diff --git a/gitnexus/src/core/ingestion/call-processor.ts b/gitnexus/src/core/ingestion/call-processor.ts
index c8c62921a..a3ca9c898 100644
--- a/gitnexus/src/core/ingestion/call-processor.ts
+++ b/gitnexus/src/core/ingestion/call-processor.ts
@@ -966,12 +966,23 @@ export const processCalls = async (
       const routed = callRouter(callNameNode.text, captureMap['call']);
       if (!routed || routed.kind !== 'properties') return;
 
+      // #1978: thread the qualifier so a routed property's owner edge points at
+      // the *qualified* nested-class node (Shapes.Circle) instead of a now-nonexistent
+      // simple `Class:file:Circle` id. Gated on the flag → byte-identical when off.
+      // MUST stay in lockstep with the worker `kind === 'properties'` block.
+      const propGetQualifiedOwnerName =
+        provider.classExtractor?.qualifiedNodeId === true
+          ? (node: SyntaxNode, simpleName: string): string | null =>
+              provider.classExtractor!.extractQualifiedName(node, simpleName)
+          : undefined;
       const propEnclosingInfo = findEnclosingClassInfo(
         captureMap['call'],
         file.path,
         provider.resolveEnclosingOwner,
+        propGetQualifiedOwnerName,
       );
-      const propEnclosingClassId = propEnclosingInfo?.classId ?? null;
+      const propEnclosingClassId =
+        propEnclosingInfo?.qualifiedClassId ?? propEnclosingInfo?.classId ?? null;
 
       // Enrich routed properties with FieldExtractor metadata so types
       // discovered from constructor assignments (e.g. `@address = Address.new`)
diff --git a/gitnexus/src/core/ingestion/class-extractors/configs/c-cpp.ts b/gitnexus/src/core/ingestion/class-extractors/configs/c-cpp.ts
index fb5df99c3..d39888aa1 100644
--- a/gitnexus/src/core/ingestion/class-extractors/configs/c-cpp.ts
+++ b/gitnexus/src/core/ingestion/class-extractors/configs/c-cpp.ts
@@ -46,6 +46,9 @@ export const cppClassConfig: ClassExtractionConfig = {
   language: SupportedLanguages.CPlusPlus,
   typeDeclarationNodes: ['class_specifier', 'struct_specifier', 'enum_specifier'],
   ancestorScopeNodeTypes: ['namespace_definition', 'class_specifier', 'struct_specifier'],
+  // #1978: key nested-type nodes by their fully-qualified path (Outer.Inner) so
+  // same-tail nested types in one TU stay distinct instead of silently merging.
+  qualifiedNodeId: true,
   extractName: (node) => {
     const nameNode = node.childForFieldName?.('name');
     if (!nameNode) return undefined;
diff --git a/gitnexus/src/core/ingestion/class-extractors/configs/ruby.ts b/gitnexus/src/core/ingestion/class-extractors/configs/ruby.ts
index 2c4c711bd..13f1fdd43 100644
--- a/gitnexus/src/core/ingestion/class-extractors/configs/ruby.ts
+++ b/gitnexus/src/core/ingestion/class-extractors/configs/ruby.ts
@@ -7,4 +7,7 @@ export const rubyClassConfig: ClassExtractionConfig = {
   language: SupportedLanguages.Ruby,
   typeDeclarationNodes: ['class'],
   ancestorScopeNodeTypes: ['module', 'class'],
+  // #1978: key nested-type nodes by their fully-qualified path (Outer.Inner) so
+  // same-tail classes nested under different modules stay distinct.
+  qualifiedNodeId: true,
 };
diff --git a/gitnexus/src/core/ingestion/class-extractors/generic.ts b/gitnexus/src/core/ingestion/class-extractors/generic.ts
index 5f20d1dc2..1f11adc44 100644
--- a/gitnexus/src/core/ingestion/class-extractors/generic.ts
+++ b/gitnexus/src/core/ingestion/class-extractors/generic.ts
@@ -165,6 +165,7 @@ export function createClassExtractor(config: ClassExtractionConfig): ClassExtrac
 
   return {
     language: config.language,
+    qualifiedNodeId: config.qualifiedNodeId ?? false,
 
     isTypeDeclaration(node: SyntaxNode): boolean {
       return typeDeclarationSet.has(node.type);
diff --git a/gitnexus/src/core/ingestion/class-types.ts b/gitnexus/src/core/ingestion/class-types.ts
index 9407d41fa..2e3d1f688 100644
--- a/gitnexus/src/core/ingestion/class-types.ts
+++ b/gitnexus/src/core/ingestion/class-types.ts
@@ -28,6 +28,13 @@ export interface ClassCaptureContext {
  */
 export interface ClassExtractor {
   language: SupportedLanguages;
+  /**
+   * When true, this language's nested-type graph nodes are keyed by their
+   * fully-qualified path (e.g. `Class:file:Outer.Inner`) instead of the simple
+   * tail name, so same-tail nested types in one file stay distinct (#1978).
+   * Surfaced from `ClassExtractionConfig.qualifiedNodeId`.
+   */
+  readonly qualifiedNodeId: boolean;
   isTypeDeclaration(node: SyntaxNode): boolean;
   extract(
     node: SyntaxNode,
@@ -48,6 +55,14 @@ export interface ClassExtractionConfig {
   typeDeclarationNodes: string[];
   fileScopeNodeTypes?: string[];
   ancestorScopeNodeTypes?: string[];
+  /**
+   * Opt-in (#1978): key this language's nested-type graph nodes (and their
+   * member-owner edges) by the fully-qualified path instead of the simple tail
+   * name, so same-tail nested types in one file stop colliding. Default false.
+   * Requires `ancestorScopeNodeTypes` to be set so `buildQualifiedName` can walk
+   * the scope chain.
+   */
+  qualifiedNodeId?: boolean;
   scopeNameNodeTypes?: string[];
   extractName?: (node: SyntaxNode) => string | undefined;
   extractType?: (node: SyntaxNode) => ClassLikeNodeLabel | undefined;
diff --git a/gitnexus/src/core/ingestion/parsing-processor.ts b/gitnexus/src/core/ingestion/parsing-processor.ts
index 6c77e7958..62346963f 100644
--- a/gitnexus/src/core/ingestion/parsing-processor.ts
+++ b/gitnexus/src/core/ingestion/parsing-processor.ts
@@ -297,10 +297,16 @@ const cachedFindEnclosingClassInfo = (
   node: SyntaxNode,
   filePath: string,
   resolveEnclosingOwner?: (node: SyntaxNode) => SyntaxNode | null,
+  getQualifiedOwnerName?: (node: SyntaxNode, simpleName: string) => string | null,
 ): EnclosingClassInfo | null => {
   const cached = classInfoCache.get(node);
   if (cached !== undefined) return cached;
-  const result = findEnclosingClassInfo(node, filePath, resolveEnclosingOwner);
+  const result = findEnclosingClassInfo(
+    node,
+    filePath,
+    resolveEnclosingOwner,
+    getQualifiedOwnerName,
+  );
   classInfoCache.set(node, result);
   return result;
 };
@@ -602,24 +608,55 @@ const processParsingSequential = async (
         nodeLabel === 'Constructor' ||
         nodeLabel === 'Property' ||
         nodeLabel === 'Function';
+      // #1978: when the language opts into qualified node ids, thread the
+      // class-extractor's qualifier into the enclosing-owner walk so a nested
+      // member resolves to its owner's *qualified* id (Outer.Inner) — matching
+      // the qualified class node id computed below. Gated on the flag, so the
+      // owner walk and its cache entry are byte-identical when the flag is off.
+      const getQualifiedOwnerName =
+        provider.classExtractor?.qualifiedNodeId === true
+          ? (node: SyntaxNode, simpleName: string): string | null =>
+              provider.classExtractor!.extractQualifiedName(node, simpleName)
+          : undefined;
       const enclosingClassInfo = needsOwner
         ? cachedFindEnclosingClassInfo(
             nameNode || definitionNodeForRange,
             file.path,
             provider.resolveEnclosingOwner,
+            getQualifiedOwnerName,
           )
         : null;
-      const enclosingClassId = enclosingClassInfo?.classId ?? null;
+      const enclosingClassId =
+        enclosingClassInfo?.qualifiedClassId ?? enclosingClassInfo?.classId ?? null;
       const objectLiteralOwnerInfo =
         !enclosingClassId && nodeLabel === 'Method' && definitionNode
           ? findObjectLiteralBindingInfo(definitionNode, file.path)
           : null;
 
+      // #1978: a class-like node opts into a fully-qualified node id (Outer.Inner)
+      // when the language enables qualifiedNodeId, so same-tail nested types in one
+      // file stay distinct. Hoisted ABOVE the node-id/qualifiedName use below and
+      // derived from the SAME extractQualifiedName the owner edge uses, so the
+      // member's owner id and the class node id agree. The order is load-bearing.
+      const classNodeForSymbol = definitionNodeForRange || definitionNode || nameNode;
+      const qualifiedTypeName =
+        extractedClassSymbol?.qualifiedName ??
+        (classNodeForSymbol && provider.classExtractor?.isTypeDeclaration(classNodeForSymbol)
+          ? (provider.classExtractor.extractQualifiedName(classNodeForSymbol, nodeName) ?? nodeName)
+          : undefined);
+
       // Qualify method/property IDs with enclosing class name to avoid collisions
-      // e.g. "Method:animal.dart:Animal.speak" vs "Method:animal.dart:Dog.speak"
-      const qualifiedName = enclosingClassInfo
-        ? `${enclosingClassInfo.className}.${nodeName}`
-        : nodeName;
+      // e.g. "Method:animal.dart:Animal.speak" vs "Method:animal.dart:Dog.speak".
+      // Class-like nodes use their own fully-qualified path as the id key when the
+      // language enables qualifiedNodeId (#1978); everything else is unchanged.
+      const qualifiedName =
+        isClassLikeLabel &&
+        provider.classExtractor?.qualifiedNodeId === true &&
+        qualifiedTypeName !== undefined
+          ? qualifiedTypeName
+          : enclosingClassInfo
+            ? `${enclosingClassInfo.className}.${nodeName}`
+            : nodeName;
 
       // Extract method metadata for Function/Method/Constructor nodes BEFORE generating
       // the node ID — parameterCount is needed to disambiguate overloaded methods.
@@ -778,12 +815,6 @@ const processParsingSequential = async (
         nodeLabel,
         `${file.path}:${qualifiedName}${classTemplateTag}${arityTag}${constraintsTag}${parameterShapeTag}`,
       );
-      const classNodeForSymbol = definitionNodeForRange || definitionNode || nameNode;
-      const qualifiedTypeName =
-        extractedClassSymbol?.qualifiedName ??
-        (classNodeForSymbol && provider.classExtractor?.isTypeDeclaration(classNodeForSymbol)
-          ? (provider.classExtractor.extractQualifiedName(classNodeForSymbol, nodeName) ?? nodeName)
-          : undefined);
       const frameworkHint = definitionNode
         ? detectFrameworkFromAST(language, (definitionNode.text || '').slice(0, 300))
         : null;
diff --git a/gitnexus/src/core/ingestion/utils/ast-helpers.ts b/gitnexus/src/core/ingestion/utils/ast-helpers.ts
index f7e7917ea..4fcf870d2 100644
--- a/gitnexus/src/core/ingestion/utils/ast-helpers.ts
+++ b/gitnexus/src/core/ingestion/utils/ast-helpers.ts
@@ -321,6 +321,15 @@ export function getLabelFromCaptures(
 export interface EnclosingClassInfo {
   classId: string; // e.g. "Class:animal.dart:Animal"
   className: string; // e.g. "Animal"
+  /**
+   * The owner node id keyed by the enclosing type's FULLY-QUALIFIED path
+   * (e.g. "Class:file:Outer.Inner"), present only when the language opts into
+   * `qualifiedNodeId` AND the enclosing type is actually nested (#1978).
+   * Consumers building HAS_METHOD/HAS_PROPERTY owner edges use this in
+   * preference to `classId` so the edge source matches the qualified class
+   * node id. When absent, `classId` (the simple-tail key) is unchanged.
+   */
+  qualifiedClassId?: string;
 }
 
 /** Walk up AST to find enclosing class/struct/interface/impl, return its ID and name.
@@ -345,6 +354,16 @@ export const findEnclosingClassInfo = (
   node: SyntaxNode,
   filePath: string,
   resolveEnclosingOwner?: (node: SyntaxNode) => SyntaxNode | null,
+  /**
+   * Optional (#1978): returns the enclosing type's fully-qualified name
+   * (e.g. "Outer.Inner") for a type-declaration container, or null. Callers
+   * pass `classExtractor.extractQualifiedName` ONLY when the language's
+   * `qualifiedNodeId` flag is on — so when omitted, behavior is byte-identical
+   * to before (qualifiedClassId stays undefined). Used by the standard
+   * class-container branch to compute `qualifiedClassId` from the SAME function
+   * the node-id is built from, guaranteeing owner-id == node-id by construction.
+   */
+  getQualifiedOwnerName?: (node: SyntaxNode, simpleName: string) => string | null,
 ): EnclosingClassInfo | null => {
   let current = node.parent;
   let iterations = 0;
@@ -485,9 +504,29 @@ export const findEnclosingClassInfo = (
           templateArguments !== undefined
             ? `${stripTemplateArguments(nameNode.text)}${templateArgumentsIdTag(templateArguments)}`
             : nameNode.text;
+        // #1978: when the language opts into qualified node ids, key the owner
+        // edge by the enclosing type's qualified path (e.g. "Outer.Inner") so it
+        // matches the qualified class node id. Derived from the SAME
+        // extractQualifiedName the node-id uses → agree by construction. Only set
+        // when actually nested (qualified !== simple); top-level types are
+        // unchanged. (Go receiver / Rust impl branches return earlier and are
+        // intentionally untouched here.)
+        const qualifiedOwnerName = getQualifiedOwnerName?.(current, nameNode.text);
+        const qualifiedClassId =
+          qualifiedOwnerName != null && qualifiedOwnerName !== nameNode.text
+            ? generateId(
+                label,
+                `${filePath}:${
+                  templateArguments !== undefined
+                    ? `${stripTemplateArguments(qualifiedOwnerName)}${templateArgumentsIdTag(templateArguments)}`
+                    : qualifiedOwnerName
+                }`,
+              )
+            : undefined;
         return {
           classId: generateId(label, `${filePath}:${classIdName}`),
           className: nameNode.text,
+          ...(qualifiedClassId !== undefined ? { qualifiedClassId } : {}),
         };
       }
     }
diff --git a/gitnexus/src/core/ingestion/workers/parse-worker.ts b/gitnexus/src/core/ingestion/workers/parse-worker.ts
index 8a7946d32..a3882c00a 100644
--- a/gitnexus/src/core/ingestion/workers/parse-worker.ts
+++ b/gitnexus/src/core/ingestion/workers/parse-worker.ts
@@ -753,11 +753,17 @@ const cachedFindEnclosingClassInfo = (
   node: SyntaxNode,
   filePath: string,
   resolveEnclosingOwner?: (node: SyntaxNode) => SyntaxNode | null,
+  getQualifiedOwnerName?: (node: SyntaxNode, simpleName: string) => string | null,
 ): EnclosingClassInfo | null => {
   const cached = classIdCache.get(node);
   if (cached !== undefined) return cached;
 
-  const result = findEnclosingClassInfo(node, filePath, resolveEnclosingOwner);
+  const result = findEnclosingClassInfo(
+    node,
+    filePath,
+    resolveEnclosingOwner,
+    getQualifiedOwnerName,
+  );
   classIdCache.set(node, result);
   return result;
 };
@@ -1517,12 +1523,23 @@ const processFileGroup = (
               }
 
               if (routed.kind === 'properties') {
+                // #1978: thread the qualifier so a routed property's owner edge
+                // points at the *qualified* nested-class node (Outer.Inner) rather
+                // than a now-nonexistent simple `Class:file:Inner` id. Gated on the
+                // flag → byte-identical when off. Mirrors the main owner path.
+                const propGetQualifiedOwnerName =
+                  provider.classExtractor?.qualifiedNodeId === true
+                    ? (node: SyntaxNode, simpleName: string): string | null =>
+                        provider.classExtractor!.extractQualifiedName(node, simpleName)
+                    : undefined;
                 const propEnclosingInfo = cachedFindEnclosingClassInfo(
                   captureMap['call'],
                   file.path,
                   provider.resolveEnclosingOwner,
+                  propGetQualifiedOwnerName,
                 );
-                const propEnclosingClassId = propEnclosingInfo?.classId ?? null;
+                const propEnclosingClassId =
+                  propEnclosingInfo?.qualifiedClassId ?? propEnclosingInfo?.classId ?? null;
                 // Enrich routed properties with FieldExtractor metadata
                 let routedFieldMap: Map<string, FieldInfo> | undefined;
                 if (provider.fieldExtractor && typeEnv) {
@@ -1803,23 +1820,51 @@ const processFileGroup = (
         nodeLabel === 'Constructor' ||
         nodeLabel === 'Property' ||
         nodeLabel === 'Function';
+      // #1978: thread the class-extractor's qualifier into the owner walk when the
+      // language opts into qualified node ids, so a nested member's owner resolves
+      // to the *qualified* class id (Outer.Inner). Gated on the flag → byte-identical
+      // when off. Mirrors parsing-processor.ts.
+      const getQualifiedOwnerName =
+        provider.classExtractor?.qualifiedNodeId === true
+          ? (node: SyntaxNode, simpleName: string): string | null =>
+              provider.classExtractor!.extractQualifiedName(node, simpleName)
+          : undefined;
       const enclosingClassInfo = needsOwner
         ? cachedFindEnclosingClassInfo(
             nameNode || definitionNode,
             file.path,
             provider.resolveEnclosingOwner,
+            getQualifiedOwnerName,
           )
         : null;
-      const enclosingClassId = enclosingClassInfo?.classId ?? null;
+      const enclosingClassId =
+        enclosingClassInfo?.qualifiedClassId ?? enclosingClassInfo?.classId ?? null;
       const objectLiteralOwnerInfo =
         !enclosingClassId && nodeLabel === 'Method' && definitionNode
           ? findObjectLiteralBindingInfo(definitionNode, file.path)
           : null;
 
-      // Qualify method/property IDs with enclosing class name to avoid collisions
-      const qualifiedName = enclosingClassInfo
-        ? `${enclosingClassInfo.className}.${nodeName}`
-        : nodeName;
+      // #1978: hoisted ABOVE qualifiedName/node-id (load-bearing order) so a
+      // class-like node can key its id by its fully-qualified path. Derived from
+      // the SAME extractQualifiedName the owner edge uses → owner id == node id.
+      const classNodeForSymbol = definitionNode || nameNode;
+      const qualifiedTypeName =
+        extractedClassSymbol?.qualifiedName ??
+        (classNodeForSymbol && provider.classExtractor?.isTypeDeclaration(classNodeForSymbol)
+          ? (provider.classExtractor.extractQualifiedName(classNodeForSymbol, nodeName) ?? nodeName)
+          : undefined);
+
+      // Qualify method/property IDs with enclosing class name to avoid collisions.
+      // Class-like nodes use their own fully-qualified path as the id key when the
+      // language enables qualifiedNodeId (#1978); everything else is unchanged.
+      const qualifiedName =
+        isClassLikeLabel &&
+        provider.classExtractor?.qualifiedNodeId === true &&
+        qualifiedTypeName !== undefined
+          ? qualifiedTypeName
+          : enclosingClassInfo
+            ? `${enclosingClassInfo.className}.${nodeName}`
+            : nodeName;
 
       // Extract method metadata BEFORE generating node ID — parameterCount is needed
       // to disambiguate overloaded methods via #<arity> suffix in the ID.
@@ -1922,12 +1967,6 @@ const processFileGroup = (
         nodeLabel,
         `${file.path}:${qualifiedName}${classTemplateTag}${arityTag}${parameterShapeTag}`,
       );
-      const classNodeForSymbol = definitionNode || nameNode;
-      const qualifiedTypeName =
-        extractedClassSymbol?.qualifiedName ??
-        (classNodeForSymbol && provider.classExtractor?.isTypeDeclaration(classNodeForSymbol)
-          ? (provider.classExtractor.extractQualifiedName(classNodeForSymbol, nodeName) ?? nodeName)
-          : undefined);
 
       const description = provider.descriptionExtractor?.(nodeLabel, nodeName, captureMap);
 
diff --git a/gitnexus/test/fixtures/lang-resolution/cpp-nested-tail-collision/shapes.cpp b/gitnexus/test/fixtures/lang-resolution/cpp-nested-tail-collision/shapes.cpp
new file mode 100644
index 000000000..515a3cbc5
--- /dev/null
+++ b/gitnexus/test/fixtures/lang-resolution/cpp-nested-tail-collision/shapes.cpp
@@ -0,0 +1,11 @@
+struct Outer {
+  struct Inner {
+    void from_outer() {}
+    int outer_field;
+  };
+};
+struct Other {
+  struct Inner {
+    void from_other() {}
+  };
+};
diff --git a/gitnexus/test/fixtures/lang-resolution/ruby-nested-tail-collision/nested.rb b/gitnexus/test/fixtures/lang-resolution/ruby-nested-tail-collision/nested.rb
new file mode 100644
index 000000000..94937fed5
--- /dev/null
+++ b/gitnexus/test/fixtures/lang-resolution/ruby-nested-tail-collision/nested.rb
@@ -0,0 +1,19 @@
+module Outer
+  class Inner
+    def from_outer; end
+  end
+end
+module Other
+  class Inner
+    def from_other; end
+  end
+end
+# Unambiguous nested class (no same-tail sibling): exercises the routed-property
+# (attr_accessor) owner path, which must resolve to the QUALIFIED owner and not
+# dangle under qualifiedNodeId. Same-tail routed-property owner identity is a
+# separate resolution-side concern (see ruby.test.ts).
+module Shapes
+  class Circle
+    attr_accessor :radius
+  end
+end
diff --git a/gitnexus/test/fixtures/lang-resolution/rust-nested-tail-collision/lib.rs b/gitnexus/test/fixtures/lang-resolution/rust-nested-tail-collision/lib.rs
new file mode 100644
index 000000000..e2675a839
--- /dev/null
+++ b/gitnexus/test/fixtures/lang-resolution/rust-nested-tail-collision/lib.rs
@@ -0,0 +1,12 @@
+pub mod outer {
+    pub struct Inner;
+    impl Inner {
+        pub fn from_outer(&self) {}
+    }
+}
+pub mod other {
+    pub struct Inner;
+    impl Inner {
+        pub fn from_other(&self) {}
+    }
+}
diff --git a/gitnexus/test/integration/resolvers/cpp.test.ts b/gitnexus/test/integration/resolvers/cpp.test.ts
index da62a243a..e2d140885 100644
--- a/gitnexus/test/integration/resolvers/cpp.test.ts
+++ b/gitnexus/test/integration/resolvers/cpp.test.ts
@@ -3733,12 +3733,16 @@ describe('C++ SFINAE filter — arity gate runs before constraint filter', () =>
 // ---------------------------------------------------------------------------
 // Out-of-line nested definitions — method ownership + collision (issue #1975)
 //
-// `struct Outer::Inner { ... }` (name = qualified_identifier) now materializes a
-// node keyed by the full scoped text, so its methods own through a real node.
-// Crucially, a same-tail type in another scope (Other::Inner) stays a DISTINCT
-// node — no merge, no method mis-attribution. (A redundant forward-decl node
-// `Inner` also exists; the pre-existing inline same-tail node collision is
-// tracked separately in #1978.)
+// `struct Outer::Inner { ... }` (name = qualified_identifier) and its in-class
+// forward declaration `struct Outer { struct Inner; }` are the SAME type. Once
+// qualified node ids are on (#1978), both key to one canonical node whose
+// qualifiedName is the normalized scope path `Outer.Inner` — so the forward
+// decl and the out-of-line definition correctly UNIFY instead of producing two
+// redundant nodes (the pre-#1978 base kept them separate). Crucially, a
+// same-tail type in another scope (`Other::Inner`) stays a DISTINCT node — no
+// merge, no method mis-attribution. Owner identity is asserted on the
+// qualifiedName + distinct node id (the real key), not the simple `name`
+// (which is just the tail `Inner` for both, by design).
 // ---------------------------------------------------------------------------
 
 describe('C++ out-of-line nested definitions — ownership + collision (issue #1975)', () => {
@@ -3760,8 +3764,100 @@ describe('C++ out-of-line nested definitions — ownership + collision (issue #1
     const other = hasMethod.find((e) => e.target === 'from_other');
     expect(outer).toBeDefined();
     expect(other).toBeDefined();
-    expect(outer!.source).toBe('Outer::Inner');
-    expect(other!.source).toBe('Other::Inner');
-    expect(outer!.source).not.toBe(other!.source);
+    const ownerQn = (e: typeof outer) =>
+      result.graph.getNode(e!.rel.sourceId)?.properties.qualifiedName;
+    expect(ownerQn(outer)).toBe('Outer.Inner');
+    expect(ownerQn(other)).toBe('Other.Inner');
+    expect(outer!.rel.sourceId).not.toBe(other!.rel.sourceId);
+    // Discriminator: with qualifiedNodeId ON the owner node id is keyed by the
+    // NORMALIZED dotted path (Struct:...:Outer.Inner); with the fix OFF the
+    // out-of-line node is keyed by the raw scoped text (...:Outer::Inner). The
+    // `qualifiedName` PROPERTY is normalized either way, so assert on the id to
+    // actually prove the fix is engaged (test-soundness, workflow finding #5).
+    expect(outer!.rel.sourceId).toContain('Outer.Inner');
+    expect(outer!.rel.sourceId).not.toContain('::');
+    expect(other!.rel.sourceId).not.toContain('::');
+  });
+});
+
+// ---------------------------------------------------------------------------
+// Inline nested same-tail collision — distinct qualified nodes (issue #1978)
+//
+// `struct Outer { struct Inner {...} }` + `struct Other { struct Inner {...} }`
+// must materialize TWO distinct Struct nodes (qn Outer.Inner vs Other.Inner),
+// each owning its own method/field. On the pre-fix base both Inner structs
+// merge into one simple-keyed node and the methods cross-wire (dangling:0 but
+// wrong). Asserts positive owner-identity via the resolved node's qualifiedName,
+// not just dangle-free (R7). Distinct from the #1977 out-of-line case above.
+// ---------------------------------------------------------------------------
+
+describe('C++ inline nested same-tail collision — distinct qualified nodes (issue #1978)', () => {
+  let result: PipelineResult;
+
+  beforeAll(async () => {
+    result = await runPipelineFromRepo(path.join(FIXTURES, 'cpp-nested-tail-collision'), () => {});
+  }, 60000);
+
+  it('materializes Outer.Inner and Other.Inner as two distinct Struct nodes', () => {
+    const qns = getNodesByLabelFull(result, 'Struct')
+      .map((n) => n.properties.qualifiedName)
+      .filter((q) => q === 'Outer.Inner' || q === 'Other.Inner')
+      .sort();
+    expect(qns).toEqual(['Other.Inner', 'Outer.Inner']);
+  });
+
+  it('owns from_outer / from_other through their OWN distinct node (positive identity, R7)', () => {
+    expect(findDanglingEdges(result, ['HAS_METHOD', 'HAS_PROPERTY'])).toEqual([]);
+    const hm = getRelationships(result, 'HAS_METHOD');
+    const ownerQn = (target: string) => {
+      const e = hm.find((x) => x.target === target);
+      expect(e, `HAS_METHOD -> ${target}`).toBeDefined();
+      return result.graph.getNode(e!.rel.sourceId)?.properties.qualifiedName;
+    };
+    expect(ownerQn('from_outer')).toBe('Outer.Inner');
+    expect(ownerQn('from_other')).toBe('Other.Inner');
+  });
+
+  it('owns outer_field under Outer.Inner (struct field via the main HAS_PROPERTY path)', () => {
+    const hp = getRelationships(result, 'HAS_PROPERTY');
+    const e = hp.find((x) => x.target === 'outer_field');
+    expect(e).toBeDefined();
+    expect(result.graph.getNode(e!.rel.sourceId)?.properties.qualifiedName).toBe('Outer.Inner');
+  });
+});
+
+// Same collision fixture, forced through the WORKER pool (parse-worker.ts) rather
+// than the sequential parsing-processor.ts. Production parses repos >= 15 files via
+// the pool, so the qualified node-id + owner-edge logic must hold on BOTH paths
+// (workflow finding #4: the #1978 fixtures otherwise only exercise the sequential
+// path). Asserts worker == sequential for the distinct-node + owner outcome.
+describe('C++ inline nested same-tail collision — worker path parity (issue #1978)', () => {
+  let result: PipelineResult;
+
+  beforeAll(async () => {
+    result = await runPipelineFromRepo(path.join(FIXTURES, 'cpp-nested-tail-collision'), () => {}, {
+      // Force the worker-pool gate low so the 1-file fixture engages the pool.
+      workerThresholdsForTest: { minFiles: 1, minBytes: 1 },
+      workerPoolSize: 2,
+    });
+  }, 120000);
+
+  it('genuinely used the worker pool (guards against silent sequential fallback)', () => {
+    expect(result.usedWorkerPool).toBe(true);
+  });
+
+  it('materializes two distinct Struct nodes and owns each method correctly (R7)', () => {
+    const qns = getNodesByLabelFull(result, 'Struct')
+      .map((n) => n.properties.qualifiedName)
+      .filter((q) => q === 'Outer.Inner' || q === 'Other.Inner')
+      .sort();
+    expect(qns).toEqual(['Other.Inner', 'Outer.Inner']);
+    expect(findDanglingEdges(result, ['HAS_METHOD', 'HAS_PROPERTY'])).toEqual([]);
+    const hm = getRelationships(result, 'HAS_METHOD');
+    const ownerQn = (target: string) =>
+      result.graph.getNode(hm.find((x) => x.target === target)!.rel.sourceId)?.properties
+        .qualifiedName;
+    expect(ownerQn('from_outer')).toBe('Outer.Inner');
+    expect(ownerQn('from_other')).toBe('Other.Inner');
   });
 });
diff --git a/gitnexus/test/integration/resolvers/ruby.test.ts b/gitnexus/test/integration/resolvers/ruby.test.ts
index cd0ea7748..08c31d3d7 100644
--- a/gitnexus/test/integration/resolvers/ruby.test.ts
+++ b/gitnexus/test/integration/resolvers/ruby.test.ts
@@ -1508,3 +1508,56 @@ describe('Ruby cross-namespace tail collision — distinct nodes (issue #1975)',
     expect(hasMethod.some((e) => e.target === 'from_baz' && e.sourceLabel === 'Class')).toBe(true);
   });
 });
+
+// ---------------------------------------------------------------------------
+// Inline module-nested same-tail collision — distinct nodes (issue #1978)
+//
+// `module Outer; class Inner; end; end` + `module Other; class Inner; end; end`
+// must own their methods through TWO distinct Class nodes (qn Outer.Inner vs
+// Other.Inner). On the pre-fix base both Inner classes merge into one
+// simple-keyed node and from_outer/from_other cross-wire (dangling:0 but wrong).
+// Asserts positive owner-identity by the resolved node's qualifiedName (R7).
+// (Distinct from the compact `Foo::Bar` collision block above, which #1977 fixed.)
+// ---------------------------------------------------------------------------
+
+describe('Ruby inline module-nested same-tail collision — distinct nodes (issue #1978)', () => {
+  let result: PipelineResult;
+
+  beforeAll(async () => {
+    result = await runPipelineFromRepo(path.join(FIXTURES, 'ruby-nested-tail-collision'), () => {});
+  }, 60000);
+
+  pit('owns from_outer / from_other through distinct Outer.Inner / Other.Inner nodes (R7)', () => {
+    expect(findDanglingEdges(result, ['HAS_METHOD'])).toEqual([]);
+    const hm = getRelationships(result, 'HAS_METHOD');
+    const ownerQn = (target: string) => {
+      const e = hm.find((x) => x.target === target);
+      expect(e, `HAS_METHOD -> ${target}`).toBeDefined();
+      return result.graph.getNode(e!.rel.sourceId)?.properties.qualifiedName;
+    };
+    expect(ownerQn('from_outer')).toBe('Outer.Inner');
+    expect(ownerQn('from_other')).toBe('Other.Inner');
+  });
+
+  // attr_accessor routes through the property-registration pre-pass — a SEPARATE
+  // code path from `def` methods: call-processor.ts (sequential/legacy) and the
+  // parse-worker `kind === 'properties'` block (worker). Under qualifiedNodeId the
+  // owner must resolve to the QUALIFIED class node (Shapes.Circle); the pre-fix
+  // simple `Class:f.rb:Circle` no longer exists and would dangle. Exercised here
+  // on an UNAMBIGUOUS nested class (no same-tail sibling) so the assertion is
+  // exact on both legs.
+  //
+  // NOTE: exact owner identity for a routed property under SAME-TAIL nested types
+  // (e.g. two `Inner` classes) is a separate resolution-side concern — the
+  // registry-primary `emitRubyMixinEdges` bridge resolves the owner by simple
+  // tail name (last-wins) and the worker path can emit a duplicate cross-wired
+  // edge. That is deferred to the #1978 resolution-side follow-up; the
+  // structure-phase HAS_METHOD ownership above is already exact on both legs.
+  pit('owns radius (attr_accessor) under the qualified Shapes.Circle node, no dangling (R7)', () => {
+    expect(findDanglingEdges(result, ['HAS_PROPERTY'])).toEqual([]);
+    const hp = getRelationships(result, 'HAS_PROPERTY');
+    const e = hp.find((x) => x.target === 'radius');
+    expect(e, 'HAS_PROPERTY -> radius').toBeDefined();
+    expect(result.graph.getNode(e!.rel.sourceId)?.properties.qualifiedName).toBe('Shapes.Circle');
+  });
+});
diff --git a/gitnexus/test/integration/resolvers/rust.test.ts b/gitnexus/test/integration/resolvers/rust.test.ts
index bcfa4200d..715295d4a 100644
--- a/gitnexus/test/integration/resolvers/rust.test.ts
+++ b/gitnexus/test/integration/resolvers/rust.test.ts
@@ -2047,3 +2047,45 @@ describe('Rust scoped inherent impl — ownership + collision (issue #1975)', ()
     expect(fromA!.source).not.toBe(fromB!.source);
   });
 });
+
+// ---------------------------------------------------------------------------
+// Inline mod-nested same-tail collision — distinct nodes (issue #1978)
+//
+// `mod outer { struct Inner; impl Inner }` + `mod other { struct Inner; impl Inner }`
+// must own their methods through TWO distinct nodes. On the pre-fix base both
+// `Inner` structs merge into one simple-keyed node and from_outer/from_other
+// cross-wire onto it (dangling:0 but wrong). Asserts the two methods resolve to
+// DISTINCT owner node ids (R7), not just dangle-free.
+//
+// DEFERRED (skip): the generic qualifiedNodeId mechanism (#1978) qualifies
+// class-like *type declarations* via the class-extractor. Rust methods live in
+// `impl Inner` blocks, and the inherent-impl owner branch in ast-helpers keys
+// the Impl node by the impl target's RAW text ("Inner") and returns BEFORE the
+// generic qualified-owner path — so it can't reuse `extractQualifiedName` (an
+// `impl_item` isn't a typeDeclaration). Qualifying the impl target by its
+// enclosing `mod` scope, plus matching it on the registry-primary graph bridge,
+// is separate machinery tracked as a follow-up. C++/Ruby land first (KTD-6).
+// ---------------------------------------------------------------------------
+
+// eslint-disable-next-line vitest/no-disabled-tests -- deferred follow-up (see above)
+describe.skip('Rust inline mod-nested same-tail collision — distinct nodes (issue #1978)', () => {
+  let result: PipelineResult;
+
+  beforeAll(async () => {
+    result = await runPipelineFromRepo(
+      path.join(FIXTURES, 'rust-nested-tail-collision'),
+      () => {},
+    );
+  }, 60000);
+
+  it('owns from_outer / from_other through distinct nodes (no merge, no mis-attribution)', () => {
+    expect(findDanglingEdges(result, ['HAS_METHOD'])).toEqual([]);
+    const hm = getRelationships(result, 'HAS_METHOD');
+    const a = hm.find((e) => e.target === 'from_outer');
+    const b = hm.find((e) => e.target === 'from_other');
+    expect(a).toBeDefined();
+    expect(b).toBeDefined();
+    // The two same-tail `Inner` methods must NOT share one owner node id.
+    expect(a!.rel.sourceId).not.toBe(b!.rel.sourceId);
+  });
+});