Integrate native error reporting into the LiteRT-LM Swift API.

LiteRT-LM-PiperOrigin-RevId: 979218526

Author: hheydary

swift/BUILD

@@ -121,6 +121,7 @@ cc_library(
         "//c:conversation.h",
         "//c:embedding_engine.h",
         "//c:engine.h",
+        "//c:error_reporter.h",
         "//c:experimental.h",
         "//c:model_info.h",
     ],
@@ -150,6 +151,7 @@ apple_xcframework(
         "//c:engine.h",
         "//c:conversation.h",
         "//c:embedding_engine.h",
+        "//c:error_reporter.h",
         "//c:experimental.h",
         "//c:model_info.h",
     ],
@@ -188,6 +190,7 @@ genrule(
         "//c:engine.h",
         "//c:conversation.h",
         "//c:embedding_engine.h",
+        "//c:error_reporter.h",
         "//c:experimental.h",
         "//c:model_info.h",
     ],
@@ -200,6 +203,7 @@ genrule(
        cp $(location //c:engine.h) CLiteRTLM_mac/Headers/
        cp $(location //c:conversation.h) CLiteRTLM_mac/Headers/
        cp $(location //c:embedding_engine.h) CLiteRTLM_mac/Headers/
+       cp $(location //c:error_reporter.h) CLiteRTLM_mac/Headers/
        cp $(location //c:experimental.h) CLiteRTLM_mac/Headers/
        cp $(location //c:model_info.h) CLiteRTLM_mac/Headers/
        # Create module map
@@ -208,6 +212,7 @@ module CLiteRTLM {
    header "engine.h"
    header "conversation.h"
    header "embedding_engine.h"
+   header "error_reporter.h"
    header "experimental.h"
    header "model_info.h"
    export *

swift/Conversation.swift

@@ -193,8 +193,10 @@ public final class Conversation: Sendable {
     }
     if let repetitionPenaltyConfig = repetitionPenaltyConfig {
       guard let cRepetitionPenaltyConfig = litert_lm_repetition_penalty_config_create() else {
-        throw LiteRTLMError.conversation(
-          .invalidResponse("Failed to create native repetition penalty config."))
+        let errorMsg =
+          LiteRTLMError.consumeLastError()
+          ?? "Failed to create native repetition penalty config."
+        throw LiteRTLMError.conversation(.invalidResponse(errorMsg))
       }
       defer { litert_lm_repetition_penalty_config_delete(cRepetitionPenaltyConfig) }
 
@@ -219,8 +221,9 @@ public final class Conversation: Sendable {
     }
     if let noRepeatNgramConfig = noRepeatNgramConfig {
       guard let cNoRepeatNgramConfig = litert_lm_no_repeat_ngram_config_create() else {
-        throw LiteRTLMError.conversation(
-          .invalidResponse("Failed to create native no repeat ngram config."))
+        let errorMsg =
+          LiteRTLMError.consumeLastError() ?? "Failed to create native no repeat ngram config."
+        throw LiteRTLMError.conversation(.invalidResponse(errorMsg))
       }
       defer { litert_lm_no_repeat_ngram_config_delete(cNoRepeatNgramConfig) }
 
@@ -237,8 +240,9 @@ public final class Conversation: Sendable {
     }
     if let suppressTokens = suppressTokensConfig?.suppressTokens, !suppressTokens.isEmpty {
       guard let cSuppressTokensConfig = litert_lm_suppress_tokens_config_create() else {
-        throw LiteRTLMError.conversation(
-          .invalidResponse("Failed to create native suppress tokens config."))
+        let errorMsg =
+          LiteRTLMError.consumeLastError() ?? "Failed to create native suppress tokens config."
+        throw LiteRTLMError.conversation(.invalidResponse(errorMsg))
       }
       defer { litert_lm_suppress_tokens_config_delete(cSuppressTokensConfig) }
 
@@ -256,8 +260,9 @@ public final class Conversation: Sendable {
     }
     if let thinkingConfig = thinkingConfig {
       guard let cThinkingConfig = litert_lm_thinking_config_create() else {
-        throw LiteRTLMError.conversation(
-          .invalidResponse("Failed to create native thinking config."))
+        let errorMsg =
+          LiteRTLMError.consumeLastError() ?? "Failed to create native thinking config."
+        throw LiteRTLMError.conversation(.invalidResponse(errorMsg))
       }
       defer { litert_lm_thinking_config_delete(cThinkingConfig) }
       litert_lm_thinking_config_set_enable_thinking(
@@ -278,16 +283,17 @@ public final class Conversation: Sendable {
       let responsePtr = litert_lm_conversation_send_message(
         handle, messageString, extraContextString, optionalArgs)
     else {
-      throw LiteRTLMError.conversation(.invalidResponse("Native sendMessage returned null."))
-
+      let errorMsg = LiteRTLMError.consumeLastError() ?? "Native sendMessage returned null."
+      throw LiteRTLMError.conversation(.invalidResponse(errorMsg))
     }
     // Delete the response pointer at the end of each iteration. Handled by defer block.
     let responsePtrRef = responsePtr
     defer { litert_lm_json_response_delete(responsePtrRef) }
 
     guard let responseChars = litert_lm_json_response_get_string(responsePtr) else {
-      throw LiteRTLMError.conversation(
-        .invalidResponse("Native get string for response returned null."))
+      let errorMsg =
+        LiteRTLMError.consumeLastError() ?? "Native get string for response returned null."
+      throw LiteRTLMError.conversation(.invalidResponse(errorMsg))
     }
     let responseString = String(cString: responseChars)
 
@@ -438,8 +444,10 @@ public final class Conversation: Sendable {
     }
     if let repetitionPenaltyConfig = repetitionPenaltyConfig {
       guard let cRepetitionPenaltyConfig = litert_lm_repetition_penalty_config_create() else {
-        throw LiteRTLMError.conversation(
-          .invalidResponse("Failed to create native repetition penalty config."))
+        let errorMsg =
+          LiteRTLMError.consumeLastError()
+          ?? "Failed to create native repetition penalty config."
+        throw LiteRTLMError.conversation(.invalidResponse(errorMsg))
       }
       defer { litert_lm_repetition_penalty_config_delete(cRepetitionPenaltyConfig) }
 
@@ -464,8 +472,9 @@ public final class Conversation: Sendable {
     }
     if let noRepeatNgramConfig = noRepeatNgramConfig {
       guard let cNoRepeatNgramConfig = litert_lm_no_repeat_ngram_config_create() else {
-        throw LiteRTLMError.conversation(
-          .invalidResponse("Failed to create native no repeat ngram config."))
+        let errorMsg =
+          LiteRTLMError.consumeLastError() ?? "Failed to create native no repeat ngram config."
+        throw LiteRTLMError.conversation(.invalidResponse(errorMsg))
       }
       defer { litert_lm_no_repeat_ngram_config_delete(cNoRepeatNgramConfig) }
 
@@ -482,8 +491,9 @@ public final class Conversation: Sendable {
     }
     if let suppressTokens = suppressTokensConfig?.suppressTokens, !suppressTokens.isEmpty {
       guard let cSuppressTokensConfig = litert_lm_suppress_tokens_config_create() else {
-        throw LiteRTLMError.conversation(
-          .invalidResponse("Failed to create native suppress tokens config."))
+        let errorMsg =
+          LiteRTLMError.consumeLastError() ?? "Failed to create native suppress tokens config."
+        throw LiteRTLMError.conversation(.invalidResponse(errorMsg))
       }
       defer { litert_lm_suppress_tokens_config_delete(cSuppressTokensConfig) }
 
@@ -501,8 +511,9 @@ public final class Conversation: Sendable {
     }
     if let thinkingConfig = thinkingConfig {
       guard let cThinkingConfig = litert_lm_thinking_config_create() else {
-        throw LiteRTLMError.conversation(
-          .invalidResponse("Failed to create native thinking config."))
+        let errorMsg =
+          LiteRTLMError.consumeLastError() ?? "Failed to create native thinking config."
+        throw LiteRTLMError.conversation(.invalidResponse(errorMsg))
       }
       defer { litert_lm_thinking_config_delete(cThinkingConfig) }
       litert_lm_thinking_config_set_enable_thinking(
@@ -532,7 +543,8 @@ public final class Conversation: Sendable {
 
     guard status == 0 else {
       Unmanaged<StreamContext>.fromOpaque(contextPtr).release()
-      throw LiteRTLMError.conversation(.failedToStartStream(status: Int(status)))
+      let errorMsg = LiteRTLMError.consumeLastError() ?? ""
+      throw LiteRTLMError.conversation(.failedToStartStream(status: Int(status), message: errorMsg))
     }
   }
 
@@ -559,7 +571,9 @@ public final class Conversation: Sendable {
 
     guard let cString = litert_lm_conversation_render_message_to_string(handle, messageString)
     else {
-      throw LiteRTLMError.conversation(.invalidResponse("Failed to render message into string."))
+      let errorMsg =
+        LiteRTLMError.consumeLastError() ?? "Failed to render message into string."
+      throw LiteRTLMError.conversation(.invalidResponse(errorMsg))
     }
     return String(cString: cString)
   }
@@ -571,7 +585,9 @@ public final class Conversation: Sendable {
   public func renderPrefaceIntoString() throws -> String {
     let handle = try checkIsAlive()
     guard let cString = litert_lm_conversation_render_preface_to_string(handle) else {
-      throw LiteRTLMError.conversation(.invalidResponse("Failed to render preface into string."))
+      let errorMsg =
+        LiteRTLMError.consumeLastError() ?? "Failed to render preface into string."
+      throw LiteRTLMError.conversation(.invalidResponse(errorMsg))
     }
     return String(cString: cString)
   }