feat(rumble): host-authoritative self-terminating envelopes (0xCA v2)

Rumble was level-triggered, unbounded state on a lossy channel: a non-zero
level meant "buzz until further notice", healed only by the host re-sending
state every 500 ms, and every client guessed when the host had died with its own
magic timeout (SDL 1.5 s, Apple 1.6 s, Android up to 60 s). A lost stop, a
reordered start, or a dead host could drone the motor for seconds.

Make "stuck rumble" inexpressible on the wire. The 0xCA datagram grows a
length-tolerant tail — [u8 seq][u16 ttl_ms] — so it self-terminates: the host
authorizes a level for at most ttl_ms and renews it (~120 ms) while it holds,
letting an abandoned one lapse client-side. seq is a per-pad wrapping reorder
gate (reusing GamepadSnapshot::seq_newer) so a reordered stale start can't
re-light a stopped motor. Decoders read the first 7 bytes as a plain level and
ignore the tail, so no wire-version bump: an old client renders a new host's
levels, and a new client falls back to its prior staleness heuristic against an
old host (ttl = None). All four generation pairings render correctly.

- core: encode_rumble_datagram_v2 / decode_rumble_envelope (datagram.rs); the
  client demux applies the seq gate then forwards (pad, low, high, Option<ttl>);
  next_rumble is unchanged (drops ttl), next_rumble_ttl keeps it; ABI adds
  punktfunk_connection_next_rumble2 + PUNKTFUNK_RUMBLE_NO_TTL, ABI_VERSION 4->5
  (WIRE_VERSION unchanged — the tail is backward-compatible).
- host (punktfunk1.rs): the flat 500 ms refresh becomes a renewal loop that bumps
  seq + stamps a fresh TTL on active pads and drains a short post-stop zero burst,
  then goes quiet. Hatches: PUNKTFUNK_RUMBLE_ENVELOPE=0 (legacy v1 + flat refresh,
  a bisect switch), PUNKTFUNK_RUMBLE_TTL_MS (clamped [150, 5000]).
- renderers honor the TTL as their playback duration/deadline and keep their old
  heuristic only for a legacy (ttl=None) update: pf-client-core (the Deck haptic
  keep-alive is now deadline-bounded so it can't sustain a host-stopped rumble),
  clients/windows (SDL duration), android (JNI packs the lease out-of-band in bit
  48 so any u16 ttl is unambiguous; Kotlin createOneShot(ttl)), apple
  (RumbleRenderer.envelopeDeadline + nextRumble2; sessionStaleSeconds demoted to
  the legacy fallback).
- tests: codec round-trip + tail tolerance + seq-gate reorder (Rust); the probe
  asserts the v2 tail arrived under PUNKTFUNK_TEST_FEEDBACK; the Apple loopback
  asserts ttlMs round-trips end to end; RumbleTuning lease-decision cases.

The host-side idle-timeout from the previous commit is defense in depth on the
game side; this is the guarantee on the client side. Design:
punktfunk-planning/design/rumble-envelope-plan.md.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
2026-07-11 03:08:27 +02:00
parent 19e9828e8d
commit 73c911cae4
17 changed files with 734 additions and 91 deletions
+60
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@@ -1752,6 +1752,10 @@ pub unsafe extern "C" fn punktfunk_connection_next_audio_pcm(
/// are 0..0xFFFF (`low` = low-frequency motor, `high` = high-frequency), `(0, 0)` = stop.
/// Same timeout/closed semantics as [`punktfunk_connection_next_audio`].
///
/// This drops the self-terminating TTL of a v2 rumble envelope — an embedder that only calls this
/// keeps its own staleness policy, exactly as before. Use [`punktfunk_connection_next_rumble2`] to
/// honor the host-supplied lease and delete the client-side timeout heuristics.
///
/// # Safety
/// `c` is a valid connection handle; out pointers are writable (NULLs are skipped). At
/// most one thread pulls rumble — it may run concurrently with the video/audio pullers.
@@ -1792,6 +1796,62 @@ pub unsafe extern "C" fn punktfunk_connection_next_rumble(
})
}
/// `*ttl_ms` sentinel written by [`punktfunk_connection_next_rumble2`] for a legacy (v1) rumble
/// datagram — an old host that sent no self-termination lease. The client then falls back to its
/// own staleness heuristic for that update instead of a host-supplied deadline.
pub const PUNKTFUNK_RUMBLE_NO_TTL: u32 = 0xFFFF_FFFF;
/// Pull the next rumble update *including its self-termination TTL* (v2 envelopes), waiting up to
/// `timeout_ms`. Same `pad`/`low`/`high` semantics as [`punktfunk_connection_next_rumble`], plus
/// `*ttl_ms`: how long (milliseconds) to render this level before silencing unless the host renews
/// it. [`PUNKTFUNK_RUMBLE_NO_TTL`] means "no lease" — a legacy host; fall back to a client-side
/// timeout. The reorder gate (seq) is applied inside the core before the update surfaces here, so a
/// stale/reordered envelope never reaches the caller.
///
/// # Safety
/// `c` is a valid connection handle; out pointers are writable (NULLs are skipped). At most one
/// thread pulls rumble — it may run concurrently with the video/audio pullers.
#[cfg(feature = "quic")]
#[no_mangle]
pub unsafe extern "C" fn punktfunk_connection_next_rumble2(
c: *mut PunktfunkConnection,
pad: *mut u16,
low: *mut u16,
high: *mut u16,
ttl_ms: *mut u32,
timeout_ms: u32,
) -> PunktfunkStatus {
guard(|| {
let c = match unsafe { c.as_ref() } {
Some(c) => c,
None => return PunktfunkStatus::NullPointer,
};
match c
.inner
.next_rumble_ttl(std::time::Duration::from_millis(timeout_ms as u64))
{
Ok((p, l, h, ttl)) => {
unsafe {
if !pad.is_null() {
*pad = p;
}
if !low.is_null() {
*low = l;
}
if !high.is_null() {
*high = h;
}
if !ttl_ms.is_null() {
*ttl_ms = ttl.map_or(PUNKTFUNK_RUMBLE_NO_TTL, u32::from);
}
}
PunktfunkStatus::Ok
}
Err(e) => e.status(),
}
})
}
/// Pull the next DualSense HID-output feedback event (lightbar / player LEDs / adaptive trigger)
/// the host's virtual pad received from a game, into `*out`. [`PunktfunkStatus::NoFrame`] on
/// timeout, [`PunktfunkStatus::Closed`] once the session ended. Only the DualSense host backend
+54 -8
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@@ -322,10 +322,17 @@ impl FrameChannel {
const AUDIO_QUEUE: usize = 64;
/// Rumble updates buffered for the embedder. Overflow drops the NEWEST update (same
/// `try_send` discipline as the other planes) — the host re-sends rumble state
/// periodically, so a dropped transition (including a stop) heals within ~500 ms.
/// `try_send` discipline as the other planes) — the host renews rumble state periodically
/// (v2 envelopes) or re-sends it (legacy v1), so a dropped transition (including a stop) heals
/// within one renewal/refresh period.
const RUMBLE_QUEUE: usize = 16;
/// A rumble update handed to the embedder: `(pad, low, high, ttl_ms)`. `ttl_ms` is `Some(ms)` for
/// a self-terminating v2 envelope (render for at most that long) and `None` for a legacy v1
/// datagram (an old host — the renderer applies its own staleness policy). The seq from a v2
/// envelope is consumed by the reorder gate in the datagram demux and is NOT forwarded.
type RumbleUpdate = (u16, u16, u16, Option<u16>);
/// HID-output (DualSense lightbar / player LEDs / adaptive triggers) buffered for the embedder.
/// Same overflow discipline as rumble; the host re-sends on the next feedback change.
const HIDOUT_QUEUE: usize = 32;
@@ -355,7 +362,7 @@ pub struct NativeClient {
// and two threads racing one plane now serialize instead of being undefined).
frames: Arc<FrameChannel>,
audio: Mutex<Receiver<AudioPacket>>,
rumble: Mutex<Receiver<(u16, u16, u16)>>,
rumble: Mutex<Receiver<RumbleUpdate>>,
/// Inbound DualSense feedback (lightbar / player LEDs / adaptive triggers) — 0xCD datagrams.
hidout: Mutex<Receiver<HidOutput>>,
/// Inbound static HDR metadata (ST.2086 mastering + content light level) — 0xCE datagrams.
@@ -564,7 +571,7 @@ impl NativeClient {
) -> Result<NativeClient> {
let frame_chan = Arc::new(FrameChannel::new());
let (audio_tx, audio_rx) = std::sync::mpsc::sync_channel::<AudioPacket>(AUDIO_QUEUE);
let (rumble_tx, rumble_rx) = std::sync::mpsc::sync_channel::<(u16, u16, u16)>(RUMBLE_QUEUE);
let (rumble_tx, rumble_rx) = std::sync::mpsc::sync_channel::<RumbleUpdate>(RUMBLE_QUEUE);
let (hidout_tx, hidout_rx) = std::sync::mpsc::sync_channel::<HidOutput>(HIDOUT_QUEUE);
let (hdr_meta_tx, hdr_meta_rx) = std::sync::mpsc::sync_channel::<HdrMeta>(HDR_META_QUEUE);
let (host_timing_tx, host_timing_rx) =
@@ -1024,8 +1031,20 @@ impl NativeClient {
}
/// Pull the next rumble update `(pad, low, high)`; same semantics as
/// [`NativeClient::next_audio`]. Amplitudes are 0..0xFFFF, `(0, 0)` = stop.
/// [`NativeClient::next_audio`]. Amplitudes are 0..0xFFFF, `(0, 0)` = stop. The self-terminating
/// TTL of a v2 envelope is dropped here — use [`NativeClient::next_rumble_ttl`] to honor it (a
/// renderer that only sees `(pad, low, high)` keeps its own staleness policy exactly as before,
/// which is what makes this back-compatible for un-updated embedders).
pub fn next_rumble(&self, timeout: Duration) -> Result<(u16, u16, u16)> {
self.next_rumble_ttl(timeout).map(|(p, l, h, _)| (p, l, h))
}
/// Pull the next rumble update including its self-termination TTL: `(pad, low, high, ttl_ms)`.
/// `ttl_ms` is `Some(ms)` for a v2 envelope — render the level for at most that long, then
/// silence — and `None` for a legacy v1 datagram (an old host with no lease; fall back to the
/// renderer's own staleness heuristic). The reorder gate (seq) is applied in the datagram demux
/// before the update reaches this queue, so a stale/reordered envelope never surfaces here.
pub fn next_rumble_ttl(&self, timeout: Duration) -> Result<RumbleUpdate> {
match self.rumble.lock().unwrap().recv_timeout(timeout) {
Ok(r) => Ok(r),
Err(RecvTimeoutError::Timeout) => Err(PunktfunkError::NoFrame),
@@ -1168,7 +1187,7 @@ struct WorkerArgs {
identity: Option<(String, String)>,
frames: Arc<FrameChannel>,
audio_tx: SyncSender<AudioPacket>,
rumble_tx: SyncSender<(u16, u16, u16)>,
rumble_tx: SyncSender<RumbleUpdate>,
hidout_tx: SyncSender<HidOutput>,
hdr_meta_tx: SyncSender<HdrMeta>,
host_timing_tx: SyncSender<crate::quic::HostTiming>,
@@ -1593,6 +1612,10 @@ async fn worker_main(args: WorkerArgs) {
// Datagram demux: host → client audio/rumble (try_send: a lagging embedder drops the
// newest packet rather than backing up the QUIC receive path).
let dgram_conn = conn.clone();
// Per-pad reorder gate for v2 rumble envelopes (the seq analog of the host's gamepad-state
// gate): a datagram the network reordered must not roll a stopped motor back on. Legacy v1
// datagrams carry no seq and bypass it (an old host's own periodic re-send is the only heal).
let mut rumble_last_seq: [Option<u8>; crate::input::MAX_PADS] = [None; crate::input::MAX_PADS];
tokio::spawn(async move {
while let Ok(d) = dgram_conn.read_datagram().await {
match d.first() {
@@ -1606,8 +1629,31 @@ async fn worker_main(args: WorkerArgs) {
}
}
Some(&crate::quic::RUMBLE_MAGIC) => {
if let Some(r) = crate::quic::decode_rumble_datagram(&d) {
let _ = rumble_tx.try_send(r);
if let Some(u) = crate::quic::decode_rumble_envelope(&d) {
// Gate v2 envelopes on their per-pad seq; forward v1 (envelope: None) as-is.
let fresh = match u.envelope {
Some(env) => {
let idx = u.pad as usize;
if idx < crate::input::MAX_PADS {
if crate::input::GamepadSnapshot::seq_newer(
env.seq,
rumble_last_seq[idx],
) {
rumble_last_seq[idx] = Some(env.seq);
true
} else {
false // reordered/duplicate — drop, keep the newer state
}
} else {
true // out-of-range pad (host never sends these): no gate
}
}
None => true,
};
if fresh {
let ttl = u.envelope.map(|e| e.ttl_ms);
let _ = rumble_tx.try_send((u.pad, u.low, u.high, ttl));
}
}
}
Some(&crate::quic::HIDOUT_MAGIC) => {
+5 -1
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@@ -57,7 +57,11 @@ pub use stats::Stats;
/// clients out-of-band via the mDNS `mac` TXT record, so no connection is required to wake).
/// v4: added `punktfunk_probe` (bounded, trust-agnostic, mDNS-independent reachability handshake —
/// the display-side companion to dial-first, so saved-host "online" pips reflect real reachability).
pub const ABI_VERSION: u32 = 4;
/// v5: added `punktfunk_connection_next_rumble2` (rumble pull that also yields the self-terminating
/// TTL of a v2 envelope; `punktfunk_connection_next_rumble` is unchanged and drops it). Additive —
/// the wire is backward-compatible (the envelope is a length-tolerant tail on 0xCA), so
/// [`WIRE_VERSION`] is unchanged.
pub const ABI_VERSION: u32 = 5;
/// The punktfunk/1 **wire** version — what `Hello`/`Welcome` carry and hosts equality-check.
/// Deliberately its own constant: [`ABI_VERSION`] tracks the embeddable **C surface**
+79 -4
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@@ -42,8 +42,12 @@ pub fn decode_audio_datagram(b: &[u8]) -> Option<(u32, u64, &[u8])> {
Some((seq, pts_ns, &b[13..]))
}
/// Rumble datagram, host → client: `[0xCA][u16 pad LE][u16 low LE][u16 high LE]`.
/// Force-feedback state for pad `pad` (0xFFFF amplitudes, 0/0 = stop).
/// Legacy rumble datagram (v1), host → client: `[0xCA][u16 pad LE][u16 low LE][u16 high LE]`.
/// Force-feedback state for pad `pad` (0xFFFF amplitudes, 0/0 = stop) as *level-triggered* state
/// — it persists until superseded, which is why the host re-sends it periodically as its loss
/// heal. New hosts emit the self-terminating [`encode_rumble_datagram_v2`] instead; this is kept
/// for the loopback tests and as the wire an old host still speaks (a new client decodes both via
/// [`decode_rumble_envelope`]).
pub fn encode_rumble_datagram(pad: u16, low: u16, high: u16) -> [u8; 7] {
let mut b = [0u8; 7];
b[0] = RUMBLE_MAGIC;
@@ -53,15 +57,86 @@ pub fn encode_rumble_datagram(pad: u16, low: u16, high: u16) -> [u8; 7] {
b
}
/// Parse a rumble datagram → `(pad, low, high)`. `None` on bad tag/length.
/// Wire length of a v1 (legacy, level) rumble datagram.
pub const RUMBLE_V1_LEN: usize = 7;
/// Wire length of a v2 (envelope) rumble datagram — the v1 body plus a `[u8 seq][u16 ttl_ms LE]`
/// tail. Decoders are length-tolerant (see [`decode_rumble_envelope`]): an old client reads the
/// first 7 bytes as a plain level and ignores the tail, so no wire-version bump is needed — the
/// same dual-size idiom the HDR-luminance `AddRequest` tail uses.
pub const RUMBLE_V2_LEN: usize = 10;
/// Rumble envelope datagram (v2), host → client:
/// `[0xCA][u16 pad LE][u16 low LE][u16 high LE][u8 seq][u16 ttl_ms LE]`.
///
/// A *self-terminating* force-feedback command: the level is authorized for at most `ttl_ms`, so
/// a rumble the host stops renewing (or a host that dies) silences on its own — "stuck forever"
/// is inexpressible on the wire. `seq` is a per-pad wrapping counter (bumped on every send,
/// changes *and* renewals) compared with [`GamepadSnapshot::seq_newer`](crate::input::GamepadSnapshot::seq_newer)
/// so a reordered stale start can't re-light the motors after a stop. Renewals fully replace the
/// prior envelope's deadline; they never stack. An explicit stop is still `low == high == 0` sent
/// immediately (expiry is the safety net, never the stop mechanism).
pub fn encode_rumble_datagram_v2(pad: u16, low: u16, high: u16, seq: u8, ttl_ms: u16) -> [u8; 10] {
let mut b = [0u8; RUMBLE_V2_LEN];
b[0] = RUMBLE_MAGIC;
b[1..3].copy_from_slice(&pad.to_le_bytes());
b[3..5].copy_from_slice(&low.to_le_bytes());
b[5..7].copy_from_slice(&high.to_le_bytes());
b[7] = seq;
b[8..10].copy_from_slice(&ttl_ms.to_le_bytes());
b
}
/// The self-termination tail of a v2 rumble envelope (see [`encode_rumble_datagram_v2`]).
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct RumbleEnvelope {
/// Per-pad wrapping send counter — the reorder gate (see [`decode_rumble_envelope`]).
pub seq: u8,
/// How long, in ms, this envelope authorizes the stated level before the client must silence.
pub ttl_ms: u16,
}
/// A decoded rumble update. `envelope` is `None` for a legacy 7-byte datagram (an old host, which
/// has no seq/ttl — the client applies its own staleness policy), `Some` for a v2 envelope.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct RumbleUpdate {
pub pad: u16,
pub low: u16,
pub high: u16,
pub envelope: Option<RumbleEnvelope>,
}
/// Parse a rumble datagram → `(pad, low, high)`, tolerating (and ignoring) a v2 envelope tail.
/// `None` on bad tag/length. Kept for callers that only need the level (the probe, the loopback
/// assertions); clients that honor TTL use [`decode_rumble_envelope`].
pub fn decode_rumble_datagram(b: &[u8]) -> Option<(u16, u16, u16)> {
if b.len() < 7 || b[0] != RUMBLE_MAGIC {
if b.len() < RUMBLE_V1_LEN || b[0] != RUMBLE_MAGIC {
return None;
}
let u16at = |o: usize| u16::from_le_bytes([b[o], b[o + 1]]);
Some((u16at(1), u16at(3), u16at(5)))
}
/// Parse a rumble datagram → [`RumbleUpdate`], detecting the v2 envelope tail by length. A
/// `>= RUMBLE_V2_LEN` buffer carries `seq`/`ttl_ms`; a 7..RUMBLE_V2_LEN buffer is a legacy level
/// (`envelope: None`) — the same tolerance as an old client would apply, so a torn/short tail
/// degrades to a level rather than dropping. `None` on bad tag/length.
pub fn decode_rumble_envelope(b: &[u8]) -> Option<RumbleUpdate> {
if b.len() < RUMBLE_V1_LEN || b[0] != RUMBLE_MAGIC {
return None;
}
let u16at = |o: usize| u16::from_le_bytes([b[o], b[o + 1]]);
let envelope = (b.len() >= RUMBLE_V2_LEN).then(|| RumbleEnvelope {
seq: b[7],
ttl_ms: u16::from_le_bytes([b[8], b[9]]),
});
Some(RumbleUpdate {
pad: u16at(1),
low: u16at(3),
high: u16at(5),
envelope,
})
}
/// Mic datagram, client → host: `[0xCB][u32 seq LE][u64 pts_ns LE][opus payload]` — the same
/// layout as [`encode_audio_datagram`] with [`MIC_MAGIC`], one Opus frame per datagram.
pub fn encode_mic_datagram(seq: u32, pts_ns: u64, opus: &[u8]) -> Vec<u8> {
+73
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@@ -949,6 +949,79 @@ fn rumble_datagram_roundtrip() {
assert!(decode_rumble_datagram(&d[..6]).is_none());
}
#[test]
fn rumble_envelope_roundtrip_and_legacy_tolerance() {
// v2 envelope round-trips seq + ttl.
let d = encode_rumble_datagram_v2(2, 0x4000, 0x8000, 7, 400);
assert_eq!(d[0], RUMBLE_MAGIC);
assert_eq!(d.len(), RUMBLE_V2_LEN);
assert_eq!(
decode_rumble_envelope(&d),
Some(RumbleUpdate {
pad: 2,
low: 0x4000,
high: 0x8000,
envelope: Some(RumbleEnvelope {
seq: 7,
ttl_ms: 400
}),
})
);
// The legacy level decoder reads a v2 datagram as a plain level — the tail is ignored, so an
// old client running against a new host still renders the right amplitudes.
assert_eq!(decode_rumble_datagram(&d), Some((2, 0x4000, 0x8000)));
// A legacy 7-byte datagram (old host) decodes as a level with no envelope — a new client then
// applies its own staleness policy.
let v1 = encode_rumble_datagram(3, 0x1111, 0x2222);
assert_eq!(
decode_rumble_envelope(&v1),
Some(RumbleUpdate {
pad: 3,
low: 0x1111,
high: 0x2222,
envelope: None,
})
);
// A torn/short tail (8 or 9 bytes) is not a valid envelope — degrade to a level, never panic
// or drop. (The host never emits these; a truncating middlebox might.)
assert_eq!(
decode_rumble_envelope(&d[..8]).map(|u| u.envelope),
Some(None)
);
assert_eq!(
decode_rumble_envelope(&d[..9]).map(|u| u.envelope),
Some(None)
);
// Bad tag / too short → None on both decoders.
assert!(decode_rumble_envelope(&d[..6]).is_none());
let mut wrong_tag = d;
wrong_tag[0] = AUDIO_MAGIC;
assert!(decode_rumble_envelope(&wrong_tag).is_none());
}
#[test]
fn rumble_envelope_seq_gate_drops_reordered_stale_start() {
use crate::input::GamepadSnapshot;
// The client-side reorder gate (reused verbatim from gamepad snapshots): a stale start
// arriving after a stop must not re-light the motors.
let stop = decode_rumble_envelope(&encode_rumble_datagram_v2(0, 0, 0, 10, 0)).unwrap();
let stale_start =
decode_rumble_envelope(&encode_rumble_datagram_v2(0, 0x8000, 0x8000, 9, 400)).unwrap();
let stop_seq = stop.envelope.unwrap().seq;
let stale_seq = stale_start.envelope.unwrap().seq;
// Nothing applied yet → the first update always passes.
assert!(GamepadSnapshot::seq_newer(stop_seq, None));
// The reordered older start does NOT supersede the stop.
assert!(!GamepadSnapshot::seq_newer(stale_seq, Some(stop_seq)));
// A genuine later renewal does.
assert!(GamepadSnapshot::seq_newer(11, Some(stop_seq)));
// Wraps: seq 1 supersedes 254.
assert!(GamepadSnapshot::seq_newer(1, Some(254)));
}
#[test]
fn mic_datagram_roundtrip_and_disjoint_from_audio() {
let opus = [0x5Au8; 80];