"$(git rev-parse --show-toplevel)/scripts/vercel-ignore.sh\" packages/app"
+}

scripts/vercel-ignore.sh

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+# Vercel "Ignored Build Step" for one package of this monorepo.
+#
+# Exit 0 = skip the build, exit 1 = build. Anything uncertain builds.
+# Wired from packages/<app>/vercel.json (Vercel reads vercel.json from each
+# project's Root Directory, so the shared logic lives here).
+#
+# Every push used to build all three Vercel projects, and the two deployment
+# branches each produced a Preview on the projects they are not production
+# for. That tripled Functions Storage for nothing.
+set -u
+pkg="${1:?usage: vercel-ignore.sh packages/<app>}"
+cd "$(git rev-parse --show-toplevel)" || exit 1
+
+# 1. `main` is production for ripguard + ripguard-sol, `testnet` for
+#    ripguard-testnet. A push to either also triggers a Preview build on the
+#    other project(s) that nobody looks at.
+if [ "${VERCEL_ENV:-}" = "preview" ]; then
+  case "${VERCEL_GIT_COMMIT_REF:-}" in
+    main|testnet)
+      echo "ignore: preview of deployment branch '$VERCEL_GIT_COMMIT_REF'"
+      exit 0
+      ;;
+  esac
+fi
+
+# 2. Nothing this package depends on changed since the last successful
+#    deployment of this branch. Compare against that SHA, not HEAD^: a
+#    fast-forward of `testnet` lands several commits at once and HEAD^ would
+#    only see the last one. Unknown base (first deploy, shallow clone too
+#    short) -> build.
+base="${VERCEL_GIT_PREVIOUS_SHA:-}"
+if [ -n "$base" ] && git cat-file -e "${base}^{commit}" 2>/dev/null; then
+  if git diff --quiet "$base" HEAD -- \
+      "$pkg" \
+      package.json pnpm-lock.yaml pnpm-workspace.yaml .npmrc .node-version \
+      scripts/vercel-ignore.sh; then
+    echo "ignore: no changes under $pkg or the workspace manifests since ${base:0:7}"
+    exit 0
+  fi
+fi
+
+exit 1