fix: Implement review comments for PR #4447 - Bedrock Extended Thinking

- Refactor Bedrock provider for clarity and type safety.
- Extract constants and helper methods.
- Update documentation.
- Rename and update reasoning tests to Vitest.
- Ensure all tests pass.

Author: hannesrudolph

src/api/providers/__tests__/bedrock-reasoning.spec.ts

@@ -0,0 +1,286 @@
+import { vi, describe, it, expect, beforeEach } from "vitest"
+
+// Mock AWS SDK modules before importing the handler
+vi.mock("@aws-sdk/credential-providers", () => ({
+	fromIni: vi.fn(),
+}))
+
+// Define a shared mock for the send function that will be used by all instances
+const sharedMockSend = vi.fn()
+
+vi.mock("@aws-sdk/client-bedrock-runtime", () => ({
+	BedrockRuntimeClient: vi.fn().mockImplementation(() => ({
+		// Ensure all instances of BedrockRuntimeClient use the sharedMockSend
+		send: sharedMockSend,
+		config: { region: "us-east-1" },
+	})),
+	ConverseStreamCommand: vi.fn(), // This will be the mock constructor for ConverseStreamCommand
+	ConverseCommand: vi.fn(),
+}))
+
+// Import after mocks are set up
+import { AwsBedrockHandler } from "../bedrock"
+// Import ConverseStreamCommand to check its mock constructor (which is vi.fn() from the mock factory)
+import { ConverseStreamCommand } from "@aws-sdk/client-bedrock-runtime"
+
+describe("AwsBedrockHandler - Extended Thinking", () => {
+	let handler: AwsBedrockHandler
+	// This will hold the reference to sharedMockSend for use in tests
+	let mockSend: typeof sharedMockSend
+
+	const mockOptions = {
+		awsRegion: "us-east-1",
+		apiModelId: "anthropic.claude-3-7-sonnet-20241029-v1:0",
+		enableReasoningEffort: false, // Default to false
+		modelTemperature: 0.7,
+	}
+
+	beforeEach(() => {
+		// Clear all mocks. This will clear sharedMockSend and the ConverseStreamCommand mock constructor.
+		vi.clearAllMocks()
+		// Assign the shared mock to mockSend so tests can configure it.
+		mockSend = sharedMockSend
+
+		// AwsBedrockHandler will instantiate BedrockRuntimeClient, which will get the sharedMockSend.
+		handler = new AwsBedrockHandler(mockOptions)
+	})
+
+	describe("Extended Thinking Configuration", () => {
+		it("should NOT enable extended thinking by default", async () => {
+			// Setup mock response
+			mockSend.mockResolvedValue({
+				stream: (async function* () {
+					yield { messageStart: { role: "assistant" } }
+					yield {
+						contentBlockStart: {
+							start: { text: "Hello" },
+							contentBlockIndex: 0,
+						},
+					}
+					yield { messageStop: { stopReason: "end_turn" } }
+				})(),
+			})
+
+			// Create message
+			const messages = [{ role: "user" as const, content: "Test message" }]
+			const stream = handler.createMessage("", messages)
+
+			// Consume stream
+			const chunks = []
+			for await (const chunk of stream) {
+				chunks.push(chunk)
+			}
+
+			// Verify the command was called
+			expect(ConverseStreamCommand).toHaveBeenCalled()
+			const payload = (ConverseStreamCommand as any).mock.calls[0][0]
+
+			// Extended thinking should NOT be enabled by default
+			expect(payload.anthropic_version).toBeUndefined()
+			expect(payload.additionalModelRequestFields).toBeUndefined()
+			expect(payload.inferenceConfig.temperature).toBeDefined()
+			expect(payload.inferenceConfig.topP).toBeDefined()
+		})
+
+		it("should enable extended thinking when explicitly enabled with reasoning budget", async () => {
+			// Enable reasoning mode with thinking tokens
+			handler = new AwsBedrockHandler({
+				...mockOptions,
+				enableReasoningEffort: true,
+				modelMaxThinkingTokens: 5000,
+			})
+
+			// Setup mock response with thinking blocks
+			mockSend.mockResolvedValue({
+				stream: (async function* () {
+					yield { messageStart: { role: "assistant" } }
+					yield {
+						contentBlockStart: {
+							contentBlock: {
+								type: "thinking",
+								thinking: "Let me think about this...",
+							},
+							contentBlockIndex: 0,
+						},
+					}
+					yield {
+						contentBlockStart: {
+							start: { text: "Here is my response" },
+							contentBlockIndex: 1,
+						},
+					}
+					yield { messageStop: { stopReason: "end_turn" } }
+				})(),
+			})
+
+			// Create message
+			const messages = [{ role: "user" as const, content: "Test message" }]
+			const stream = handler.createMessage("", messages)
+
+			// Consume stream
+			const chunks = []
+			for await (const chunk of stream) {
+				chunks.push(chunk)
+			}
+
+			// Verify the command was called
+			expect(ConverseStreamCommand).toHaveBeenCalled()
+			const payload = (ConverseStreamCommand as any).mock.calls[0][0]
+
+			// Extended thinking should be enabled
+			expect(payload.anthropic_version).toBe("bedrock-20250514")
+			expect(payload.additionalModelRequestFields).toEqual({
+				thinking: {
+					type: "enabled",
+					budget_tokens: 5000,
+				},
+			})
+			// Temperature and topP should be removed
+			expect(payload.inferenceConfig.temperature).toBeUndefined()
+			expect(payload.inferenceConfig.topP).toBeUndefined()
+
+			// Verify thinking content was processed
+			const reasoningChunk = chunks.find((c) => c.type === "reasoning")
+			expect(reasoningChunk).toBeDefined()
+			expect(reasoningChunk?.text).toBe("Let me think about this...")
+		})
+
+		it("should NOT enable extended thinking for unsupported models", async () => {
+			// Use a model that doesn't support reasoning
+			handler = new AwsBedrockHandler({
+				...mockOptions,
+				apiModelId: "anthropic.claude-3-haiku-20240307-v1:0",
+				enableReasoningEffort: true,
+				modelMaxThinkingTokens: 5000,
+			})
+
+			// Setup mock response
+			mockSend.mockResolvedValue({
+				stream: (async function* () {
+					yield { messageStart: { role: "assistant" } }
+					yield {
+						contentBlockStart: {
+							start: { text: "Hello" },
+							contentBlockIndex: 0,
+						},
+					}
+					yield { messageStop: { stopReason: "end_turn" } }
+				})(),
+			})
+
+			// Create message
+			const messages = [{ role: "user" as const, content: "Test message" }]
+			const stream = handler.createMessage("", messages)
+
+			// Consume stream
+			const chunks = []
+			for await (const chunk of stream) {
+				chunks.push(chunk)
+			}
+
+			// Verify the command was called
+			expect(ConverseStreamCommand).toHaveBeenCalled()
+			const payload = (ConverseStreamCommand as any).mock.calls[0][0]
+
+			// Extended thinking should NOT be enabled for unsupported models
+			expect(payload.anthropic_version).toBeUndefined()
+			expect(payload.additionalModelRequestFields).toBeUndefined()
+			expect(payload.inferenceConfig.temperature).toBeDefined()
+			expect(payload.inferenceConfig.topP).toBeDefined()
+		})
+	})
+
+	describe("Stream Processing", () => {
+		it("should handle thinking delta events", async () => {
+			// Enable reasoning mode
+			handler = new AwsBedrockHandler({
+				...mockOptions,
+				enableReasoningEffort: true,
+				modelMaxThinkingTokens: 5000,
+			})
+
+			// Setup mock response with thinking deltas
+			mockSend.mockResolvedValue({
+				stream: (async function* () {
+					yield { messageStart: { role: "assistant" } }
+					yield {
+						contentBlockDelta: {
+							delta: {
+								type: "thinking_delta",
+								thinking: "First part of thinking...",
+							},
+							contentBlockIndex: 0,
+						},
+					}
+					yield {
+						contentBlockDelta: {
+							delta: {
+								type: "thinking_delta",
+								thinking: " Second part of thinking.",
+							},
+							contentBlockIndex: 0,
+						},
+					}
+					yield { messageStop: { stopReason: "end_turn" } }
+				})(),
+			})
+
+			// Create message
+			const messages = [{ role: "user" as const, content: "Test message" }]
+			const stream = handler.createMessage("", messages)
+
+			// Consume stream
+			const chunks = []
+			for await (const chunk of stream) {
+				chunks.push(chunk)
+			}
+
+			// Verify thinking deltas were processed
+			const reasoningChunks = chunks.filter((c) => c.type === "reasoning")
+			expect(reasoningChunks).toHaveLength(2)
+			expect(reasoningChunks[0].text).toBe("First part of thinking...")
+			expect(reasoningChunks[1].text).toBe(" Second part of thinking.")
+		})
+
+		it("should handle signature delta events as reasoning", async () => {
+			// Enable reasoning mode
+			handler = new AwsBedrockHandler({
+				...mockOptions,
+				enableReasoningEffort: true,
+				modelMaxThinkingTokens: 5000,
+			})
+
+			// Setup mock response with signature deltas
+			mockSend.mockResolvedValue({
+				stream: (async function* () {
+					yield { messageStart: { role: "assistant" } }
+					yield {
+						contentBlockDelta: {
+							delta: {
+								type: "signature_delta",
+								signature: "[Signature content]",
+							},
+							contentBlockIndex: 0,
+						},
+					}
+					yield { messageStop: { stopReason: "end_turn" } }
+				})(),
+			})
+
+			// Create message
+			const messages = [{ role: "user" as const, content: "Test message" }]
+			const stream = handler.createMessage("", messages)
+
+			// Consume stream
+			const chunks = []
+			for await (const chunk of stream) {
+				chunks.push(chunk)
+			}
+
+			// Verify signature delta was processed as reasoning
+			const reasoningChunk = chunks.find((c) => c.type === "reasoning")
+			expect(reasoningChunk).toBeDefined()
+			expect(reasoningChunk?.text).toBe("[Signature content]")
+		})
+	})
+})