Add linker stubs for unimplemented LoRA and RAG symbols

The LoRA functions (rac_llm_component_*_lora) are declared in headers
but not yet implemented in the RACommons C++ library. The RAG functions
(rac_rag_*) are implemented in RABackendRAG which is excluded from
remote releases. Both cause undefined symbol linker errors.

Add weak stub implementations in shim.c that return
RAC_ERROR_NOT_IMPLEMENTED. When the real backends are available, the
strong definitions will override these stubs automatically.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sanchitmonga22

sdk/runanywhere-swift/Sources/RunAnywhere/CRACommons/shim.c

@@ -1,3 +1,121 @@
 // CRACommons shim file
 // This file exists to ensure Xcode's Swift Package Manager integration
 // can build this module. The actual implementation is in the binary target.
+//
+// Stub implementations below satisfy the linker for functions that are
+// declared in headers but whose backends (RAG, LoRA) are not yet compiled
+// into the release binary targets. At runtime these return
+// RAC_ERROR_NOT_IMPLEMENTED so callers get a clear error instead of a crash.
+//
+// When the real backend binaries include these symbols the linker will
+// prefer the strong definitions and these weak stubs are ignored.
+
+#include "include/rac_types.h"
+#include "include/rac_error.h"
+#include "include/rac_llm_component.h"
+#include "include/rac_rag_pipeline.h"
+#include <stddef.h>
+
+// =============================================================================
+// LoRA stubs  (declared in rac_llm_component.h, not yet in RACommons binary)
+// TODO: Remove these stubs once LoRA support is implemented in the
+//       runanywhere-commons C++ library and compiled into RACommons.xcframework.
+// =============================================================================
+
+__attribute__((weak))
+rac_result_t rac_llm_component_load_lora(rac_handle_t handle,
+                                          const char* adapter_path,
+                                          float scale) {
+    (void)handle; (void)adapter_path; (void)scale;
+    return RAC_ERROR_NOT_IMPLEMENTED; // TODO: Replace with real implementation in RACommons C++
+}
+
+__attribute__((weak))
+rac_result_t rac_llm_component_remove_lora(rac_handle_t handle,
+                                            const char* adapter_path) {
+    (void)handle; (void)adapter_path;
+    return RAC_ERROR_NOT_IMPLEMENTED; // TODO: Replace with real implementation in RACommons C++
+}
+
+__attribute__((weak))
+rac_result_t rac_llm_component_clear_lora(rac_handle_t handle) {
+    (void)handle;
+    return RAC_ERROR_NOT_IMPLEMENTED; // TODO: Replace with real implementation in RACommons C++
+}
+
+__attribute__((weak))
+rac_result_t rac_llm_component_get_lora_info(rac_handle_t handle,
+                                              char** out_json) {
+    (void)handle; (void)out_json;
+    return RAC_ERROR_NOT_IMPLEMENTED; // TODO: Replace with real implementation in RACommons C++
+}
+
+// =============================================================================
+// RAG stubs  (declared in rac_rag_pipeline.h, implemented in RABackendRAG
+//             which is not included in remote-mode releases yet)
+// TODO: Remove these stubs once RABackendRAG.xcframework is published to
+//       GitHub releases and ragRemoteBinaryAvailable is set to true.
+// =============================================================================
+
+__attribute__((weak))
+rac_result_t rac_rag_pipeline_create(const rac_rag_config_t* config,
+                                      rac_rag_pipeline_t** out_pipeline) {
+    (void)config; (void)out_pipeline;
+    return RAC_ERROR_NOT_IMPLEMENTED; // TODO: Remove stub when RABackendRAG release binary is available
+}
+
+__attribute__((weak))
+rac_result_t rac_rag_add_document(rac_rag_pipeline_t* pipeline,
+                                   const char* document_text,
+                                   const char* metadata_json) {
+    (void)pipeline; (void)document_text; (void)metadata_json;
+    return RAC_ERROR_NOT_IMPLEMENTED; // TODO: Remove stub when RABackendRAG release binary is available
+}
+
+__attribute__((weak))
+rac_result_t rac_rag_add_documents_batch(rac_rag_pipeline_t* pipeline,
+                                          const char** documents,
+                                          const char** metadata_array,
+                                          size_t count) {
+    (void)pipeline; (void)documents; (void)metadata_array; (void)count;
+    return RAC_ERROR_NOT_IMPLEMENTED; // TODO: Remove stub when RABackendRAG release binary is available
+}
+
+__attribute__((weak))
+rac_result_t rac_rag_query(rac_rag_pipeline_t* pipeline,
+                            const rac_rag_query_t* query,
+                            rac_rag_result_t* out_result) {
+    (void)pipeline; (void)query; (void)out_result;
+    return RAC_ERROR_NOT_IMPLEMENTED; // TODO: Remove stub when RABackendRAG release binary is available
+}
+
+__attribute__((weak))
+rac_result_t rac_rag_clear_documents(rac_rag_pipeline_t* pipeline) {
+    (void)pipeline;
+    return RAC_ERROR_NOT_IMPLEMENTED; // TODO: Remove stub when RABackendRAG release binary is available
+}
+
+__attribute__((weak))
+size_t rac_rag_get_document_count(rac_rag_pipeline_t* pipeline) {
+    (void)pipeline;
+    return 0; // TODO: Remove stub when RABackendRAG release binary is available
+}
+
+__attribute__((weak))
+rac_result_t rac_rag_get_statistics(rac_rag_pipeline_t* pipeline,
+                                     char** out_stats_json) {
+    (void)pipeline; (void)out_stats_json;
+    return RAC_ERROR_NOT_IMPLEMENTED; // TODO: Remove stub when RABackendRAG release binary is available
+}
+
+__attribute__((weak))
+void rac_rag_result_free(rac_rag_result_t* result) {
+    (void)result;
+    // TODO: Remove stub when RABackendRAG release binary is available
+}
+
+__attribute__((weak))
+void rac_rag_pipeline_destroy(rac_rag_pipeline_t* pipeline) {
+    (void)pipeline;
+    // TODO: Remove stub when RABackendRAG release binary is available
+}