diff --git a/docs/plans/2026-08-12-lock-guard-meeting-suppression-design.md b/docs/plans/2026-08-12-lock-guard-meeting-suppression-design.md
index e3a674e..0279fda 100644
--- a/docs/plans/2026-08-12-lock-guard-meeting-suppression-design.md
+++ b/docs/plans/2026-08-12-lock-guard-meeting-suppression-design.md
@@ -1,7 +1,31 @@
 # `lock-guard`: suppress lock during meetings
 
 Date: 2026-08-12
-Status: approved, ready to implement
+Status: implemented, with one deviation (see "Implementation note" below)
+
+## Implementation note: mic-active check uses `pmset`, not `ioreg`
+
+This document is the plan as approved on 2026-08-12 and is kept as the
+historical record. The shipped implementation deviates from it in one
+place: **the microphone-active signal.**
+
+- **Planned:** `ioreg -c IOAudioEngine -r -l`, matching an audio engine in
+  `running` state, stubbed in tests via `LOCK_SYNC_IOREG`.
+- **Shipped:** `pmset -g assertions`, matching
+  `coreaudiod.*preventuseridlesleep`, stubbed in tests via
+  `LOCK_SYNC_PMSET` (the same override already used for the
+  `pmset displaysleepnow` call, so there is no separate mic stub).
+
+**Why:** `IOAudioEngine` is a legacy Intel/kext-era class. On Apple Silicon
+the audio HAL runs in userspace and publishes no live `IOAudioEngine`
+instances, so the planned check never matched — it would have silently
+failed open on every current Mac. `pmset -g assertions` reports the power
+assertion `coreaudiod` takes while an audio input stream is open, which was
+verified against real mic open/close on Apple Silicon.
+
+Every `ioreg`, `IOAudioEngine`, and `LOCK_SYNC_IOREG` reference below is
+part of the superseded plan and does **not** describe the shipped code.
+See `check_mic_active` in `bin/lock-guard` for the real implementation.
 
 ## Purpose
 
@@ -33,6 +57,8 @@ call `pmset displaysleepnow` or skip it and log why.
 2. **Microphone actively in use** — `ioreg -c IOAudioEngine -r -l` shows an
    audio engine in `running` state. Catches apps not in the process list,
    and any call where you're actually speaking.
+   (**Superseded:** shipped as `pmset -g assertions` — see "Implementation
+   note" above.)
 3. **Google Meet tab open in Chrome** — `osascript` asks Chrome for open tab
    URLs and checks for the Meet in-call URL pattern
    (`meet.google.com/xxx-yyyy-zzz`, not the bare landing page). This is the
@@ -106,6 +132,13 @@ scripts under a `STUB_DIR`, matching `lock-fanout.bats`'s `make_ssh_stub`
 pattern. `pmset` itself is also stubbed the same way
 (`LOCK_SYNC_PMSET`), so tests can assert whether it was called or not.
 
+**Superseded:** `LOCK_SYNC_IOREG` was never implemented. Because the mic
+check shipped on `pmset -g assertions` (see "Implementation note" above),
+the mic-active stub is `LOCK_SYNC_PMSET` — the same override that already
+covers the `pmset displaysleepnow` call. `lock-guard` therefore has three
+overridable commands, not four: `LOCK_SYNC_PGREP`, `LOCK_SYNC_OSASCRIPT`,
+and `LOCK_SYNC_PMSET`.
+
 ## Config file: `~/.config/lock-sync/guard-processes`
 
 Same shape as the existing `~/.config/lock-sync/config` (plain text,
diff --git a/tests/lock-fanout.bats b/tests/lock-fanout.bats
index 7886f6a..6ceb665 100755
--- a/tests/lock-fanout.bats
+++ b/tests/lock-fanout.bats
@@ -153,6 +153,17 @@ mimolette.local"
 tilsit.local
 mimolette.local"
   export STUB_SSH_FAIL_HOST="tilsit.local"
+  # Pin the two non-failing clients to the steady state (remote checksum
+  # already matches local), so this test isolates the one variable it is
+  # about: a single host's SSH failure. Without this, asiago and mimolette
+  # answer their shasum call with empty stdout, which never matches
+  # local_sha, so provision_host pushes lock-guard to both on every run —
+  # the test would still pass (both paths end in ssh_exit=0) while
+  # silently exercising the push path instead of the steady-state path.
+  # STUB_SSH_FAIL_HOST is checked before the checksum stubs in the ssh
+  # stub, so tilsit still fails as intended.
+  local_sha=$(shasum -a 256 "$BATS_TEST_DIRNAME/../bin/lock-guard" | awk '{print $1}')
+  export STUB_SSH_CHECKSUM_ALL_MATCH="$local_sha"
   make_ssh_stub
 
   run "$SCRIPT"
@@ -166,6 +177,10 @@ mimolette.local"
   [[ "${lines[2]}" == *"ssh_exit=255"* ]]
   [[ "${lines[3]}" == *"client=mimolette.local"* ]]
   [[ "${lines[3]}" == *"ssh_exit=0"* ]]
+  # No client should have been pushed to: asiago and mimolette are pinned to
+  # the steady state, and tilsit fails its checksum check before any push.
+  run grep -q 'CMD=.*cat >' "$SSH_LOG"
+  [ "$status" -ne 0 ]
 }
 
 @test "host with config override uses override user in ssh target" {