fix(cli): pick the argument-error format the way clap picks -o

The raw scan took the first -o and missed clustered short flags, so
`idx -o table config -o json get` and `idx -qojson config get` printed
plain-text errors. Resolve -o with clap itself, ignoring the error being
reported (Pullfrog review on #56).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01V3syn2fN2LNo5pvTSqc6eh

crates/idx-cli/src/main.rs

@@ -112,27 +112,19 @@ fn argument_error(err: clap::Error) -> IdxError {
 }
 
 /// The output format the raw arguments ask for, when they did not parse:
-/// `-o`/`--output` (any spelling), then `IDX_OUTPUT`, then auto.
+/// `-o`/`--output` as clap reads it (clustered short flags, the last one
+/// at any subcommand level), then `IDX_OUTPUT`, then auto.
 fn requested_output_from_args() -> OutputFormat {
-    // args_os: an argument that is not UTF-8 (itself the error being
+    use clap::CommandFactory;
-    // reported) must not panic here.
+    // ignore_errors keeps every argument clap could read; args_os, because an
-    let args: Vec<String> = std::env::args_os()
+    // argument that is not UTF-8 (itself the error being reported) must not
-        .skip(1)
+    // panic here.
-        .map(|arg| arg.to_string_lossy().into_owned())
+    let flag = Cli::command()
-        .collect();
+        .ignore_errors(true)
-    let flag = args.iter().enumerate().find_map(|(i, arg)| {
+        .try_get_matches_from(std::env::args_os())
-        if arg == "-o" || arg == "--output" {
+        .ok()
-            args.get(i + 1).cloned()
+        .and_then(|matches| matches.get_one::<OutputSetting>("output").copied());
-        } else if let Some(value) = arg.strip_prefix("--output=") {
-            Some(value.to_string())
-        } else if arg.starts_with("-o") && arg.len() > 2 {
-            Some(arg[2..].trim_start_matches('=').to_string())
-        } else {
-            None
-        }
-    });
     let setting = flag
-        .and_then(|value| OutputSetting::parse(&value))
         .or_else(|| {
             std::env::var("IDX_OUTPUT")
                 .ok()

crates/idx-cli/tests/cli.rs

@@ -2117,6 +2117,29 @@ fn offline_and_no_cache_flags_are_rejected() {
     );
 }
 
+#[test]
+fn argument_errors_follow_the_output_format_clap_resolves() {
+    // The last -o wins at any subcommand level, and -o may sit in a cluster:
+    // argument errors pick the same format a successful command would.
+    for args in [
+        &["-o", "table", "config", "-o", "json", "get"][..],
+        &["-qojson", "config", "get"][..],
+    ] {
+        run_error_json(test_bin("argument-error-json").args(args), "INVALIDINPUT");
+    }
+    for args in [
+        &["-o", "json", "config", "-o", "table", "get"][..],
+        &["-qotable", "config", "get"][..],
+    ] {
+        test_bin("argument-error-table")
+            .args(args)
+            .assert()
+            .failure()
+            .stdout("")
+            .stderr(predicate::str::starts_with("error: "));
+    }
+}
+
 #[test]
 fn msn_screen_rejects_invalid_filter() {
     test_bin("msn-screen-invalid-filter")