Emit thinking parts incrementally for Anthropic thinking deltas (#1805)

* Emit thinking parts incrementally for Anthropic thinking deltas

* Update src/extension/byok/common/anthropicMessageConverter.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Make tool_call handling part of the if/else chain and remove extra blank line

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: bhavyaus

src/extension/byok/common/anthropicMessageConverter.ts

@@ -11,13 +11,24 @@ import { LanguageModelChatMessageRole, LanguageModelDataPart, LanguageModelTextP
 
 function apiContentToAnthropicContent(content: (LanguageModelTextPart | LanguageModelToolResultPart | LanguageModelToolCallPart | LanguageModelDataPart | LanguageModelThinkingPart)[]): ContentBlockParam[] {
 	const convertedContent: ContentBlockParam[] = [];
+
 	for (const part of content) {
 		if (part instanceof LanguageModelThinkingPart) {
-			convertedContent.push({
-				type: 'thinking',
-				thinking: Array.isArray(part.value) ? part.value.join('') : part.value,
-				signature: part.metadata?.signature ?? '',
-			});
+			// Check if this is a redacted thinking block
+			if (part.metadata?.redactedData) {
+				convertedContent.push({
+					type: 'redacted_thinking',
+					data: part.metadata.redactedData,
+				});
+			} else if (part.metadata?._completeThinking) {
+				// Only push thinking block when we have the complete thinking marker
+				convertedContent.push({
+					type: 'thinking',
+					thinking: part.metadata._completeThinking,
+					signature: part.metadata.signature || '',
+				});
+			}
+			// Skip incremental thinking parts - we only care about the complete one
 		} else if (part instanceof LanguageModelToolCallPart) {
 			convertedContent.push({
 				type: 'tool_use',
@@ -75,7 +86,6 @@ function apiContentToAnthropicContent(content: (LanguageModelTextPart | Language
 		}
 	}
 	return convertedContent;
-
 }
 
 export function apiMessageToAnthropicMessage(messages: LanguageModelChatMessage[]): { messages: MessageParam[]; system: TextBlockParam } {
@@ -122,7 +132,6 @@ export function apiMessageToAnthropicMessage(messages: LanguageModelChatMessage[
 			}
 		}
 	}
-
 	return { messages: mergedMessages, system: systemMessage };
 }
 
@@ -222,6 +231,11 @@ export function anthropicMessagesToRawMessages(messages: MessageParam[], system:
 						type: Raw.ChatCompletionContentPartKind.Text,
 						text: `[THINKING: ${block.thinking}]`
 					});
+				} else if (block.type === 'redacted_thinking') {
+					content.push({
+						type: Raw.ChatCompletionContentPartKind.Text,
+						text: '[REDACTED THINKING]'
+					});
 				} else if (block.type === 'tool_use') {
 					// tool_use appears in assistant messages; represent as toolCalls on assistant message
 					toolCalls ??= [];

src/extension/byok/vscode-node/anthropicProvider.ts

@@ -372,6 +372,9 @@ export class AnthropicLMProvider implements BYOKModelProvider<LanguageModelChatI
 			thinking?: string;
 			signature?: string;
 		} | undefined;
+		let pendingRedactedThinking: {
+			data: string;
+		} | undefined;
 		let pendingServerToolCall: {
 			toolId?: string;
 			name?: string;
@@ -413,6 +416,11 @@ export class AnthropicLMProvider implements BYOKModelProvider<LanguageModelChatI
 						thinking: '',
 						signature: ''
 					};
+				} else if ('content_block' in chunk && chunk.content_block.type === 'redacted_thinking') {
+					const redactedBlock = chunk.content_block as Anthropic.Messages.RedactedThinkingBlock;
+					pendingRedactedThinking = {
+						data: redactedBlock.data
+					};
 				} else if ('content_block' in chunk && chunk.content_block.type === 'web_search_tool_result') {
 					if (!pendingServerToolCall || !pendingServerToolCall.toolId) {
 						continue;
@@ -486,6 +494,7 @@ export class AnthropicLMProvider implements BYOKModelProvider<LanguageModelChatI
 				} else if (chunk.delta.type === 'thinking_delta') {
 					if (pendingThinking) {
 						pendingThinking.thinking = (pendingThinking.thinking || '') + (chunk.delta.thinking || '');
+						progress.report(new LanguageModelThinkingPart(chunk.delta.thinking || ''));
 					}
 				} else if (chunk.delta.type === 'signature_delta') {
 					// Accumulate signature
@@ -529,14 +538,17 @@ export class AnthropicLMProvider implements BYOKModelProvider<LanguageModelChatI
 					}
 					pendingToolCall = undefined;
 				} else if (pendingThinking) {
-					progress.report(
-						new LanguageModelThinkingPart(
-							pendingThinking.thinking || '',
-							undefined, // id
-							{ signature: pendingThinking.signature || '' }
-						)
-					);
+					if (pendingThinking.signature) {
+						const finalThinkingPart = new LanguageModelThinkingPart('');
+						finalThinkingPart.metadata = {
+							signature: pendingThinking.signature,
+							_completeThinking: pendingThinking.thinking
+						};
+						progress.report(finalThinkingPart);
+					}
 					pendingThinking = undefined;
+				} else if (pendingRedactedThinking) {
+					pendingRedactedThinking = undefined;
 				}
 			}