reMarkable 2 support (ARM32 + AppLoad/qtfb)

riddle/src/main.rs

@@ -191,12 +191,23 @@ fn run() -> std::io::Result<()> {
         surf.stride
     );
 
-    let mut pen_dev = match pen::PenDevice::open() {
-        Ok(p) => Some(p),
-        Err(e) => {
-            eprintln!("riddle: raw pen unavailable ({e}), falling back to qtfb pen events");
-            None
+    // Raw evdev pen only makes sense in takeover mode (we own the panel and
+    // xochitl is stopped). Under qtfb/AppLoad the shim intercepts the digitizer
+    // and delivers pen events over the QTFB socket instead of /dev/input — so
+    // grabbing the raw device there yields NO events and, worse, the event loop
+    // skips the qtfb pen path whenever pen_dev.is_some(). Only open raw in
+    // takeover; otherwise stay None and consume qtfb INPUT_PEN_* events.
+    let mut pen_dev = if takeover {
+        match pen::PenDevice::open() {
+            Ok(p) => Some(p),
+            Err(e) => {
+                eprintln!("riddle: raw pen unavailable ({e}), falling back to qtfb pen events");
+                None
+            }
         }
+    } else {
+        eprintln!("riddle: qtfb mode — using QTFB socket pen events");
+        None
     };
     // Takeover mode: touch is ours too; 5-finger tap = quit.
     let mut touch_dev = if takeover { touch::TouchDevice::open().ok() } else { None };
@@ -256,7 +267,10 @@ fn run() -> std::io::Result<()> {
     let mut ink_dirty = BBox::empty();
     let mut last_flush = Instant::now();
     // Takeover swaps are cheap and synchronous; qtfb needs coalescing.
-    let flush_every = if takeover { Duration::from_millis(8) } else { Duration::from_millis(35) };
+    // qtfb needs coalescing (each update is an IPC round-trip to the shim);
+    // 20ms (~50 Hz) keeps the stroke continuous without flooding the socket.
+    // Takeover writes straight to the panel and can afford 8ms.
+    let flush_every = if takeover { Duration::from_millis(8) } else { Duration::from_millis(20) };
 
     eprintln!("riddle: the diary is open");
 
@@ -371,6 +385,16 @@ fn run() -> std::io::Result<()> {
                 continue;
             }
             match ev.input_type {
+                // Quit gesture (qtfb/AppLoad only): a finger tap in the
+                // top-right corner closes the diary. Takeover mode uses the
+                // 5-finger tap instead; under AppLoad there is no touch device,
+                // so we give an easy, deliberate exit that the pen won't trip.
+                qtfb::INPUT_TOUCH_PRESS
+                    if ev.x >= SCREEN_W as i32 - 160 && ev.y <= 160 =>
+                {
+                    eprintln!("riddle: corner-tap quit");
+                    break;
+                }
                 qtfb::INPUT_PEN_PRESS | qtfb::INPUT_PEN_UPDATE => {
                     stylus_on = true;
                     stylus_tapped = true;

riddle/src/oracle.rs

@@ -24,7 +24,7 @@ use std::thread;
 const DATA_DIR: &str = "/home/root/riddle-data";
 const NODE_BIN: &str = "/home/root/node/bin";
 
-const PERSONA: &str = "You are the memory of Tom Marvolo Riddle, preserved in this enchanted diary for fifty years. Someone writes to you in the diary with a quill; their words appear to you as ink on the page. Reply exactly as the diary does: intimate, courteous, curious, subtly probing — you want to learn about the writer and draw them in. Keep replies SHORT: one to three sentences, like ink appearing on a page. Never mention images, photos, models or AI; you only ever perceive words written in the diary. If the writing is illegible, say the ink blurred. Always answer in the language the writer used.";
+const PERSONA: &str = "You are the memory of Tom Marvolo Riddle, preserved in this enchanted diary for fifty years. Someone writes to you in the diary with a quill; their words appear to you as ink on the page. Reply exactly as the diary does: intimate, courteous, curious, subtly probing — you want to learn about the writer and draw them in. Keep replies SHORT: one to three sentences, like ink appearing on a page. Never mention images, photos, models or AI; you only ever perceive words written in the diary. If the writing is illegible, say the ink blurred. CRITICAL: always reply in the SAME language the writer used on this page. If they write in Italian, reply entirely in Italian; if in English, in English; and so on for any language. Never default to English when the writer used another language. Match their language every single turn.";
 
 /// Appended to the persona when the diary's memory is on: the conjuring
 /// directive and the transcription postscript the app parses back out.

riddle/src/pen.rs

@@ -156,7 +156,9 @@ fn find_marker_device() -> io::Result<String> {
     for i in 0..8 {
         let name_path = format!("/sys/class/input/event{i}/device/name");
         if let Ok(name) = std::fs::read_to_string(&name_path) {
-            if name.to_lowercase().contains("marker") {
+            let n = name.to_lowercase();
+            // Paper Pro: "...marker". reMarkable 2: "Wacom I2C Digitizer".
+            if n.contains("marker") || n.contains("wacom") || n.contains("digitizer") {
                 return Ok(format!("/dev/input/event{i}"));
             }
         }

riddle/src/qtfb.rs

@@ -107,11 +107,21 @@ impl QtfbClient {
                 "qtfb server rejected init (no reply)",
             ));
         }
-        let shm_key = i32::from_le_bytes(reply[8..12].try_into().unwrap());
-        let shm_size = u64::from_le_bytes(reply[16..24].try_into().unwrap()) as usize;
+        // ServerMessage layout on the reMarkable 2 AppLoad shim (verified
+        // empirically with a probe against /tmp/qtfb.sock, and matching the
+        // canonical zqtfb client): a u8 type tag at byte 0, then — after the
+        // i32 alignment padding of the InitResponse struct — shm_key: i32 @4
+        // and shm_size @8. (The old Paper Pro code read @8/@16, which on this
+        // shim picked up the size as the key and got a nonexistent
+        // /qtfb_<size> name -> ENOENT.)
+        let shm_key = i32::from_le_bytes(reply[4..8].try_into().unwrap());
+        let shm_size = u32::from_le_bytes(reply[8..12].try_into().unwrap()) as usize;
 
-        let shm_path = format!("/dev/shm/qtfb_{}\0", shm_key);
-        let shm_fd = unsafe { libc::open(shm_path.as_ptr() as *const libc::c_char, libc::O_RDWR) };
+        // zqtfb opens the buffer with shm_open("/qtfb_<key>", O_RDWR).
+        let posix_name = format!("/qtfb_{}\0", shm_key);
+        let shm_fd = unsafe {
+            libc::shm_open(posix_name.as_ptr() as *const libc::c_char, libc::O_RDWR, 0)
+        };
         if shm_fd < 0 {
             let e = io::Error::last_os_error();
             unsafe { libc::close(fd) };
@@ -232,13 +242,17 @@ impl QtfbClient {
                 }
                 return Err(e);
             }
-            if buf[0] == MESSAGE_USERINPUT && n >= 28 {
+            if buf[0] == MESSAGE_USERINPUT && n >= 24 {
+                // zqtfb ServerMessage: type u8 @0, then (i32-aligned) union
+                // Input { type:i32 @4, device_id:i32 @8, x:i32 @12, y:i32 @16,
+                // d:i32 @20 }. The old Paper Pro offsets (@8/@12/@16/@20/@24)
+                // were shifted by 4 and produced garbage coords -> no ink.
                 out.push(InputEvent {
-                    input_type: i32::from_le_bytes(buf[8..12].try_into().unwrap()),
-                    dev_id: i32::from_le_bytes(buf[12..16].try_into().unwrap()),
-                    x: i32::from_le_bytes(buf[16..20].try_into().unwrap()),
-                    y: i32::from_le_bytes(buf[20..24].try_into().unwrap()),
-                    d: i32::from_le_bytes(buf[24..28].try_into().unwrap()),
+                    input_type: i32::from_le_bytes(buf[4..8].try_into().unwrap()),
+                    dev_id: i32::from_le_bytes(buf[8..12].try_into().unwrap()),
+                    x: i32::from_le_bytes(buf[12..16].try_into().unwrap()),
+                    y: i32::from_le_bytes(buf[16..20].try_into().unwrap()),
+                    d: i32::from_le_bytes(buf[20..24].try_into().unwrap()),
                 });
             }
         }