feat: prepare VS Code LM API for image support

- Updated VS Code engine requirement to 1.95.0 for image API support
- Added TODO comment in vscode-lm.ts for future image capability detection
- Improved image placeholder messages in convertToVsCodeLmMessages
- Updated tests to match new placeholder format

This prepares the codebase for when VS Code fully exposes the image
support capabilities through the LanguageModelChat interface.

Author: roomote

pnpm-lock.yaml

@@ -510,7 +510,10 @@ export class VsCodeLmHandler extends BaseProvider implements SingleCompletionHan
 					typeof this.client.maxInputTokens === "number"
 						? Math.max(0, this.client.maxInputTokens)
 						: openAiModelInfoSaneDefaults.contextWindow,
-				supportsImages: false, // VSCode Language Model API currently doesn't support image inputs
+				// TODO: Enable image support when VS Code LM API provides capability detection
+				// The newer VS Code API (1.95+) includes LanguageModelChatInformation.capabilities.imageInput
+				// but it's not directly accessible from the LanguageModelChat interface yet
+				supportsImages: false,
 				supportsPromptCache: true,
 				inputPrice: 0,
 				outputPrice: 0,

src/api/providers/vscode-lm.ts

@@ -170,7 +170,9 @@ describe("convertToVsCodeLmMessages", () => {
 
 		expect(result).toHaveLength(1)
 		const imagePlaceholder = result[0].content[1] as MockLanguageModelTextPart
-		expect(imagePlaceholder.value).toContain("[Image (base64): image/png not supported by VSCode LM API]")
+		expect(imagePlaceholder.value).toContain(
+			"[Image placeholder: base64 (image/png) - VS Code LM API image support pending]",
+		)
 	})
 })
 

src/api/transform/__tests__/vscode-lm-format.spec.ts

@@ -85,8 +85,12 @@ export function convertToVsCodeLmMessages(
 					// Convert non-tool messages to TextParts after tool messages
 					...nonToolMessages.map((part) => {
 						if (part.type === "image") {
+							// TODO: When VS Code LM API adds LanguageModelImagePart support, convert images properly
+							// For now, we provide a placeholder text description
+							const imageType = part.source?.type || "unknown"
+							const mediaType = part.source?.media_type || "unknown"
 							return new vscode.LanguageModelTextPart(
-								`[Image (${part.source?.type || "Unknown source-type"}): ${part.source?.media_type || "unknown media-type"} not supported by VSCode LM API]`,
+								`[Image placeholder: ${imageType} (${mediaType}) - VS Code LM API image support pending]`,
 							)
 						}
 						return new vscode.LanguageModelTextPart(part.text)
@@ -129,7 +133,10 @@ export function convertToVsCodeLmMessages(
 					// Convert non-tool messages to TextParts after tool messages
 					...nonToolMessages.map((part) => {
 						if (part.type === "image") {
-							return new vscode.LanguageModelTextPart("[Image generation not supported by VSCode LM API]")
+							// Assistant-generated images are not yet supported
+							return new vscode.LanguageModelTextPart(
+								"[Image generation not yet supported by VS Code LM API]",
+							)
 						}
 						return new vscode.LanguageModelTextPart(part.text)
 					}),

src/api/transform/vscode-lm-format.ts

@@ -10,7 +10,7 @@
 		"theme": "dark"
 	},
 	"engines": {
-		"vscode": "^1.84.0",
+		"vscode": "^1.95.0",
 		"node": "20.19.2"
 	},
 	"author": {
@@ -531,7 +531,7 @@
 		"@types/string-similarity": "^4.0.2",
 		"@types/tmp": "^0.2.6",
 		"@types/turndown": "^5.0.5",
-		"@types/vscode": "^1.84.0",
+		"@types/vscode": "^1.104.0",
 		"@vscode/test-electron": "^2.5.2",
 		"@vscode/vsce": "3.3.2",
 		"esbuild": "^0.25.0",