2026-04-06 — Idle mode, Docker diet, and unified branding (v2.55.0)

The final day of the week was a feature-driven release: a new idle mode system that replaced two confusing numeric inputs with a single dropdown of four human-readable strategies, a major Docker image diet, and a visual identity unification across all channels. Twelve RC iterations led to v2.55.0 stable.

What shipped

Per-device idle mode

The old idle behavior had two independent settings per device: keepalive_interval (seconds between silence bursts) and idle_disconnect_minutes (timeout before BT disconnect). Users had to understand the interaction between them — setting both was contradictory, setting neither was the implicit “default”. The new idle_mode enum replaces both with a single dropdown:

Mode	Behavior	Use case
default	No action; speaker’s hardware timer decides	Speakers that sleep fine on their own
power_save	Suspend PA sink after delay → release A2DP → speaker sleeps, BT stays connected	Fast resume without reconnect latency
auto_disconnect	Full BT disconnect + daemon → null-sink after timeout	Same as old idle_disconnect_minutes
keep_alive	Stream periodic infrasound bursts to keep A2DP active	Speakers that disconnect on digital silence

Power save mode is new. It leverages the SinkMonitor infrastructure from v2.54.0: after the configurable delay (1–60 minutes, default 1 min), the bridge suspends the PulseAudio sink via asuspend_sink() (pulsectl API with pactl suspend-sink fallback). This releases the A2DP transport so the speaker can enter hardware sleep, but keeps the Bluetooth connection alive. On next play, PA resumes the sink automatically — no reconnect latency.

Infrasound keepalive is an improvement to the old keepalive mode. Previously, keepalive streamed pure digital silence — which some speakers ignore (they detect “no meaningful audio” and disconnect anyway). The new implementation generates 2 Hz sine wave bursts at −50 dB: below human hearing threshold but non-zero PCM data that keeps the A2DP transport active.

Config migration runs automatically on startup: keepalive_interval > 0 → keep_alive, idle_disconnect_minutes > 0 → auto_disconnect, both zero → default. Explicit idle_mode values are never overwritten.

The UI dropdown was restyled after rc.1 shipped with an unstyled <select> element (rc.2), and the delay unit was changed from seconds to minutes after testing showed that sub-minute granularity wasn’t useful (rc.3).

Docker image −51%

The Docker image shrank from 916 MB to ~450 MB through three rounds of optimization:

Round 1 (rc.7): Remove system FFmpeg (−37%, 916→580 MB). Investigation revealed that PyAV wheels bundle their own FFmpeg libraries in av.libs/, making the system FFmpeg installation redundant on amd64 and arm64. System FFmpeg is still needed on armv7 (compiled from source since there are no prebuilt wheels).

Round 2 (rc.9): Deep cleanup (−51%, 916→450 MB). The apt-get install pulseaudio-utils pulls in transitive dependencies for FFmpeg, GStreamer, and various codecs that pactl doesn’t need at runtime. These are now force-removed after installation. Additionally:

• Debug symbols stripped from all .so files (saves ~30 MB)
• Unused Python stdlib modules removed: ensurepip, idlelib, lib2to3, pydoc_data, turtledemo, test
• pip, pygments, numpy test suite, and __pycache__ directories stripped from the runtime image

Round 3 (rc.10): Keep libasound2-plugins. The cleanup in rc.9 accidentally removed libasound2-plugins, which provides libasound_module_pcm_pulse.so — the ALSA→PulseAudio bridge that sounddevice/PortAudio uses to discover audio sinks. Without it, daemon subprocesses crashed with “No audio output device found”. This was the PipeWire-specific failure — on PulseAudio, the direct PA connection works; on PipeWire, PortAudio needs the ALSA→PulseAudio shim.

Unified branding

All visual assets across the project were replaced with the landing page wave-bridge design (two rounded pillars with three sine-wave curves):

• HA addon icons (rc.11): stable=teal-purple gradient, rc=gold, beta=red. Total icon size reduced from 316 KB to 80 KB.
• All logos and favicons (rc.12): web UI favicon, docs-site logo, and all remaining assets unified. Total asset size from ~310 KB to ~55 KB.

The channel color differentiation is important for HA users who might have multiple addon channels installed — the icon color immediately identifies which channel a device is running.

Dependency updates and CI

Six Dependabot PRs merged:

• dbus-fast 4.0.0→4.0.4 (D-Bus performance improvements)
• ruff 0.11.13→0.15.8 (linter)
• numpy pin restored to <2.0 after rc.5 widened it to <3.0 and hit the X86_V2 CPU baseline crash on QEMU
• docker/build-push-action v6→v7 (Node 24)
• actions/download-artifact v4→v8 (hash enforcement)
• actions/upload-pages-artifact v3→v4

The NumPy pin deserves a note: numpy 2.x requires the X86_V2 instruction set baseline (POPCNT, SSE4.2) which is unavailable on QEMU’s default qemu64 CPU model and older physical CPUs. This was previously fixed in v2.50.0 but the Dependabot PR widened it back; rc.6 reverted.

Other fixes

• Config download 404 in HA addon ingress mode — hardcoded download path bypassed the ingress SCRIPT_NAME prefix; now uses API_BASE (rc.4)
• Auto-expand device detail row — clicking “Configure” from onboarding or guidance auto-expands the target device row before highlighting it (rc.4)

Community activity

• Issue #123: User @bugensui2022 reported no audio output after installing and uninstalling the bridge on HAOS. Investigation revealed the null-sink fallback (sendspin_fallback) was set as the default PA sink and persisted after uninstallation. Resolved with guidance to reset the default sink via pactl set-default-sink <original_sink>. This highlighted a gap in the uninstall cleanup — future versions should restore the original default sink on addon removal.
• Issue #133: User @mdorchain reported sinks not appearing after host reboot on PipeWire/Ubuntu. The bridge connects to PulseAudio before the BT A2DP sink is created by WirePlumber. Investigation ongoing.

Release timeline

Version	Date	Key change
2.55.0-rc.1	Apr 6	idle_mode enum, infrasound keepalive, PA suspend
2.55.0-rc.2	Apr 6	Idle mode dropdown styling
2.55.0-rc.3	Apr 6	Delay unit: seconds → minutes
2.55.0-rc.4	Apr 6	Config download ingress fix, auto-expand CTA
2.55.0-rc.5/6	Apr 6	Dependency updates, NumPy <2.0 revert
2.55.0-rc.7	Apr 6	Docker −37% (FFmpeg removal)
2.55.0-rc.9	Apr 6	Docker −51% (deep cleanup)
2.55.0-rc.10	Apr 6	Keep libasound2-plugins
2.55.0-rc.11/12	Apr 6	Unified branding
2.55.0	Apr 6	Stable release

Why this matters

The idle mode system is the culmination of the SinkMonitor work from v2.53–2.54. Without PA sink state awareness, power save mode (suspend/resume) would be impossible. The four-mode enum gives users a clear mental model instead of two interacting numeric parameters.

The Docker diet matters for Raspberry Pi users where SD card space and download time are real constraints. Going from 916 MB to 450 MB means faster addon updates and less wear on flash storage.

The unified branding closes a visual inconsistency: the landing page had the wave-bridge design, but the HA addon and web UI still used the old bridge+equalizer icon. Now everything is visually coherent.

The twelve-RC day is a record for the project — but each RC addressed a real issue discovered in testing. The rapid iteration cycle (code → RC → test → fix → next RC) keeps quality high without multi-day stabilization periods.

Follow-up

Issue #133 (sink not available after reboot on PipeWire) needs investigation — likely requires WirePlumber readiness detection or a delayed sink scan at startup. The null-sink cleanup gap from #123 should be addressed in a future release with proper uninstall hooks.

Test suite: 1088 Python tests. Total releases since v2.52.0: 33 (8 stable + 25 RC).