Creator was recording on the Release build and hit "Couldn't start the audio — another copy of
LlamaCasty is already using the audio pipe" when going live on Debug. The guard did its job (no
crash), but the collision should not have been possible: the pipe name only suffixed when
`YTLIVE_INSTANCE` was set, and a Debug launched straight from the IDE has no id — so it asked for
the same `ytllive_audio` the Release build was serving.
DEBUG now always suffixes: the claimed instance id when there is one, otherwise the process id. Any
number of dev builds can run beside the Release app, and each Debug process is distinct from every
other. Release is unchanged — it resolves to the plain name, and the whole mechanism disappears in
`#if DEBUG` as before.
`TryStartAudioPipe` now logs the resolved name (`Audio pipe: …`), so the next report of this kind is
one grep instead of a code hunt.
Tests: AudioPipeInstanceTests pins that an id-less DEBUG process never resolves to the bare name;
572 green, 0 warnings.
Reported 2026-11-06: a Release instance crashed when clicking Go Live in test mode, while a Debug
instance was recording its window. The Windows event log gave the cause:
System.IO.IOException: All pipe instances are busy.
at System.IO.Pipes.NamedPipeServerStream.Create(...)
at ytLive.Services.Audio.NamedPipeAudioWriter.Start(...)
at ytLive.Services.Audio.AudioMixer.StartLive(...)
at MainViewModel.StartStreamingSession(...)
at MainViewModel.BeginTestStream(...)
at MainViewModel.StartFromPrimaryButton(...)
at System.Windows.Controls.Button.OnClick()
Two defects, both fixed:
1. **A button click could end the process.** `StartLive` throws when the pipe name is taken, and nothing
on the go-live path caught it. `TryStartAudioPipe` now catches, logs, toasts ("Another copy of
LlamaCasty is already using the audio pipe") and rolls the session back. Recording-only takes the same
path.
2. **The pipe name was a shared constant**, so a second instance could never go live on the same machine.
`InstanceProfile.AudioPipeName` appends the dev instance id (DEBUG only); Release keeps the plain name
so the normal single-instance case is unchanged. The encoder reads the same derived name, so mixer and
ffmpeg cannot disagree.
Tests: `AudioPipeInstanceTests` — a second server on one name throws (the collision is real), dev names
derive per instance, and a writer on a taken name throws rather than silently reusing the pipe.
Debug and Release both build clean.
Pre-1.0 the creator streams in one instance and screen-captures it from
another. Nothing prevented a second instance - there is no single-instance
mutex and no port anywhere. What broke it was SHARED STATE, and two of the
collisions were hard failures rather than annoyances:
- the layout DB. The model is read-whole-scene / write-whole-scene, so two
instances saving different layouts clobber each other.
- the WebView2 user data folder. Chromium takes an exclusive lock on it, so
the second instance of the same exe does not start at all.
- the auth token store. A test instance would overwrite the real YouTube
sign-in with its own.
- startup.log, where two appenders interleave and a crash in either instance
becomes ambiguous.
Set YTLIVE_INSTANCE=<id> and the process gets a private root at
%APPDATA%\ytLlive\instances/<id>/ for those four. Recording folder and the
ffmpeg tools cache stay shared on purpose - the cache should be shared, and
the creator picks the record folder. Global hotkeys stay un-namespaced: if
both instances register the same one, Windows refusing the second is the
correct answer.
An id that is not letters/digits/dash/underscore is rejected and degrades to
the primary profile, so the variable can never walk out of the profile
directory or name a UNC path.
The entire implementation is inside #if DEBUG. A Release build compiles to
DataRoot => DefaultRoot and WebViewDataFolder => null, and the call sites are
unconditional so Release cannot drift by forgetting an #if. The harness lives
with the tests: InstanceIsolationTests covers the two-identities contract,
the primary-instance no-op, per-instance WebView folders, path-traversal
rejection, that the real output paths actually move with the profile, and a
source-level assertion that the #else arm IS production behaviour.
Verified against a real Release build: the InstanceVariable field is absent
from its metadata and no "instances" path segment survives, while DataRoot
and WebViewDataFolder are present in both configurations. Grepping for
YTLIVE_INSTANCE proves nothing - a const is inlined at compile time and
appears in neither build, which cost one wasted verification round.
Docs for this unit (the InstanceProfile paragraph in ai.md, the 1.0 gate in
TASKS.md, and the MyMistakes/HANDOFF entries) landed in the previous commit,
because they share those files with the branding-credit work.
gramps