fix(python): a method call on the receiver is not a construction

Review finding on f4e1ead0d. `constructorCallTypeName` accepted ANY call with
an identifier or attribute callee, so `self.p = self.build()` bound `p` to the
non-type `"self.build"` — and because that shares the weakest tier with a real
construction, a later such assignment DISPLACED an earlier `self.p = Outer()`
and left the field untyped again.

Measured before the fix: `self.p = Outer()` followed by `self.p = self.rebuild()`
emitted no CALLS edge at all from a method chaining off `self.p`, and
`self.q = self.make()` bound a type name that resolves to nothing. After:
the real construction survives the reassignment, and a pure method call binds
nothing rather than something wrong.

Rejects a callee rooted at the receiver name. `models.Outer()` still binds —
only `self`-rooted callees are refused, which is exactly the method-call shape.

The matrix gains a `reassigned-from-method-call` row that fails without this
rejection; that discrimination is the only reason the row exists.

Refs #2807

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

gitnexus/src/core/ingestion/languages/python/receiver-binding.ts

@@ -126,13 +126,24 @@ export function synthesizeReceiverTypeBinding(fnNode: SyntaxNode): CaptureMatch
  * (subscript, await, comprehension, bare name) is left alone — that is the
  * "name-only guess" this module deliberately refuses.
  */
-function constructorCallTypeName(right: SyntaxNode | null): string | undefined {
+function constructorCallTypeName(
+  right: SyntaxNode | null,
+  receiverName: string,
+): string | undefined {
   if (right === null || right.type !== 'call') return undefined;
   const callee = right.childForFieldName('function');
   if (callee === null) return undefined;
   if (callee.type !== 'identifier' && callee.type !== 'attribute') return undefined;
   const text = callee.text.trim();
-  return text.length > 0 ? text : undefined;
+  if (text.length === 0) return undefined;
+  // `self.p = self.build()` is a METHOD call, not a construction. Accepting it
+  // bound `p` to the non-type `"self.build"`, which resolves to nothing — and
+  // because it shares this weakest tier, a later such assignment DISPLACED an
+  // earlier real `self.p = Outer()`, leaving the field untyped again. Measured:
+  // both `self.q = self.make()` and the displacement pair emitted no CALLS edge
+  // at all. Rejecting a callee rooted at the receiver keeps the construction.
+  if (text === receiverName || text.startsWith(`${receiverName}.`)) return undefined;
+  return text;
 }
 
 /**
@@ -217,7 +228,7 @@ export function synthesizeConstructorFieldTypeBindings(fnNode: SyntaxNode): Capt
           // an explicit annotation or a parameter annotation still wins.
           const constructedType =
             explicitType === null && parameterType === undefined
-              ? constructorCallTypeName(right)
+              ? constructorCallTypeName(right, receiverName)
               : undefined;
           const typeName = explicitType?.text ?? parameterType ?? constructedType;
           if (typeName !== undefined) {

gitnexus/test/integration/resolvers/inferred-field-receiver-matrix.test.ts

@@ -142,6 +142,18 @@ class AssignedField:
 
     def run(self, x):
         return self.q.inner().compute(x)
+
+
+class ReassignedField:
+    def __init__(self):
+        self.r = Outer()
+        self.r = self.rebuild()
+
+    def rebuild(self):
+        return Outer()
+
+    def run(self, x):
+        return self.r.inner().compute(x)
 `;
 
 // ── Ruby ─────────────────────────────────────────────────────────────────────
@@ -376,6 +388,19 @@ const CASES: readonly LanguageCase[] = [
         targets: [`Method:${PY_FILE}:Outer.inner#0`],
         status: 'resolves',
       },
+      // A method call is not a construction. `self.r = Outer()` followed by
+      // `self.r = self.rebuild()` must keep the FIRST binding: both would sit
+      // in the weakest tier, so accepting `self.rebuild()` as a constructor let
+      // the later one displace the real type and the field went untyped again —
+      // measured as zero CALLS edges before `constructorCallTypeName` learned to
+      // reject a callee rooted at the receiver. This row fails without that
+      // rejection, which is the only reason it exists.
+      {
+        name: 'reassigned-from-method-call',
+        callerId: `Method:${PY_FILE}:ReassignedField.run#1`,
+        targets: [`Method:${PY_FILE}:Outer.inner#0`],
+        status: 'resolves',
+      },
     ],
   },
   {