1 files changed, 15 insertions, 0 deletions
diff --git a/lua/clever_f/acquisition_service.lua b/lua/clever_f/acquisition_service.lua
index a81c501..52b3949 100644
--- a/lua/clever_f/acquisition_service.lua
+++ b/lua/clever_f/acquisition_service.lua
@@ -20,6 +20,7 @@ M.RepeatedDirection = {
   SAME = "same",
 }
 M.PROMPT = "clever-f: "
+M.PREVIOUS_INPUT_NOT_FOUND = "Previous input not found."
 
 local request_records = setmetatable({}, { __mode = "k" })
 local result_records = setmetatable({}, { __mode = "k" })
@@ -142,6 +143,7 @@ function AcquisitionResult.new(request, options)
     previous_input_trigger = options.previous_input_trigger,
     previous_target_source = options.previous_target_source,
     cached_target = options.cached_target,
+    missing_previous_input = options.missing_previous_input == true,
     completed = outcome ~= nil or target ~= nil,
   }
   return result
@@ -187,6 +189,7 @@ function TemporaryResourceScope.new(request, feedback)
     previous_input_trigger = nil,
     previous_target_source = nil,
     cached_target = nil,
+    missing_previous_input = false,
     outcome = nil,
   }
   return scope
@@ -238,6 +241,13 @@ function TemporaryResourceScope:set_cached_target(context, target)
   return set_scope_resource(self, "cached_target", target)
 end
 
+function TemporaryResourceScope:set_missing_previous_input(missing)
+  if type(missing) ~= "boolean" then
+    fail("missing previous-input state must be a Boolean", 2)
+  end
+  return set_scope_resource(self, "missing_previous_input", missing)
+end
+
 function TemporaryResourceScope:set_outcome(outcome)
   if not domain.ActionOutcome.is(outcome) then
     fail("temporary resource scope outcome must be an ActionOutcome", 2)
@@ -639,6 +649,10 @@ function AcquisitionService:acquire(descriptor, context, position, count, macro_
     scope:set_cached_target(source, cached_target)
     if cached_target ~= nil then
       target = cached_target
+    else
+      target = nil
+      scope:set_missing_previous_input(true)
+      record.host:emit_diagnostic("error", M.PREVIOUS_INPUT_NOT_FOUND)
     end
   end
   scope:set_resolved_target(target)
@@ -647,6 +661,7 @@ function AcquisitionService:acquire(descriptor, context, position, count, macro_
     previous_input_trigger = trigger,
     previous_target_source = scope.previous_target_source,
     cached_target = scope.cached_target,
+    missing_previous_input = scope.missing_previous_input,
   })
 end