feat(linux): add no-output test capture printer

README.md

@@ -58,4 +58,6 @@ Windows creates the virtual queue with the selected destination printer's existi
 
 Linux creates a CUPS queue named `FieldLens-Print` using the selected physical printer's capabilities and device URI. A FieldLens CUPS PDF pre-filter copies the original submitted PDF into `/var/spool/fieldlens-print` before the physical printer driver renders it, then passes the PDF onward unchanged through the normal CUPS filter chain. FieldLens Print watches that spool for capture/decoding while CUPS continues printing normally.
 
+On Linux the same repair action also installs **FieldLens Test Capture**. It uses the same PPD and FieldLens pre-filter, but its rendered output is sent to a local discard sink at `127.0.0.1:9101`. Selecting that queue from a browser exercises original-document capture, spool ingestion, decoding, and the normal printer render/filter chain without sending anything to physical hardware.
+
 USB/shared queues may not expose a RAW/TCP address. In that case the installed-printer selector still supplies the driver for the virtual Windows queue, while the physical destination address must be entered manually.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@fieldlens/print",
-  "version": "0.1.7",
+  "version": "0.1.8",
   "private": true,
   "type": "module",
   "scripts": {

src-tauri/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "fieldlens-print"
-version = "0.1.7"
+version = "0.1.8"
 description = "FieldLens print-stream barcode capture companion"
 authors = ["Arrowstack"]
 edition = "2021"

src-tauri/src/capture.rs

@@ -26,6 +26,8 @@ use crate::{
 
 #[cfg(target_os = "linux")]
 const SYSTEM_CUPS_SPOOL_DIR: &str = "/var/spool/fieldlens-print";
+#[cfg(target_os = "linux")]
+const TEST_CAPTURE_SINK_ADDR: &str = "127.0.0.1:9101";
 
 pub struct CaptureRuntime {
     stop: Arc<AtomicBool>,
@@ -101,6 +103,12 @@ pub fn start(config: AppConfig, state: SharedState, app: AppHandle) -> Result<Ca
                 )
             }));
         }
+
+        let sink = TcpListener::bind(TEST_CAPTURE_SINK_ADDR)
+            .with_context(|| format!("bind test-capture sink {TEST_CAPTURE_SINK_ADDR}"))?;
+        sink.set_nonblocking(true)?;
+        let worker_stop = stop.clone();
+        handles.push(thread::spawn(move || test_capture_sink_loop(sink, worker_stop)));
     }
 
     if handles.is_empty() {
@@ -110,6 +118,37 @@ pub fn start(config: AppConfig, state: SharedState, app: AppHandle) -> Result<Ca
     Ok(CaptureRuntime { stop, handles })
 }
 
+#[cfg(target_os = "linux")]
+fn test_capture_sink_loop(listener: TcpListener, stop: Arc<AtomicBool>) {
+    while !stop.load(Ordering::SeqCst) {
+        match listener.accept() {
+            Ok((stream, _)) => {
+                thread::spawn(move || drain_test_capture_stream(stream));
+            }
+            Err(error) if error.kind() == ErrorKind::WouldBlock => {
+                thread::sleep(Duration::from_millis(80));
+            }
+            Err(_) => {
+                thread::sleep(Duration::from_millis(250));
+            }
+        }
+    }
+}
+
+#[cfg(target_os = "linux")]
+fn drain_test_capture_stream(mut stream: TcpStream) {
+    let _ = stream.set_read_timeout(Some(Duration::from_secs(2)));
+    let mut buffer = [0u8; 32 * 1024];
+    loop {
+        match stream.read(&mut buffer) {
+            Ok(0) => break,
+            Ok(_) => {}
+            Err(error) if matches!(error.kind(), ErrorKind::WouldBlock | ErrorKind::TimedOut) => break,
+            Err(_) => break,
+        }
+    }
+}
+
 fn raw_proxy_loop(
     listener: TcpListener,
     config: AppConfig,

src-tauri/src/printers.rs

@@ -11,6 +11,12 @@ use serde::{Deserialize, Serialize};
 use serde_json::Value;
 
 pub const VIRTUAL_PRINTER_NAME: &str = "FieldLens Print";
+#[cfg(target_os = "linux")]
+pub const TEST_VIRTUAL_PRINTER_NAME: &str = "FieldLens Test Capture";
+#[cfg(target_os = "linux")]
+const TEST_VIRTUAL_PRINTER_QUEUE: &str = "FieldLens-Test-Capture";
+#[cfg(target_os = "linux")]
+const TEST_CAPTURE_DEVICE_URI: &str = "socket://127.0.0.1:9101";
 const WINDOWS_PORT_NAME: &str = "FieldLensPrint-9100";
 
 #[cfg(target_os = "linux")]
@@ -108,8 +114,20 @@ pub struct VirtualPrinterStatus {
 }
 
 fn is_virtual_printer_name(name: &str) -> bool {
-    name.eq_ignore_ascii_case(VIRTUAL_PRINTER_NAME)
+    if name.eq_ignore_ascii_case(VIRTUAL_PRINTER_NAME)
         || name.eq_ignore_ascii_case("FieldLens-Print")
+    {
+        return true;
+    }
+
+    #[cfg(target_os = "linux")]
+    {
+        return name.eq_ignore_ascii_case(TEST_VIRTUAL_PRINTER_NAME)
+            || name.eq_ignore_ascii_case(TEST_VIRTUAL_PRINTER_QUEUE);
+    }
+
+    #[cfg(not(target_os = "linux"))]
+    false
 }
 
 pub fn list_system_printers() -> Result<Vec<SystemPrinter>> {
@@ -389,7 +407,7 @@ fn linux_virtual_printer_status() -> Result<VirtualPrinterStatus> {
     let printers = list_linux_printers()?;
     let installed = printers
         .iter()
-        .any(|printer| is_virtual_printer_name(&printer.name));
+        .any(|printer| printer.name.eq_ignore_ascii_case("FieldLens-Print"));
 
     if !installed {
         return Ok(VirtualPrinterStatus {
@@ -420,7 +438,7 @@ fn linux_virtual_printer_status() -> Result<VirtualPrinterStatus> {
         installed: ready,
         name: VIRTUAL_PRINTER_NAME.into(),
         detail: if ready {
-            "Ready. Original PDF jobs are captured before the physical printer driver renders them.".into()
+            "Ready. FieldLens Print sends to the physical printer; FieldLens Test Capture runs the same capture/render path but discards the rendered output.".into()
         } else {
             "FieldLens Print exists but CUPS has it disabled or not accepting jobs. Click Create / repair FieldLens Print.".into()
         },
@@ -556,7 +574,8 @@ fn install_linux_virtual_printer(target_printer: &str) -> Result<()> {
 
     install_linux_capture_filter()?;
     let ppd_path = build_fieldlens_ppd(target_printer)?;
-    let args = vec![
+
+    let production_args = vec![
         "-p".to_string(),
         "FieldLens-Print".to_string(),
         "-E".to_string(),
@@ -567,34 +586,57 @@ fn install_linux_virtual_printer(target_printer: &str) -> Result<()> {
         "-D".to_string(),
         VIRTUAL_PRINTER_NAME.to_string(),
     ];
+    run_linux_admin(
+        "lpadmin",
+        &production_args,
+        "configure FieldLens production CUPS printer",
+    )?;
 
-    let setup_result = run_linux_admin("lpadmin", &args, "configure FieldLens CUPS printer");
+    let test_args = vec![
+        "-p".to_string(),
+        TEST_VIRTUAL_PRINTER_QUEUE.to_string(),
+        "-E".to_string(),
+        "-v".to_string(),
+        TEST_CAPTURE_DEVICE_URI.to_string(),
+        "-P".to_string(),
+        ppd_path.to_string_lossy().into_owned(),
+        "-D".to_string(),
+        TEST_VIRTUAL_PRINTER_NAME.to_string(),
+    ];
+    let test_result = run_linux_admin(
+        "lpadmin",
+        &test_args,
+        "configure FieldLens test-capture CUPS printer",
+    );
     let _ = fs::remove_file(&ppd_path);
-    setup_result?;
+    test_result?;
 
-    // lpadmin -E normally enables the queue, but explicitly repair both CUPS
-    // state flags because Chromium disables Print when either is stale.
-    run_cups_repair_command("cupsenable", &["FieldLens-Print"])?;
-    run_cups_repair_command("cupsaccept", &["FieldLens-Print"])?;
+    // Explicitly repair both CUPS state flags because Chromium disables Print
+    // when either is stale.
+    for queue in ["FieldLens-Print", TEST_VIRTUAL_PRINTER_QUEUE] {
+        run_cups_repair_command("cupsenable", &[queue])?;
+        run_cups_repair_command("cupsaccept", &[queue])?;
+    }
     Ok(())
 }
 
 #[cfg(target_os = "linux")]
 fn remove_linux_virtual_printer() -> Result<()> {
-    let direct = Command::new("lpadmin")
-        .args(["-x", "FieldLens-Print"])
-        .status();
+    for queue in ["FieldLens-Print", TEST_VIRTUAL_PRINTER_QUEUE] {
+        let args = vec!["-x".to_string(), queue.to_string()];
+        let direct = Command::new("lpadmin").args(&args).status();
         if matches!(direct, Ok(status) if status.success()) {
-        return Ok(());
+            continue;
         }
 
         let status = Command::new("pkexec")
-        .args(["lpadmin", "-x", "FieldLens-Print"])
+            .arg("lpadmin")
+            .args(&args)
             .status()
             .context("run elevated CUPS printer removal")?;
-
         if !status.success() {
-        return Err(anyhow!("removing FieldLens Print from CUPS failed"));
+            return Err(anyhow!("removing FieldLens CUPS printer '{queue}' failed"));
+        }
     }
     Ok(())
 }

src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "FieldLens Print",
-  "version": "0.1.7",
+  "version": "0.1.8",
   "identifier": "dev.arrowstack.fieldlens.print",
   "build": {
     "beforeDevCommand": "npm run dev",

src/main.ts

@@ -85,7 +85,7 @@ let config: AppConfig
 let jobs: Job[] = []
 let status: Status
 let loginTimer: number | undefined
-let currentVersion = '0.1.7'
+let currentVersion = '0.1.8'
 let bundleType: BundleType | null = null
 let availableUpdate: Update | null = null
 let availableManualUpdate: ManualUpdate | null = null
@@ -138,7 +138,7 @@ app.innerHTML = `
             <div>
               <strong>System printer</strong>
               <span id="virtual-printer-state" class="muted">Checking whether FieldLens Print is installed…</span>
-              <small class="muted">Creates a printer named <b>FieldLens Print</b> in the normal OS print dialog and routes it into the local RAW listener.</small>
+              <small class="muted">Linux creates <b>FieldLens Print</b> for real printing and <b>FieldLens Test Capture</b> for a full capture/render test with no physical output.</small>
             </div>
             <div class="actions printer-actions">
               <button class="btn" id="refresh-printers">Refresh printers</button>