The Linux injection leg of design/pen-tablet-input.md: 0xCC/0x05 pen batches now
route through the per-session PenTracker into a lazily-created 'Punktfunk Pen'
uinput tablet (BTN_TOOL_PEN/RUBBER, pressure, tilt-from-polar, ABS_Z barrel
roll, hover distance, INPUT_PROP_DIRECT) — compositors pick it up via libinput
and hand apps zwp_tablet_v2 with full fidelity. The host now advertises
HOST_CAP_PEN when /dev/uinput is accessible (PUNKTFUNK_PEN=0 kill-switch);
transitions group into SYN frames so proximity-enter carries its position.
Stroke failsafe: clients heartbeat ≤100ms while in range (documented wire
contract — capture APIs are silent for a stationary pen); 200ms of silence
force-releases. 'punktfunk-host pen-test' draws a pressure-ramped sine stroke
through the real tracker→uinput chain, no client needed.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The pen plane from design/pen-tablet-input.md, protocol side only (the P1 uinput
tablet injector will consume it): 0xCC kind 0x05 carries batches of state-full
PenSamples (pressure, polar tilt + azimuth, barrel roll, hover distance, eraser
tool, barrel buttons); PenTracker diffs samples into injector transitions so a
lost datagram self-heals; HOST_CAP_PEN (0x10) gates sending and stays
unadvertised until a real backend exists. C ABI: PunktfunkPenSample +
punktfunk_connection_send_pen, documented in docs/embedding-the-c-abi.md §8.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Developer integration guide for building a punktfunk client on any platform
by linking punktfunk-core through its stable C ABI: what the core does vs.
what the embedder supplies, build/link/cross-compile, the full client
lifecycle (identity/pairing, connect ladder, video+recovery loop, audio,
input, feedback planes, teardown), plus worked blueprints for webOS, Xbox
(GDK), and Tizen.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehlerandClaude Fable 5