diff --git a/tabbycat/draw/templates/DraggableTeam.vue b/tabbycat/draw/templates/DraggableTeam.vue
index 45e9e1c0d78..ce3bbd7605e 100644
--- a/tabbycat/draw/templates/DraggableTeam.vue
+++ b/tabbycat/draw/templates/DraggableTeam.vue
@@ -1,6 +1,8 @@
 <template>
-  <draggable-item :drag-payload="dragPayload" :class="[{'bg-dark text-white': isUnavailable},
-                                                       highlightsCSS, conflictsCSS, hoverConflictsCSS]"
+  <draggable-item :drag-payload="dragPayload"
+                  :hover-panel="true" :hover-panel-item="hoverableData" :hover-panel-type="'team'"
+                  :hover-conflicts="true" :hover-conflicts-item="clashableID" :hover-conflicts-type="'team'"
+                  :class="[{'bg-dark text-white': isUnavailable}, highlightsCSS, conflictsCSS, hoverConflictsCSS]"
                   :enable-hover="true" :hover-item="hoverableData" :hover-type="hoverableType">
 
       <span slot="number" class="d-none"><span></span></span>
@@ -17,9 +19,10 @@ import { mapState } from 'vuex'
 import DraggableItem from '../../templates/allocations/DraggableItem.vue'
 import HighlightableMixin from '../../templates/allocations/HighlightableMixin.vue'
 import HoverablePanelMixin from '../../templates/allocations/HoverablePanelMixin.vue'
+import HoverableConflictReceiverMixin from '../../templates/allocations/HoverableConflictReceiverMixin.vue'
 
 export default {
-  mixins: [HoverablePanelMixin, HighlightableMixin],
+  mixins: [HoverablePanelMixin, HighlightableMixin, HoverableConflictReceiverMixin],
   components: { DraggableItem },
   props: {
     item: Object,
@@ -49,6 +52,12 @@ export default {
     highlightData: function () {
       return this.item
     },
+    clashableType: function () {
+      return 'team'
+    },
+    clashableID: function () {
+      return this.item && this.item.id ? this.item.id : null
+    },
     hoverableData: function () {
       return this.item
     },
@@ -62,6 +71,46 @@ export default {
         return this.gettext('Unaffiliated')
       }
     },
+    conflictsCSS: function () {
+      // Panel-level team-vs-team conflicts within the same debate
+      const debateId = this.dragPayload && this.dragPayload.assignment
+      if (!debateId || !this.item) { return '' }
+      const debate = this.$store.getters.allDebatesOrPanels[debateId]
+      if (!debate || !debate.teams) { return '' }
+
+      // Collect other team IDs in this debate
+      const otherIds = []
+      for (const pos in debate.teams) {
+        const tid = debate.teams[pos]
+        if (tid !== null && tid !== this.item.id) { otherIds.push(tid) }
+      }
+      if (otherIds.length === 0) { return '' }
+
+      // Same-institution (orange)
+      if (this.item.institution) {
+        for (const oid of otherIds) {
+          const ot = this.$store.getters.allocatableItems[oid]
+          if (ot && ot.institution && ot.institution === this.item.institution) {
+            return 'conflictable panel-institution'
+          }
+        }
+      }
+
+      // History (blue shades): pick most recent ago among opponents in this debate
+      const histories = this.$store.getters.teamHistoriesForItem(this.item.id)
+      if (histories && histories.team) {
+        let smallestAgo = 99
+        for (const h of histories.team) {
+          if (otherIds.includes(h.id) && h.ago < smallestAgo) {
+            smallestAgo = h.ago
+          }
+        }
+        if (smallestAgo !== 99) {
+          return `conflictable panel-histories-${smallestAgo}-ago`
+        }
+      }
+      return ''
+    },
     ...mapState(['extra']),
   },
 }
diff --git a/tabbycat/draw/templates/EditDebateTeamsContainer.vue b/tabbycat/draw/templates/EditDebateTeamsContainer.vue
index e08bcb6e9d5..bb768483c2c 100644
--- a/tabbycat/draw/templates/EditDebateTeamsContainer.vue
+++ b/tabbycat/draw/templates/EditDebateTeamsContainer.vue
@@ -4,7 +4,22 @@
                         :unallocatedComponent="unallocatedComponent"
                         :handle-unused-drop="moveTeam">
 
-    <drag-and-drop-actions slot="actions" :count="debatesOrPanelsCount"></drag-and-drop-actions>
+    <drag-and-drop-actions slot="actions" :count="debatesOrPanelsCount">
+      <template slot="default-highlights">
+        <button
+          class="btn conflictable conflicts-toolbar hover-histories-2-ago"
+          data-toggle="tooltip"
+          v-text="gettext('Seen')"
+          :title="'Has been in the same debate previously.'"
+        />
+        <button
+          class="btn conflictable conflicts-toolbar hover-institution"
+          data-toggle="tooltip"
+          v-text="gettext('Institution')"
+          :title="'Is from the same institution.'"
+        />
+      </template>
+    </drag-and-drop-actions>
 
    <template slot="extra-messages">
       <div id="alertdiv" class="alert alert-warning show">
diff --git a/tabbycat/draw/views.py b/tabbycat/draw/views.py
index d73ea8c72fe..3c50b5246e5 100644
--- a/tabbycat/draw/views.py
+++ b/tabbycat/draw/views.py
@@ -1,7 +1,7 @@
 import datetime
 import logging
 import unicodedata
-from itertools import product
+from itertools import combinations, product
 from zoneinfo import ZoneInfo
 
 from django.contrib import messages
@@ -898,9 +898,39 @@ class EditDebateTeamsView(DebateDragAndDropMixin, AdministratorMixin, TemplateVi
     prefetch_teams = False # Fetched in full as get_serialised
     edit_permission = Permission.EDIT_DEBATETEAMS
 
+    def _get_team_histories_map(self):
+        now_seq = self.round.seq
+        histories = {}
+        debates = Debate.objects.filter(
+            round__tournament=self.tournament,
+            round__seq__lt=now_seq,
+        ).select_related('round').prefetch_related('debateteam_set')
+
+        for debate in debates:
+            team_ids = [dt.team_id for dt in debate.debateteam_set.all()]
+            if len(team_ids) < 2:
+                continue
+            ago = now_seq - debate.round.seq
+            for a, b in combinations(team_ids, 2):
+                histories.setdefault(a, {'team': []})['team'].append({'id': b, 'ago': ago})
+                histories.setdefault(b, {'team': []})['team'].append({'id': a, 'ago': ago})
+        return histories
+
+    def get_extra_info(self):
+        info = super().get_extra_info()
+        teams = Team.objects.filter(tournament=self.tournament).only('id', 'institution_id')
+        team_institution_clashes = {}
+        for t in teams:
+            if t.institution_id:
+                team_institution_clashes[t.id] = {'institution': [{'id': t.institution_id}]}
+        team_histories = self._get_team_histories_map()
+        info['clashes'] = {'teams': team_institution_clashes, 'adjudicators': {}}
+        info['histories'] = {'teams': team_histories, 'adjudicators': {}}
+        return info
+
     def get_serialised_allocatable_items(self):
         # TODO: account for shared teams
-        teams = Team.objects.filter(tournament=self.tournament).prefetch_related('speaker_set')
+        teams = Team.objects.filter(tournament=self.tournament).prefetch_related('speaker_set', 'break_categories')
         teams = annotate_availability(teams, self.round)
         populate_win_counts(teams)
         serialized_teams = EditDebateTeamsTeamSerializer(teams, many=True)