fix(FlowiseChatGoogleGenerativeAI): handle 'thinking' content type round-trip

packages/components/nodes/chatmodels/ChatGoogleGenerativeAI/FlowiseChatGoogleGenerativeAI.test.ts

@@ -0,0 +1,97 @@
+import { AIMessage } from '@langchain/core/messages'
+import { convertMessageContentToParts } from './FlowiseChatGoogleGenerativeAI'
+
+describe('convertMessageContentToParts — Gemini "thinking" content blocks', () => {
+    it('round-trips a thinking content block back into a Gemini text Part with thought=true', () => {
+        const msg = new AIMessage({
+            content: [
+                { type: 'thinking', thinking: 'First I should validate the inputs.' } as any,
+                { type: 'text', text: 'OK, validated.' }
+            ]
+        })
+
+        const parts = convertMessageContentToParts(msg, false, [])
+
+        const thoughtPart = parts.find((p: any) => p.thought === true) as any
+        expect(thoughtPart).toBeDefined()
+        expect(thoughtPart.text).toBe('First I should validate the inputs.')
+        expect(thoughtPart.thought).toBe(true)
+        // No signature in the input → no thoughtSignature in the output
+        expect(thoughtPart.thoughtSignature).toBeUndefined()
+
+        const textPart = parts.find((p: any) => p.text === 'OK, validated.' && !p.thought) as any
+        expect(textPart).toBeDefined()
+    })
+
+    it('preserves the thoughtSignature for Gemini-3 multi-turn tool-call continuity', () => {
+        // signature is stored under `signature` on the LangChain block (see
+        // the response parsers' output in FlowiseChatGoogleGenerativeAI.ts);
+        // it must be emitted as `thoughtSignature` on the outgoing Part.
+        const msg = new AIMessage({
+            content: [
+                {
+                    type: 'thinking',
+                    thinking: 'Need to call the search tool.',
+                    signature: 'abc123-thought-sig'
+                } as any
+            ]
+        })
+
+        const parts = convertMessageContentToParts(msg, false, [])
+        const p = parts[0] as any
+        expect(p.thought).toBe(true)
+        expect(p.thoughtSignature).toBe('abc123-thought-sig')
+    })
+
+    it('also accepts thoughtSignature on the LangChain block (alternate key name)', () => {
+        const msg = new AIMessage({
+            content: [
+                {
+                    type: 'thinking',
+                    thinking: 'alt',
+                    thoughtSignature: 'sig-from-alt-key'
+                } as any
+            ]
+        })
+
+        const parts = convertMessageContentToParts(msg, false, [])
+        const p = parts[0] as any
+        expect(p.thought).toBe(true)
+        expect(p.thoughtSignature).toBe('sig-from-alt-key')
+    })
+
+    it('treats undefined/null thinking as empty text rather than throwing', () => {
+        // Producer sites in this file always emit a string `thinking`,
+        // but defensive: missing fields should not crash the converter
+        // — they should just degrade to an empty thought part. (`??`
+        // collapses both undefined and null into the fallback.)
+        const msg = new AIMessage({
+            content: [{ type: 'thinking' } as any] // no `thinking` field at all
+        })
+        const parts = convertMessageContentToParts(msg, false, [])
+        const p = parts[0] as any
+        expect(p.thought).toBe(true)
+        expect(p.text).toBe('')
+    })
+
+    it('fails fast on non-string thinking payload (per code-review feedback)', () => {
+        const msg = new AIMessage({
+            content: [{ type: 'thinking', thinking: 42 } as any]
+        })
+        expect(() => convertMessageContentToParts(msg, false, [])).toThrow(/Invalid 'thinking' content: expected string, got number/)
+    })
+
+    it('fails fast on non-string thinking signature', () => {
+        const msg = new AIMessage({
+            content: [{ type: 'thinking', thinking: 'ok', signature: 42 } as any]
+        })
+        expect(() => convertMessageContentToParts(msg, false, [])).toThrow(/Invalid 'thinking' signature: expected string, got number/)
+    })
+
+    it('still throws "Unknown content type" for truly unrecognized types', () => {
+        const msg = new AIMessage({
+            content: [{ type: 'definitely-not-a-real-type', value: 1 } as any]
+        })
+        expect(() => convertMessageContentToParts(msg, false, [])).toThrow(/Unknown content type/)
+    })
+})

packages/components/nodes/chatmodels/ChatGoogleGenerativeAI/FlowiseChatGoogleGenerativeAI.ts

@@ -302,6 +302,23 @@ function _convertLangChainContentToPart(content: MessageContentComplex, isMultim
         }
     } else if ('functionCall' in content) {
         return undefined
+    } else if (content.type === 'thinking') {
+        // Map LangChain `thinking` blocks back to Google's native shape:
+        // a text Part with `thought: true` and optional `thoughtSignature`.
+        // https://ai.google.dev/gemini-api/docs/thinking
+        const text = (content as any).thinking ?? (content as any).text
+        if (text !== undefined && typeof text !== 'string') {
+            throw new Error(`Invalid 'thinking' content: expected string, got ${typeof text}`)
+        }
+        const signature = (content as any).signature ?? (content as any).thoughtSignature
+        if (signature !== undefined && typeof signature !== 'string') {
+            throw new Error(`Invalid 'thinking' signature: expected string, got ${typeof signature}`)
+        }
+        return {
+            text: text ?? '',
+            thought: true,
+            ...(signature ? { thoughtSignature: signature } : {})
+        } as Part
     } else {
         if ('type' in content) {
             throw new Error(`Unknown content type ${content.type}`)