Resolve an open's extension constructor only through its module

Why:
    Codex review on #9085: an `open A` after a local extension `Value`
    resolved the payload of an unqualified `Value(...)` to the local
    constructor. Matching `A.Value` against the constructors also accepted
    the bare local `Value` as a suffix, and the later declaration won. A
    constructor named without a module is declared around the cursor, so
    an open no longer brings it into scope.

Completion modified (extension payload after an open):
Example:
    type attr = ..
    module A = {
      type attr += Value(bool)
    }
    type attr += Value(option<int>)
    open A
    let x: attr = Value()
Before (text): payload completion inside `Value()` completes
    option<int>, the payload of the local Value
After (text): payload completion inside `Value()` completes
    bool, the payload of A.Value: true, false

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Kr4cjoUi2f5VpMvE6wT9bo
Signed-off-by: Christoph Knittel <ck@cca.io>

Author: cknitt

analysis/src/type_utils.ml

@@ -426,7 +426,10 @@ let find_payload_constructor ~(env : Query_env.t) ~constructors ~extension_envs
           let opened =
             List.filteri (fun i _ -> i < List.length opened - 1) opened
           in
-          match last (named (opened @ path)) with
+          (* A constructor named without a module path is declared around
+             the cursor, so no open brings it into scope. *)
+          let in_module (c : Constructor.t) = List.length (parts c) > 1 in
+          match last (named (opened @ path) |> List.filter in_module) with
           | Some c -> Some c
           | None -> lookup scope)
         | _ :: scope -> lookup scope

tests/analysis_tests/tests/src/CompletionExtensiblePayload.res

@@ -120,3 +120,12 @@ module type S = {
 
 // switch v
 //         ^com
+
+// An open after a local declaration shadows it in turn
+open A
+
+// let x: attr = Value()
+//                     ^com
+
+// switch v { | Value() }
+//                    ^com

tests/analysis_tests/tests/src/expected/CompletionExtensiblePayload.res.txt

@@ -1254,3 +1254,32 @@ Path v
   }
 ]
 
+Complete src/CompletionExtensiblePayload.res 126:23
+XXX Not found!
+Completable: Cexpression Type[attr]->variantPayload::Value($0)
+Raw opens: 3 A.place holder ... B.place holder ... A.place holder
+Package opens Stdlib.place holder Pervasives.JsxModules.place holder
+Resolved opens 4 Stdlib CompletionExtensiblePayload CompletionExtensiblePayload CompletionExtensiblePayload
+ContextPath Type[attr]
+Path attr
+[
+  { "detail": "bool", "kind": 4, "label": "true", "tags": [] },
+  { "detail": "bool", "kind": 4, "label": "false", "tags": [] }
+]
+
+Complete src/CompletionExtensiblePayload.res 129:22
+pos_cursor:[129:22] pos_no_white:[129:21] Found pattern:[129:16->129:23]
+Ppat_construct Value:[129:16->129:21]
+pos_cursor:[129:22] pos_no_white:[129:21] Found pattern:[129:21->129:23]
+Ppat_construct ():[129:21->129:23]
+Completable: Cpattern Value[v]->variantPayload::Value($0)
+Raw opens: 3 A.place holder ... B.place holder ... A.place holder
+Package opens Stdlib.place holder Pervasives.JsxModules.place holder
+Resolved opens 4 Stdlib CompletionExtensiblePayload CompletionExtensiblePayload CompletionExtensiblePayload
+ContextPath Value[v]
+Path v
+[
+  { "detail": "bool", "kind": 4, "label": "true", "tags": [] },
+  { "detail": "bool", "kind": 4, "label": "false", "tags": [] }
+]
+