From 33602b9114e0afa7c9113a3a8ca9f7d2c589645a Mon Sep 17 00:00:00 2001
From: Miguel de Benito Delgado <m.debenito.d@gmail.com>
Date: Mon, 9 Nov 2026 12:53:18 +0100
Subject: [PATCH] :wrench: Allow skipping renderer build setup via env. var
 (#12882)

Set PENPOT_WASM_PREPARED=1 to speed up repeated builds
---
 render-wasm/README.md                    |  5 +++
 render-wasm/_build_env                   |  5 +++
 render-wasm/build                        |  4 +-
 render-wasm/scripts/cargo-build.test.cjs | 55 ++++++++++++++++++++++++
 4 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/render-wasm/README.md b/render-wasm/README.md
index a6e0c1e25a..736b540bc2 100644
--- a/render-wasm/README.md
+++ b/render-wasm/README.md
@@ -52,6 +52,11 @@ Each target keeps its own `CARGO_TARGET_DIR` (`target/<target>`), so switching
 between them does not invalidate the other's cache. Set `BUILD_MODE=release`
 (or `NODE_ENV=production`) for an optimized build; the default is `debug`.
 
+Set `PENPOT_WASM_PREPARED=1` when the pinned Rust toolchain is selected, its
+Emscripten target is installed, and this package's Node dependencies are
+installed. `./build` and `./test` then skip `rustup` setup and `pnpm install`.
+Benchmark preparation sets this flag for each retained build.
+
 ### Serialize builds in one checkout
 
 All targets in one checkout share one `flock` lock stored at
diff --git a/render-wasm/_build_env b/render-wasm/_build_env
index c8d1fdd1e5..5c804469d0 100644
--- a/render-wasm/_build_env
+++ b/render-wasm/_build_env
@@ -164,6 +164,11 @@ function setup_rust {
 }
 
 function setup {
+    if [ "${PENPOT_WASM_PREPARED:-}" = "1" ]; then
+        echo "Skipping rustup and pnpm setup (PENPOT_WASM_PREPARED=1)" >&2
+        return 0
+    fi
+
     setup_rust
     pnpm install;
 }
diff --git a/render-wasm/build b/render-wasm/build
index c4061068f2..c033654c5f 100755
--- a/render-wasm/build
+++ b/render-wasm/build
@@ -3,7 +3,9 @@
 # Usage: ./build [frontend|export] [extra cargo params...]
 #
 # With no target, builds both. Set BUILD_MODE=release (or NODE_ENV=production)
-# for an optimized build. See `_build_env` for what each target changes.
+# for an optimized build. Set PENPOT_WASM_PREPARED=1 when the pinned toolchain
+# and Node dependencies are prepared to skip their setup. See `_build_env` for
+# what each target changes.
 
 _SCRIPT_DIR=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)
 _RENDER_TARGET=${1:-}
diff --git a/render-wasm/scripts/cargo-build.test.cjs b/render-wasm/scripts/cargo-build.test.cjs
index e757c7cd95..01a080aa42 100644
--- a/render-wasm/scripts/cargo-build.test.cjs
+++ b/render-wasm/scripts/cargo-build.test.cjs
@@ -347,3 +347,58 @@ test("rejects malformed Cargo JSON and removes stale build facts", (t) => {
   assert.match(result.stderr, /ERROR:/);
   assert.equal(fs.existsSync(f.info), false);
 });
+
+function runSetup(t, prepared) {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), "render-wasm-setup-"));
+  t.after(() => fs.rmSync(root, { recursive: true, force: true }));
+  const bin = path.join(root, "bin");
+  const marker = path.join(root, "calls");
+  fs.mkdirSync(bin);
+  for (const name of ["rustup", "pnpm"]) {
+    fs.writeFileSync(
+      path.join(bin, name),
+      `#!/bin/sh\nprintf '%s\\n' "${name} $*" >> "$MARKER"\n`,
+      { mode: 0o755 },
+    );
+  }
+  const env = {
+    ...process.env,
+    MARKER: marker,
+    PATH: `${bin}:${process.env.PATH}`,
+  };
+  if (prepared === undefined) {
+    delete env.PENPOT_WASM_PREPARED;
+  } else {
+    env.PENPOT_WASM_PREPARED = prepared;
+  }
+  const result = spawnSync(
+    "bash",
+    [
+      "--noprofile",
+      "--norc",
+      "-c",
+      'source "$1" frontend; setup',
+      "setup-test",
+      path.resolve(__dirname, "..", "_build_env"),
+    ],
+    {
+      cwd: path.resolve(__dirname, ".."),
+      env,
+      encoding: "utf8",
+    },
+  );
+  assert.equal(result.status, 0, result.stderr);
+  return fs.existsSync(marker) ? fs.readFileSync(marker, "utf8") : "";
+}
+
+test("prepared setup skips rustup and pnpm", (t) => {
+  const normal = runSetup(t);
+  assert.match(normal, /^rustup default /m);
+  assert.match(normal, /^pnpm install$/m);
+
+  const disabled = runSetup(t, "0");
+  assert.match(disabled, /^rustup default /m);
+  assert.match(disabled, /^pnpm install$/m);
+
+  assert.equal(runSetup(t, "1"), "");
+});