add getter for manifest json (#12)

* add getter for manifest json

* Initial plan

* docs: add lgx_get_manifest_json to C API reference

Co-authored-by: iurimatias <176720+iurimatias@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: iurimatias <176720+iurimatias@users.noreply.github.com>
Co-authored-by: Iuri Matias <iuri.matias@gmail.com>

docs/project.md

@@ -234,6 +234,7 @@ The header file `src/lgx.h` is installed to `include/` when using `make install`
 - `lgx_set_version(pkg, version) → lgx_result_t` - Set package version
 - `lgx_get_description(pkg) → const char*` - Get package description (owned by library)
 - `lgx_set_description(pkg, description)` - Set package description
+- `lgx_get_manifest_json(pkg) → const char*` - Get the full manifest as a JSON string (owned by library)
 
 **Memory Management:**
 - `lgx_free_package(pkg)` - Free a package handle

src/lgx.h

@@ -184,12 +184,20 @@ LGX_EXPORT const char* lgx_get_description(lgx_package_t pkg);
 
 /**
  * Set the package description in manifest.
- * 
+ *
  * @param pkg Package handle
  * @param description New description string
  */
 LGX_EXPORT void lgx_set_description(lgx_package_t pkg, const char* description);
 
+/**
+ * Get the full manifest as a JSON string.
+ *
+ * @param pkg Package handle
+ * @return JSON string of the manifest, owned by library (valid until package is freed)
+ */
+LGX_EXPORT const char* lgx_get_manifest_json(lgx_package_t pkg);
+
 /* Memory management */
 
 /**

src/lib.cpp

@@ -68,6 +68,7 @@ struct lgx_package_opaque {
     std::string name_cache;
     std::string version_cache;
     std::string description_cache;
+    std::string manifest_json_cache;
 };
 
 /* Package creation and loading */
@@ -279,6 +280,17 @@ LGX_EXPORT void lgx_set_description(lgx_package_t pkg, const char* description)
     pkg->pkg->getManifest().description = description;
 }
 
+LGX_EXPORT const char* lgx_get_manifest_json(lgx_package_t pkg) {
+    if (!pkg) {
+        set_error("Invalid argument: pkg cannot be NULL");
+        return nullptr;
+    }
+
+    clear_error();
+    pkg->manifest_json_cache = pkg->pkg->getManifest().toJson();
+    return pkg->manifest_json_cache.c_str();
+}
+
 /* Memory management */
 
 LGX_EXPORT void lgx_free_package(lgx_package_t pkg) {