fix(napi): keep vite_task_client_napi type-defs out of consumer bindings

This crate is embedded as a cdylib artifact dependency of `vite_task`.
napi-derive's `type-def` feature is force-enabled by feature unification with
consumers that need it, so it would otherwise write this crate's `#[napi]`
items (RunnerClient/load) into the consumer's shared NAPI_TYPE_DEF_TMP_FOLDER,
which @napi-rs/cli sweeps into the consumer's generated binding as dead exports
(the symbols live in the separately-loaded addon, not the consumer's .node).

build.rs redirects this crate's type-def emission to an isolated sink and prunes
any stale entry a pre-redirect build left in the consumer's (reused) folder. The
public JS surface is the hand-written @voidzero-dev/vite-task-client package, so
these generated defs are never needed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: wan9chi

crates/vite_task_client_napi/build.rs

@@ -1,5 +1,42 @@
+#![expect(
+    clippy::disallowed_types,
+    reason = "build.rs interfaces with std::path and cargo's env-var API"
+)]
+
 extern crate napi_build;
 
+use std::{env, fs, path::PathBuf};
+
 fn main() {
     napi_build::setup();
+
+    // Keep this crate's napi-derive type-defs out of any consumer's generated
+    // binding.
+    //
+    // `vite_task_client_napi` is embedded as a cdylib *artifact* dependency of
+    // `vite_task`. napi-derive's `type-def` feature is force-enabled by feature
+    // unification with consumers that need it (e.g. vite-plus's CLI binding), so
+    // disabling the feature here has no effect. By default napi-derive then
+    // writes this crate's `#[napi]` items (`RunnerClient`/`load`) into the
+    // consumer's shared `NAPI_TYPE_DEF_TMP_FOLDER`, which `@napi-rs/cli` sweeps
+    // into the consumer's `index.cjs`/`index.d.cts` as dead exports (the symbols
+    // live in the separately-loaded addon, not the consumer's `.node`). The
+    // public JS surface is the hand-written `@voidzero-dev/vite-task-client`
+    // package, so these generated defs are never needed.
+    //
+    // `@napi-rs/cli` reuses that folder across builds without pruning it, so
+    // first remove any entry a pre-redirect build left there, then redirect this
+    // crate's emission to an isolated, clearly-named sink. The override applies
+    // only to this crate's rustc invocation, where the napi-derive proc-macro
+    // reads the env at expansion time, so consumers' own type-defs are
+    // unaffected.
+    println!("cargo::rerun-if-env-changed=NAPI_TYPE_DEF_TMP_FOLDER");
+    let pkg = env::var("CARGO_PKG_NAME").expect("CARGO_PKG_NAME not set");
+    if let Ok(consumer_folder) = env::var("NAPI_TYPE_DEF_TMP_FOLDER") {
+        let _ = fs::remove_file(PathBuf::from(consumer_folder).join(&pkg));
+    }
+    let sink = PathBuf::from(env::var("OUT_DIR").expect("OUT_DIR not set"))
+        .join("discarded-napi-type-defs");
+    fs::create_dir_all(&sink).expect("failed to create napi type-def sink dir");
+    println!("cargo::rustc-env=NAPI_TYPE_DEF_TMP_FOLDER={}", sink.display());
 }