feat(menu): #76 slice 2 — Hibernate notifies on failure

Per the settled #76 UX call: keep the Power-menu Hibernate row
unconditional, but when hibernate fails (typically a swap=0 machine with
no disk swap), surface a notification pointing at the enable-hibernation
runbook instead of a silent no-op. On success `systemctl hibernate`
blocks until resume, so the notify only fires on a real failure.

Verification: V1 — homeConfigurations.nomarchy.activationPackage builds
(rebuilds nomarchy-menu; writeShellScriptBin runs bash -n). Control-flow
proved on the arm extracted from the built script: failing systemctl ->
notify fires, succeeding -> no notify. flake check --no-build green.
V2 hibernate->resume VM test + V3 laptop remain open (#76 slice 3).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

agent/BACKLOG.md

@@ -75,8 +75,13 @@ interplay handled in `modules/nixos/default.nix` / `modules/home/idle.nix`.
 1. ~~**Docs** — `docs/MIGRATION.md` hibernation-enable runbook (V0).~~ ✓
    shipped 2026-07-10 (§ "Enabling hibernation on an existing machine";
    commands verified live against the dev machine's LUKS+@swap layout).
-2. **Menu** — Hibernate row: notify-on-failure when no swap configured
-   (behavioral, V1/V2). Keep the row unconditional.
+2. ~~**Menu** — Hibernate row: notify-on-failure when no swap configured.~~
+   ✓ shipped 2026-07-10 (`rofi.nix` power arm: `systemctl hibernate ||
+   notify-send …`; success blocks until resume so the notify only fires on
+   real failure). V1 (HM generation builds; `writeShellScriptBin` bash -n) +
+   control-flow proof (fail→notify, success→no notify). Row kept unconditional.
+   The session-level "no-swap pick surfaces a mako notification" is folded
+   into the V3 laptop check below.
 3. **Verify (required)**
    - **V0:** eval / option / disko contracts.
    - **V2 (mandatory, agent):** exercise hibernation in the **VM harness**

agent/JOURNAL.md

@@ -17,6 +17,25 @@ Template:
 
 ---
 
+## 2026-07-10 — #76 slice 2: Hibernate notify-on-failure
+- **Task:** BACKLOG #76 remaining slice 2 — per the settled "keep row, notify
+  on failure" call.
+- **Did:** `modules/home/rofi.nix` power menu Hibernate arm now runs
+  `systemctl hibernate 2>/dev/null || notify-send "Hibernate" "…see
+  docs/MIGRATION.md"`. On success the call blocks until resume, so the notify
+  only fires on a genuine failure (e.g. swap=0 no-swap machine). Row stays
+  unconditional (no hiding).
+- **Verified:** **V1** — `nix build …homeConfigurations.nomarchy.activationPackage`
+  green (rebuilds `nomarchy-menu.drv`; `writeShellScriptBin` runs bash -n at
+  build). Control-flow proof on the arm extracted from the built script:
+  failing `systemctl` → notify fires; succeeding → no notify. `nix flake
+  check --no-build` green.
+- **Pending:** slice 3 = the V2 hibernate→resume VM test + V3 laptop
+  (Hibernate→power off→resume on the LUKS+@swap machine; plus confirm the
+  no-swap notify surfaces in a real session). Both remain open on #76.
+- **Next suggestion:** slice 3 — add a `checks.*` hibernate VM test (as far
+  as QEMU allows) and queue the V3 laptop steps in HARDWARE-QUEUE.
+
 ## 2026-07-10 — #76 slice 1: MIGRATION.md hibernation runbook
 - **Task:** BACKLOG #76 remaining slice 1 — docs runbook for enabling
   hibernation on an existing machine (per the settled "docs not tool" call).

modules/home/rofi.nix

@@ -252,7 +252,13 @@ let
           *Lock)      loginctl lock-session ;;
           *Logout)    hyprctl dispatch exit ;;
           *Suspend)   systemctl suspend ;;
-          *Hibernate) systemctl hibernate ;;
+          *Hibernate)
+            # zram can't hold a hibernate image; a machine installed with
+            # swap=0 has no disk swap. Attempt, and if logind rejects it,
+            # say why instead of a silent no-op. On success this blocks
+            # until resume, so the notify only fires on a real failure.
+            systemctl hibernate 2>/dev/null \
+              || notify-send "Hibernate" "Couldn't hibernate — likely no swap is configured. See docs/MIGRATION.md → Enabling hibernation." ;;
           *Reboot)    systemctl reboot ;;
           *Shutdown)  systemctl poweroff ;;
         esac ;;