diff --git a/CLAUDE.md b/CLAUDE.md
index f69a422..dbab7d0 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -101,9 +101,15 @@ protocol; the config in `deploy/mavend.json` (with `${VAR}` env expansion from g
 Count against compose, not against the table. Four of the nine daemons are absent, and each
 absence has a different reason.
 
-`mavmaild` is commented out in compose, with the reason written beside it: it needs a mail
-account and this box has none. `mavcaldav` appears nowhere at all, and unlike the other
-three that is an oversight rather than a decision (V-644).
+`mavmaild` and `mavcaldav` are commented out in compose, each with the reason written
+beside it: the first needs a mail account, the second a CalDAV account, and this box has
+neither. `mavcaldav` used to appear nowhere at all, which was an oversight; it became a
+recorded decision on 07-08-2026 (V-644). Two things ride on that absence and the block
+names them. Agenda questions route to `IntentQuery` at stage 0 (V-498) and the `calendar`
+query source then reads a table nobody writes. And `loop.State.CalendarBusy` is fed by the
+same facts, so the gate's "do not nag mid-meeting" is permanently false. Its password is
+read from a file (`-pass-file`, and `-render-pass-file` for the render collection), never
+taken as a flag value, which is the rule `mavpoll` and `mavmaild` follow too.
 
 **`mavwaked` and `mavenclient` are absent by decision, not oversight** (Vikunja #463,
 `docs/plans/17-where-the-voice-loop-runs.md`).
diff --git a/docker-compose.yml b/docker-compose.yml
index eb8a7aa..2eedef6 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -157,6 +157,44 @@ services:
   #     - maildata:/var/lib/mavmaild
   #     - ./deploy/imap.password:/run/secrets/imap.password:ro
 
+  # The calendar reader (Vikunja #644) is OFF and commented out: it needs a
+  # CalDAV account, and there is none on this box. It was built, listed in
+  # `make build`, and deployed nowhere, which is the worst of the three states —
+  # this block records the decision instead.
+  #
+  # What its absence costs, so the cost is visible from here:
+  #   - Agenda questions route correctly and answer from nothing. Stage 0 sends
+  #     "что у меня сегодня" to IntentQuery (V-498) and the `calendar` query
+  #     source reads facts(kind=env, source=caldav:*) that nobody writes.
+  #   - The nudge gate loses a suppressor. loop.State.CalendarBusy is fed by
+  #     those same facts, so "do not nag mid-meeting" is permanently false.
+  #
+  # Core never sees the CalDAV password: the reader polls the collection itself
+  # and hands core one fact per event over WriteFact. Nothing here can create a
+  # reminder, so a misread event cannot fire.
+  #
+  # The password is read from a FILE, so it never appears in `ps`, in this file,
+  # or in shell history — the same rule mavpoll and mavmaild follow.
+  #
+  # To enable: write the password to deploy/caldav.password (0600, gitignored),
+  # point -url at the collection, and uncomment this service. No mavend.json
+  # block is needed — events arrive over IPC as facts. -render-url is optional
+  # and OFF here: it publishes Maven's own reminders back as events, and it must
+  # not name the collection -url reads, or the poller reads its own writes back
+  # in (checkRenderTarget refuses that). It takes -render-pass-file, and falls
+  # back to this password when that is not given.
+  # mavcaldav:
+  #   <<: *image
+  #   command: ["mavcaldav", "-socket", "/run/maven/mavend.sock",
+  #             "-url", "http://localhost:5232/kami/personal",
+  #             "-user", "kami",
+  #             "-pass-file", "/run/secrets/caldav.password",
+  #             "-interval", "5m"]
+  #   depends_on: [mavend]
+  #   volumes:
+  #     - sockets:/run/maven
+  #     - ./deploy/caldav.password:/run/secrets/caldav.password:ro
+
 volumes:
   dbdata:
   sockets: