[Condense] Fix bug where bedrock requires a user message first (#4150)

* [Condense] Fix bug where bedrock requires a user message first

* update tests

* Revert previous commits

* always prepend user message

* fix tests

* changeset

Author: canrobins13

.changeset/little-news-warn.md

@@ -0,0 +1,5 @@
+---
+"roo-cline": major
+---
+
+Fixes bug with context condensing on Amazon Bedrock

src/core/condense/__tests__/index.test.ts

@@ -36,7 +36,7 @@ describe("getMessagesSinceLastSummary", () => {
 		expect(result).toEqual(messages)
 	})
 
-	it("should return messages since the last summary", () => {
+	it("should return messages since the last summary with prepended user message", () => {
 		const messages: ApiMessage[] = [
 			{ role: "user", content: "Hello", ts: 1 },
 			{ role: "assistant", content: "Hi there", ts: 2 },
@@ -47,13 +47,14 @@ describe("getMessagesSinceLastSummary", () => {
 
 		const result = getMessagesSinceLastSummary(messages)
 		expect(result).toEqual([
+			{ role: "user", content: "Please continue from the following summary:", ts: 0 },
 			{ role: "assistant", content: "Summary of conversation", ts: 3, isSummary: true },
 			{ role: "user", content: "How are you?", ts: 4 },
 			{ role: "assistant", content: "I'm good", ts: 5 },
 		])
 	})
 
-	it("should handle multiple summary messages and return since the last one", () => {
+	it("should handle multiple summary messages and return since the last one with prepended user message", () => {
 		const messages: ApiMessage[] = [
 			{ role: "user", content: "Hello", ts: 1 },
 			{ role: "assistant", content: "First summary", ts: 2, isSummary: true },
@@ -64,6 +65,7 @@ describe("getMessagesSinceLastSummary", () => {
 
 		const result = getMessagesSinceLastSummary(messages)
 		expect(result).toEqual([
+			{ role: "user", content: "Please continue from the following summary:", ts: 0 },
 			{ role: "assistant", content: "Second summary", ts: 4, isSummary: true },
 			{ role: "user", content: "What's new?", ts: 5 },
 		])

src/core/condense/index.ts

@@ -213,5 +213,14 @@ export function getMessagesSinceLastSummary(messages: ApiMessage[]): ApiMessage[
 	}
 
 	const lastSummaryIndex = messages.length - lastSummaryIndexReverse - 1
-	return messages.slice(lastSummaryIndex)
+	const messagesSinceSummary = messages.slice(lastSummaryIndex)
+
+	// Bedrock requires the first message to be a user message.
+	// See https://github.com/RooCodeInc/Roo-Code/issues/4147
+	const userMessage: ApiMessage = {
+		role: "user",
+		content: "Please continue from the following summary:",
+		ts: messages[0]?.ts ? messages[0].ts - 1 : Date.now(),
+	}
+	return [userMessage, ...messagesSinceSummary]
 }