fix(edge_builder): restrict same-file this-dispatch fallback to caller's own class

crates/codegraph-core/src/edge_builder.rs

@@ -460,15 +460,27 @@ fn resolve_call_targets<'a>(
                 if !class_scoped.is_empty() { return class_scoped; }
             }
 
-            // Broader fallback: same-file suffix scan to pick up CHA-expanded targets
-            // (subclasses that override the method).
+            // Broader fallback: same-file suffix scan.  Always restrict to the caller's
+            // own class prefix — regardless of how many matches are found — to avoid
+            // false-positive edges to unrelated classes in the same file.
+            // (e.g. this.area() inside Shape.describe must never yield Calculator.area,
+            // even when Calculator.area is the only method with that name in the file.)
             let suffix = format!(".{}", call.name);
             if let Some(file_nodes) = ctx.nodes_by_file.get(rel_path) {
                 let same_file_methods: Vec<&NodeInfo> = file_nodes.iter()
                     .filter(|n| n.kind == "method" && n.name.ends_with(&suffix))
                     .copied()
                     .collect();
-                if !same_file_methods.is_empty() { return same_file_methods; }
+                if !same_file_methods.is_empty() {
+                    if let Some(dot_pos) = caller_name.find('.') {
+                        let caller_prefix = format!("{}.", &caller_name[..dot_pos]);
+                        let caller_scoped: Vec<&NodeInfo> = same_file_methods.iter()
+                            .filter(|n| n.name.starts_with(&caller_prefix))
+                            .copied()
+                            .collect();
+                        if !caller_scoped.is_empty() { return caller_scoped; }
+                    }
+                }
             }
         }
         return exact; // empty

tests/fixtures/this-dispatch-scope/shapes.ts

@@ -0,0 +1,24 @@
+// Three unrelated classes in one file, each with an area() method.
+// this.area() inside Shape.describe must resolve only to Shape.area,
+// not to Calculator.area or Formatter.area.
+
+export class Shape {
+  describe(): string {
+    return `area=${this.area()}`;
+  }
+  area(): number {
+    return 0;
+  }
+}
+
+export class Calculator {
+  area(): number {
+    return 100;
+  }
+}
+
+export class Formatter {
+  area(): string {
+    return 'n/a';
+  }
+}

tests/fixtures/this-dispatch-scope/single-sibling.ts

@@ -0,0 +1,16 @@
+// Two classes in one file; only one defines area().
+// this.area() inside Caller.run must NOT resolve to Sibling.area
+// even when Sibling.area is the only method with that suffix in the file.
+// The caller's own class (Caller) has no area() → the edge must be omitted.
+
+export class Caller {
+  run(): string {
+    return `result=${this.area()}`;
+  }
+}
+
+export class Sibling {
+  area(): number {
+    return 42;
+  }
+}

tests/integration/this-dispatch-scope.test.ts

@@ -0,0 +1,118 @@
+/**
+ * this-dispatch scope: same-file fallback must not emit false-positive edges
+ * to methods in unrelated classes.
+ *
+ * Fixtures:
+ *  - shapes.ts — three unrelated classes (Shape, Calculator, Formatter) all
+ *    defining area().  this.area() inside Shape.describe must resolve only to
+ *    Shape.area (multi-match disambiguation path).
+ *  - single-sibling.ts — two classes: Caller (no area()) and Sibling (area()).
+ *    this.area() inside Caller.run must NOT resolve to Sibling.area even though
+ *    it is the only method with that suffix in the file (single-match path).
+ *
+ * Covers the Rust edge_builder fix in issue #1324.
+ */
+
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+import Database from 'better-sqlite3';
+import { afterAll, beforeAll, describe, expect, it } from 'vitest';
+import { buildGraph } from '../../src/domain/graph/builder.js';
+import type { EngineMode } from '../../src/types.js';
+
+const FIXTURE_DIR = path.join(import.meta.dirname, '..', 'fixtures', 'this-dispatch-scope');
+
+interface CallEdgeRow {
+  caller_name: string;
+  callee_name: string;
+}
+
+function readCallEdges(dbPath: string): CallEdgeRow[] {
+  const db = new Database(dbPath, { readonly: true });
+  try {
+    return db
+      .prepare(
+        `SELECT n1.name AS caller_name, n2.name AS callee_name
+         FROM edges e
+         JOIN nodes n1 ON e.source_id = n1.id
+         JOIN nodes n2 ON e.target_id = n2.id
+         WHERE e.kind = 'calls'`,
+      )
+      .all() as CallEdgeRow[];
+  } finally {
+    db.close();
+  }
+}
+
+const ENGINES: EngineMode[] = ['wasm', 'native'];
+
+describe.each(ENGINES)('this-dispatch scope (%s)', (engine) => {
+  let tmpDir: string;
+  let callEdges: CallEdgeRow[] = [];
+
+  beforeAll(async () => {
+    tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), `codegraph-this-scope-${engine}-`));
+    fs.cpSync(FIXTURE_DIR, tmpDir, { recursive: true });
+    await buildGraph(tmpDir, { incremental: false, skipRegistry: true, engine });
+    callEdges = readCallEdges(path.join(tmpDir, '.codegraph', 'graph.db'));
+  }, 60_000);
+
+  afterAll(() => {
+    if (tmpDir) fs.rmSync(tmpDir, { recursive: true, force: true });
+  });
+
+  it('emits Shape.describe → Shape.area (correct this-dispatch)', () => {
+    const edge = callEdges.find(
+      (e) => e.caller_name === 'Shape.describe' && e.callee_name === 'Shape.area',
+    );
+    expect(
+      edge,
+      `Expected Shape.describe → Shape.area edge.\nActual edges:\n${JSON.stringify(callEdges, null, 2)}`,
+    ).toBeDefined();
+  });
+
+  // Native binary v3.11.2 does not include the edge_builder.rs fix for issue #1324 yet.
+  // These assertions are active for WASM and will be re-enabled for native once a new
+  // binary is published that includes the Rust fix.
+  if (engine === 'native') {
+    it.todo('does NOT emit Shape.describe → Calculator.area (native binary gap #1324)');
+    it.todo('does NOT emit Shape.describe → Formatter.area (native binary gap #1324)');
+    it.todo(
+      'does NOT emit Caller.run → Sibling.area (single-match false-positive, native binary gap #1324)',
+    );
+  } else {
+    it('does NOT emit Shape.describe → Calculator.area (unrelated class, same method name)', () => {
+      const edge = callEdges.find(
+        (e) => e.caller_name === 'Shape.describe' && e.callee_name === 'Calculator.area',
+      );
+      expect(
+        edge,
+        `Expected NO Shape.describe → Calculator.area edge (false-positive from same-file scan).\nActual edges:\n${JSON.stringify(callEdges, null, 2)}`,
+      ).toBeUndefined();
+    });
+
+    it('does NOT emit Shape.describe → Formatter.area (unrelated class, same method name)', () => {
+      const edge = callEdges.find(
+        (e) => e.caller_name === 'Shape.describe' && e.callee_name === 'Formatter.area',
+      );
+      expect(
+        edge,
+        `Expected NO Shape.describe → Formatter.area edge (false-positive from same-file scan).\nActual edges:\n${JSON.stringify(callEdges, null, 2)}`,
+      ).toBeUndefined();
+    });
+
+    // single-sibling.ts: only one class (Sibling) has area(); Caller does not.
+    // The single-match arm must still check the caller's own class — Caller.run
+    // must not gain a false edge to Sibling.area.
+    it('does NOT emit Caller.run → Sibling.area (single-match false-positive, same-file scan)', () => {
+      const edge = callEdges.find(
+        (e) => e.caller_name === 'Caller.run' && e.callee_name === 'Sibling.area',
+      );
+      expect(
+        edge,
+        `Expected NO Caller.run → Sibling.area edge (false-positive from single-match suffix scan).\nActual edges:\n${JSON.stringify(callEdges, null, 2)}`,
+      ).toBeUndefined();
+    });
+  }
+});