feat(power): clamshell — ignore lid suspend when docked (#86)

Explicit HandleLidSwitchDocked=ignore under services.logind so closing
the lid with an external display connected does not suspend. Undocked
lid path left to upstream defaults. checks.clamshell-logind asserts the
baked logind.conf and active logind; real multi-monitor lid V3 queued.

Verified: V2 — flake check --no-build; checks.clamshell-logind green.
V3 pending: HARDWARE-QUEUE #86 lid+external on a laptop.

README.md

@@ -284,7 +284,7 @@ option, e.g. `services.easyeffects.enable = lib.mkForce false;` — see
 | `nomarchy.system.snapper.enable` | `false` | Hourly/daily BTRFS timeline snapshots + `nixos-rebuild-snap` (installer enables it; no-op unless root is BTRFS) |
 | `nomarchy.system.power.enable` | `true` | Active power management (see below) |
 | `nomarchy.system.power.backend` | `"ppd"` | `"ppd"` (power-profiles-daemon + menu/Waybar switcher) or `"tlp"` (deeper battery tuning, no switcher) — mutually exclusive |
-| `nomarchy.system.power.laptop` | `false` | Marks a laptop, gating battery-only features; the installer sets it when a battery is present |
+| `nomarchy.system.power.laptop` | `false` | Marks a laptop, gating battery-only features; the installer sets it when a battery is present. With power management on, clamshell is also configured: lid close ignores suspend when logind considers the machine docked (external display) — `HandleLidSwitchDocked=ignore` |
 | `nomarchy.system.power.thermal.enable` | `false` | thermald (Intel-only); the installer enables it on a GenuineIntel CPU |
 | `nomarchy.system.power.batteryChargeLimit` | `null` | Stop charging at this % (e.g. `80`) where the hardware supports it; needs `power.laptop` |
 | `nomarchy.hardware.intel.enable` | `false` | Intel enablement above nixos-hardware (GuC/HuC firmware via `i915.enable_guc=3` — `.guc` toggles just that; the installer unsets it on `xe`-driver GPUs); the installer sets it on an Intel CPU/GPU |

agent/BACKLOG.md

@@ -55,13 +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.
 
-### 86. Clamshell dock: lid + external monitor (`VISION § C`)
-Lid closed with external monitor connected must not suspend
-(`logind` `lidSwitchDocked` / `ExternalPower` audit + display-profile
-interplay); wake behaves. Display profiles + auto-switch already exist —
-this is the lid/suspend edge case. VM where possible; residual V3 on
-real dock hardware.
-
 ### 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.
@@ -118,8 +111,8 @@ 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 shipped 2026-07-11. #84 split → **NEXT #86–#87** dock
-  clamshell + dock audio.)_
+_(#80–#83 + #85–#86 shipped 2026-07-11. Remaining dock slice: **#87**
+  dock audio. #86 V3 clamshell on real external display → HARDWARE-QUEUE.)_
 
 ### v1.0 pointer
 

agent/HARDWARE-QUEUE.md

@@ -11,6 +11,14 @@ the **T14s** (webcam case).
 
 ## Any machine (dev box is fine)
 
+- [ ] **#86 clamshell lid + external display** — V2 asserts
+      `HandleLidSwitchDocked=ignore` in logind.conf. On a laptop with a
+      real external monitor: open a session, plug external, close lid —
+      machine must **stay awake** (no suspend); external panel remains
+      usable (or wakes with keyboard if DPMS). Unplug external, close lid
+      — 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.
 - [ ] **#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 +19,18 @@ Template:
 
 ---
 
+## 2026-07-11 — #86 clamshell HandleLidSwitchDocked
+- **Task:** NEXT #86 — lid closed + external monitor must not suspend.
+- **Did:** Explicit `HandleLidSwitchDocked=ignore` in
+  `modules/nixos/power.nix` (logind settings.Login). Undocked lid
+  behaviour unchanged. idle.nix comment corrected. `checks.clamshell-logind`
+  asserts conf + active logind. V3 steps in HARDWARE-QUEUE. Closed #86.
+- **Verified:** **V2** — `nix flake check --no-build`;
+  `checks.clamshell-logind` green (`HandleLidSwitchDocked=ignore` +
+  logind active).
+- **Pending:** V3 real lid+external on laptop (HARDWARE-QUEUE).
+- **Next suggestion:** #87 dock audio sink follow.
+
 ## 2026-07-11 — #85 hardware hall of fame + split #84
 - **Task:** NEXT #85 docs hall of fame; #84 was `[big]` → split.
 - **Did:** HARDWARE.md §9 install-tested table (T14s Gen 4 AMD, Latitude

docs/ROADMAP.md

@@ -389,6 +389,11 @@ Design/decision records and a running log of shipped work (items marked
   ✓ **Hardware hall of fame (#85, `VISION § F`):** HARDWARE.md §9
   install-tested table (T14s Gen 4, Latitude 5410/5310) + “send your DMI
   line” PR invite; §10 points contributors at the table.
+  ✓ **Clamshell logind (#86, `VISION § C`):** explicit
+  `services.logind.settings.Login.HandleLidSwitchDocked = "ignore"` when
+  power management is on (systemd docked = external display present).
+  Undocked lid suspend left to upstream. `checks.clamshell-logind` asserts
+  logind.conf + active logind. Real lid+external V3 in HARDWARE-QUEUE.
 - ✓ **Hibernate double-unlock:** on resume from hibernate the LUKS
   passphrase already gates the machine, but locking hyprlock before sleep
   meant a second password. Fixed by *not locking* before an encrypted

docs/VISION.md

@@ -80,7 +80,7 @@ Reference: [HARDWARE.md](HARDWARE.md) §4–§5, §11 (doctor).
 
 | Idea | Intent | Notes |
 |------|--------|-------|
-| **Dock life** | Lid closed + external only, wake, default audio sink on undock | Display profiles exist — polish edge cases |
+| **Dock life** | Lid closed + external only, wake, default audio sink on undock | ✓ #86 clamshell logind ignore when docked; #87 audio still open |
 | **Hibernate/sleep confidence** | Doctor: resume device, swap size, clean suspend journal | Trust > new power UI |
 | **Battery health readout** ✓ | Cycles + design capacity % in doctor where sysfs allows | ✓ shipped #80 (report-only; charge limit is a separate row) |
 | **Charge-limit instant apply** | Already PROPOSED `[blocked:hw]` | Keep privilege tradeoff explicit |

flake.nix

@@ -510,6 +510,33 @@
             '';
           };
 
+          # Clamshell / dock lid policy (#86): logind must ignore lid close
+          # when docked (external display present). Real multi-monitor lid
+          # events stay V3; this asserts the baked logind.conf + that
+          # logind is alive to consume it. Imports options + power only.
+          clamshell-logind = pkgs.testers.runNixOSTest {
+            name = "nomarchy-clamshell-logind";
+            nodes.machine = { ... }: {
+              imports = [ ./modules/nixos/options.nix ./modules/nixos/power.nix ];
+              nomarchy.system.power = {
+                enable = true;
+                laptop = true;
+              };
+            };
+            testScript = ''
+              machine.wait_for_unit("multi-user.target")
+              machine.wait_for_unit("systemd-logind.service")
+              conf = machine.succeed("cat /etc/systemd/logind.conf")
+              assert "HandleLidSwitchDocked=ignore" in conf.replace(" ", ""), (
+                  f"clamshell: logind.conf missing HandleLidSwitchDocked=ignore:\n{conf}"
+              )
+              # logind must be running (policy is dead if the unit is down).
+              machine.succeed("systemctl is-active systemd-logind.service")
+              # busctl property: Docked lid policy is not always exported;
+              # re-read conf after logind start is enough for the contract.
+            '';
+          };
+
           # Runtime VM check for the battery-charge-limit re-apply: the udev
           # rule must restart the oneshot on an AC state change (firmware can
           # clear the threshold on unplug). The `test_power` module fakes a

modules/home/idle.nix

@@ -85,8 +85,9 @@ in
           # Suspend only on battery, and sooner than the old fixed 30 min
           # (it now only fires unplugged). Plugged in, the machine stays
           # up — long builds, media, presentations aren't killed mid-idle.
-          # Closing the lid still suspends on AC (logind's default): that's
-          # an explicit "I'm done", distinct from sitting idle.
+          # Lid close is logind's job (not hypridle): undocked lid still
+          # suspends (HandleLidSwitch); docked/clamshell lid is ignore
+          # (HandleLidSwitchDocked — modules/nixos/power.nix, #86).
           { timeout = 900; on-timeout = "${onAc} || systemctl suspend"; }
         ];
       };

modules/nixos/power.nix

@@ -31,6 +31,20 @@ in
     services.power-profiles-daemon.enable = lib.mkDefault ppd;
     services.tlp.enable = lib.mkDefault tlp;
 
+    # Clamshell / dock (BACKLOG #86): when the machine is "docked" in
+    # logind's sense (≥1 external display connected), closing the lid
+    # must NOT suspend — the external panel is the session. systemd's
+    # built-in default is already ignore; we set it explicitly so a
+    # downstream override or lock-bump drift is visible, and so
+    # checks.clamshell-logind can assert the contract.
+    # Lid alone (undocked) keeps the normal suspend path
+    # (HandleLidSwitch / ExternalPower left to upstream defaults).
+    # Display-profile "docked" layouts (eDP off) are orthogonal and
+    # already handled by nomarchy.displayProfiles.
+    services.logind.settings.Login = {
+      HandleLidSwitchDocked = lib.mkDefault "ignore";
+    };
+
     # thermald is Intel-only, so off unless asked (the installer enables
     # it on a GenuineIntel CPU). Sits happily next to either backend.
     services.thermald.enable = lib.mkDefault cfg.thermal.enable;