fix: suppress all output in single-prompt mode unless --verbose

In -s mode, redirect both stdout and stderr to /dev/null during model
loading and generation. Only the final response prints to stdout.
--verbose/-v overrides this and shows logs on stderr as before.

Previously only stdout was redirected to stderr, so loading spinners,
cache profiles, GPU info etc. still appeared in the terminal and
polluted unix pipes.

Closes #76

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: scouzi1966

Sources/MacLocalAPI/main.swift

@@ -700,10 +700,24 @@ struct MlxCommand: ParsableCommand {
 
         let group = DispatchGroup()
         var output: Result<String, Error>?
+        // In single-prompt mode, suppress ALL output (stdout + stderr) during model loading
+        // and generation. Only the final response goes to stdout. --verbose overrides this.
         let stdoutFD = dup(STDOUT_FILENO)
-        if stdoutFD == -1 || dup2(STDERR_FILENO, STDOUT_FILENO) == -1 {
-            if stdoutFD != -1 { close(stdoutFD) }
-            throw ValidationError("Failed to redirect single-prompt operational logs to stderr")
+        let stderrFD = dup(STDERR_FILENO)
+        let quietMode = !verbose && !veryVerbose && !vv
+        if stdoutFD == -1 {
+            throw ValidationError("Failed to save stdout for single-prompt mode")
+        }
+        if quietMode {
+            let devNull = open("/dev/null", O_WRONLY)
+            if devNull != -1 {
+                dup2(devNull, STDOUT_FILENO)
+                dup2(devNull, STDERR_FILENO)
+                close(devNull)
+            }
+        } else {
+            // Verbose: redirect stdout to stderr so only the response goes to stdout
+            dup2(STDERR_FILENO, STDOUT_FILENO)
         }
         group.enter()
         Task {
@@ -757,11 +771,14 @@ struct MlxCommand: ParsableCommand {
         }
         group.wait()
         fflush(stdout)
-        if dup2(stdoutFD, STDOUT_FILENO) == -1 {
-            close(stdoutFD)
-            throw ValidationError("Failed to restore stdout after single-prompt execution")
-        }
+        fflush(stderr)
+        // Restore stdout (and stderr if we suppressed it)
+        dup2(stdoutFD, STDOUT_FILENO)
         close(stdoutFD)
+        if stderrFD != -1 {
+            dup2(stderrFD, STDERR_FILENO)
+            close(stderrFD)
+        }
 
         switch output {
         case .success(let text):