feat(audio): prefer dock/HDMI/USB sinks in WirePlumber (#87)

Raise priority.session for HDMI/DisplayPort (1100) and USB (1050) ALSA
outputs so the default sink follows dock plug/unplug; built-in analog
wins again when externals disappear. Rules live in
modules/nixos/dock-audio-rules.nix; checks.dock-audio covers the contract.

Verified: V2 — flake check --no-build; checks.dock-audio green.
V3 pending: HARDWARE-QUEUE #87 real HDMI/USB-dock hotplug.

agent/BACKLOG.md

@@ -55,10 +55,6 @@ runtime-computed `resume_offset` into the boot cmdline, and the dev box runs
 exactly this layout (`/proc/cmdline` verified) but isn't Nomarchy. Steps in
 HARDWARE-QUEUE. Close #76 on PASS.
 
-### 87. Dock audio sink follows plug/unplug (`VISION § C`)
-Default audio sink: dock sink on plug, internal on unplug (WirePlumber
-policy or udev hook). Complements #86; can ship independently.
-
 ## LATER
 
 - **Wallpapers artifact split** (ROADMAP § Faster switches — decided,
@@ -111,8 +107,8 @@ high-ROI, etc.) live in the journal + ROADMAP — not here.*
   2026-07-10). Keep #59 commented install guidance; no
   `nomarchy.hardware.nvidia.*` until a hybrid maintainer + queue.
 
-_(#80–#83 + #85–#86 shipped 2026-07-11. Remaining dock slice: **#87**
-  dock audio. #86 V3 clamshell on real external display → HARDWARE-QUEUE.)_
+_(#80–#83 + #85–#87 shipped 2026-07-11. Dock V3 residuals: #86
+  clamshell + #87 audio on real hardware → HARDWARE-QUEUE.)_
 
 ### v1.0 pointer
 

agent/HARDWARE-QUEUE.md

@@ -19,6 +19,13 @@ the **T14s** (webcam case).
       — should suspend as usual. Optional: with a docked display-profile
       (`eDP-1` disable), confirm clamshell layout still looks right after
       lid close. Pass = no surprise suspend when docked.
+- [ ] **#87 dock audio sink follow** — V2 asserts WirePlumber
+      `90-nomarchy-dock-audio` rules (HDMI/USB priority). On a laptop
+      with HDMI or USB-dock audio: play sound on speakers, plug external
+      audio → default sink should move to HDMI/dock (`wpctl status` shows
+      `*` on the external sink); unplug → `*` returns to built-in.
+      Manual `wpctl set-default` still works; Bluetooth may outrank dock
+      (by design). Pass = auto switch without menu intervention.
 - [ ] **#55 fingerprint enroll on real reader** — with
       `nomarchy.hardware.fingerprint.enable` and a physical reader: System ›
       Fingerprint › Enroll a finger; List shows it; Verify succeeds; optional

agent/JOURNAL.md

@@ -19,6 +19,17 @@ Template:
 
 ---
 
+## 2026-07-11 — #87 dock audio sink priority
+- **Task:** NEXT #87 — default audio follows dock plug/unplug.
+- **Did:** WirePlumber `90-nomarchy-dock-audio` (HDMI/DP session prio
+  1100, USB 1050) via `modules/nixos/dock-audio-rules.nix` + default.nix
+  pipewire. `checks.dock-audio` pure rule asserts + conf-file VM. V3
+  hotplug steps in HARDWARE-QUEUE. Closed #87.
+- **Verified:** **V2** — `nix flake check --no-build`; `checks.dock-audio`
+  green (pure rule asserts + conf installed under wireplumber.conf.d).
+- **Pending:** V3 real HDMI/USB-dock hotplug (HARDWARE-QUEUE).
+- **Next suggestion:** QA sweep or LATER wallpapers split if promoted.
+
 ## 2026-07-11 — #86 clamshell HandleLidSwitchDocked
 - **Task:** NEXT #86 — lid closed + external monitor must not suspend.
 - **Did:** Explicit `HandleLidSwitchDocked=ignore` in