fix: preserve tool alias name in API history for consistent conversation context

hannesrudolph · hannesrudolph · commit ec15a07477ed · 2025-12-10T13:47:31.000-07:00
When tool aliases are used (e.g., 'edit_file' -&gt; 'search_and_replace'), the alias
name is now preserved and written to API history instead of the canonical name.
This prevents confusion in multi-turn conversations where the model sees a different
tool name in history than what it was told the tool was named.

Changes:
- NativeToolCallParser.ts already stores originalName when alias differs from resolved
- Task.ts now uses originalName (alias) when available for API history
diff --git a/src/core/assistant-message/NativeToolCallParser.ts b/src/core/assistant-message/NativeToolCallParser.ts
@@ -249,13 +249,16 @@ export class NativeToolCallParser {
 
 			// Resolve tool alias to canonical name
 			const resolvedName = resolveToolAlias(toolCall.name) as ToolName
+			// Preserve original name if it differs from resolved (i.e., it was an alias)
+			const originalName = toolCall.name !== resolvedName ? toolCall.name : undefined
 
 			// Create partial ToolUse with extracted values
 			return this.createPartialToolUse(
 				toolCall.id,
 				resolvedName,
 				partialArgs || {},
 				true, // partial
+				originalName,
 			)
 		} catch {
 			// Even partial-json-parser can fail on severely malformed JSON
@@ -331,12 +334,14 @@ export class NativeToolCallParser {
 	/**
 	 * Create a partial ToolUse from currently parsed arguments.
 	 * Used during streaming to show progress.
+	 * @param originalName - The original tool name as called by the model (if different from canonical name)
 	 */
 	private static createPartialToolUse(
 		id: string,
 		name: ToolName,
 		partialArgs: Record<string, any>,
 		partial: boolean,
+		originalName?: string,
 	): ToolUse | null {
 		// Build legacy params for display
 		// NOTE: For streaming partial updates, we MUST populate params even for complex types
@@ -530,13 +535,20 @@ export class NativeToolCallParser {
 				break
 		}
 
-		return {
+		const result: ToolUse = {
 			type: "tool_use" as const,
 			name,
 			params,
 			partial,
 			nativeArgs,
 		}
+
+		// Preserve original name for API history when an alias was used
+		if (originalName) {
+			;(result as any).originalName = originalName
+		}
+
+		return result
 	}
 
 	/**
@@ -798,6 +810,11 @@ export class NativeToolCallParser {
 				nativeArgs,
 			}
 
+			// Preserve original name for API history when an alias was used
+			if (toolCall.name !== resolvedName) {
+				;(result as any).originalName = toolCall.name
+			}
+
 			return result
 		} catch (error) {
 			console.error(
diff --git a/src/core/task/Task.ts b/src/core/task/Task.ts
@@ -3106,10 +3106,16 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 								// nativeArgs is already in the correct API format for all tools
 								const input = toolUse.nativeArgs || toolUse.params
 
+								// Use originalName (alias) if present for API history consistency.
+								// When tool aliases are used (e.g., "edit_file" -> "search_and_replace"),
+								// we want the alias name in the conversation history to match what the model
+								// was told the tool was named, preventing confusion in multi-turn conversations.
+								const toolNameForHistory = (toolUse as any).originalName || toolUse.name
+
 								assistantContent.push({
 									type: "tool_use" as const,
 									id: toolCallId,
-									name: toolUse.name,
+									name: toolNameForHistory,
 									input,
 								})
 							}
