diff --git a/plugins/computers/frontend/views/PCForm.vue b/plugins/computers/frontend/views/PCForm.vue
index 9b125aab..e1b84148 100644
--- a/plugins/computers/frontend/views/PCForm.vue
+++ b/plugins/computers/frontend/views/PCForm.vue
@@ -166,7 +166,7 @@
             >
               <option value="">Select vendor...</option>
               <option
-                v-for="v in vendors"
+                v-for="v in filteredVendors"
                 :key="v.vendorid"
                 :value="v.vendorid"
               >
@@ -452,6 +452,17 @@ const filteredModels = computed(() => {
   return models.value.filter(m => m.vendorid === form.value.vendorid)
 })
 
+// Only offer vendors that actually have PC-category models. models is already
+// scoped to category PC at load, so its vendorids are the PC vendor set. Keep
+// the record's own vendor even if it falls outside that set, so editing an
+// existing PC never silently drops its saved vendor.
+const filteredVendors = computed(() => {
+  const pcVendorIds = new Set(models.value.map(m => m.vendorid))
+  return vendors.value.filter(
+    v => pcVendorIds.has(v.vendorid) || v.vendorid === form.value.vendorid
+  )
+})
+
 onMounted(async () => {
   try {
     // Load reference data
@@ -460,7 +471,7 @@ onMounted(async () => {
       computersApi.types.list({ perpage: 100 }),
       assetsApi.statuses.list(),
       vendorsApi.list({ perpage: 100 }),
-      modelsApi.listAll(),  // backend caps perpage at 100; page through all
+      modelsApi.listAll({ category: 'PC' }),  // backend caps perpage at 100; page through all
       locationsApi.list({ perpage: 100 }),
       operatingsystemsApi.list({ perpage: 100 }),
       computersApi.protocols.list(),
diff --git a/plugins/machines/frontend/views/MachineForm.vue b/plugins/machines/frontend/views/MachineForm.vue
index cf8c28f2..ef012ff0 100644
--- a/plugins/machines/frontend/views/MachineForm.vue
+++ b/plugins/machines/frontend/views/MachineForm.vue
@@ -123,7 +123,7 @@
             >
               <option value="">Select vendor...</option>
               <option
-                v-for="v in vendors"
+                v-for="v in filteredVendors"
                 :key="v.vendorid"
                 :value="v.vendorid"
               >
@@ -168,7 +168,7 @@
             >
               <option value="">Select vendor...</option>
               <option
-                v-for="v in vendors"
+                v-for="v in filteredControllerVendors"
                 :key="v.vendorid"
                 :value="v.vendorid"
               >
@@ -446,16 +446,43 @@ const existingRelationshipId = ref(null)
 const loadedControllingPcId = ref(null)
 const currentMachine = ref(null)
 
-// Filter models by selected machine vendor
+// Filter models by selected machine vendor. Controller-type models are offered
+// only in the controller dropdown, so keep them out of the machine list.
 const filteredModels = computed(() => {
-  if (!form.value.vendorid) return models.value
-  return models.value.filter(m => m.vendorid === form.value.vendorid)
+  const machineModels = models.value.filter(m => m.modeltype !== 'Controller')
+  if (!form.value.vendorid) return machineModels
+  return machineModels.filter(m => m.vendorid === form.value.vendorid)
 })
 
-// Filter models by selected controller vendor
+// Filter models by selected controller vendor. Only Controller-type models are
+// valid here.
 const filteredControllerModels = computed(() => {
-  if (!form.value.controllervendorid) return models.value
-  return models.value.filter(m => m.vendorid === form.value.controllervendorid)
+  const controllerModels = models.value.filter(m => m.modeltype === 'Controller')
+  if (!form.value.controllervendorid) return controllerModels
+  return controllerModels.filter(m => m.vendorid === form.value.controllervendorid)
+})
+
+// Only offer vendors that have machine (non-controller Equipment) models. Keep
+// the record's own vendor even if it falls outside that set, so editing an
+// existing machine never silently drops its saved vendor.
+const filteredVendors = computed(() => {
+  const machineVendorIds = new Set(
+    models.value.filter(m => m.modeltype !== 'Controller').map(m => m.vendorid)
+  )
+  return vendors.value.filter(
+    v => machineVendorIds.has(v.vendorid) || v.vendorid === form.value.vendorid
+  )
+})
+
+// Only offer controller vendors that have Controller-type models. Keep the
+// record's own controller vendor even if it falls outside that set.
+const filteredControllerVendors = computed(() => {
+  const controllerVendorIds = new Set(
+    models.value.filter(m => m.modeltype === 'Controller').map(m => m.vendorid)
+  )
+  return vendors.value.filter(
+    v => controllerVendorIds.has(v.vendorid) || v.vendorid === form.value.controllervendorid
+  )
 })
 
 // Clear model selection when vendor changes
@@ -486,7 +513,7 @@ onMounted(async () => {
       assetsApi.statuses.list(),
       vendorsApi.list({ perpage: 500 }),
       locationsApi.list({ perpage: 500 }),
-      modelsApi.listAll(),  // backend caps perpage at 100; page through all
+      modelsApi.listAll({ category: 'Equipment' }),  // backend caps perpage at 100; page through all
       businessunitsApi.list({ perpage: 500 }),
       computersApi.listAll(),  // backend caps perpage at 100; page through all
       assetsApi.types.list()  // Used for relationship types, will fix below
diff --git a/plugins/printers/frontend/views/PrinterForm.vue b/plugins/printers/frontend/views/PrinterForm.vue
index 40eca7a7..316dbe74 100644
--- a/plugins/printers/frontend/views/PrinterForm.vue
+++ b/plugins/printers/frontend/views/PrinterForm.vue
@@ -134,7 +134,7 @@
             >
               <option value="">Select vendor...</option>
               <option
-                v-for="v in vendors"
+                v-for="v in filteredVendors"
                 :key="v.vendorid"
                 :value="v.vendorid"
               >
@@ -387,6 +387,17 @@ const filteredModels = computed(() => {
   })
 })
 
+// Only offer vendors that actually have Printer-category models. models is
+// already scoped to category Printer at load, so its vendorids are the printer
+// vendor set. Keep the record's own vendor even if it falls outside that set,
+// so editing an existing printer never silently drops its saved vendor.
+const filteredVendors = computed(() => {
+  const printerVendorIds = new Set(models.value.map(m => m.vendorid))
+  return vendors.value.filter(
+    v => printerVendorIds.has(v.vendorid) || v.vendorid === form.value.vendorid
+  )
+})
+
 // Get short description from model number for naming
 function getModelShortDesc(modelNumber) {
   if (!modelNumber) return ''
@@ -493,7 +504,7 @@ onMounted(async () => {
       printersApi.types.list({ perpage: 100 }),
       assetsApi.statuses.list(),
       vendorsApi.list({ perpage: 100 }),
-      modelsApi.listAll(),
+      modelsApi.listAll({ category: 'Printer' }),
       locationsApi.list({ perpage: 100 })
     ])
 
diff --git a/shopdb/core/api/models.py b/shopdb/core/api/models.py
index 7eac4806..a292fd83 100644
--- a/shopdb/core/api/models.py
+++ b/shopdb/core/api/models.py
@@ -8,7 +8,7 @@ from flask_jwt_extended import jwt_required
 from werkzeug.utils import secure_filename
 
 from shopdb.extensions import db
-from shopdb.core.models import Model
+from shopdb.core.models import Model, ModelType
 from shopdb.utils.responses import (
     success_response,
     error_response,
@@ -55,6 +55,12 @@ def list_models():
     if modeltype_id := request.args.get('modeltype', type=int):
         query = query.filter(Model.modeltypeid == modeltype_id)
 
+    # Scope to a model-type category (Equipment, PC, Network, Printer) so a
+    # subtype form only offers models that make sense for it. Models with no
+    # type are excluded, since a null category cannot satisfy the filter.
+    if category := request.args.get('category'):
+        query = query.join(ModelType).filter(ModelType.category == category)
+
     # Exact-match natural-key lookup for idempotent import. Natural key is
     # modelnumber + vendor; pair this with ?vendor=<id> to disambiguate.
     if exactmodelnumber := request.args.get('modelnumber'):
@@ -72,6 +78,7 @@ def list_models():
         d = m.to_dict()
         d['vendor'] = m.vendor.vendor if m.vendor else None
         d['modeltype'] = m.modeltype.modeltype if m.modeltype else None
+        d['category'] = m.modeltype.category if m.modeltype else None
         data.append(d)
 
     return paginated_response(data, page, per_page, total)