test: add local windows input gauntlet (#4298)

* test: add local windows input gauntlet

refs #4251

* test: add local windows input gauntlet

Harden elevation and channel identity checks, distinguish known host limitations, and surface incomplete cleanup.

refs #4251

* test(windows): harden input gauntlet execution

refs #4251

* test(windows): make input gauntlet self-contained

refs #4251

* test(windows): bound input gauntlet failure paths

refs #4251

* test(windows): extend input qualification gauntlet

refs #4251

* test(windows): complete input qualification matrix

refs #4251

---------

Co-authored-by: akbash-bot <300245827+akbash-bot@users.noreply.github.com>
Co-authored-by: Jonathan Liebig <jonathan.liebig@gmail.com>

2 files changed, 22 insertions, 1 deletions

diff --git a/src/client/input.rs b/src/client/input.rs
index 848d0156..41850f96 100644
--- a/src/client/input.rs
+++ b/src/client/input.rs
@@ -327,13 +327,18 @@ fn windows_stdin_reader_loop(
     should_quit: &Arc<AtomicBool>,
 ) {
     if !super::windows_vti_input_backend_enabled() {
+        windows_vti::trace_input_transport("reader=crossterm");
         windows_crossterm_reader_loop(event_tx, should_quit);
     } else {
         match windows_vti::console_input_handle() {
             Ok(handle) => {
+                windows_vti::trace_input_transport("reader=windows-console");
                 windows_vti::raw_console_reader_loop(handle, event_tx, should_quit);
             }
-            _ => windows_crossterm_reader_loop(event_tx, should_quit),
+            _ => {
+                windows_vti::trace_input_transport("reader=crossterm-fallback");
+                windows_crossterm_reader_loop(event_tx, should_quit);
+            }
         }
     }
 }
diff --git a/src/client/input/windows_vti.rs b/src/client/input/windows_vti.rs
index 48fe8220..2b92c167 100644
--- a/src/client/input/windows_vti.rs
+++ b/src/client/input/windows_vti.rs
@@ -4,6 +4,8 @@ use std::collections::VecDeque;
 use std::sync::atomic::{AtomicBool, Ordering};
 #[cfg(windows)]
 use std::sync::Arc;
+#[cfg(windows)]
+use std::{fs::OpenOptions, io::Write as _};
 
 #[cfg(windows)]
 use tokio::sync::mpsc;
@@ -57,6 +59,19 @@ pub(super) fn raw_console_reader_loop(
 }
 
 #[cfg(windows)]
+pub(super) fn trace_input_transport(value: &str) {
+    let Some(path) = std::env::var_os("HERDR_WINDOWS_INPUT_TRACE_FILE") else {
+        return;
+    };
+    if let Ok(mut output) = OpenOptions::new().create(true).append(true).open(path) {
+        let _ = writeln!(output, "{value}");
+    }
+}
+
+#[cfg(not(windows))]
+fn trace_input_transport(_value: &str) {}
+
+#[cfg(windows)]
 fn process_platform_input_items(
     items: Vec<PlatformInputItem>,
     pump: &mut WindowsInputPump,
@@ -774,6 +789,7 @@ impl WindowsInputMapper {
                     items.push(PlatformInputItem::Bytes(bytes))
                 }
                 WindowsWin32InputModeItem::Key { bytes, record } => {
+                    trace_input_transport("transport=win32-serialized");
                     let win32_paste_bytes =
                         self.paste_payload_bytes_for_key(record).unwrap_or_default();
                     if let Some(raw_bytes) = self.win32_input_mode_key_record_raw_bytes(record) {