fix: toBase64() encoder which only accepts string

Author: laileni-aws

server/aws-lsp-codewhisperer/src/language-server/agenticChat/context/additionalContextProvider.ts

@@ -600,13 +600,22 @@ export class AdditionalContextProvider {
                         continue
                     }
                     if ('content' in context && context.content) {
-                        imageBlocks.push({
-                            format: format as ImageFormat,
-                            source: {
-                                bytes: new Uint8Array(Object.values(context.content)),
-                            },
-                        })
-                        continue
+                        // Validate content has actual byte data before creating Uint8Array
+                        // After JSON deserialization, Uint8Array becomes plain object with numeric keys
+                        const values = Object.values(context.content)
+                        if (values.length > 0 && values.every((v): v is number => typeof v === 'number')) {
+                            imageBlocks.push({
+                                format: format as ImageFormat,
+                                source: {
+                                    bytes: new Uint8Array(values),
+                                },
+                            })
+                            continue
+                        }
+                        // Invalid content data, fall through to read from file
+                        this.features.logging.warn(
+                            `Invalid image content data for ${imagePath}, attempting to read from file`
+                        )
                     }
                     const fileContent = await this.features.workspace.fs.readFile(imagePath, {
                         encoding: 'binary',

server/aws-lsp-codewhisperer/src/language-server/agenticChat/tools/chatDb/util.ts

@@ -175,11 +175,34 @@ export function messageToStreamingMessage(msg: Message): StreamingMessage {
                   userIntent: msg.userIntent,
                   origin: msg.origin || 'IDE',
                   userInputMessageContext: msg.userInputMessageContext,
-                  images: msg.images || [],
+                  images: restoreImageBytes(msg.images || []),
               },
           }
 }
 
+/**
+ * Restores image bytes to proper Uint8Array after deserialization from JSON.
+ *
+ * When images are persisted via LokiJS (JSON serialization), Uint8Array bytes
+ * are serialized as plain objects with numeric keys (e.g., {"0": 137, "1": 80, ...}).
+ * On reload, these need to be converted back to Uint8Array for the AWS SDK's
+ * toBase64() encoder which only accepts string | Uint8Array.
+ */
+function restoreImageBytes(images: ImageBlock[]): ImageBlock[] {
+    return images.map(image => {
+        if (image.source?.bytes && !(image.source.bytes instanceof Uint8Array)) {
+            return {
+                ...image,
+                source: {
+                    ...image.source,
+                    bytes: new Uint8Array(Object.values(image.source.bytes)),
+                },
+            }
+        }
+        return image
+    })
+}
+
 /**
  * Converts Message to LSP Protocol ChatMessage
  */