feat(gamepad): SC2 Puck-dongle passthrough with the native 28DE:1304 topology

Community-contributed round 5 of the Steam Controller 2 passthrough,
reviewed + verified. A Puck-captured pad now presents the dongle's real
seven-interface identity (CDC pair, four controller HID slots, management
HID) instead of relabelling its reports as a wired 1302 — Steam's Puck
feature dances (wireless_transport / esb/bond / 0xB4 slot status) get
capture-shaped answers, and the wired identity's canned replies are
corrected to the real captures (attribute count, string-attr framing,
0xF2 firmware info, bcdDevice nibble encoding).

- new wire pref 10 = SteamController2Puck (Hello/Welcome byte; older
  peers degrade to Auto), selected by the Android capture link when the
  transport is a dongle, or by VID/PID in the degraded InputDevice path
- TRITON_RDESC is now the captured numbered descriptor (mouse/keyboard
  lizard collections + per-id vendor reports); unnumbered framing made
  hidraw mangle feature report 2 and Steam eventually closed the device
- interrupt-IN now queues sparse reports (battery/RSSI/wireless edges)
  instead of keeping latest-only, so a 250 Hz state packet can no longer
  erase them before the USB/IP poll observes them; EP0 SET_REPORT is
  split by wValue report type (OUTPUT parsed for rumble vs FEATURE)
- vendored usbip-sim: config attributes/max-power, IAD prefix + BOS
  descriptor support, correct BCD minor.patch encoding (Deck's 0x0300/
  0x0200 values are nibble-zero, so its bytes are unchanged), and
  full-speed interrupt pacing in ms (was 8 kHz from the HS formula)
- Triton feedback is serviced at 1 kHz while an SC2 backend exists so
  Steam's trackpad haptic writes reach the client unbatched

Verified: clippy -D warnings + 319 host tests green on Linux, core wire
tests green, Android kit/app compile + unit tests green. On-glass Puck
retest owed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

clients/android/app/src/main/kotlin/io/unom/punktfunk/ControllersScreen.kt

@@ -495,6 +495,7 @@ private fun prefLabel(pref: Int): String = when (pref) {
     Gamepad.PREF_DUALSENSEEDGE -> "DualSense Edge"
     Gamepad.PREF_SWITCHPRO -> "Switch Pro"
     Gamepad.PREF_STEAMCONTROLLER2 -> "Steam Controller 2"
+    Gamepad.PREF_STEAMCONTROLLER2_PUCK -> "Steam Controller 2 Puck"
     else -> "Automatic"
 }
 

clients/android/kit/src/main/kotlin/io/unom/punktfunk/kit/Gamepad.kt

@@ -65,6 +65,7 @@ object Gamepad {
     const val PREF_DUALSENSEEDGE = 7
     const val PREF_SWITCHPRO = 8
     const val PREF_STEAMCONTROLLER2 = 9
+    const val PREF_STEAMCONTROLLER2_PUCK = 10
 
     // USB vendor ids of the controllers we can identify by VID/PID.
     private const val VID_SONY = 0x054C
@@ -92,12 +93,11 @@ object Gamepad {
     private val PID_STEAMDECK = setOf(0x1205)
     private val PID_STEAMCONTROLLER = setOf(0x1102, 0x1142)
 
-    // Steam Controller 2: wired (0x1302), BLE (0x1303), Puck dongles (0x1304/0x1305). Normally
-    // the Sc2 capture link CLAIMS the USB device (detaching it from the input stack), so this
-    // entry only fires in the degraded path — capture off / permission denied — where the pad
-    // surfaces as a plain InputDevice. Declaring SC2 there lets the host build the matching
-    // virtual pad from the typed plane instead of falling back to Xbox 360.
-    private val PID_STEAMCONTROLLER2 = setOf(0x1302, 0x1303, 0x1304, 0x1305)
+    // Steam Controller 2: wired (0x1302), BLE (0x1303), and Puck dongles (0x1304/0x1305).
+    // Sc2Capture normally claims these directly; the plain InputDevice path is only a degraded
+    // fallback. Keep Puck distinct so even that path requests the native multi-interface identity.
+    private val PID_STEAMCONTROLLER2 = setOf(0x1302, 0x1303)
+    private val PID_STEAMCONTROLLER2_PUCK = setOf(0x1304, 0x1305)
 
     // Microsoft Xbox One / Series product ids (wired + the common Bluetooth/dongle revisions). All
     // behave like Xbox 360 on the host minus the glyph identity, so they share one pref byte.
@@ -125,6 +125,8 @@ object Gamepad {
             vid == VID_MICROSOFT && pid in PID_XBOXONE -> PREF_XBOXONE
             vid == VID_VALVE && pid in PID_STEAMDECK -> PREF_STEAMDECK
             vid == VID_VALVE && pid in PID_STEAMCONTROLLER -> PREF_STEAMCONTROLLER
+            vid == VID_VALVE && pid in PID_STEAMCONTROLLER2_PUCK ->
+                PREF_STEAMCONTROLLER2_PUCK
             vid == VID_VALVE && pid in PID_STEAMCONTROLLER2 -> PREF_STEAMCONTROLLER2
             vid == VID_NINTENDO && pid in PID_SWITCHPRO -> PREF_SWITCHPRO
             else -> PREF_XBOX360

clients/android/kit/src/main/kotlin/io/unom/punktfunk/kit/Sc2Capture.kt

@@ -47,6 +47,10 @@ class Sc2Capture(
 
     private var pad: GamepadRouter.ExternalPad? = null
     private val rawBuf: ByteBuffer = ByteBuffer.allocateDirect(64)
+    /** Puck connect arrives before its first state report (and therefore before a wire pad exists).
+     * Preserve it so the native virtual Puck slot sees the same connect edge before state. */
+    private val pendingWireless = ByteArray(2)
+    private var pendingWirelessLen = 0
 
     // Typed-mirror diff state (wire units).
     private val state = Sc2Device.State()
@@ -141,10 +145,20 @@ class Sc2Capture(
         // saying "no radio link" — and must NOT tear the slot down (SDL's wired path likewise
         // marks the controller connected unconditionally and reconnects on any state report).
         if ((id == Sc2Device.ID_WIRELESS || id == Sc2Device.ID_WIRELESS_X) && len >= 2) {
-            if (dongleLink && (report[1].toInt() and 0xFF) == Sc2Device.WIRELESS_DISCONNECT) {
-                Log.i(TAG, "Puck reports controller powered off — releasing wire slot")
-                releaseSlot()
-                releaseUiKeys()
+            if (dongleLink) {
+                when (report[1].toInt() and 0xFF) {
+                    Sc2Device.WIRELESS_CONNECT -> {
+                        pendingWireless[0] = report[0]
+                        pendingWireless[1] = report[1]
+                        pendingWirelessLen = 2
+                    }
+                    Sc2Device.WIRELESS_DISCONNECT -> {
+                        pendingWirelessLen = 0
+                        Log.i(TAG, "Puck reports controller powered off — releasing wire slot")
+                        releaseSlot()
+                        releaseUiKeys()
+                    }
+                }
             }
             return
         }
@@ -157,9 +171,21 @@ class Sc2Capture(
             mirrorUi()
             return
         }
-        val p = pad ?: router.openExternal(Gamepad.PREF_STEAMCONTROLLER2)?.also {
+        val pref = if (dongleLink) {
+            Gamepad.PREF_STEAMCONTROLLER2_PUCK
+        } else {
+            Gamepad.PREF_STEAMCONTROLLER2
+        }
+        val p = pad ?: router.openExternal(pref)?.also {
             pad = it
-            Log.i(TAG, "SC2 captured → wire pad ${it.index} (as-is passthrough)")
+            Log.i(
+                TAG,
+                "SC2 captured → wire pad ${it.index} (${if (dongleLink) "Puck" else "direct"} passthrough)",
+            )
+            if (pendingWirelessLen > 0) {
+                forwardRaw(pendingWireless, pendingWirelessLen)
+                pendingWirelessLen = 0
+            }
         } ?: return // all 16 wire indices taken — drop until one frees
         forwardRaw(report, len)
         mirrorTyped(p)
@@ -259,6 +285,7 @@ class Sc2Capture(
         pad = null
         wireButtons = 0
         lastAxis.fill(Int.MIN_VALUE)
+        pendingWirelessLen = 0
     }
 
     private companion object {