fix(cpp): a call through a template parameter links to each class written as its argument

AGENTS.md

@@ -78,7 +78,7 @@ The public API surface is `src/index.ts` — the `CodeGraph` class wires all the
   **It must stay light to load:** a read command, a query worker and the prompt hook all load it, and never index. What only indexing needs (extraction, resolution, the watcher) goes through `engine()` (`src/lazy-engine.ts`, listed in `src/engine.ts`), never an import of its own; `__tests__/lazy-engine.test.ts` fails otherwise.
 - `src/db/` — `DatabaseConnection`, `QueryBuilder` (prepared statements), `schema.sql`, `sqlite-adapter.ts`. Backed by Node's built-in **`node:sqlite`** (`DatabaseSync`) — real SQLite with WAL + FTS5, exposed through a thin better-sqlite3-shaped adapter. The bundled runtime always ships Node ≥22.5, so `node:sqlite` is always available: **no native build step and no wasm fallback**. (Running from source needs Node ≥22.5.) `codegraph status` reports the live backend (`node-sqlite`, the sole backend).
 - `src/extraction/` — `ExtractionOrchestrator`, tree-sitter wrappers, per-language extractors under `languages/` (one file per language), plus standalone extractors for non-tree-sitter formats (`svelte-extractor.ts`, `vue-extractor.ts`, `liquid-extractor.ts`, `dfm-extractor.ts` for Delphi). `parse-worker.ts` runs heavy parsing off the main thread.
-- `src/resolution/` — `ReferenceResolver` orchestrates `import-resolver.ts` (with `path-aliases.ts` for tsconfig path aliases + cargo workspace member globs), `name-matcher.ts`, and `frameworks/` (Express, Laravel, CodeIgniter 3, Rails, FastAPI, Django, Flask, Spring, Gin, Axum, ASP.NET, Vapor, React Router, Next.js — `nextjs.ts`: pages and `route.ts` handlers from files, `router.push` / `redirect` / `NextResponse.redirect` as `navigates` edges, with `next-router-synthesizer.ts` for `<Link href>` and for the routes a proxy's `config.matcher` accepts, read by `next-proxy.ts` — Expo Router, SvelteKit, Vue/Nuxt, Cargo workspaces). Frameworks emit `route` nodes and `references` edges. `callback-synthesizer.ts` holds the whole-graph synthesis passes (`SYNTH_PASSES`, merged in registry order — first-seen wins a duplicate pair) with the language gates; `tier-synthesizer.ts` is the cross-tier pass (a client's literal `fetch`/`axios` path onto its own route, a queue job onto its consumer, a bus / socket event onto its handler — `channel`, `tier`, `registeredAt` on every edge; registered before the in-process emitter pass so its more specific edge wins); `synth-utils.ts` has the helpers they share (`enclosingFn`, `enclosingValue`, `makeLineAt`). Express's `postExtract` composes `app.use('/prefix', router)` mounts onto a mounted file's route names, idempotently (the original path stays in `qualifiedName`).
+- `src/resolution/` — `ReferenceResolver` orchestrates `import-resolver.ts` (with `path-aliases.ts` for tsconfig path aliases + cargo workspace member globs), `name-matcher.ts`, and `frameworks/` (Express, Laravel, CodeIgniter 3, Rails, FastAPI, Django, Flask, Spring, Gin, Axum, ASP.NET, Vapor, React Router, Next.js — `nextjs.ts`: pages and `route.ts` handlers from files, `router.push` / `redirect` / `NextResponse.redirect` as `navigates` edges, with `next-router-synthesizer.ts` for `<Link href>` and for the routes a proxy's `config.matcher` accepts, read by `next-proxy.ts` — Expo Router, SvelteKit, Vue/Nuxt, Cargo workspaces). Frameworks emit `route` nodes and `references` edges. `callback-synthesizer.ts` holds the whole-graph synthesis passes (`SYNTH_PASSES`, merged in registry order — first-seen wins a duplicate pair) with the language gates; `cpp-template-instantiations.ts` is the pass for a C++ call through a template parameter, onto each class the project writes as the argument (read from `Name<Foo>`, `f<Foo>()`, a deduced call or a gtest type list), capped per parameter; `tier-synthesizer.ts` is the cross-tier pass (a client's literal `fetch`/`axios` path onto its own route, a queue job onto its consumer, a bus / socket event onto its handler — `channel`, `tier`, `registeredAt` on every edge; registered before the in-process emitter pass so its more specific edge wins); `synth-utils.ts` has the helpers they share (`enclosingFn`, `enclosingValue`, `makeLineAt`). Express's `postExtract` composes `app.use('/prefix', router)` mounts onto a mounted file's route names, idempotently (the original path stays in `qualifiedName`).
 - `src/graph/` — `GraphTraverser` (BFS/DFS, impact radius, path finding) and `GraphQueryManager` (high-level queries), plus the shared query-time derivations more than one surface renders: `named-symbol-flow.ts` (the one path finder, behind `codegraph_explore`'s Flow section and the viewer's Flow strip), `dynamic-boundary-report.ts` (where the graph stops), `type-hierarchy.ts` (ancestors/subtypes and the implementation count explore prints and the viewer draws),
   `dead-code.ts` (unreferenced symbols, and every reason a candidate is NOT claimed), `synthesized-hop.ts` (how a synthesized hop reads, in explore's Flow, the `codegraph_node` trail and ContextBuilder's call paths — a new synthesizer's wording goes here), `file-cycles.ts` (circular imports, in `codegraph cycles` and the viewer's map). A derivation that two callers render must live here, not in `ToolHandler` — two derivations eventually disagree.
 - `src/context/` — `ContextBuilder` + formatter for markdown/JSON output.
@@ -158,7 +158,7 @@ Two functions in `src/mcp/tools.ts` scale explore with indexed file count. This
 
 ### Dynamic-dispatch coverage — the flow must EXIST in the graph end-to-end
 
-Static tree-sitter extraction misses computed/indirect calls, so flows break at dynamic dispatch and the agent reads to reconstruct them. Synthesizers/resolvers bridge these so `codegraph_explore` connects them end-to-end (`src/resolution/callback-synthesizer.ts`, `src/resolution/frameworks/`). Channels today: callback/observer, EventEmitter, **React re-render** (`setState`→`render`), **JSX child** (`render`→child component), **React Native native→JS events** (`sendEvent(withName:)` / JVM `emit` → the `addListener` handler, named or inline, `rn-event-channel`), django ORM descriptor. The JS→native direction is a *resolver* (`frameworks/react-native.ts`: `RCT_EXPORT_METHOD`, `RCT_EXTERN_MODULE` Swift shims, TurboModules), which trusts receiver evidence — an alias bound to `NativeModules.X` — over the import resolver. All synthesized edges are `provenance:'heuristic'` with `metadata.synthesizedBy` + `registeredAt` (the wiring site), surfaced inline in `codegraph_explore`'s Flow section and the `codegraph_node` trail.
+Static tree-sitter extraction misses computed/indirect calls, so flows break at dynamic dispatch and the agent reads to reconstruct them. Synthesizers/resolvers bridge these so `codegraph_explore` connects them end-to-end (`src/resolution/callback-synthesizer.ts`, `src/resolution/frameworks/`). Channels today: callback/observer, EventEmitter, **React re-render** (`setState`→`render`), **JSX child** (`render`→child component), **React Native native→JS events** (`sendEvent(withName:)` / JVM `emit` → the `addListener` handler, named or inline, `rn-event-channel`), django ORM descriptor, **C++ template arguments** (`Txn::Put` or `shard.Clear()` in a template → that member of each class the project instantiates it with). The JS→native direction is a *resolver* (`frameworks/react-native.ts`: `RCT_EXPORT_METHOD`, `RCT_EXTERN_MODULE` Swift shims, TurboModules), which trusts receiver evidence — an alias bound to `NativeModules.X` — over the import resolver. All synthesized edges are `provenance:'heuristic'` with `metadata.synthesizedBy` + `registeredAt` (the wiring site), surfaced inline in `codegraph_explore`'s Flow section and the `codegraph_node` trail.
 
 **Principle: partial coverage is WORSE than none.** Bridging one boundary but not the next reveals a hop the agent then drills + reads to finish. Measured on excalidraw: react-render alone *raised* reads to 5–7; only completing the flow (adding the jsx-child hop) dropped it to 0–1. **Always close the flow end-to-end and re-measure** — never ship a half-bridged flow.
 

CHANGELOG.md

@@ -260,6 +260,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 - In C, C++ and Objective-C, a struct or class member declared as a pointer, reference, array or function, like `SharedState* shared;`, `jv elements[];` or `virtual Status Put(…) = 0;`, no longer makes the struct look like it inherits from the member's type. Before, `codegraph_explore` and impact listed those types as base classes, every struct holding a pointer to a type as one of its subclasses, and a method of that struct as an override of the type's method with the same name. Real base classes like `class Derived : public Base`, Objective-C superclasses and Go's embedded fields are unchanged. Re-index C, C++ and Objective-C projects after upgrading.
 - In C, C++ and Objective-C, a struct, class or union now links to the types its members are declared with, whether held by value, by pointer, in an array, through a function pointer or inside a template like `std::vector<Foo>`, and a `typedef` or `using` alias links to the type it names, so impact on a type reaches every struct that holds one, like redis's `redisServer` for `pause_event`. A member's type is the one C++ name lookup finds from the class, so a builtin, a macro or a function of the same name links nothing, and a type a macro renames is what the macro names where the file sees it, like hiredis's `#define sds hisds` in redis-cli.c. Re-index C, C++ and Objective-C projects after upgrading.
 - In C and C++, a function-pointer table's handler, like `.read = impl_read` in an ops struct, no longer links to a Python or Rust function that only shares its name, and such a function no longer takes the place of the C function the table names. Re-index C and C++ projects that also hold Python or Rust after upgrading. Thanks @bompus.
+- In C++, a call through a template parameter now links to that member of each class the project writes as the template's argument: `Txn::Put(…)` in a `template <typename Txn> class Mixin`, `shard.Clear()` on a `CacheShard& shard`, a function template's `Traits::Make()`, or `TypeParam::Make()` in a googletest typed test. `codegraph_explore`, callers and impact now follow a flow through the template, and the hop says which argument it came from. A template written with a great many classes, such as a container, is left unlinked.
 - In C++, a call on a variable, parameter or member declared through a `typedef` or `using` alias now links to the method of the type the alias names, with the alias looked up the way C++ does it: in the calling function, its class and the classes that class inherits from, then the namespaces around it. In google/leveldb, `table_.Insert(buf)` on a `Table table_;` declared next to `typedef SkipList<const char*, KeyComparator> Table;` now reaches `SkipList::Insert` instead of the unrelated `HandleTable::Insert`, and `Table::Iterator iter(&table_);` reaches `SkipList::Iterator`'s constructor. A class that only shares the alias's name is no longer taken for it, and when the aliased type has no such method, as with an alias of `std::vector` or of a template parameter, no method is guessed from the receiver's name. An alias of a type written from the global scope names that global type, also inside a namespace of the same name: protocolbuffers/protobuf's `using Arena = ::upb::Arena;` in `hpb::internal::backend::upb`, so hpb's `arena_.Fuse(…)` on a `backend::Arena` now reaches `upb::Arena::Fuse` instead of the calling method itself. Re-index C++ projects after upgrading.
 - In C++, indexing no longer fails with "Maximum call stack size exceeded" on a call whose arguments call the same overloaded method, like darts-clone's `extras(extras(id).prev()).set_next(…)` on a class with a `const` and a non-`const` `extras(id)`. Choosing the overload read its arguments, which chose the same overload again without end, and the whole index run failed. Such a call now takes the first overload when the choice comes back to itself, as one whose argument types are unknown does. Thanks @JosefAschauer.
 - In C++, a call on a variable, parameter or member declared with template arguments nested inside its template arguments, like `autovector<std::pair<int, FileMetaData*>>` or `Striped<CacheAlignedWrapper<port::Mutex>>`, now links to the method of the class it is declared as. Before, the nested arguments hid that class: in RocksDB, `files_marked_for_compaction_.clear()` on such an `autovector` linked to an unrelated `CompactionInputFiles::clear` that only shares words with the variable's name, and `mutex_.Get(key)` on a `Striped` linked to nothing. Re-index C++ projects after upgrading.