Klangbruecke 1.0.0

Windows tray app that bridges your phone to your PC over Bluetooth — music (A2DP sink) and cellular calls (HFP hands-free) on the built-in radio. No Phone Link, no dongle. This first full release also adds an optional phone media remote.

Highlights

• Music — your phone's audio plays through the PC (A2DP sink), routed to the output you choose.
• Calls — cellular calls use the PC as a hands-free device (HFP), with audio both directions.
• Phone media remote (new, optional) — a small Android companion mirrors your phone's now-playing into the Windows media overlay / ModernFlyouts: title, artist, album art, a live seek bar, and transport (play / pause / next / previous / seek) driven from the PC over Bluetooth RFCOMM. Fully event-driven and power-light — the phone streams nothing at idle, and the PC advances the seek bar itself.
• Tray-first and headless — runs in the tray, starts with Windows, and reconnects on its own after sleep, reboot, or range loss.

Install — PC

1. Download Klangbruecke.cer and Klangbruecke-1.0.0.msix.
2. Trust the signing certificate once — right-click Klangbruecke.cer → Install Certificate → Local Machine → place in Trusted People.
   (Or, in an elevated PowerShell: Import-Certificate -FilePath Klangbruecke.cer -CertStoreLocation Cert:\LocalMachine\TrustedPeople.)
3. Install the app — double-click Klangbruecke-1.0.0.msix, or run Add-AppxPackage -Path Klangbruecke-1.0.0.msix.
4. Pair your phone in Windows Bluetooth settings. Klangbruecke connects and routes automatically.

Requires Windows 10 build 19041+ (19045 recommended). The MSIX is signed with a development certificate — this is a sideloaded app, not a Store submission, which is why step 2 is needed.

Install — phone media remote (optional)

Android-only and sideloaded — not on the Play Store.

1. Download and install Klangbruecke-Remote-1.0.apk (allow install from unknown sources).
2. Open Klangbruecke Remote and grant Notification access (to read the active media session) and Bluetooth. The service then runs quietly in the background and reconnects on its own — including after a reboot.
3. Turn on Phone remote in the Windows app's tray menu.

The companion app versions independently from the Windows app and ships with every release, even when it hasn't changed.

Notes

• Music and calls are verified on Windows 10 19045; see docs/FINDINGS.md for the empirical details behind the approach (why the inbox Bluetooth stack, no dongle, and how the media remote works over RFCOMM).

Klangbruecke v0.2.4

Everything from 0.2.3, plus a second round of tray UX and a smarter Connect Now.

New in this build

• Connect Now actually connects. It now actively reaches out and pulls a paired, in-range phone up
  from the PC (the same thing Windows' own Bluetooth "Connect" does), instead of only working when the
  phone was already connected. If the phone is genuinely unreachable it backs off rather than hanging.
• Left-click opens the tray menu (previously right-click only).
• Event sounds — a soft low chime on connect / disconnect / and when one half drops (degraded),
  with a Sounds toggle in the menu to silence them.
• Auto-pick phone — the Phone submenu is now a checkable list: tick the phones you use, and the app
  auto-connects whichever is present (first one present wins; a working connection is never dropped to
  switch). Your previous single selection is migrated automatically.
• Copy Diagnostics now spans midnight (it reads recent log lines across the day boundary, not just
  today's file).

Known limitations (unchanged)

• Windows 10 (19041+) only. Not Windows 11 — call registration is blocked there for sideloaded apps.
• Outgoing call audio can be narrowband depending on your Bluetooth stack (driver, not the app).
• No in-app call-output picker; call audio follows the Windows default communications device.
• The in-call keypad (DTMF) does not work — that window is Windows' own call UI.
• If a phone won't connect even from Windows' own Connect button, the pairing is stale — re-pair on both
  sides.

Prerelease (0.x). Requires the one-time certificate-trust step below.

Install

Klangbruecke is a sideloaded MSIX signed with a self-signed certificate, so Windows will not install
it until that certificate is trusted. There is no "install anyway" prompt for MSIX - this step is
required, and it is a one-time thing per machine.

1. Trust the certificate (one time, from an elevated PowerShell):

Import-Certificate -FilePath .\Klangbruecke.cer -CertStoreLocation Cert:\LocalMachine\TrustedPeople

2. Install (or upgrade) the app - from Windows PowerShell, not PowerShell 7 (the Appx module
does not load in pwsh):

Add-AppxPackage -Path .\Klangbruecke-0.2.4.msix

Klangbruecke then starts automatically and lives in the system tray. Windows 10 build 19041 or later
is required. See the README for what it does and
how to test music and calls.

Klangbruecke v0.2.3

Everything from 0.2.2 (music + cellular calls over Bluetooth, unattended reconnect, the ~5 s fast
reconnect probe) plus a set of tray affordances.

New in this build

• Connect Now — a manual, one-shot reconnect that overrides a deliberate Disconnect or a
  switched-off "Reconnect automatically", without changing that setting.
• Diagnostics submenu:
  • Open Logs — opens the log folder.
  • Copy Diagnostics — a paste-ready snapshot (version, OS, connection state, recent log lines) to
    the clipboard, for bug reports. Review it before sharing.
  • Check for Updates — compares the running version against the latest GitHub release.
  • About — version and a link to the project.
• The tray menu is reordered so Connect Now / Disconnect sit above the Calls / Reconnect toggles.
• A Troubleshooting section in the README.

Known limitations (unchanged)

• Windows 10 (19041+) only. Not Windows 11 — call registration is blocked there for sideloaded apps.
• Outgoing call audio can be narrowband depending on your Bluetooth stack (driver, not the app).
• No in-app call-output picker; call audio follows the Windows default communications device.
• The in-call keypad (DTMF) does not work — that window is Windows' own call UI, and DTMF is not
  reachable from a Win10 app. Use a phone for phone trees.

Prerelease (0.x). Requires the one-time certificate-trust step below.

Install

Klangbruecke is a sideloaded MSIX signed with a self-signed certificate, so Windows will not install
it until that certificate is trusted. There is no "install anyway" prompt for MSIX - this step is
required, and it is a one-time thing per machine.

1. Trust the certificate (one time, from an elevated PowerShell):

Import-Certificate -FilePath .\Klangbruecke.cer -CertStoreLocation Cert:\LocalMachine\TrustedPeople

2. Install (or upgrade) the app - from Windows PowerShell, not PowerShell 7 (the Appx module
does not load in pwsh):

Add-AppxPackage -Path .\Klangbruecke-0.2.3.msix

Klangbruecke then starts automatically and lives in the system tray. Windows 10 build 19041 or later
is required. See the README for what it does and
how to test music and calls.

Klangbruecke v0.2.2

Klangbruecke bridges phone audio to your PC over Bluetooth on the built-in radio — music (A2DP sink)
and cellular calls (HFP hands-free) in one tray app. No USB dongle, no second app.

This build

• Both halves work and recover unattended. Music and calls come back on their own after the phone
  leaves and returns to range, after a reboot, and on a phone-initiated reconnect.
• Fast reconnect. Phone-initiated reconnect is bounded to ~5 s by a reconnect probe — the Bluetooth
  DeviceWatcher never fires on reconnect, so a short probe closes the gap the 30 s reconcile poll used
  to leave.
• State-reflecting tray icon — blue = connected, amber = connecting / degraded, grey = idle.

Known limitations

• Windows 10 (19041+) only. Not Windows 11 — call registration is blocked there for sideloaded apps,
  and Win11 has an A2DP-capture regression this app depends on.
• Outgoing call audio can be narrowband depending on your Bluetooth stack (a 2021 MediaTek RZ616
  driver forces a narrowband SCO codec — this is the driver, not the app).
• No in-app call-output picker. Call audio follows the system default communications device; set it
  in Windows Sound settings.

First public build, so it is marked a prerelease. Requires the one-time certificate-trust step below.

Install

Klangbruecke is a sideloaded MSIX signed with a self-signed certificate, so Windows will not install
it until that certificate is trusted. There is no "install anyway" prompt for MSIX - this step is
required, and it is a one-time thing per machine.

1. Trust the certificate (one time, from an elevated PowerShell):

Import-Certificate -FilePath .\Klangbruecke.cer -CertStoreLocation Cert:\LocalMachine\TrustedPeople

2. Install (or upgrade) the app - from Windows PowerShell, not PowerShell 7 (the Appx module
does not load in pwsh):

Add-AppxPackage -Path .\Klangbruecke-0.2.2.msix

Klangbruecke then starts automatically and lives in the system tray. Windows 10 build 19041 or later
is required. See the README for what it does and
how to test music and calls.