Add C++ SDK Support by nenad1002 · Pull Request #544 · microsoft/Foundry-Local

nenad1002 · 2026-03-23T20:08:39Z

pipeline support missing, will come in future
ARM support will come soon

vercel · 2026-03-23T20:08:45Z

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Project	Deployment	Actions	Updated (UTC)
foundry-local	Ready	Preview, Comment	Mar 23, 2026 9:51pm

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Pull request overview

This PR introduces an initial C++ SDK under sdk/cpp/, including the core API surface (manager/catalog/model/client), a CMake-based build, unit tests, and sample usage.

Changes:

Add C++ SDK public headers and a Windows (WIL-based) implementation.
Add CMake project/presets plus formatting configuration for the C++ SDK.
Add GTest unit tests and JSON testdata fixtures covering parsing, catalog/model behavior, and client requests.

Reviewed changes

Copilot reviewed 29 out of 29 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
sdk/cpp/CMakeLists.txt	Defines the C++ SDK library, sample, and unit tests; Windows-only guard and dependencies.
sdk/cpp/CMakePresets.json	Adds configure/build/test presets for building the C++ SDK.
sdk/cpp/.clang-format	Establishes C++ formatting rules for the SDK.
sdk/cpp/include/foundry_local.h	Public C++ SDK API surface (manager, catalog, model/variant, chat/audio clients, types).
sdk/cpp/include/configuration.h	Configuration types/validation for initializing Foundry Local from C++.
sdk/cpp/include/core_interop_request.h	Helper for building JSON-wrapped core requests with Params.
sdk/cpp/include/flcore_native.h	Native ABI struct/function-pointer definitions for calling the core DLL.
sdk/cpp/include/foundry_local_exception.h	SDK exception type with optional logging.
sdk/cpp/include/foundry_local_internal_core.h	Internal core interface abstraction used by SDK types/tests.
sdk/cpp/include/logger.h	Logger interface + NullLogger implementation.
sdk/cpp/include/log_level.h	LogLevel enum and string conversion helper.
sdk/cpp/include/parser.h	JSON (de)serialization helpers for model info, chat, tool calling, etc.
sdk/cpp/src/foundry_local.cpp	Main SDK implementation: DLL loading, manager/catalog/model/clients, streaming callbacks.
sdk/cpp/sample/main.cpp	Example app demonstrating catalog browsing, chat (streaming/non), audio, tool calling, and variant selection.
sdk/cpp/test/mock_core.h	Mock/file-backed core implementations + file reading helper for tests.
sdk/cpp/test/mock_object_factory.h	Test factory enabling construction of private-constructor SDK types.
sdk/cpp/test/parser_and_types_test.cpp	Unit tests for parsing/serialization utilities and small type behaviors.
sdk/cpp/test/model_variant_test.cpp	Unit tests for ModelVariant and Model behaviors (load/cache/download/path/selection).
sdk/cpp/test/client_test.cpp	Unit tests for ChatClient/AudioClient request formatting and streaming.
sdk/cpp/test/catalog_test.cpp	Unit tests for Catalog grouping/filtering/caching and file-based fixtures.
sdk/cpp/test/testdata/empty_models_list.json	Fixture: empty model list.
sdk/cpp/test/testdata/malformed_models_list.json	Fixture: malformed JSON for error-path testing.
sdk/cpp/test/testdata/missing_name_field_models_list.json	Fixture: missing required fields for validation/error tests.
sdk/cpp/test/testdata/mixed_openai_and_local.json	Fixture: mix of OpenAI-prefixed and local models for filtering tests.
sdk/cpp/test/testdata/real_models_list.json	Fixture: richer realistic model entries with optional fields/runtime/template.
sdk/cpp/test/testdata/single_cached_model.json	Fixture: one cached model entry for subset tests.
sdk/cpp/test/testdata/three_variants_one_model.json	Fixture: multiple variants under one alias for grouping tests.
sdk/cpp/test/testdata/valid_cached_models.json	Fixture: cached model IDs list.
sdk/cpp/test/testdata/valid_loaded_models.json	Fixture: loaded model IDs list.

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sdk/cpp/include/parser.h

sdk/cpp/src/foundry_local.cpp

sdk/cpp/CMakePresets.json

sdk/cpp/include/foundry_local.h

sdk/cpp/sample/main.cpp

sdk/cpp/test/model_variant_test.cpp

sdk/cpp/include/flcore_native.h

skottmckay · 2026-03-25T00:20:12Z

sdk/cpp/include/foundry_local.h

+
+#include "logger.h"
+
+namespace FoundryLocal {


nit: should we follow the ORT conventions for naming etc. for consistency? If so namespace would be foundry_local

skottmckay · 2026-03-25T04:59:38Z

sdk/cpp/CMakeLists.txt

+FetchContent_Declare(
+  nlohmann_json
+  GIT_REPOSITORY https://github.com/nlohmann/json.git
+  GIT_TAG v3.12.0
+)
+FetchContent_MakeAvailable(nlohmann_json)


Is using FetchContent allowed by security rules or do we need to use vcpkg? I have a working vcpkg based setup in my WIP branch if you need to copy from somewhere.

skottmckay · 2026-03-25T05:00:05Z

sdk/cpp/CMakeLists.txt

+# -----------------------------
+FetchContent_Declare(
+  wil_src
+  GIT_REPOSITORY https://github.com/microsoft/wil.git


Is the SDK Windows only or it builds/runs on other platforms?

skottmckay · 2026-03-25T05:00:56Z

sdk/cpp/CMakeLists.txt

+add_library(CppSdk STATIC
+  src/foundry_local.cpp
+  # Add more .cpp files as you migrate:
+  # src/parser.cpp
+  # src/dllmain.cpp
+  # src/pch.cpp
+)


Should we build a shared library as well or there's no requirement for that currently?

skottmckay · 2026-03-25T05:01:31Z

sdk/cpp/CMakePresets.json

+      }
+    },
+    {
+      "name": "x86-debug",


Do we care about x86? We don't have FL Core builds of that do we?

skottmckay · 2026-03-25T08:26:48Z

sdk/cpp/src/foundry_local.cpp

+            for (const auto& v : it->second.variants_) {
+                modelIdToModelVariant_[v.GetInfo().name] = &v;
+            }


Do we need to iterate all variants here or just add the current one?
If we're adding to modelIdToModelVariant should it be using v.GetId() rather than the name? id == name:version and should be unique.

skottmckay · 2026-03-25T09:30:34Z

sdk/cpp/src/foundry_local.cpp

+        return CollectVariantsByIds(modelIdToModelVariant_, GetLoadedModelsInternal(core_, *logger_));
+    }
+
+    std::vector<const ModelVariant*> Catalog::GetCachedModels() const {
+        return CollectVariantsByIds(modelIdToModelVariant_, GetCachedModelsInternal(core_, *logger_));


Not quite understanding this. The loaded and cached model getters should return model ids which we should be able to directly looked up in the model id to variant map.

skottmckay · 2026-03-25T09:41:11Z

sdk/cpp/src/foundry_local.cpp

+    FoundryLocalManager::FoundryLocalManager(FoundryLocalManager&& other) noexcept
+        : config_(std::move(other.config_)),
+          core_(std::move(other.core_)),
+          catalog_(std::move(other.catalog_)),
+          logger_(other.OwnsLogger() ? &defaultLogger_ : other.logger_),
+          urls_(std::move(other.urls_)) {
+        other.logger_ = &other.defaultLogger_;
+    }
+
+    FoundryLocalManager& FoundryLocalManager::operator=(FoundryLocalManager&& other) noexcept {
+        if (this != &other) {
+            config_ = std::move(other.config_);
+            core_ = std::move(other.core_);
+            catalog_ = std::move(other.catalog_);
+            logger_ = other.OwnsLogger() ? &defaultLogger_ : other.logger_;
+            urls_ = std::move(other.urls_);
+            other.logger_ = &other.defaultLogger_;
+        }
+        return *this;
+    }


Do we need these?

skottmckay · 2026-03-25T09:43:32Z

sdk/cpp/src/foundry_local.cpp

+            core_->call(initReq.Command(), *logger_, &initJson);
+
+            if (config_.model_cache_dir) {
+                std::string current = core_->call("get_cache_directory", *logger_);


We should be able to provide the cache dir in the call to initialize. I believe there's logic in Core to create the directory if it doesn't exist as well.

skottmckay · 2026-03-25T09:56:24Z

sdk/cpp/test/client_test.cpp

+
+using Factory = MockObjectFactory;
+
+class ChatClientTest : public ::testing::Test {


Do we have e2e or functional tests that exercise the public API overall (not just the chat client) with minimal mocking similar to the C# SDK?

I thought we setup some test data so that we can avoid the model download when running in the CI, although we should have a test that downloads a model if not already cached when run locally as a sanity check (C# has a 'SkipInCI' attribute so we might need something similar).

Should be fine to hit the catalog for the latest model list.

Add C++ SDK with CMake build, tests, and sample

8e7350f

Copilot AI review requested due to automatic review settings March 23, 2026 20:08

Copilot started reviewing on behalf of nenad1002 March 23, 2026 20:09 View session

Copilot AI reviewed Mar 23, 2026

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Copilot comments fix 1

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vercel bot deployed to Preview March 23, 2026 21:33 View deployment

Copilot comments fix 2

44f86d1

vercel bot deployed to Preview March 23, 2026 21:51 View deployment

skottmckay reviewed Mar 25, 2026

View reviewed changes


		using Factory = MockObjectFactory;

		class ChatClientTest : public ::testing::Test {

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nenad1002 commented Mar 23, 2026

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vercel bot commented Mar 23, 2026 •

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