fix: ensure coerced follow_up suggestions always include mode field

The tool schema requires mode on each suggestion item (required: ["text", "mode"]).
When follow_up was coerced from a string, the mode field was missing entirely.
Some model Jinja templates (e.g. Qwen via llama.cpp) fail with
"Cannot convert value of type Optional<Any> to Jinja Value" when a required
field is absent from tool call arguments in conversation history.

Now all coercion paths (coerceFollowUp helper + NativeToolCallParser partial
and finalization handlers) normalize every suggestion to include mode: null
when not explicitly set.

src/core/assistant-message/NativeToolCallParser.ts

@@ -479,11 +479,18 @@ export class NativeToolCallParser {
 					if (!Array.isArray(coercedPartialFollowUp) && typeof coercedPartialFollowUp === "string") {
 						try {
 							const parsed = JSON.parse(coercedPartialFollowUp)
-							coercedPartialFollowUp = Array.isArray(parsed) ? parsed : undefined
+							coercedPartialFollowUp = Array.isArray(parsed)
+								? parsed.map((s: any) => ({ text: s.text, mode: s.mode ?? null }))
+								: undefined
 						} catch {
 							coercedPartialFollowUp = undefined
 						}
-					} else if (!Array.isArray(coercedPartialFollowUp)) {
+					} else if (Array.isArray(coercedPartialFollowUp)) {
+						coercedPartialFollowUp = coercedPartialFollowUp.map((s: any) => ({
+							text: s.text,
+							mode: s.mode ?? null,
+						}))
+					} else {
 						coercedPartialFollowUp = undefined
 					}
 					nativeArgs = {
@@ -837,11 +844,18 @@ export class NativeToolCallParser {
 							if (trimmed.length > 0) {
 								try {
 									const parsed = JSON.parse(trimmed)
-									coercedFinalFollowUp = Array.isArray(parsed) ? parsed : [{ text: trimmed }]
+									coercedFinalFollowUp = Array.isArray(parsed)
+										? parsed.map((s: any) => ({ text: s.text, mode: s.mode ?? null }))
+										: [{ text: trimmed, mode: null }]
 								} catch {
-									coercedFinalFollowUp = [{ text: trimmed }]
+									coercedFinalFollowUp = [{ text: trimmed, mode: null }]
 								}
 							}
+						} else if (Array.isArray(coercedFinalFollowUp)) {
+							coercedFinalFollowUp = coercedFinalFollowUp.map((s: any) => ({
+								text: s.text,
+								mode: s.mode ?? null,
+							}))
 						}
 						nativeArgs = {
 							question: args.question,

src/core/tools/AskFollowupQuestionTool.ts

@@ -6,7 +6,7 @@ import { BaseTool, ToolCallbacks } from "./BaseTool"
 
 interface Suggestion {
 	text: string
-	mode?: string
+	mode?: string | null
 }
 
 interface AskFollowupQuestionParams {
@@ -27,7 +27,7 @@ interface AskFollowupQuestionParams {
  */
 export function coerceFollowUp(value: unknown): Suggestion[] | undefined {
 	if (Array.isArray(value)) {
-		return value
+		return normalizeSuggestions(value)
 	}
 
 	if (typeof value === "string" && value.trim().length > 0) {
@@ -35,19 +35,31 @@ export function coerceFollowUp(value: unknown): Suggestion[] | undefined {
 		try {
 			const parsed = JSON.parse(value)
 			if (Array.isArray(parsed)) {
-				return parsed
+				return normalizeSuggestions(parsed)
 			}
 		} catch {
 			// Not valid JSON -- fall through to plain-string wrapping
 		}
 
 		// Wrap plain string as a single suggestion
-		return [{ text: value }]
+		return [{ text: value, mode: null }]
 	}
 
 	return undefined
 }
 
+/**
+ * Ensure every suggestion has an explicit `mode` field (defaulting to `null`).
+ * The tool schema requires `mode` on each item (`required: ["text", "mode"]`),
+ * and some model Jinja templates fail if a required field is absent.
+ */
+function normalizeSuggestions(items: Suggestion[]): Suggestion[] {
+	return items.map((s) => ({
+		text: s.text,
+		mode: s.mode ?? null,
+	}))
+}
+
 export class AskFollowupQuestionTool extends BaseTool<"ask_followup_question"> {
 	readonly name = "ask_followup_question" as const
 

src/core/tools/__tests__/askFollowupQuestionTool.spec.ts

@@ -45,7 +45,7 @@ describe("askFollowupQuestionTool", () => {
 
 		expect(mockCline.ask).toHaveBeenCalledWith(
 			"followup",
-			expect.stringContaining('"suggest":[{"answer":"Option 1"},{"answer":"Option 2"}]'),
+			expect.stringContaining('"suggest":[{"answer":"Option 1","mode":null},{"answer":"Option 2","mode":null}]'),
 			false,
 		)
 	})
@@ -105,7 +105,7 @@ describe("askFollowupQuestionTool", () => {
 		expect(mockCline.ask).toHaveBeenCalledWith(
 			"followup",
 			expect.stringContaining(
-				'"suggest":[{"answer":"Regular option"},{"answer":"Plan architecture","mode":"architect"}]',
+				'"suggest":[{"answer":"Regular option","mode":null},{"answer":"Plan architecture","mode":"architect"}]',
 			),
 			false,
 		)
@@ -189,7 +189,7 @@ describe("askFollowupQuestionTool", () => {
 			// Plain string should be coerced to [{ text: "not an array" }]
 			expect(mockCline.ask).toHaveBeenCalledWith(
 				"followup",
-				expect.stringContaining('"suggest":[{"answer":"not an array"}]'),
+				expect.stringContaining('"suggest":[{"answer":"not an array","mode":null}]'),
 				false,
 			)
 		})
@@ -217,7 +217,9 @@ describe("askFollowupQuestionTool", () => {
 			// JSON string should be parsed into a proper array
 			expect(mockCline.ask).toHaveBeenCalledWith(
 				"followup",
-				expect.stringContaining('"suggest":[{"answer":"Option A"},{"answer":"Option B","mode":"code"}]'),
+				expect.stringContaining(
+					'"suggest":[{"answer":"Option A","mode":null},{"answer":"Option B","mode":"code"}]',
+				),
 				false,
 			)
 		})
@@ -248,18 +250,32 @@ describe("askFollowupQuestionTool", () => {
 	})
 
 	describe("coerceFollowUp helper", () => {
-		it("should return arrays as-is", () => {
+		it("should normalize arrays to include mode: null when missing", () => {
 			const input = [{ text: "Option 1" }, { text: "Option 2" }]
-			expect(coerceFollowUp(input)).toEqual(input)
+			expect(coerceFollowUp(input)).toEqual([
+				{ text: "Option 1", mode: null },
+				{ text: "Option 2", mode: null },
+			])
+		})
+
+		it("should preserve existing mode values in arrays", () => {
+			const input = [{ text: "Option 1", mode: "code" }, { text: "Option 2" }]
+			expect(coerceFollowUp(input)).toEqual([
+				{ text: "Option 1", mode: "code" },
+				{ text: "Option 2", mode: null },
+			])
 		})
 
 		it("should parse a JSON string containing an array", () => {
 			const input = '[{"text":"A"},{"text":"B","mode":"code"}]'
-			expect(coerceFollowUp(input)).toEqual([{ text: "A" }, { text: "B", mode: "code" }])
+			expect(coerceFollowUp(input)).toEqual([
+				{ text: "A", mode: null },
+				{ text: "B", mode: "code" },
+			])
 		})
 
-		it("should wrap a plain string as a single suggestion", () => {
-			expect(coerceFollowUp("some option")).toEqual([{ text: "some option" }])
+		it("should wrap a plain string as a single suggestion with mode: null", () => {
+			expect(coerceFollowUp("some option")).toEqual([{ text: "some option", mode: null }])
 		})
 
 		it("should return undefined for null", () => {
@@ -278,9 +294,9 @@ describe("askFollowupQuestionTool", () => {
 			expect(coerceFollowUp("   ")).toBeUndefined()
 		})
 
-		it("should wrap a JSON string that parses to a non-array as a suggestion", () => {
+		it("should wrap a JSON string that parses to a non-array as a suggestion with mode: null", () => {
 			// A JSON string like '{"text":"hello"}' is valid JSON but not an array
-			expect(coerceFollowUp('{"text":"hello"}')).toEqual([{ text: '{"text":"hello"}' }])
+			expect(coerceFollowUp('{"text":"hello"}')).toEqual([{ text: '{"text":"hello"}', mode: null }])
 		})
 	})
 
@@ -400,7 +416,7 @@ describe("askFollowupQuestionTool", () => {
 					follow_up: Array<{ text: string; mode?: string }>
 				}
 				expect(nativeArgs.question).toBe("Pick one")
-				expect(nativeArgs.follow_up).toEqual([{ text: "Option A" }])
+				expect(nativeArgs.follow_up).toEqual([{ text: "Option A", mode: null }])
 			}
 		})
 
@@ -422,7 +438,10 @@ describe("askFollowupQuestionTool", () => {
 					follow_up: Array<{ text: string; mode?: string }>
 				}
 				expect(nativeArgs.question).toBe("Pick one")
-				expect(nativeArgs.follow_up).toEqual([{ text: "A" }, { text: "B" }])
+				expect(nativeArgs.follow_up).toEqual([
+					{ text: "A", mode: null },
+					{ text: "B", mode: null },
+				])
 			}
 		})
 	})