feat: add new dependencies for testing and enhance error reporting in package command

Author: TrueNine

Cargo.lock

@@ -69,6 +69,10 @@ tauri-plugin-updater = "2"
 # JSON5 (for GUI log parsing compat)
 json5 = "1.3.1"
 
+# Tests
+assert_cmd = "2.1.1"
+predicates = "3.1.3"
+
 [profile.release]
 strip = true
 lto = true

Cargo.toml

@@ -16,3 +16,7 @@ path = "src/main.rs"
 tnmsd = { workspace = true }
 clap = { workspace = true }
 serde_json = { workspace = true }
+
+[dev-dependencies]
+assert_cmd = { workspace = true }
+predicates = { workspace = true }

mcp/Cargo.toml

@@ -1,4 +1,5 @@
 use std::fs;
+use std::io::{self, Write};
 use std::path::{Path, PathBuf};
 use std::process::ExitCode;
 
@@ -39,19 +40,22 @@ const PACKAGE_TARGETS: &[PackageTarget] = &[
 ];
 
 pub fn execute(args: &AssembleNpmArgs) -> ExitCode {
+  let mut stderr = io::stderr().lock();
+  execute_with_stderr(args, &mut stderr)
+}
+
+fn execute_with_stderr(args: &AssembleNpmArgs, stderr: &mut impl Write) -> ExitCode {
   match assemble_packages(args) {
     Ok(copied) => {
-      // Use stderr: this binary's primary mode is the MCP stdio server,
-      // and stdout is reserved for JSON-RPC framing. Routing all
-      // assemble-npm chatter to stderr keeps stdout protocol-safe even
-      // if the subcommand is ever invoked from a wrapped context.
+      // Fixes #225: stdout is reserved for MCP JSON-RPC framing, so even
+      // package-hydration status output must stay off stdout.
       for path in copied {
-        eprintln!("Hydrated {}", path.display());
+        let _ = writeln!(stderr, "Hydrated {}", path.display());
       }
       ExitCode::SUCCESS
     }
     Err(error) => {
-      eprintln!("Error: {error}");
+      let _ = writeln!(stderr, "Error: {error}");
       ExitCode::FAILURE
     }
   }
@@ -187,3 +191,26 @@ fn set_executable_permissions(path: &Path) -> Result<(), String> {
 fn set_executable_permissions(_path: &Path) -> Result<(), String> {
   Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[test]
+  fn assemble_npm_reports_errors_to_stderr_only() {
+    let mut stderr = Vec::new();
+    let args = AssembleNpmArgs {
+      artifacts_dir: None,
+      profile: "missing-profile-for-issue-225".to_string(),
+    };
+
+    let exit = execute_with_stderr(&args, &mut stderr);
+
+    assert_eq!(exit, ExitCode::FAILURE);
+    let stderr = String::from_utf8(stderr).expect("stderr output should be UTF-8");
+    assert!(
+      stderr.contains("Error: Missing local host binary"),
+      "expected assemble-npm errors to be written to stderr, got: {stderr}"
+    );
+  }
+}

mcp/src/commands/package.rs

@@ -391,23 +391,17 @@ fn main() -> ExitCode {
   );
 
   let cli = Cli::parse();
-  let logger = tnmsd::infra::logger::create_logger("tnmsm", None);
 
   match resolve_command(&cli) {
     ResolvedCommand::Serve => {
-      let _span = logger.span("server.serve").enter();
-      logger.info(
-        "MCP server started",
-        Some(json!({
-          "serverName": SERVER_NAME,
-          "protocolVersion": PROTOCOL_VERSION,
-        })),
-      );
+      // Fixes #225: in stdio mode stdout is the MCP JSON-RPC transport, so
+      // server startup must not emit logger messages or spans there.
       run_stdio_server();
       ExitCode::SUCCESS
     }
     ResolvedCommand::AssembleNpm(args) => {
-      let _span = logger.span("command.assemble_npm").enter();
+      // Fixes #225: keep hidden packaging output off stdout as well; the
+      // package command writes human-readable status to stderr internally.
       commands::package::execute(&args)
     }
   }

mcp/src/main.rs

@@ -0,0 +1,16 @@
+use assert_cmd::Command;
+
+#[test]
+fn assemble_npm_does_not_write_human_output_to_stdout() {
+  // Fixes #225: stdout belongs to MCP JSON-RPC framing, so human-readable
+  // package command failures must stay on stderr.
+  Command::cargo_bin("tnmsm")
+    .expect("tnmsm binary should be available")
+    .args(["assemble-npm", "--profile", "missing-profile-for-issue-225"])
+    .assert()
+    .failure()
+    .stdout("")
+    .stderr(predicates::str::contains(
+      "Error: Missing local host binary",
+    ));
+}