docs(agent): propose 3 more deep-dive workstation tasks

- [usefulness] Hardware security key support (pcscd + u2f)
- [usefulness] Microphone noise cancellation (easyeffects)
- [stability] Drive health monitoring (smartd)

agent/BACKLOG.md

@@ -362,6 +362,27 @@ implement. Bernardo moves accepted items into a tier.*
   polish. Cost: moderate — requires `hardware.i2c.enable = true`, adding
   `ddcutil` to udev/groups, and building a UI path to control it.
 
+- **[usefulness] Hardware security key support (`pcscd` + `u2f`)**:
+  Currently, there is no setup for FIDO2/U2F hardware tokens (like Yubikeys).
+  Without `services.pcscd.enable = true`, these tokens often silently fail to
+  authenticate in WebAuthn (browsers), SSH, and GPG. Enabling this (and
+  `hardware.u2f.enable`) provides zero-friction physical 2FA support, which is
+  a critical requirement for a secure developer workstation.
+
+- **[usefulness] Microphone noise cancellation (`easyeffects`)**:
+  PipeWire is robust, but it lacks out-of-the-box noise reduction for
+  microphones. Adding `easyeffects` with a noise cancellation plugin (like
+  `rnnoise`) provides system-wide background noise filtering for voice calls
+  (Zoom, Teams, Discord). This is a massive quality-of-life boost for remote
+  workers that elevates the audio stack from "functioning" to "premium".
+
+- **[stability] Drive health monitoring (`smartd`)**:
+  While BTRFS auto-scrub prevents silent bitrot, it doesn't warn about
+  impending physical hardware failure. Enabling `services.smartd.enable = true`
+  with desktop notifications (via `-M exec` custom scripts or local mail)
+  provides early warnings when an NVMe/SSD starts throwing SMART errors, giving
+  the user a critical window to back up data before the drive dies.
+
 ## Decisions `[human]`
 
 Open calls only Bernardo can make; agents add options/evidence but never

agent/JOURNAL.md

@@ -17,9 +17,9 @@ Template:
 
 ---
 
-## 2026-07-08 — Stability + usefulness survey → 3 PROPOSED (iteration #74)
+## 2026-07-08 — Stability + usefulness survey → 6 PROPOSED (iteration #74)
-- **Task:** Bernardo requested new actionable items for stability and workstation feature-completeness.
+- **Task:** Bernardo requested new actionable items for stability and workstation feature-completeness, including a deeper dive.
-- **Did:** Researched the codebase for gaps. Pitched three new PROPOSED items: BTRFS auto-scrub (stability), udiskie automounter (usefulness), and ddcutil external display brightness control (usefulness).
+- **Did:** Researched the codebase for gaps. Pitched six new PROPOSED items: BTRFS auto-scrub, udiskie automounter, ddcutil external display control, pcscd+u2f security key support, easyeffects mic noise cancellation, and smartd drive health monitoring.
 - **Verified:** n/a (research only).
 - **Pending:** awaiting Bernardo's triage to elevate to the active queue.
 - **Next suggestion:** triage the PROPOSED items.