The audio engine could already seek and nothing called it: no rpc, no
playback command, no binding. This wires it from every client.
The one real decision was where the arithmetic lives. A seek is relative
but the engine seeks to an absolute position, so either the client computes
a target from the last position update or it sends an offset and the engine
adds it to the live position. The offset wins on the ordinary case of
pressing the key twice: positions are broadcast on a 250 ms tick and then
cross the network, so three quick presses would all read the same stale
base and jump 15 s instead of 45. It also keeps the clamping policy in one
place instead of three clients, and matters more while paused, where no
position updates arrive at all.
So the wire carries sint32 delta_millis and the step is a client constant.
It also uncovered a live panic: seek_to did
`time.clamp(Duration::from_secs(1), duration)`, and `Ord::clamp` asserts
min <= max while `duration()` returns 0 for any source that reported no
length (HLS, some streams). That panicked the engine thread, killing audio.
Unreachable only because nothing called it; wiring seek made it reachable
from user input. It is now saturating arithmetic in a pure, exhaustively
tested function.
Boundaries: backwards saturates at 0 and never enters the previous track;
forwards stops 1 s short of the end so the track finishes through the
ordinary end-of-stream path (which advances the queue) instead of relying
on seek-to-exact-end, which decoders disagree about; an unknown duration
has no upper clamp. The engine emits Elapsed from the seek path itself,
because tick() skips a paused sink and a paused seek would otherwise show
the old position until playback resumed. An unseekable source (SoundCloud
HLS) warns server-side and changes nothing.
Ctrl-b/Ctrl-f join the existing control-chord family; plain f still toggles
the spectrum because lookup compares every modifier but SHIFT exactly. In
the browser Ctrl-f would open the find bar, but the keydown handler already
prevent_defaults any chord that resolves.
Seek is deliberately not tested through the playback loop: every test there
builds a real Player whose engine thread opens an audio device, so a test
that awaits a player reply passes or hangs depending on whether the machine
has working audio. The arithmetic is tested as a pure function, and the
rpc -> command mapping (the layer the paste bug lived in) in rpc.rs.
Verified: 20 audio-player tests (5 new: i64::MIN/MAX, zero duration,
sub-second tracks, composition, near-end saturation), 95 crabidy-server,
119 cbd-tui, 21 cbd-web, 58 server tests with --no-default-features,
workspace clippy clean under -D warnings, fmt clean, wasm bundle and book
build. Not exercised: an actual seek through an audio device.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Test User