CATCH sends a one-byte class mask. A non-zero mask subscribes; 0 unsubscribes. Opcode 0x0B.

CATCH 0x0B · payload 1 byte

Fire-and-forget

Each bit turns on one class of change. The mask only chooses which reports trigger an event (every event carries the full held-usage snapshot), so a buttons-only subscription stays sparse even though the mouse reports at ~1 kHz. Combine bits with OR; 0x1F subscribes to every class.

The stream reports the user's physical input, never your injected overrides, and it reads the report before LOCK clamps it, so a locked axis or blocked button is still reported here. That's the intercept-and-rebind loop: lock an input to hide it from the game, catch it to act on it.

The box streams from the moment a non-zero mask arrives until you send 0. The subscription is PC-owned and clears on the same triggers as injection: control-PC silence (the ~1 s timeout), a RESET, a mouse detach, or inter-chip link loss, plus an explicit unsubscribe. The host library holds an open subscription alive with its keepalive (re-asserting it after a device-side blip) and across a reconnect. QUERY(CATCH) reads the active mask and a dropped-event count; the HEALTH CATCH_ON bit is set while subscribed. Library binding: catch_events.

Subscribe to every class (mask = 0x1F):

+--------+--------+--------+--------+--------+--------+
| A5     | 0B     | 00     | 01 00  | 1F     | lo hi  |
+--------+--------+--------+--------+--------+--------+
| SOF    | TYPE   | SEQ    | LEN    | mask   | CRC16  |
+--------+--------+--------+--------+--------+--------+

While a subscription with Motion or Wheel is active the box pushes a MOTION_EVENT for each physical report whose motion changed. It's unsolicited (there's no QUERY to correlate), so SEQ is a rolling per-event counter shared with USAGE_EVENT: a host detects dropped events as SEQ gaps. Opcode 0x0C.

MOTION_EVENT 0x0C · payload 6 bytes

Unsolicited

Delivery is best-effort: under back-pressure the box drops events (counted in QUERY(CATCH)) rather than stalling the report path, so the stream never delays the game-PC-facing reports.

The user moves +10 right, no vertical or wheel motion (dx = 10):

+--------+--------+--------+--------+--------+--------+--------+--------+
| A5     | 0C     | 2A     | 06 00  | 0A 00  | 00 00  | 00 00  | lo hi  |
+--------+--------+--------+--------+--------+--------+--------+--------+
| SOF    | TYPE   | SEQ    | LEN    | dx     | dy     | dz     | CRC16  |
+--------+--------+--------+--------+--------+--------+--------+--------+

While a subscription with Buttons, Keys, or Media is active the box pushes a USAGE_EVENT when that class changes: a class-tagged snapshot of the usages currently held, so a mouse-button press and a key press have the same shape. It's a full snapshot, not edge deltas, so a dropped frame self-corrects on the next one; diff successive snapshots per class for press / release edges. Opcode 0x0F.

USAGE_EVENT 0x0F · payload 1 + 3n bytes

Unsolicited

Each entry is 3 bytes; the snapshot is n of them, all one class (one physical report is one class), so a Keys event lists every held key and a Buttons event every held button. Best-effort like MOTION_EVENT: dropped events are counted in QUERY(CATCH).

Left Shift held while pressing A (a keys snapshot, two usages both class = 1: Left Shift id = 0xE1, then A id = 0x04):

+--------+--------+--------+--------+--------+----------+----------+--------+
| A5     | 0F     | 2B     | 07 00  | 02     | 01 E1 00 | 01 04 00 | lo hi  |
+--------+--------+--------+--------+--------+----------+----------+--------+
| SOF    | TYPE   | SEQ    | LEN    | n      | usage[0] | usage[1] | CRC16  |
+--------+--------+--------+--------+--------+----------+----------+--------+