The A2DP output is a single unmixed PCM stream. A second process
opening audio while a stream was active would reconfigure the SBC
encoder and media clock under the owner and interleave both apps' PCM
into one ring, garbling playback (e.g. launching DOOM destabilized
Music). Add ClaimOutput/ReleaseOutput pid ownership: the first opener
gets the BT sink, later openers fall back to the HDA mixer, and only
the owner can tear the stream down. The scheduler releases ownership
on process exit so a killed app cannot leak the claim.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Four fixes, each a root cause verified on hardware (AX211 + Bose QC Ultra):
1. Link Key Request Reply TRUNCATED: the pending-command queue's params
buffer was 16 bytes; the reply is 22 (addr 6 + key 16). The controller
got 10 key bytes -> every stored-key reconnection failed authentication
(status 5) since 2026-06-03 (0f16785). Fresh pairings never touch this
path, which kept the bug perfectly disguised as a headset quirk.
2. Secure Connections host support (0x0C7A) now enabled: bonds are minted
as P-256 (Type=7), interoperable with BlueZ's, and SC-bonded peers can
actually authenticate us.
3. Never write the BD_ADDR override (0xFC31) with the factory address:
it desyncs the firmware's crypto address from the on-air one and ALL
SSP pairing fails with status 5. (The spoofing feature itself was
already known-cosmetic: the baseband answers pages on the factory
address regardless.) import-bluez-bond.sh now removes the override.
4. A2DP channel setup: wait for Encryption Change before dialing L2CAP
(post-SSP sinks ignore unencrypted CONN_REQ), and LISTEN 2.5s first --
on reconnection the sink dials AVDTP itself and ignores our dials while
doing so. Ends the historical connRsp=FFFF retry-then-give-up failures.
Plus: queued security replies now log delivery + controller status.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
daniel
