fix(openrouter): Fix reasoning details preservation and schema validation

- Re-index reasoning_details sequentially to prevent duplicate indices (fixes 400 error)
- Ensure reasoning_details is omitted if empty to avoid invalid empty array error
- Prevent creation of invalid empty text blocks from metadata-only updates
- Force creation of text block in Task.ts if reasoning_details exist but text is empty, ensuring preservation

src/api/transform/__tests__/openai-format.spec.ts

@@ -128,4 +128,125 @@ describe("convertToOpenAiMessages", () => {
 		expect(toolMessage.tool_call_id).toBe("weather-123")
 		expect(toolMessage.content).toBe("Current temperature in London: 20°C")
 	})
+	it("should handle assistant messages with reasoning details and preserve index field", () => {
+		const anthropicMessages: Anthropic.Messages.MessageParam[] = [
+			{
+				role: "assistant",
+				content: [
+					{
+						type: "text",
+						text: "I will now reason about this.",
+						// @ts-ignore
+						reasoning_details: [
+							{
+								type: "reasoning.text",
+								text: "This is the first part",
+								index: 0,
+								signature: "sig1",
+								format: "format1",
+							},
+							{
+								type: "reasoning.text",
+								text: " of the reasoning.",
+								index: 0,
+								signature: "sig1",
+								format: "format1",
+							},
+						],
+					},
+				],
+			},
+		]
+
+		const openAiMessages = convertToOpenAiMessages(anthropicMessages)
+		expect(openAiMessages).toHaveLength(1)
+
+		const assistantMessage = openAiMessages[0] as any
+		expect(assistantMessage.role).toBe("assistant")
+		expect(assistantMessage.content).toBe("I will now reason about this.")
+		expect(assistantMessage.reasoning_details).toHaveLength(1)
+		expect(assistantMessage.reasoning_details[0]).toEqual({
+			type: "reasoning.text",
+			text: "This is the first part of the reasoning.",
+			signature: "sig1",
+			format: "format1",
+			index: 0,
+		})
+		expect(assistantMessage.reasoning_details[0]).toHaveProperty("index")
+	})
+	it("should not include reasoning_details if they consolidate to empty array", () => {
+		const anthropicMessages: Anthropic.Messages.MessageParam[] = [
+			{
+				role: "assistant",
+				content: [
+					{
+						type: "text",
+						text: "Response.",
+						// @ts-ignore
+						reasoning_details: [
+							{
+								index: 0,
+								// No text, no data
+							},
+						],
+					},
+				],
+			},
+		]
+
+		const openAiMessages = convertToOpenAiMessages(anthropicMessages)
+		expect(openAiMessages).toHaveLength(1)
+
+		const assistantMessage = openAiMessages[0] as any
+		expect(assistantMessage.role).toBe("assistant")
+		expect(assistantMessage.reasoning_details).toBeUndefined()
+	})
+	it("should re-index reasoning details sequentially", () => {
+		const anthropicMessages: Anthropic.Messages.MessageParam[] = [
+			{
+				role: "assistant",
+				content: [
+					{
+						type: "text",
+						text: "Response.",
+						// @ts-ignore
+						reasoning_details: [
+							{
+								type: "reasoning.text",
+								text: "Part 1",
+								index: 0,
+								format: "fmt",
+							},
+							{
+								type: "reasoning.encrypted",
+								data: "data1",
+								index: 0,
+								format: "fmt",
+							},
+							{
+								type: "reasoning.text",
+								text: "Part 2",
+								index: 5, // Gap in index
+								format: "fmt",
+							},
+						],
+					},
+				],
+			},
+		]
+
+		const openAiMessages = convertToOpenAiMessages(anthropicMessages)
+		const assistantMessage = openAiMessages[0] as any
+		const reasoning = assistantMessage.reasoning_details
+
+		expect(reasoning).toHaveLength(3)
+		expect(reasoning[0].index).toBe(0)
+		expect(reasoning[0].text).toBe("Part 1")
+
+		expect(reasoning[1].index).toBe(1)
+		expect(reasoning[1].data).toBe("data1")
+
+		expect(reasoning[2].index).toBe(2)
+		expect(reasoning[2].text).toBe("Part 2")
+	})
 })

src/api/transform/openai-format.ts

@@ -148,6 +148,10 @@ export function convertToOpenAiMessages(
 					},
 				}))
 
+				// @ts-ignore-next-line
+				const consolidatedReasoning =
+					reasoningDetails.length > 0 ? consolidateReasoningDetails(reasoningDetails) : undefined
+
 				openAiMessages.push({
 					role: "assistant",
 					content,
@@ -155,7 +159,7 @@ export function convertToOpenAiMessages(
 					tool_calls: tool_calls.length > 0 ? tool_calls : undefined,
 					// @ts-ignore-next-line
 					reasoning_details:
-						reasoningDetails.length > 0 ? consolidateReasoningDetails(reasoningDetails) : undefined,
+						consolidatedReasoning && consolidatedReasoning.length > 0 ? consolidatedReasoning : undefined,
 				})
 			}
 		}
@@ -203,18 +207,21 @@ function consolidateReasoningDetails(reasoningDetails: ReasoningDetail[]): Reaso
 
 	// Consolidate each group
 	const consolidated: ReasoningDetail[] = []
+	let outputIndex = 0
 
-	for (const [index, details] of groupedByIndex.entries()) {
+	for (const [_, details] of groupedByIndex.entries()) {
 		// Concatenate all text parts
 		let concatenatedText = ""
+		let hasText = false
 		let signature: string | undefined
 		let id: string | undefined
 		let format = "unknown"
 		let type = "reasoning.text"
 
 		for (const detail of details) {
-			if (detail.text) {
+			if (detail.text !== undefined) {
 				concatenatedText += detail.text
+				hasText = true
 			}
 			// Keep the signature from the last item that has one
 			if (detail.signature) {
@@ -233,15 +240,16 @@ function consolidateReasoningDetails(reasoningDetails: ReasoningDetail[]): Reaso
 			}
 		}
 
-		// Create consolidated entry for text
-		if (concatenatedText) {
+		// Create consolidated entry for text if any text parts were found
+		// This avoids creating text entries for purely encrypted blocks or metadata-only updates that belong to encrypted blocks
+		if (hasText) {
 			const consolidatedEntry: ReasoningDetail = {
 				type: type,
 				text: concatenatedText,
 				signature: signature,
 				id: id,
 				format: format,
-				index: index,
+				index: outputIndex++,
 			}
 			consolidated.push(consolidatedEntry)
 		}
@@ -256,7 +264,7 @@ function consolidateReasoningDetails(reasoningDetails: ReasoningDetail[]): Reaso
 					signature: detail.signature,
 					id: detail.id,
 					format: detail.format,
-					index: index,
+					index: outputIndex++,
 				}
 			}
 		}

src/core/task/Task.ts

@@ -2657,8 +2657,9 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 				// Check if we have any content to process (text or tool uses)
 				const hasTextContent = assistantMessage.length > 0
 				const hasToolUses = this.assistantMessageContent.some((block) => block.type === "tool_use")
+				const hasReasoningDetails = reasoningDetails.length > 0
 
-				if (hasTextContent || hasToolUses) {
+				if (hasTextContent || hasToolUses || hasReasoningDetails) {
 					// Display grounding sources to the user if they exist
 					if (pendingGroundingSources.length > 0) {
 						const citationLinks = pendingGroundingSources.map((source, i) => `[${i + 1}](${source.url})`)
@@ -2672,11 +2673,11 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 					// Build the assistant message content array
 					const assistantContent: Array<Anthropic.TextBlockParam | Anthropic.ToolUseBlockParam> = []
 
-					// Add text content if present
-					if (assistantMessage) {
+					// Add text content if present, or if we have reasoning details that need a text block to be attached to
+					if (assistantMessage || hasReasoningDetails) {
 						assistantContent.push({
 							type: "text" as const,
-							text: assistantMessage,
+							text: assistantMessage, // This will be empty string if !assistantMessage, which is fine
 						})
 					}