fix(cli): set `npm_config_user_agent` when running npm packages or tasks (#26639)

Fixes #25342.

Still not sure on the exact user agent to set (should it include
`node`?).

After this PR, here's the state of running some `create-*` packages
(just ones I could think of off the top of my head):

| package                  | prints/runs/suggests deno install | notes |
| ---------------- | ------------- | ------ |
| `create-next-app` | ❌ | falls back to npm, needs a PR
([code](https://github.com/vercel/next.js/blob/c32e2802097c03fd9f95b1dae228d6e0257569c0/packages/create-next-app/helpers/get-pkg-manager.ts#L3))
| `sv create` | ❌ | uses `package-manager-detector`, needs a PR
([code](https://github.com/antfu-collective/package-manager-detector/tree/main))
| `create-qwik` | ✅ | runs `deno install` but suggests `deno start`
which doesn't work (should be `deno task start` or `deno run start`)
| `create-astro` | ✅ | runs `deno install` but suggests `npm run dev`
later in output, probably needs a PR
| `nuxi init` | ❌ | deno not an option in dialog, needs a PR
([code](https://github.com/nuxt/cli/blob/f04e2e894446f597da9d971b7eb03191d5a0da7e/src/commands/init.ts#L96-L102))
| `create-react-app` | ❌ | uses npm
| `ng new` (`@angular/cli`) | ❌ | uses npm
| `create-vite` | ✅ | suggests working deno commands 🎉 
| `create-solid` |  ❌ | suggests npm commands, needs PR

It's possible that fixing `package-manager-detector` or other packages
might make some of these just work, but haven't looked too carefully at
each

3 files changed, 39 insertions, 1 deletions

diff --git a/cli/npm/mod.rs b/cli/npm/mod.rs
index f48f7a740..3971b1a0b 100644
--- a/cli/npm/mod.rs
+++ b/cli/npm/mod.rs
@@ -189,3 +189,15 @@ impl NpmFetchResolver {
     info
   }
 }
+
+pub const NPM_CONFIG_USER_AGENT_ENV_VAR: &str = "npm_config_user_agent";
+
+pub fn get_npm_config_user_agent() -> String {
+  format!(
+    "deno/{} npm/? deno/{} {} {}",
+    env!("CARGO_PKG_VERSION"),
+    env!("CARGO_PKG_VERSION"),
+    std::env::consts::OS,
+    std::env::consts::ARCH
+  )
+}
diff --git a/cli/task_runner.rs b/cli/task_runner.rs
index 418043b23..43840e868 100644
--- a/cli/task_runner.rs
+++ b/cli/task_runner.rs
@@ -155,6 +155,12 @@ fn prepare_env_vars(
       initial_cwd.to_string_lossy().to_string(),
     );
   }
+  if !env_vars.contains_key(crate::npm::NPM_CONFIG_USER_AGENT_ENV_VAR) {
+    env_vars.insert(
+      crate::npm::NPM_CONFIG_USER_AGENT_ENV_VAR.into(),
+      crate::npm::get_npm_config_user_agent(),
+    );
+  }
   if let Some(node_modules_dir) = node_modules_dir {
     prepend_to_path(
       &mut env_vars,
@@ -204,7 +210,7 @@ impl ShellCommand for NpmCommand {
     mut context: ShellCommandContext,
   ) -> LocalBoxFuture<'static, ExecuteResult> {
     if context.args.first().map(|s| s.as_str()) == Some("run")
-      && context.args.len() > 2
+      && context.args.len() >= 2
       // for now, don't run any npm scripts that have a flag because
       // we don't handle stuff like `--workspaces` properly
       && !context.args.iter().any(|s| s.starts_with('-'))
@@ -267,10 +273,12 @@ impl ShellCommand for NodeCommand {
       )
       .execute(context);
     }
+
     args.extend(["run", "-A"].into_iter().map(|s| s.to_string()));
     args.extend(context.args.iter().cloned());
 
     let mut state = context.state;
+
     state.apply_env_var(USE_PKG_JSON_HIDDEN_ENV_VAR_NAME, "1");
     ExecutableCommand::new("deno".to_string(), std::env::current_exe().unwrap())
       .execute(ShellCommandContext {
diff --git a/cli/tools/run/mod.rs b/cli/tools/run/mod.rs
index 152e2650b..bebb3f588 100644
--- a/cli/tools/run/mod.rs
+++ b/cli/tools/run/mod.rs
@@ -30,6 +30,16 @@ To grant permissions, set them before the script argument. For example:
   }
 }
 
+fn set_npm_user_agent() {
+  static ONCE: std::sync::Once = std::sync::Once::new();
+  ONCE.call_once(|| {
+    std::env::set_var(
+      crate::npm::NPM_CONFIG_USER_AGENT_ENV_VAR,
+      crate::npm::get_npm_config_user_agent(),
+    );
+  });
+}
+
 pub async fn run_script(
   mode: WorkerExecutionMode,
   flags: Arc<Flags>,
@@ -58,6 +68,10 @@ pub async fn run_script(
 
   let main_module = cli_options.resolve_main_module()?;
 
+  if main_module.scheme() == "npm" {
+    set_npm_user_agent();
+  }
+
   maybe_npm_install(&factory).await?;
 
   let worker_factory = factory.create_cli_main_worker_factory().await?;
@@ -119,6 +133,10 @@ async fn run_with_watch(
         let cli_options = factory.cli_options()?;
         let main_module = cli_options.resolve_main_module()?;
 
+        if main_module.scheme() == "npm" {
+          set_npm_user_agent();
+        }
+
         maybe_npm_install(&factory).await?;
 
         let _ = watcher_communicator.watch_paths(cli_options.watch_paths());