From da59dea46f55c64a3090b83a6321fbecd2ee6f60 Mon Sep 17 00:00:00 2001
From: erdgeist <erdgeist@erdgeist.org>
Date: Sun, 2 Aug 2026 22:45:51 +0200
Subject: Witness calendar entries

---
 app/models/event.rb       | 77 +++++++++++++++++++++++++++++++++++++++++++++++
 app/models/node_action.rb | 30 ++++++++++++++++++
 2 files changed, 107 insertions(+)

(limited to 'app/models')

diff --git a/app/models/event.rb b/app/models/event.rb
index b8651a81..7726f9bf 100644
--- a/app/models/event.rb
+++ b/app/models/event.rb
@@ -20,8 +20,85 @@ class Event < ApplicationRecord
     title.presence || node&.head&.title || "Untitled event"
   end
 
+  def save_witnessed(actor:)
+    saved = false
+    transaction do
+      saved = save
+      raise ActiveRecord::Rollback unless saved
+      witness_event!("event_create", actor)
+    end
+    saved
+  end
+
+  def update_witnessed(attributes, actor:)
+    updated = false
+    transaction do
+      updated = update(attributes)
+      raise ActiveRecord::Rollback unless updated
+      changes = event_changes
+      witness_event!("event_update", actor, changes) if changes.any?
+    end
+    updated
+  end
+
+  def destroy_witnessed(actor:)
+    destroyed = false
+    transaction do
+      witness_event!("event_destroy", actor)
+      destroyed = destroy
+      raise ActiveRecord::Rollback unless destroyed
+    end
+    destroyed
+  end
+
   private
     def generate_occurrences
       Occurrence.generate self
     end
+
+    def event_snapshot
+      {
+        :event_title => title.presence || node&.unique_name || "##{id}",
+        :start_time  => start_time&.iso8601,
+        :end_time    => end_time&.iso8601,
+        :allday      => allday,
+        :rrule       => rrule.presence,
+        :location    => location.presence,
+        :url         => url.presence,
+        :event_tags  => tag_list.to_a.sort,
+        :path        => node&.unique_name
+      }.compact
+    end
+
+    def event_changes
+      pairs = {}
+
+      saved_changes.except("updated_at", "created_at", "description")
+                   .each do |attribute, (before, after)|
+        key, pair =
+          case attribute
+          when "node_id"
+            ["node_path", { "from" => Node.find_by(:id => before)&.unique_name,
+                            "to"   => Node.find_by(:id => after)&.unique_name }]
+          when "start_time", "end_time"
+            [attribute, { "from" => before&.iso8601, "to" => after&.iso8601 }]
+          when "tag_list"
+            ["tags", { "from" => Array(before).sort, "to" => Array(after).sort }]
+          else
+            [attribute, { "from" => before, "to" => after }]
+          end
+        pairs[key] = pair
+      end
+
+      extra = {}
+      extra[:changes] = pairs if pairs.any?
+      extra[:description_changed] = true if saved_changes.key?("description")
+      extra
+    end
+
+    def witness_event!(verb, actor, extra = {})
+      NodeAction.record!(:node => node, :participants => [node, self].compact,
+                          :action => verb, :user => actor,
+                          **event_snapshot, **extra)
+    end
 end
diff --git a/app/models/node_action.rb b/app/models/node_action.rb
index 82a3ef44..0167762b 100644
--- a/app/models/node_action.rb
+++ b/app/models/node_action.rb
@@ -107,6 +107,36 @@ class NodeAction < ApplicationRecord
   # participant differ:
   #   "target_login" -- flat string, the affected account's login
   #
+  # "event_create" / "event_update" / "event_destroy" (calendar
+  # entries; participants: the Event and, when it has one, its Node,
+  # which also fills the node column. Deliberately not gated --
+  # events reach chapter pages and widgets, never the feeds, and
+  # protection here follows emission, not position).
+  #
+  # Events carry no revisions, so the log is their only history:
+  # every entry holds a full snapshot of the state it produced, and
+  # walking an event's entries reconstructs it. Times are ISO 8601
+  # and the rrule is raw, never humanised -- entries are read in both
+  # locales and event_schedule_text resolves that at render time.
+  #   "event_title" -- flat string; the title, else the node's
+  #                    unique_name, else "#<id>"
+  #   "start_time", "end_time" -- ISO 8601, when set
+  #   "allday"      -- boolean
+  #   "rrule"       -- raw RRULE, when set
+  #   "location", "url" -- flat strings, when set
+  #   "event_tags"  -- array of names, sorted, always. Named apart
+  #                    from the node verbs' "tags", which is a pair,
+  #                    so one renderer cannot mistake the other.
+  #   "path"        -- the node's unique_name, when it has a node
+  #
+  # On "event_update" only, and only when something changed -- an
+  # update that changes nothing records no entry at all:
+  #   "changes"     -- {field => pair}, node_id resolved to paths
+  #                    under "node_path", tag_list under "tags",
+  #                    times as ISO 8601
+  #   "description_changed" -- boolean; prose, flagged not quoted,
+  #                    as abstract_changed and body_changed are
+  #
   # Reserved: "demote" (via "trash" | "depublish") for an explicit
   # depublish workflow, if ever built.
   #
-- 
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