fix(union): complete downstream container handling

__tests__/c-fnptr-synthesizer.test.ts

@@ -86,6 +86,45 @@ int dispatch(struct ops o) { return o.handler(); }
     expect(edges.every((e) => e.via === 'ops.handler')).toBe(true);
   });
 
+  it('bridges function-pointer fields declared in a union', async () => {
+    write('union-ops.c', `
+union ops { int (*handler)(void); };
+static int on_open(void) { return 1; }
+static union ops the_ops = { .handler = on_open };
+
+int dispatch(union ops o) { return o.handler(); }
+`);
+    const edges = await load();
+    expect(has(edges, 'dispatch', 'on_open')).toBe(true);
+    expect(edges.every((e) => e.via === 'ops.handler')).toBe(true);
+  });
+
+  it('bridges an inline union table whose entries are macro-built', async () => {
+    write('inline-union.c', `
+#define SLOT(fn) { fn }
+static int on_open(void) { return 1; }
+static union inline_ops { int (*handler)(void); } ops[] = { SLOT(on_open) };
+
+int dispatch(union inline_ops o) { return o.handler(); }
+`);
+    const edges = await load();
+    expect(has(edges, 'dispatch', 'on_open')).toBe(true);
+  });
+
+  it('bridges a union table declared through an object-macro type alias', async () => {
+    write('alias-union.c', `
+#define OPS_TYPE union ops
+#define SLOT(fn) { fn }
+union ops { int (*handler)(void); };
+static int on_open(void) { return 1; }
+static OPS_TYPE ops[] = { SLOT(on_open) };
+
+int dispatch(union ops o) { return o.handler(); }
+`);
+    const edges = await load();
+    expect(has(edges, 'dispatch', 'on_open')).toBe(true);
+  });
+
   it('bridges the typedef-field + field←field double-hop (the hook_demo.c shape)', async () => {
     write('hook.c', `
 typedef void (*hook_func)(void);

__tests__/context.test.ts

@@ -135,10 +135,16 @@ export function validateEmail(email: string): boolean {
 `
     );
 
+    fs.writeFileSync(
+      path.join(srcDir, 'callback_ops.c'),
+      `union CallbackOps { int (*run)(int); };
+`
+    );
+
     // Initialize CodeGraph
     cg = CodeGraph.initSync(testDir, {
       config: {
-        include: ['**/*.ts'],
+        include: ['**/*.ts', '**/*.c'],
         exclude: [],
       },
     });
@@ -194,6 +200,15 @@ export function validateEmail(email: string): boolean {
       ).toBe(true);
     });
 
+    it('includes union definitions in the default context search', async () => {
+      const result = await cg.findRelevantContext('CallbackOps');
+      const union = [...result.nodes.values()].find(
+        (node) => node.kind === 'union' && node.name === 'CallbackOps'
+      );
+
+      expect(union).toBeDefined();
+    });
+
     it('should include edges in the result', async () => {
       const result = await cg.findRelevantContext('checkout', {
         traversalDepth: 2,

__tests__/resolution.test.ts

@@ -1045,6 +1045,34 @@ void initialize() { Packet(); }
       expect(outgoing.some((e) => e.kind === 'calls' && e.target === packet!.id)).toBe(false);
     });
 
+    it('resolves a static call through an imported C++ union to its member', async () => {
+      fs.writeFileSync(
+        path.join(tempDir, 'ops.hpp'),
+        `union Ops {
+  static int run() { return 1; }
+};
+`
+      );
+      fs.writeFileSync(
+        path.join(tempDir, 'main.cpp'),
+        `#include "ops.hpp"
+
+int invoke() { return Ops::run(); }
+`
+      );
+
+      cg = await CodeGraph.init(tempDir, { index: true });
+      cg.resolveReferences();
+
+      const invoke = cg.getNodesByKind('function').find((n) => n.name === 'invoke');
+      const run = cg.getNodesByKind('method').find((n) => n.name === 'run');
+      expect(invoke).toBeDefined();
+      expect(run).toBeDefined();
+
+      const outgoing = cg.getOutgoingEdges(invoke!.id);
+      expect(outgoing.some((e) => e.kind === 'calls' && e.target === run!.id)).toBe(true);
+    });
+
     it('records instantiates for C++ stack/brace construction, targeting the class (#1035)', async () => {
       // `Calculator calc(0)` (direct-init) and `Widget w{1, 2}` (brace-init)
       // carry the constructor args directly on the declarator — there's no

codegraph-kernel/src/cfnptr.rs

@@ -432,8 +432,19 @@ struct InlineScan {
 fn scan_inline_structs(s: &[u8]) -> InlineScan {
     let mut out = InlineScan { ptr: false, types: Vec::new(), tags: Vec::new() };
     let mut last = 0;
-    while let Some(t) = find_word(s, b"struct", last) {
-        let after_kw = t + 6;
+    loop {
+        let next_struct = find_word(s, b"struct", last);
+        let next_union = find_word(s, b"union", last);
+        let Some((t, keyword_len)) = (match (next_struct, next_union) {
+            (Some(st), Some(un)) if st < un => Some((st, 6)),
+            (Some(_), Some(un)) => Some((un, 5)),
+            (Some(st), None) => Some((st, 6)),
+            (None, Some(un)) => Some((un, 5)),
+            (None, None) => None,
+        }) else {
+            break;
+        };
+        let after_kw = t + keyword_len;
         let ws = skip_jsws(s, after_kw);
         if ws == after_kw || !is_word_at(s, ws) {
             last = t + 1;
@@ -569,10 +580,10 @@ fn init_body(s: &[u8], p: usize) -> Option<(String, usize)> {
     let i = skip_jsws(s, p);
     let mods = modifier_positions(s, i);
     for &pos in mods.iter().rev() {
-        for with_struct in [true, false] {
-            let q = if with_struct {
-                if s.len() >= pos + 6 && &s[pos..pos + 6] == b"struct" {
-                    let e = pos + 6;
+        for keyword in [Some(b"struct".as_slice()), Some(b"union".as_slice()), None] {
+            let q = if let Some(keyword) = keyword {
+                if s.len() >= pos + keyword.len() && &s[pos..pos + keyword.len()] == keyword {
+                    let e = pos + keyword.len();
                     let w = skip_jsws(s, e);
                     if w == e {
                         continue;
@@ -729,12 +740,19 @@ fn alias_line(line: &[u8]) -> Option<&[u8]> {
     if v0 == name_end {
         return None; // [ \t]+ before the value
     }
-    // (?:struct[ \t]+)* greedy, k-descending on value failure.
+    // (?:(?:struct|union)[ \t]+)* greedy, k-descending on value failure.
     let mut stack = vec![v0];
     loop {
         let cur = *stack.last().unwrap();
-        if line.len() >= cur + 6 && &line[cur..cur + 6] == b"struct" {
-            let e = cur + 6;
+        let keyword_len = if line.len() >= cur + 6 && &line[cur..cur + 6] == b"struct" {
+            Some(6)
+        } else if line.len() >= cur + 5 && &line[cur..cur + 5] == b"union" {
+            Some(5)
+        } else {
+            None
+        };
+        if let Some(keyword_len) = keyword_len {
+            let e = cur + keyword_len;
             let w2 = skip_sp_tab(line, e);
             if w2 > e {
                 stack.push(w2);

src/context/index.ts

@@ -157,7 +157,7 @@ const DEFAULT_BUILD_OPTIONS: Required<BuildContextOptions> = {
  * they tell you something exists, not how it works.
  */
 const HIGH_VALUE_NODE_KINDS: NodeKind[] = [
-  'function', 'method', 'class', 'interface', 'type_alias', 'struct', 'trait',
+  'function', 'method', 'class', 'interface', 'type_alias', 'struct', 'union', 'trait',
   'component', 'route', 'variable', 'constant', 'enum', 'module', 'namespace',
 ];
 
@@ -503,7 +503,7 @@ export class ContextBuilder {
     // like RestController, BulkRequest, AllocationService — not nodes named exactly that.
     // Also tries stem variants: "caching" → "cache" finds Cache, CacheBuilder.
     if (symbolsFromQuery.length > 0) {
-      const definitionKinds: NodeKind[] = ['class', 'interface', 'struct', 'trait',
+      const definitionKinds: NodeKind[] = ['class', 'interface', 'struct', 'union', 'trait',
         'protocol', 'enum', 'type_alias'];
       // Expand symbols with stem variants for broader definition matching
       const expandedSymbols = new Set(symbolsFromQuery);
@@ -754,7 +754,7 @@ export class ContextBuilder {
     // LIKE reliably finds these substring matches. Results are appended with
     // guaranteed slots so they don't compete with higher-scoring prefix matches.
     if (symbolsFromQuery.length > 0) {
-      const camelDefinitionKinds: NodeKind[] = ['class', 'interface', 'struct', 'trait',
+      const camelDefinitionKinds: NodeKind[] = ['class', 'interface', 'struct', 'union', 'trait',
         'protocol', 'enum', 'type_alias'];
       // Callable kinds participate too: in service-layer codebases the
       // camel-infix definers of a queried FIELD are methods/functions
@@ -977,7 +977,7 @@ export class ContextBuilder {
     // before reaching extends/implements neighbors. This dedicated step
     // ensures subclasses and superclasses always appear in results.
     // Budget: up to maxNodes/4 hierarchy nodes to avoid flooding.
-    const typeHierarchyKinds = new Set<string>(['class', 'interface', 'struct', 'trait', 'protocol']);
+    const typeHierarchyKinds = new Set<string>(['class', 'interface', 'struct', 'union', 'trait', 'protocol']);
     const maxHierarchyNodes = Math.ceil(opts.maxNodes / 4);
     let hierarchyNodesAdded = 0;
     for (const result of filteredResults) {

src/graph/queries.ts

@@ -173,6 +173,7 @@ export class GraphQueryManager {
     const allNodes: Node[] = [];
     const kinds: Node['kind'][] = [
       'class',
+      'union',
       'function',
       'method',
       'interface',
@@ -347,6 +348,7 @@ export class GraphQueryManager {
       'module',
       'class',
       'struct',
+      'union',
       'interface',
       'trait',
       'function',

src/graph/traversal.ts

@@ -564,7 +564,7 @@ export class GraphTraverser {
     // into their children so that callers of contained methods appear in impact
     const focalNode = this.queries.getNodeById(nodeId);
     if (focalNode) {
-      const containerKinds = new Set(['class', 'interface', 'struct', 'trait', 'protocol', 'module', 'enum']);
+      const containerKinds = new Set(['class', 'interface', 'struct', 'union', 'trait', 'protocol', 'module', 'enum']);
       if (containerKinds.has(focalNode.kind)) {
         const containsEdges = this.queries.getOutgoingEdges(nodeId, ['contains']);
         if (containsEdges.length > 0) {

src/mcp/tools.ts

@@ -118,7 +118,7 @@ const RUST_PATH_PREFIXES = new Set(['crate', 'super', 'self']);
  * multi-thousand-character wall of source that bloats the agent's context.
  */
 const CONTAINER_NODE_KINDS = new Set<NodeKind>([
-  'class', 'struct', 'interface', 'trait', 'protocol', 'enum', 'namespace', 'module',
+  'class', 'struct', 'union', 'interface', 'trait', 'protocol', 'enum', 'namespace', 'module',
 ]);
 
 /** Last `::` / `.` / `/`-separated segment of a qualified symbol. */
@@ -2927,7 +2927,7 @@ export class ToolHandler {
     const ROOT_CAP = 5; // only the symbols the query actually targeted
     const FILE_CAP = 4; // caller files listed per symbol before "+N more"
     const MEANINGFUL = new Set<string>([
-      'function', 'method', 'class', 'interface', 'struct', 'trait', 'protocol',
+      'function', 'method', 'class', 'interface', 'struct', 'union', 'trait', 'protocol',
       'enum', 'type_alias', 'component', 'constant', 'variable', 'property', 'field',
     ]);
     const rel = (p: string) => p.replace(/\\/g, '/');
@@ -3452,7 +3452,7 @@ export class ToolHandler {
     // displaces a flow-central file. Bounded: only the few named seeds, only the
     // types in their signatures.
     const CALLABLE_KINDS = new Set(['method', 'function', 'component', 'constructor']);
-    const TYPE_KINDS = new Set(['class', 'struct', 'interface', 'trait', 'protocol', 'enum', 'type_alias']);
+    const TYPE_KINDS = new Set(['class', 'struct', 'union', 'interface', 'trait', 'protocol', 'enum', 'type_alias']);
     const SIG_EDGE = new Set(['references', 'type_of', 'returns']);
     const changeSurfaceCandidates: Node[] = [];
     const seenChangeSurface = new Set<string>();
@@ -4538,7 +4538,7 @@ export class ToolHandler {
       // query actually asked about (#185 follow-up — Session.swift in
       // Alamofire is the canonical case: the `Session` class spans ~1,400
       // lines). We want the granular symbols inside, not the envelope.
-      const ENVELOPE_KINDS = new Set(['file', 'module', 'class', 'struct', 'interface', 'enum', 'namespace', 'protocol', 'trait', 'component']);
+      const ENVELOPE_KINDS = new Set(['file', 'module', 'class', 'struct', 'union', 'interface', 'enum', 'namespace', 'protocol', 'trait', 'component']);
       // Cluster from this file's gathered nodes PLUS any callable the agent NAMED that
       // lives here. Explore's relevance gather can miss a named method def in a huge
       // non-sibling file — Django's query.py is 3,040 lines and `_fetch_all` (L2237)

src/resolution/c-fnptr-synthesizer.ts

@@ -296,7 +296,7 @@ function resolveTypeName(name: string, objEnv: Map<string, string> | undefined):
   let n = name;
   for (let i = 0; objEnv && i < 5; i++) {
     const v = objEnv.get(n);
-    const t = v?.trim().match(/^(?:struct\s+)?(\w+)$/);
+    const t = v?.trim().match(/^(?:(?:struct|union)\s+)?(\w+)$/);
     if (!t) break;
     n = t[1]!;
   }
@@ -370,20 +370,20 @@ const INCLUDABLE_EXT = /\.(def|inc|h|hh|hpp|hxx|c|cc|cpp|cxx|ipp|tcc|tbl)$/i;
  *  are excluded: `resolveTypeName` would rewrite to a dead-end token that can
  *  never name a struct, so skipping them is exact, and it drops the register
  *  flood. */
-const OBJ_ALIAS_RE = /^[ \t]*#[ \t]*define[ \t]+(\w+)[ \t]+(?:struct[ \t]+)*[A-Za-z_]\w*[ \t\r]*$/gm;
+const OBJ_ALIAS_RE = /^[ \t]*#[ \t]*define[ \t]+(\w+)[ \t]+(?:(?:struct|union)[ \t]+)*[A-Za-z_]\w*[ \t\r]*$/gm;
 
 /** `(?:struct )?TYPE name[opt] = {` initializers, where TYPE is a struct that
  *  has ≥1 fn-pointer field. Handles both single (`= {…}`) and array
  *  (`[] = { {…}, {…} }`) forms. Macro calls inside an element are expanded first. */
 const INIT_RE =
-  /(?:^|[;{}])\s*(?:(?:static|const|extern|register|volatile)\s+)*(?:struct\s+)?(\w+)\s+(\w+)\s*(\[[^\]]*\])?\s*=\s*\{/g;
+  /(?:^|[;{}])\s*(?:(?:static|const|extern|register|volatile)\s+)*(?:(?:struct|union)\s+)?(\w+)\s+(\w+)\s*(\[[^\]]*\])?\s*=\s*\{/g;
 /** `struct TAG { … } var[opt] [= {…}]` — the struct is defined INLINE with the
  *  table (vim's `cmdname`/`nv_cmd`); its layout never became a node, so parse it
  *  here and register it before reading the entries. No leading anchor: a
  *  `struct TAG {` with a brace body is always a definition (it may be preceded
  *  by a `#define …` line ending in a digit, as in vim), and the trailing
  *  `var … = {` check below is what distinguishes a TABLE from a plain type. */
-const INLINE_STRUCT_RE = /\bstruct\s+(\w+)\s*\{/g;
+const INLINE_STRUCT_RE = /\b(?:struct|union)\s+(\w+)\s*\{/g;
 /** `(?:static …)* ELEMTYPE [*] name[…] = { … }` — a bare array of function
  *  pointers (no struct wrapper). The optional `*` covers a function-TYPE
  *  typedef element (`opcode_t *opcodes[]`); a function-pointer typedef element
@@ -854,12 +854,14 @@ export async function cFnPointerDispatchEdges(
     if (fields.some((f) => f.isFnPtr)) structLayout.set(name, fields);
   };
 
-  for (const st of (ctx.iterateNodesByKind?.('struct') ?? ctx.getNodesByKind('struct'))) {
-    if ((++scannedFiles & 255) === 0) await onYield();
-    if (!C_CPP_EXT.test(st.filePath)) continue;
-    const rawFields = rawFieldsByNode.get(st.id);
-    if (!rawFields) continue; // file unreadable or body unparsable at sweep time — the old pass skipped it too
-    registerStructLayout(st.name, classifyFields(rawFields));
+  for (const kind of ['struct', 'union'] as const) {
+    for (const st of (ctx.iterateNodesByKind?.(kind) ?? ctx.getNodesByKind(kind))) {
+      if ((++scannedFiles & 255) === 0) await onYield();
+      if (!C_CPP_EXT.test(st.filePath)) continue;
+      const rawFields = rawFieldsByNode.get(st.id);
+      if (!rawFields) continue; // file unreadable or body unparsable at sweep time — the old pass skipped it too
+      registerStructLayout(st.name, classifyFields(rawFields));
+    }
   }
   rawFieldsByNode.clear();
   if (prof) { prof.B = Date.now() - tPass; tPass = Date.now(); }
@@ -1211,7 +1213,7 @@ export async function cFnPointerDispatchEdges(
   const recvTypeIn = (fnSrc: string, recv: string): string | null => {
     let re = recvReCache.get(recv);
     if (!re) {
-      re = new RegExp(`(?:struct\\s+)?(\\w+)\\s*\\*?\\s*\\b${recv}\\b\\s*(?:[,)=;]|\\[)`, 'g');
+      re = new RegExp(`(?:(?:struct|union)\\s+)?(\\w+)\\s*\\*?\\s*\\b${recv}\\b\\s*(?:[,)=;]|\\[)`, 'g');
       recvReCache.set(recv, re);
     }
     re.lastIndex = 0;
@@ -1230,7 +1232,7 @@ export async function cFnPointerDispatchEdges(
   const varTypeIn = (fnSrc: string, v: string): string | null => {
     let re = varReCache.get(v);
     if (!re) {
-      re = new RegExp(`(?:struct\\s+)?(\\w+)\\s*\\*?\\s*\\b${escapeRe(v)}\\b\\s*(?:[,)=;]|\\[)`, 'g');
+      re = new RegExp(`(?:(?:struct|union)\\s+)?(\\w+)\\s*\\*?\\s*\\b${escapeRe(v)}\\b\\s*(?:[,)=;]|\\[)`, 'g');
       varReCache.set(v, re);
     }
     re.lastIndex = 0;

src/resolution/import-resolver.ts

@@ -2192,7 +2192,7 @@ function findExportedSymbolWalk(
 
 /** Node kinds that own static members reachable as `Container.member`. */
 const STATIC_MEMBER_CONTAINERS = new Set<Node['kind']>([
-  'class', 'struct', 'interface', 'enum', 'trait', 'protocol',
+  'class', 'struct', 'union', 'interface', 'enum', 'trait', 'protocol',
 ]);
 
 /**