diff --git a/backend/app/routers/dewar.py b/backend/app/routers/dewar.py
index 5dd7b8c..ce7299e 100644
--- a/backend/app/routers/dewar.py
+++ b/backend/app/routers/dewar.py
@@ -595,14 +595,23 @@ async def assign_beamtime_to_dewar(
     db: Session = Depends(get_db),
 ):
     dewar = db.query(DewarModel).filter(DewarModel.id == dewar_id).first()
-    if not dewar:  # <- Move check earlier!
+    if not dewar:
         raise HTTPException(status_code=404, detail="Dewar not found")
-    if beamtime_id == 0:
-        dewar.beamtime_id = None
-    else:
-        dewar.beamtime_id = beamtime_id
+
+    dewar.beamtime_id = None if beamtime_id == 0 else beamtime_id
     db.commit()
     db.refresh(dewar)
+    for puck in dewar.pucks:
+        puck.beamtime_id = None if beamtime_id == 0 else beamtime_id
+        for sample in puck.samples:
+            has_sample_event = (
+                db.query(SampleEvent).filter(SampleEvent.sample_id == sample.id).count()
+                > 0
+            )
+            if not has_sample_event:
+                sample.beamtime_id = None if beamtime_id == 0 else beamtime_id
+
+    db.commit()
     return {"status": "success", "dewar_id": dewar.id, "beamtime_id": beamtime_id}
 
 
diff --git a/backend/app/routers/puck.py b/backend/app/routers/puck.py
index 953bd00..5da02dd 100644
--- a/backend/app/routers/puck.py
+++ b/backend/app/routers/puck.py
@@ -20,6 +20,7 @@ from app.models import (
     Sample as SampleModel,
     LogisticsEvent as LogisticsEventModel,
     Dewar as DewarModel,
+    SampleEvent,
 )
 from app.dependencies import get_db
 import logging
@@ -669,10 +670,16 @@ async def assign_beamtime_to_puck(
     puck = db.query(PuckModel).filter(PuckModel.id == puck_id).first()
     if not puck:
         raise HTTPException(status_code=404, detail="Puck not found")
-    if beamtime_id == 0:
-        puck.beamtime_id = None
-    else:
-        puck.beamtime_id = beamtime_id
+
+    puck.beamtime_id = None if beamtime_id == 0 else beamtime_id
     db.commit()
     db.refresh(puck)
+    # Update samples
+    for sample in puck.samples:
+        has_sample_event = (
+            db.query(SampleEvent).filter(SampleEvent.sample_id == sample.id).count() > 0
+        )
+        if not has_sample_event:
+            sample.beamtime_id = None if beamtime_id == 0 else beamtime_id
+    db.commit()
     return {"status": "success", "puck_id": puck.id, "beamtime_id": beamtime_id}
diff --git a/frontend/src/components/Calendar.tsx b/frontend/src/components/Calendar.tsx
index 3c06b7c..cbd6945 100644
--- a/frontend/src/components/Calendar.tsx
+++ b/frontend/src/components/Calendar.tsx
@@ -268,12 +268,11 @@ const Calendar: React.FC = () => {
             return;
         }
 
-        // Find out if it's already assigned to this shift!
+        // Get current association state
         const prev = eventAssociations[selectedEventId] || { dewars: [], pucks: [] };
         const isAssigned = prev.pucks.includes(puckId);
 
         if (!isAssigned) {
-            // Assign it immediately
             assignPuckToBeamtime(Number(puckId), Number(beamtimeId))
                 .then(() => {
                     setEventAssociations(prevAssoc => {
@@ -291,7 +290,6 @@ const Calendar: React.FC = () => {
                     console.error("Failed to assign puck to beamtime", e);
                 });
         } else {
-            // Unassign (patch to None) immediately
             unassignPuckFromBeamtime(Number(puckId))
                 .then(() => {
                     setEventAssociations(prevAssoc => {
@@ -387,10 +385,8 @@ const Calendar: React.FC = () => {
                     <h4>Select Dewars</h4>
                     <ul>
                         {shipments.map(dewar => {
-                            // Are *all* pucks assigned to this event? (Assigned at Dewar level)
-                            const thisEvent = eventAssociations[selectedEventId] || {dewars: [], pucks: []};
+                            const thisEvent = eventAssociations[selectedEventId] || { dewars: [], pucks: [] };
                             const dewarAssigned = thisEvent.dewars.includes(dewar.id);
-                            const puckAssignments = thisEvent.pucks;
 
                             return (
                                 <li key={dewar.id}>
@@ -405,8 +401,20 @@ const Calendar: React.FC = () => {
                                     {!dewarAssigned && dewar.pucks && dewar.pucks.length > 0 && (
                                         <ul>
                                             {(dewar.pucks || []).map(puck => {
-                                                const isAssigned =
-                                                    !!eventAssociations[selectedEventId]?.pucks.includes(puck.id);
+                                                // Find eventId for this puck, if assigned
+                                                const associatedEventId = Object.keys(eventAssociations).find(eid =>
+                                                    eventAssociations[eid]?.pucks.includes(puck.id)
+                                                );
+                                                const associatedEvent = associatedEventId
+                                                    ? events.find(ev => ev.id === associatedEventId)
+                                                    : null;
+
+                                                const associatedShift = associatedEvent?.beamtime_shift;
+                                                const associatedDate = associatedEvent?.start;
+                                                const associatedBeamline = associatedEvent?.beamline;
+
+                                                const currentShift = eventDetails?.beamtime_shift;
+                                                const isAssignedToCurrentShift = associatedShift && currentShift && associatedShift === currentShift;
 
                                                 return (
                                                     <div key={puck.id} style={{ display: 'flex', alignItems: 'center' }}>
@@ -415,32 +423,67 @@ const Calendar: React.FC = () => {
                                                             type="button"
                                                             style={{
                                                                 marginLeft: 8,
-                                                                background: isAssigned ? '#4CAF50' : '#e0e0e0',
-                                                                color: isAssigned ? 'white' : 'black',
-                                                                border: isAssigned ? '1px solid #388e3c' : '1px solid #bdbdbd',
+                                                                background: isAssignedToCurrentShift ? '#4CAF50' : (associatedShift ? '#B3E5B3' : '#e0e0e0'),
+                                                                color: isAssignedToCurrentShift ? 'white' : 'black',
+                                                                border: isAssignedToCurrentShift ? '1px solid #388e3c' : '1px solid #bdbdbd',
                                                                 borderRadius: 4,
                                                                 padding: '4px 10px',
                                                                 cursor: 'pointer',
                                                                 transition: 'background 0.2s',
                                                             }}
-                                                            onClick={() => handlePuckAssignment(dewar.id, puck.id)}
+                                                            onClick={() => handlePuckAssignment(puck.id)}
                                                         >
-                                                            {isAssigned ? puck.puck_name : puck.puck_name}
+                                                            {puck.puck_name}
                                                         </button>
-                                                        {/* Optionally show assignment info, as before */}
-                                                        {findAssociatedEventForPuck(puck.id) && (
-                                                            <span style={{marginLeft: 8, color: 'green'}}>← Assigned to shift: {findAssociatedEventForPuck(puck.id)}</span>
+                                                        {associatedEvent && (
+                                                            <span
+                                                                style={{
+                                                                    marginLeft: 8,
+                                                                    color: isAssignedToCurrentShift ? 'green' : '#388e3c',
+                                                                    fontWeight: isAssignedToCurrentShift ? 700 : 400
+                                                                }}
+                                                            >
+                      ← Assigned to shift: {associatedShift}
+                                                                {associatedDate && (
+                                                                    <> on {new Date(associatedDate).toLocaleDateString()}</>
+                                                                )}
+                                                                {associatedBeamline && (
+                                                                    <> ({associatedBeamline})</>
+                                                                )}
+                    </span>
                                                         )}
                                                     </div>
                                                 );
                                             })}
-
                                         </ul>
                                     )}
-                                    {/* Show associated shift, if any */}
-                                    {findAssociatedEventForDewar(dewar.id) && (
-                                        <span style={{marginLeft: 8, color: 'green'}}>← Assigned to shift: {findAssociatedEventForDewar(dewar.id)}</span>
-                                    )}
+                                    {/* Show associated shift, date, and beamline for Dewar, if any */}
+                                    {(() => {
+                                        const associatedEventId = Object.keys(eventAssociations).find(eid =>
+                                            eventAssociations[eid]?.dewars.includes(dewar.id)
+                                        );
+                                        const associatedEvent = associatedEventId
+                                            ? events.find(ev => ev.id === associatedEventId)
+                                            : null;
+                                        const associatedShift = associatedEvent?.beamtime_shift;
+                                        const associatedDate = associatedEvent?.start;
+                                        const associatedBeamline = associatedEvent?.beamline;
+
+                                        const currentShift = eventDetails?.beamtime_shift;
+                                        const isAssignedToCurrentShift = associatedShift && currentShift && associatedShift === currentShift;
+
+                                        return associatedEvent && (
+                                            <span style={{ marginLeft: 8, color: isAssignedToCurrentShift ? 'green' : '#388e3c', fontWeight: isAssignedToCurrentShift ? 700 : 400 }}>
+              ← Assigned to shift: {associatedShift}
+                                                {associatedDate && (
+                                                    <> on {new Date(associatedDate).toLocaleDateString()}</>
+                                                )}
+                                                {associatedBeamline && (
+                                                    <> ({associatedBeamline})</>
+                                                )}
+            </span>
+                                        );
+                                    })()}
                                 </li>
                             );
                         })}