File drop: mount and autostart .d64 images, mount the other image types

CLAUDE.md

@@ -146,6 +146,27 @@ both on every push and PR.
   programs that never return to the prompt). `run_crt` runs the posted cart
   on purpose, so no parking there. `$CC` reads 0x00 at the READY prompt,
   verified.
+- **Disk images (verified on 1.1.0)**: the DMA socket's `RUN_IMG` (0xFF0B,
+  header `0B FF <len16 LE> <len bits 16-23>` then the image) saves the
+  payload as `/temp/tcpimage.d64`, mounts it on drive A and runs
+  `C64_DRIVE_LOAD` with `RUNCODE_MOUNT_LOAD_RUN`: the firmware resets,
+  types `LOAD"*",8,1` and `RUN` itself (screen RAM confirms). Payload cap
+  is `SOCKET_BUFFER_SIZE` = 200000 bytes (every .d64 variant fits; the
+  firmware silently truncates beyond). Always saved as .d64, so only that
+  type autostarts; `POST /v1/drives/a:mount?type=<d64|g64|d71|g71|d81>`
+  with the image as the body mounts the others (lands as `/Temp/temp0000`).
+  `MOUNT_IMG` (0xFF0A) is the socket twin of that mount. With a network
+  password the socket needs `AUTHENTICATE` (0xFF1F, password as payload,
+  one-byte reply 1/0, 1 s throttle on failure) before any other command,
+  or the firmware drops the connection; `dma_connect` does it for both
+  the keyboard channel and image runs. `C64U_DMA_PORT` redirects port 64
+  for tests (fakeultimate.py logs `DMA cmd=FFxx len=N`). **One DMA client
+  at a time**: `dmaThread` accepts a connection and serves it until it
+  closes before accepting the next, so the viewer's open keyboard
+  connection stalls an image transfer behind it (seen as a 30 s stall then
+  EAGAIN; a bare socket takes 0.1 s for a .d64 whether or not the stream
+  runs or the C64 is loading). Hence `run_file_async` closes the keyboard
+  socket and `keyb_try_connect` stays off port 64 while `g_run_busy`.
 
 ## Dev workflow (no hardware needed)
 
@@ -186,6 +207,25 @@ control + password, drag-and-drop run, help overlay) shipped in v0.2.0.
    comes from SDL3's HIDAPI drivers + mapping db (worst case Steam udev
    rules or SDL_GAMECONTROLLERCONFIG); code against generic SDL_Gamepad.
 
+3. **Persistent drop storage** (agreed 2026-09-02, not started): the drop
+   path keeps the firmware's temp area (RAM disk, gone at power-off) as
+   the fast default; a `--store <folder>` flag and/or a modifier held
+   during the drop switch to FTP-upload-then-mount-by-path. FTP is the
+   only upload route: the REST files API has no upload on any firmware
+   (verified: `curl -T` to `ftp://<ult>/Temp/` works, `files/<path>:info`
+   then sees the file, the FTP service is on by default on 1.1.0). Sequence:
+   check `files/<path>:info` (refuse to overwrite), `curl -T` the file,
+   `PUT drives/a:mount?image=<path>&mode=readwrite`, then for autostart
+   `machine:reset` + readiness gate + `LOAD"*",8,1` / `RUN` over the
+   keyboard channel (no firmware autostart for a path mount). Michal's
+   preference: upload to `/Temp` and move the file from the Ultimate menu
+   himself. Open questions: whether SDL reports a modifier held during a
+   drag on Wayland (`SDL_GetKeyboardState` at drop time; if not, flag
+   only), and the static release build needs curl rebuilt with FTP
+   (`--disable-ftp` today in release.yml). Follow-up on top of it: in the
+   F9 view, upload into the folder the menu currently shows (path line
+   parse; truncated long paths need a fallback).
+
 Dormant follow-up: when official firmware ships `machine:input`, re-verify
 the matrix-keyboard mapping against real hardware and activate the gamepad
 path alongside it.

README.md

@@ -46,9 +46,14 @@ cable.
 
 | Service | Needed for |
 |---|---|
-| Web Remote Control Service (REST API) | starting/stopping the streams |
-| Ultimate DMA Service | keyboard input (port 64) |
-| Telnet Remote Menu Service | the F9 menu view (port 23) |
+| Web Remote Control Service (REST API, port 80) | discovery, starting/stopping the streams, the Ctrl+R/P/M machine controls and `--do`, running dropped `.prg`/`.crt`/`.sid` files, mounting `.g64`/`.d71`/`.g71`/`.d81` images, cartridge parking, and matrix-level typing on firmware that has `machine:input` |
+| Ultimate DMA Service (port 64) | typing into the C64 (KERNAL buffer), RUN/STOP, and mount-and-run of a dropped `.d64` |
+| Telnet Remote Menu Service (port 23) | the F9 menu view |
+
+Everything else the viewer does needs no service: the video/audio streams
+arrive on UDP 11000/11001 once started. The REST API alone gets you a
+picture and sound; add the DMA service to type, and telnet to browse the
+Ultimate's menu from the viewer.
 
 ### Wired Ethernet is required for the streams
 
@@ -89,11 +94,23 @@ refuses to start a stream toward an address missing from its ARP table.
 | Ctrl+M | press the Ultimate's menu button (the on-screen menu then answers the physical keyboard only; use F9 to drive a menu from the viewer) |
 | Ctrl+Q | quit |
 
-**Drop a `.prg`, `.crt`, or `.sid` file onto the window** and the Ultimate
-runs it (DMA program run, cartridge run, or SID player). If a cartridge is
-configured on the machine, it is parked for the run and restored afterwards,
-so a freezer cart won't hijack the program's reset; the cart is back on your
-next manual reset. The same works headless: `c64uv --run game.prg`.
+**Drop a `.prg`, `.crt`, `.sid`, or `.d64` file onto the window** and the
+Ultimate runs it (DMA program run, cartridge run, SID player, or for a
+`.d64`: mount on drive A, reset, `LOAD"*",8,1` and `RUN`, all done by the
+firmware over the DMA socket). If a cartridge is configured on the machine,
+it is parked for the run and restored afterwards, so a freezer cart won't
+hijack the program's reset; the cart is back on your next manual reset. The
+same works headless: `c64uv --run game.prg`.
+
+The window title shows the transfer progress ("sending game.d64 42%").
+The Ultimate serves one DMA-socket client at a time, so the viewer drops its
+keyboard connection for the duration and reconnects it on your next keypress;
+a second drop while one is in flight is refused.
+
+Other disk images (`.g64`, `.d71`, `.g71`, `.d81`) are mounted on drive A
+without touching the machine; type `LOAD"*",8,1` yourself. Every image is
+copied to the Ultimate's temp area first, so writes never reach the file you
+dropped.
 
 The same machine controls work headless: `c64uv --do reset` (also `reboot`,
 `pause`, `resume`, `menu`, `poweroff`) issues one REST call and exits. If

src/compat.h

@@ -75,8 +75,15 @@ int compat_wait_readable(const compat_sock *socks, int n, int timeout_ms);
 
 void compat_close(compat_sock s);
 
+// Waits until `s` can take more data or timeout_ms elapsed. 1 when
+// writable, 0 on timeout, -1 on error.
+int compat_wait_writable(compat_sock s, int timeout_ms);
+
 // Text for the last socket error (errno / WSAGetLastError).
 const char *compat_neterr(void);
+// True when the last socket error was a would-block / timeout (EAGAIN,
+// EWOULDBLOCK, EINTR; WSAEWOULDBLOCK, WSAETIMEDOUT), i.e. worth retrying.
+bool compat_neterr_transient(void);
 
 // Source address the OS would use to reach `ip` (UDP connect +
 // getsockname). Dotted quad in out (>= COMPAT_IP_STRLEN bytes).

src/compat_posix.c

@@ -134,6 +134,12 @@ int compat_wait_readable(const compat_sock *socks, int n, int timeout_ms)
     return poll(pfd, (nfds_t)n, timeout_ms); // negative fds are ignored
 }
 
+int compat_wait_writable(compat_sock s, int timeout_ms)
+{
+    struct pollfd pfd = {.fd = s, .events = POLLOUT};
+    return poll(&pfd, 1, timeout_ms);
+}
+
 void compat_close(compat_sock s)
 {
     if (s >= 0)
@@ -145,6 +151,11 @@ const char *compat_neterr(void)
     return strerror(errno);
 }
 
+bool compat_neterr_transient(void)
+{
+    return errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR;
+}
+
 bool compat_route_source_ip(const char *ip, char *out, size_t cap)
 {
     int s = socket(AF_INET, SOCK_DGRAM, 0);

src/keys.c

@@ -133,7 +133,7 @@ const struct viewer_binding viewer_bindings[] = {
     // ASCII only: the overlay renders through the 8x8 basic font
     {.label = "Tab, PgUp, Ins, End", .desc = "CTRL, RESTORE, pound, + (matrix)",
      .action = VA_INFO, .gap = true},
-    {.label = "file drop", .desc = "run a .prg/.crt/.sid on the machine",
+    {.label = "file drop", .desc = "run .prg/.crt/.sid/.d64 on the C64",
      .action = VA_INFO},
     {.key = SDLK_F9, .label = "F9", .desc = "toggle the Ultimate menu view",
      .action = VA_MENU_VIEW},