maestro/crates/maestro-web/build.rs

//! Build the embedded SPA bundle before the crate compiles.
//!
//! `static_bundle.rs` embeds `web/dist` at compile time via `include_dir!`.
//! This script guarantees that directory holds a freshly built bundle by
//! running `pnpm install --frozen-lockfile && pnpm build` in `web/`. pnpm and
//! node are HARD requirements — a missing toolchain fails the build with an
//! actionable message rather than silently shipping the placeholder.

use std::env;
use std::path::PathBuf;
use std::process::Command;

fn main() {
    let manifest_dir =
        PathBuf::from(env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR set by cargo"));
    let web_dir = manifest_dir.join("../../web");

    // Rebuild the bundle only when a frontend input changes — not on every
    // unrelated Rust recompile.
    for rel in [
        "src",
        "index.html",
        "package.json",
        "pnpm-lock.yaml",
        "vite.config.ts",
    ] {
        println!("cargo:rerun-if-changed={}", web_dir.join(rel).display());
    }

    // Also watch the embedded OUTPUT directory. The input watches above decide
    // whether THIS script re-runs and regenerates `web/dist`; but `include_dir!`
    // in `static_bundle.rs` reads `web/dist`, and cargo has no other declared
    // dependency on those output files. Without this watch, an incremental build
    // could regenerate `web/dist` yet keep the OLD bundle embedded. Tying the
    // crate's recompilation to the regenerated output makes the fresh assets
    // actually get re-embedded.
    let dist_dir = web_dir.join("dist");
    println!("cargo:rerun-if-changed={}", dist_dir.display());

    require_tool("pnpm");
    require_tool("node");

    run(
        Command::new("pnpm")
            .args(["install", "--frozen-lockfile"])
            .current_dir(&web_dir),
        "pnpm install --frozen-lockfile",
    );
    run(
        Command::new("pnpm").arg("build").current_dir(&web_dir),
        "pnpm build",
    );

    // Sanity-check that pnpm build actually produced the bundle `include_dir!`
    // expects. A green build that embeds an empty/placeholder dir is worse than
    // a loud failure here.
    let index_html = dist_dir.join("index.html");
    let produced = std::fs::metadata(&index_html)
        .map(|m| m.is_file() && m.len() > 0)
        .unwrap_or(false);
    if !produced {
        panic!(
            "`pnpm build` did not produce the expected bundle at {} \
             (missing or empty) — check the vite `outDir`.",
            index_html.display()
        );
    }
}

fn require_tool(tool: &str) {
    let ok = Command::new(tool)
        .arg("--version")
        .output()
        .map(|o| o.status.success())
        .unwrap_or(false);
    if !ok {
        panic!(
            "maestro-web requires `{tool}` to build its embedded SPA bundle. \
             Install pnpm + node (https://pnpm.io) or use a prebuilt binary."
        );
    }
}

fn run(cmd: &mut Command, label: &str) {
    let status = cmd
        .status()
        .unwrap_or_else(|e| panic!("failed to spawn `{label}`: {e}"));
    if !status.success() {
        panic!("`{label}` failed with {status}");
    }
}