fix(extractors): resolve inline object-literal dispatch tables on WASM

WASM's extractSubscriptCallInfo had no equivalent of native's RES-2
extract_dispatch_table_call, so ({a:fnA,b:fnB})[key]() classified as a
generic flagged computed-key sink while native resolved it to fnA/fnB
via the points-to wildcard solver — a genuine engine-parity gap.

Add extractDispatchTableCall, mirroring the native extractor: when a
subscript call's object is an object literal (optionally unwrapped
from a parenthesized expression) and the index is a bare identifier,
seed arrayElemBindings under a synthetic <dt_line_col> name and emit a
<dt_line_col>[*] call with dynamicKind 'dispatch-table' so the existing
pts wildcard resolution path (already used for array-literal dispatch)
picks it up identically on both engines. Threaded through both
extraction paths (dispatchQueryMatch for the WASM worker, handleCallExpr
for direct/test callers) per the two-path extractor architecture.

Adds 'dispatch-table' to the DynamicKind union and restores the
pts-javascript dispatch-table fixture, points-to unit tests, and a
query-vs-walk + cross-engine parity case that were dropped from a prior
merge without being ported to WASM.

Impact: 9 functions changed, 20 affected

Author: carlos-alm

src/extractors/javascript.ts

@@ -331,6 +331,7 @@ function dispatchQueryMatch(
   classes: ClassRelation[],
   exps: Export[],
   callbackParamShapes: CallbackParamShapes,
+  arrayElemBindings: ArrayElemBinding[],
 ): void {
   if (c.fn_node) {
     handleFnCapture(c, definitions);
@@ -365,7 +366,7 @@ function dispatchQueryMatch(
     if (cbDef) definitions.push(cbDef);
     calls.push(...extractCallbackReferenceCalls(c.callmem_node, callbackParamShapes));
   } else if (c.callsub_node) {
-    const callInfo = extractCallInfo(c.callsub_fn!, c.callsub_node);
+    const callInfo = extractCallInfo(c.callsub_fn!, c.callsub_node, arrayElemBindings);
     if (callInfo) calls.push(callInfo);
     calls.push(...extractCallbackReferenceCalls(c.callsub_node, callbackParamShapes));
   } else if (c.newfn_node) {
@@ -421,7 +422,16 @@ function extractSymbolsQuery(tree: TreeSitterTree, query: TreeSitterQuery): Extr
     // Build capture lookup for this match (1-3 captures each, very fast)
     const c: Record<string, TreeSitterNode> = Object.create(null);
     for (const cap of match.captures) c[cap.name] = cap.node;
-    dispatchQueryMatch(c, definitions, calls, imports, classes, exps, callbackParamShapes);
+    dispatchQueryMatch(
+      c,
+      definitions,
+      calls,
+      imports,
+      classes,
+      exps,
+      callbackParamShapes,
+      arrayElemBindings,
+    );
   }
 
   // Extract top-level constants via targeted walk (query patterns don't cover these)
@@ -1630,7 +1640,7 @@ function handleCallExpr(
       ctx.calls.push({ name: 'this', line: nodeStartLine(node) });
       return; // no further processing needed for this()-style calls
     }
-    const callInfo = extractCallInfo(fn, node);
+    const callInfo = extractCallInfo(fn, node, ctx.arrayElemBindings);
     if (callInfo) ctx.calls.push(callInfo);
     if (fn.type === 'member_expression') {
       const cbDef = extractCallbackDefinition(node, fn);
@@ -3497,7 +3507,11 @@ function extractReceiverName(objNode: TreeSitterNode | null): string | undefined
   return objNode.text;
 }
 
-function extractCallInfo(fn: TreeSitterNode, callNode: TreeSitterNode): Call | null {
+function extractCallInfo(
+  fn: TreeSitterNode,
+  callNode: TreeSitterNode,
+  arrayElemBindings?: ArrayElemBinding[],
+): Call | null {
   const fnType = fn.type;
   if (fnType === 'identifier') {
     if (fn.text === 'eval') {
@@ -3528,7 +3542,7 @@ function extractCallInfo(fn: TreeSitterNode, callNode: TreeSitterNode): Call | n
     return extractMemberExprCallInfo(fn, callNode);
   }
   if (fnType === 'subscript_expression') {
-    return extractSubscriptCallInfo(fn, callNode);
+    return extractSubscriptCallInfo(fn, callNode, arrayElemBindings);
   }
   return null;
 }
@@ -3684,8 +3698,72 @@ function extractMemberExprCallInfo(fn: TreeSitterNode, callNode: TreeSitterNode)
   return { name: propText, line: callLine, receiver };
 }
 
+/**
+ * RES-2: inline object-literal dispatch table — `({a:fnA,b:fnB})[key]()`.
+ *
+ * Mirrors `extract_dispatch_table_call` in
+ * `crates/codegraph-core/src/extractors/javascript.rs`. When the subscript's
+ * object is an object literal (optionally unwrapped from a parenthesized
+ * expression) and the index is a bare identifier, records each property's
+ * identifier value as an `ArrayElemBinding` under a synthetic `<dt_line_col>`
+ * name and returns a `<dt_line_col>[*]` call — the existing points-to
+ * wildcard resolution path (already used for `const arr = [f1, f2]; arr[i]()`
+ * patterns) then resolves it to each concrete target identically on both
+ * engines (#1897).
+ *
+ * Returns `null` when the object isn't an object literal, or none of its
+ * property values are resolvable bare identifiers.
+ */
+function extractDispatchTableCall(
+  obj: TreeSitterNode | null,
+  index: TreeSitterNode,
+  callNode: TreeSitterNode,
+  arrayElemBindings: ArrayElemBinding[],
+): Call | null {
+  if (!obj) return null;
+  // Unwrap parenthesized_expression: ({a:fn})[key]()
+  const objNode =
+    obj.type === 'parenthesized_expression'
+      ? (obj.childForFieldName('expression') ?? obj.child(1) ?? obj)
+      : obj;
+  if (objNode.type !== 'object') return null;
+
+  const line = nodeStartLine(callNode);
+  const col = callNode.startPosition.column;
+  const tableName = `<dt_${line}_${col}>`;
+  let idx = 0;
+  for (let i = 0; i < objNode.childCount; i++) {
+    const child = objNode.child(i);
+    if (!child) continue;
+    if (child.type === 'shorthand_property_identifier') {
+      if (!BUILTIN_GLOBALS.has(child.text)) {
+        arrayElemBindings.push({ arrayName: tableName, index: idx, elemName: child.text });
+        idx++;
+      }
+    } else if (child.type === 'pair') {
+      const val = child.childForFieldName('value');
+      if (val?.type === 'identifier' && !BUILTIN_GLOBALS.has(val.text)) {
+        arrayElemBindings.push({ arrayName: tableName, index: idx, elemName: val.text });
+        idx++;
+      }
+    }
+  }
+  if (idx === 0) return null;
+  return {
+    name: `${tableName}[*]`,
+    line,
+    dynamic: true,
+    dynamicKind: 'dispatch-table',
+    keyExpr: index.text,
+  };
+}
+
 /** Extract call info from a subscript_expression function node (obj[key]()). */
-function extractSubscriptCallInfo(fn: TreeSitterNode, callNode: TreeSitterNode): Call | null {
+function extractSubscriptCallInfo(
+  fn: TreeSitterNode,
+  callNode: TreeSitterNode,
+  arrayElemBindings?: ArrayElemBinding[],
+): Call | null {
   const obj = fn.childForFieldName('object');
   const index = fn.childForFieldName('index');
   if (!index) return null;
@@ -3705,8 +3783,12 @@ function extractSubscriptCallInfo(fn: TreeSitterNode, callNode: TreeSitterNode):
     }
   }
 
-  // obj[variable]() — key is a variable; may be resolvable via pts (RES-1), else flagged
+  // obj[variable]() — key is a variable; may be resolvable via pts (RES-1/RES-2), else flagged
   if (indexType === 'identifier') {
+    if (arrayElemBindings) {
+      const dispatchCall = extractDispatchTableCall(obj, index, callNode, arrayElemBindings);
+      if (dispatchCall) return dispatchCall;
+    }
     const receiver = extractReceiverName(obj);
     return {
       name: '<dynamic:computed-key>',

src/types.ts

@@ -491,7 +491,8 @@ export type DynamicKind =
   | 'reflection' // .call/.apply/.bind / Reflect.* / callable-ref — resolved when target is in codebase; sink edge emitted if unresolved
   | 'eval' // eval() / new Function() — undecidable; always flagged
   | 'unresolved-dynamic' // any other detected dynamic pattern; flagged
-  | 'value-ref'; // bare identifier used as a value reference rather than a call site — object-literal property value (dispatch-table pattern, e.g. `{ resolve: someFn }`, #1771), assignment to a Lua global/builtin identifier (e.g. `require = tracedRequire`, #1776), or the right operand of an `instanceof` check (e.g. `err instanceof CodegraphError`, #1784) — resolved only against function/method/class-kind targets (class only relevant for the instanceof site); unresolved (e.g. plain data references) are dropped silently, NOT flagged
+  | 'value-ref' // bare identifier used as a value reference rather than a call site — object-literal property value (dispatch-table pattern, e.g. `{ resolve: someFn }`, #1771), assignment to a Lua global/builtin identifier (e.g. `require = tracedRequire`, #1776), or the right operand of an `instanceof` check (e.g. `err instanceof CodegraphError`, #1784) — resolved only against function/method/class-kind targets (class only relevant for the instanceof site); unresolved (e.g. plain data references) are dropped silently, NOT flagged
+  | 'dispatch-table'; // inline object-literal subscript dispatch, e.g. `({a:fnA,b:fnB})[key]()` (#1897) — resolved via the points-to wildcard solver against synthetic `<dt_line_col>[*]` array-elem bindings seeded from each property's identifier value; never flagged (excluded from FLAG_ONLY_DYNAMIC_KINDS) so an unresolved table produces no sink edge, matching the named-array `[fn1,fn2][*]` dispatch pattern
 
 /** A function/method call detected by an extractor. */
 export interface Call {

tests/benchmarks/resolution/fixtures/pts-javascript/dispatch-table.js

@@ -0,0 +1,7 @@
+// pts-dispatch-table: inline object-literal subscript dispatch {a:fnA,b:fnB}[k]()
+function dtFn1() {}
+function dtFn2() {}
+
+function runDispatch(key) {
+  ({ a: dtFn1, b: dtFn2 })[key]();
+}

tests/benchmarks/resolution/fixtures/pts-javascript/expected-edges.json

@@ -93,6 +93,20 @@
       "kind": "calls",
       "mode": "pts-spread",
       "notes": "y() inside consumer2 — spread consumer2(...[sprFn3, sprFn4]) binds sprFn4 to y"
+    },
+    {
+      "source": { "name": "runDispatch", "file": "dispatch-table.js" },
+      "target": { "name": "dtFn1", "file": "dispatch-table.js" },
+      "kind": "calls",
+      "mode": "pts-dispatch-table",
+      "notes": "({a:dtFn1,b:dtFn2})[key]() — inline dispatch table; pts resolves wildcard to each value"
+    },
+    {
+      "source": { "name": "runDispatch", "file": "dispatch-table.js" },
+      "target": { "name": "dtFn2", "file": "dispatch-table.js" },
+      "kind": "calls",
+      "mode": "pts-dispatch-table",
+      "notes": "({a:dtFn1,b:dtFn2})[key]() — inline dispatch table; pts resolves wildcard to each value"
     }
   ]
 }

tests/engines/parity.test.ts

@@ -227,6 +227,23 @@ router.get('/users/:id', authHandler);
 Array.from(arr, mapCallback);
 Array.from(arr, mapCallback, thisArg);
 Uint8Array.from(arr, mapCallback);
+`,
+    },
+    {
+      // Regression guard for #1897: WASM previously had no mirror of native's
+      // RES-2 inline object-literal dispatch-table detection
+      // (extract_dispatch_table_call), so `({a:fnA,b:fnB})[key]()` classified
+      // as a generic flagged computed-key sink on WASM while native resolved
+      // it via the pts wildcard. Both engines must now emit the exact same
+      // synthetic `<dt_line_col>[*]` call name (line/col computed identically).
+      name: 'JavaScript — inline object-literal dispatch table must agree between engines',
+      file: 'dispatch-table.js',
+      code: `
+function dtFn1() {}
+function dtFn2() {}
+function runDispatch(key) {
+  return ({ a: dtFn1, b: dtFn2 })[key]();
+}
 `,
     },
     {

tests/engines/query-walk-parity.test.ts

@@ -274,6 +274,23 @@ function runDemo(users: string[]): void {
   processEach(users, logUser);
   findMergeCandidates(users);
 }
+`,
+  },
+  {
+    // Regression guard for #1897: inline object-literal dispatch-table
+    // subscript calls (`({a:fnA,b:fnB})[key]()`) must produce the same
+    // synthetic `<dt_line_col>[*]` call on both extraction paths — the query
+    // path threads `arrayElemBindings` through `dispatchQueryMatch`'s
+    // `callsub_node` branch, the walk path through `handleCallExpr`'s
+    // `ctx.arrayElemBindings`.
+    name: 'inline object-literal dispatch table (#1897)',
+    file: 'test.js',
+    code: `
+function fnA() {}
+function fnB() {}
+function run(key) {
+  return ({ a: fnA, b: fnB })[key]();
+}
 `,
   },
   // TSX

tests/parsers/javascript.test.ts

@@ -1555,6 +1555,97 @@ function runDemo(users: string[]): void {
     });
   });
 
+  describe('inline object-literal dispatch table extraction (RES-2, #1897)', () => {
+    // Mirrors the Rust `dispatch_table_emits_dt_call_and_array_elem_bindings`
+    // / `dispatch_table_parenthesized_object_also_works` unit tests in
+    // crates/codegraph-core/src/extractors/javascript.rs.
+    it('emits a <dt_line_col>[*] call and array-elem bindings for each identifier value', () => {
+      const symbols = parseJS(`
+        function dtFn1() {}
+        function dtFn2() {}
+        function runDispatch(key) { ({ a: dtFn1, b: dtFn2 })[key](); }
+      `);
+      const dtCall = symbols.calls.find(
+        (c) => c.name.startsWith('<dt_') && c.name.endsWith('>[*]'),
+      );
+      expect(dtCall).toBeDefined();
+      expect(dtCall?.dynamic).toBe(true);
+      expect(dtCall?.dynamicKind).toBe('dispatch-table');
+      expect(dtCall?.keyExpr).toBe('key');
+
+      const tableName = dtCall!.name.slice(0, -3); // strip trailing "[*]"
+      expect(symbols.arrayElemBindings).toContainEqual({
+        arrayName: tableName,
+        index: 0,
+        elemName: 'dtFn1',
+      });
+      expect(symbols.arrayElemBindings).toContainEqual({
+        arrayName: tableName,
+        index: 1,
+        elemName: 'dtFn2',
+      });
+    });
+
+    it('also detects the pattern without wrapping parens in a non-ambiguous expression position', () => {
+      // `{...}` needs parens only where it would otherwise be parsed as a
+      // block (statement position). In a `return` expression it's already
+      // unambiguous, so the object node is not wrapped in a
+      // parenthesized_expression — exercising the non-unwrap branch of
+      // extractDispatchTableCall, the mirror image of the first test above.
+      const symbols = parseJS(`
+        function fnA() {}
+        function fnB() {}
+        function run(k) { return { a: fnA, b: fnB }[k](); }
+      `);
+      const dtCall = symbols.calls.find(
+        (c) => c.name.startsWith('<dt_') && c.name.endsWith('>[*]'),
+      );
+      expect(dtCall).toBeDefined();
+    });
+
+    it('resolves the shorthand-property form (`{ fnA, fnB }[k]()`)', () => {
+      const symbols = parseJS(`
+        function fnA() {}
+        function fnB() {}
+        function run(k) { ({ fnA, fnB })[k](); }
+      `);
+      const dtCall = symbols.calls.find(
+        (c) => c.name.startsWith('<dt_') && c.name.endsWith('>[*]'),
+      );
+      expect(dtCall).toBeDefined();
+      const tableName = dtCall!.name.slice(0, -3);
+      expect(symbols.arrayElemBindings).toContainEqual({
+        arrayName: tableName,
+        index: 0,
+        elemName: 'fnA',
+      });
+      expect(symbols.arrayElemBindings).toContainEqual({
+        arrayName: tableName,
+        index: 1,
+        elemName: 'fnB',
+      });
+    });
+
+    it('falls back to the generic computed-key classification for a non-literal object', () => {
+      const symbols = parseJS(`function run(handlers, key) { return handlers[key](); }`);
+      expect(symbols.calls).toContainEqual(
+        expect.objectContaining({ name: '<dynamic:computed-key>', dynamicKind: 'computed-key' }),
+      );
+      expect(symbols.calls.find((c) => c.dynamicKind === 'dispatch-table')).toBeUndefined();
+    });
+
+    it('does not treat a string-literal key on an object literal as a dispatch table', () => {
+      const symbols = parseJS(`
+        function fnA() {}
+        function run() { return ({ a: fnA })['a'](); }
+      `);
+      expect(symbols.calls.find((c) => c.dynamicKind === 'dispatch-table')).toBeUndefined();
+      expect(symbols.calls).toContainEqual(
+        expect.objectContaining({ name: 'a', dynamicKind: 'computed-literal' }),
+      );
+    });
+  });
+
   describe('instanceof value-ref extraction (#1784)', () => {
     it('extracts a value-ref call for `instanceof ClassName`', () => {
       const symbols = parseJS(`

tests/unit/points-to.test.ts

@@ -477,3 +477,40 @@ describe('buildPointsToMap — maxIterations cap (issue #1753)', () => {
     expect(resolveViaPointsTo('a0', pts)).toEqual(['handler']);
   });
 });
+
+describe('buildPointsToMap — dispatch-table pts constraints (RES-2, #1897)', () => {
+  it('seeds wildcard for synthetic dispatch-table array elem bindings', () => {
+    const defNames = new Set(['dtFn1', 'dtFn2']);
+    const arrayElemBindings = [
+      { arrayName: '<dt_5_2>', index: 0, elemName: 'dtFn1' },
+      { arrayName: '<dt_5_2>', index: 1, elemName: 'dtFn2' },
+    ];
+    const pts = buildPointsToMap([], defNames, NO_IMPORTS, undefined, undefined, arrayElemBindings);
+    expect(resolveViaPointsTo('<dt_5_2>[*]', pts)).toContain('dtFn1');
+    expect(resolveViaPointsTo('<dt_5_2>[*]', pts)).toContain('dtFn2');
+  });
+
+  it('resolves only identifier values, not string keys', () => {
+    const defNames = new Set(['fn1']);
+    const arrayElemBindings = [{ arrayName: '<dt_1_0>', index: 0, elemName: 'fn1' }];
+    const pts = buildPointsToMap([], defNames, NO_IMPORTS, undefined, undefined, arrayElemBindings);
+    expect(resolveViaPointsTo('<dt_1_0>[*]', pts)).toEqual(['fn1']);
+  });
+
+  it('two dispatch tables in the same file use distinct synthetic names', () => {
+    const defNames = new Set(['fnA', 'fnB', 'fnC', 'fnD']);
+    const arrayElemBindings = [
+      { arrayName: '<dt_3_0>', index: 0, elemName: 'fnA' },
+      { arrayName: '<dt_3_0>', index: 1, elemName: 'fnB' },
+      { arrayName: '<dt_7_0>', index: 0, elemName: 'fnC' },
+      { arrayName: '<dt_7_0>', index: 1, elemName: 'fnD' },
+    ];
+    const pts = buildPointsToMap([], defNames, NO_IMPORTS, undefined, undefined, arrayElemBindings);
+    expect(resolveViaPointsTo('<dt_3_0>[*]', pts)).toContain('fnA');
+    expect(resolveViaPointsTo('<dt_3_0>[*]', pts)).toContain('fnB');
+    expect(resolveViaPointsTo('<dt_3_0>[*]', pts)).not.toContain('fnC');
+    expect(resolveViaPointsTo('<dt_7_0>[*]', pts)).toContain('fnC');
+    expect(resolveViaPointsTo('<dt_7_0>[*]', pts)).toContain('fnD');
+    expect(resolveViaPointsTo('<dt_7_0>[*]', pts)).not.toContain('fnA');
+  });
+});