Migrate LLM tools and remove Positron Assistant (#14718)

Fixes #14638

### Summary

As part of reverting to Copilot Chat, the Positron Assistant extension
is no longer needed. This PR removes the `positron-assistant` extension
and migrates the pieces Copilot Chat still relies on into Positron core,
so core can supply Positron-specific context (runtime sessions,
variables, code execution) to Copilot Chat through the Positron API.

- **Removes** the `positron-assistant` extension -- participants, tools,
prompt rendering, provider configuration/migration, and its tests --
along with its entries in `product.json` and the build config
(`gulpfile.extensions.ts`, `dirs.ts`, `.vscode-test.js`).
- **Migrates to core** under
`src/vs/workbench/contrib/positronAssistant/`: the prompt template
engine and renderer, the chat prompt templates, the Positron assistant
tools, and the execute-code observer.
- **Extends the Positron API** with the assistant's LLM tools and a tool
filter (`positronToolFilter.ts`), wired through `mainThreadAiFeatures` /
`extHostAiFeatures`, so Copilot Chat consumes Positron context via the
public API rather than a bundled extension.
- **Updates Copilot Chat** (`extensions/copilot/`) to render the
Positron assistant prompt and register the migrated tools through the
Positron API.

### Release Notes

#### New Features
- Positron assistant context (runtime sessions, variables, and code
execution) is now provided to Copilot Chat through Positron core instead
of a separate extension (#14638)

#### Bug Fixes
- N/A

### Validation Steps

@:assistant @:posit-assistant

1. Open Copilot Chat and start a Python or R session.
2. Ask a question that requires Positron context (e.g. "what variables
are in my session?" or "run this code and explain the output").
3. Verify the assistant sees the active session, can list variables, and
can execute code in the console.
4. Confirm the `positron-assistant` extension no longer appears in the
Extensions view.

Author: timtmok

.github/workflows/test-tag-paths-map.json

@@ -33,7 +33,9 @@
   "src/vs/workbench/contrib/runtimeSession/": ["@:sessions"],
   "src/vs/workbench/contrib/runtimeNotebookKernel/": ["@:positron-notebooks"],
 
-  "extensions/positron-assistant/": ["@:assistant"],
+  "extensions/authentication/": ["@:assistant"],
+  "extensions/copilot/": ["@:assistant"],
+  "extensions/copilot/src/extension/prompts/node/base/positronAssistant.tsx/": ["@:assistant"],
   "extensions/positron-connections/": ["@:connections"],
   "extensions/positron-notebooks/": ["@:positron-notebooks"],
   "extensions/positron-reticulate/": ["@:reticulate"],

.vscode-test.js

@@ -68,11 +68,6 @@ const extensions = [
 		workspaceFolder: path.join(os.tmpdir(), `authentication-${Math.floor(Math.random() * 100000)}`),
 		mocha: { timeout: 60_000 }
 	},
-	{
-		label: 'positron-assistant',
-		workspaceFolder: 'extensions/positron-assistant/test-workspace',
-		mocha: { timeout: 60_000 }
-	},
 	{
 		label: 'next-edit-suggestions',
 		workspaceFolder: path.join(os.tmpdir(), `next-edit-suggestions-${Math.floor(Math.random() * 100000)}`),

build/gulpfile.extensions.ts

@@ -58,7 +58,6 @@ const compilations = [
 	'extensions/authentication/tsconfig.json',
 	'extensions/open-remote-ssh/tsconfig.json',
 	'extensions/next-edit-suggestions/tsconfig.json',
-	'extensions/positron-assistant/tsconfig.json',
 	'extensions/positron-catalog-explorer/tsconfig.json',
 	'extensions/positron-code-cells/tsconfig.json',
 	'extensions/positron-connections/tsconfig.json',

build/gulpfile.vscode.ts

@@ -129,6 +129,8 @@ const vscodeResourceIncludes = [
 	// Positron Help
 	'out-build/vs/workbench/contrib/positronHelp/browser/resources/*.html',
 	'out-build/vs/workbench/browser/media/*.svg',
+	// Positron Assistant chat prompt templates
+	'out-build/vs/workbench/contrib/positronAssistant/browser/media/prompts/chat/*.md',
 	// --- End Positron ---
 
 	// Tree Sitter highlights

build/gulpfile.vscode.web.ts

@@ -77,6 +77,8 @@ export const vscodeWebResourceIncludes = [
 	// Positron Help
 	'out-build/vs/workbench/contrib/positronHelp/browser/resources/*.html',
 	'out-build/vs/workbench/browser/media/*.svg',
+	// Positron Assistant chat prompt templates
+	'out-build/vs/workbench/contrib/positronAssistant/browser/media/prompts/chat/*.md',
 	'out-build/esm-package-dependencies/**',
 	// --- End Positron ---
 

build/next/index.ts

@@ -261,6 +261,8 @@ const desktopResourcePatterns = [
 	// --- Start Positron ---
 	// Positron Help welcome/help HTML loaded by positronHelpService at runtime.
 	'vs/workbench/contrib/positronHelp/browser/resources/*.html',
+	// Positron Assistant chat prompt templates, loaded by PromptRenderer at runtime.
+	'vs/workbench/contrib/positronAssistant/browser/media/prompts/chat/*.md',
 	// --- End Positron ---
 
 	// HTML
@@ -342,6 +344,8 @@ const serverWebResourcePatterns = [
 	// --- Start Positron ---
 	// Positron Help welcome/help HTML loaded by positronHelpService at runtime.
 	'vs/workbench/contrib/positronHelp/browser/resources/*.html',
+	// Positron Assistant chat prompt templates, loaded by PromptRenderer at runtime.
+	'vs/workbench/contrib/positronAssistant/browser/media/prompts/chat/*.md',
 	// --- End Positron ---
 
 	// Web HTML
@@ -374,6 +378,8 @@ const webResourcePatterns = [
 	// --- Start Positron ---
 	// Positron Help welcome/help HTML loaded by positronHelpService at runtime.
 	'vs/workbench/contrib/positronHelp/browser/resources/*.html',
+	// Positron Assistant chat prompt templates, loaded by PromptRenderer at runtime.
+	'vs/workbench/contrib/positronAssistant/browser/media/prompts/chat/*.md',
 	// --- End Positron ---
 
 	// Web HTML

build/npm/dirs.ts

@@ -22,7 +22,6 @@ export let dirs = [
 	'extensions/authentication',
 	'extensions/next-edit-suggestions',
 	'extensions/open-remote-ssh',
-	'extensions/positron-assistant',
 	'extensions/positron-catalog-explorer',
 	'extensions/positron-code-cells',
 	'extensions/positron-connections',
@@ -142,7 +141,6 @@ if (existsSync(`${import.meta.dirname}/../../.build/distro/npm`)) {
 // THIS IS THE SINGLE SOURCE OF TRUTH for volatile extension list
 export const volatileExtensions = [
 	'extensions/positron-python',
-	'extensions/positron-assistant',
 	'extensions/positron-r'
 ];
 

extensions/authentication/src/test/providerSources.test.ts

@@ -12,28 +12,23 @@ import { PROVIDER_METADATA } from '../providerSources';
  * Guards against drift between PROVIDER_METADATA in providerSources.ts and the
  * package.json contributions that own the same data. The metadata hardcodes
  * provider ids, display names, setting names, and maturity status that really
- * live in the manifests; nothing but this test keeps them in sync.
+ * live in this extension's manifest; nothing but this test keeps them in sync.
  *
- * Two manifests are involved:
- *   - this extension's package.json: `contributes.authentication` (id + label)
- *     and the `assistant.provider.<settingName>.enabled` settings for providers
- *     that don't ship via positron-assistant (googleVertex, deepseek).
- *   - positron-assistant's package.json: the `positron.assistant.provider.
- *     <settingName>.enable` settings (and their tags, which `status` mirrors).
+ * Two sets of contributions in this extension's package.json are involved:
+ *   - `contributes.authentication` (id + label).
+ *   - the provider enablement settings (and their tags, which `status`
+ *     mirrors). posit-dev/positron#13811 already moved every enablement
+ *     setting into this manifest (the old positron-assistant home is gone) and
+ *     is still renaming the legacy `positron.assistant.provider.<name>.enable`
+ *     keys to the new `assistant.provider.<name>.enabled` format (note the
+ *     trailing `d`). Until every key is renamed, both formats coexist here.
  *
- * NOTE: posit-dev/positron#13811 migrates the old `positron.assistant.provider.
- * <name>.enable` keys to the new `assistant.provider.<name>.enabled` format
- * (note the trailing `d`) and moves every enablement setting into a single home.
- * Once that lands, this test simplifies:
- *   - If the settings move here, drop `assistantPkg` and its `collect()` call;
- *     the cross-extension read into positron-assistant goes away (it's being
- *     deprecated anyway). If they move elsewhere, point the single read there.
- *   - Tighten the `provider\.(?<name>[^.]+)\.enabled?$` regex to `\.enabled$`;
- *     the optional `d` only exists to match both the old and new key formats.
- *   - If the migration keeps the old keys around as deprecated aliases instead
- *     of removing them, both keys will exist for the same provider. They map to
- *     the same capture group, so skip anything carrying a `deprecationMessage`/
- *     `markdownDeprecationMessage` to avoid the deprecated entry's tags winning.
+ * The `provider\.(?<name>[^.]+)\.enabled?$` regex matches both formats; the
+ * optional `d` only exists to bridge them. Tighten it to `\.enabled$` once the
+ * rename is complete. If any legacy key is kept around as a deprecated alias
+ * (so both keys exist for one provider, mapping to the same capture group),
+ * skip entries carrying a `deprecationMessage`/`markdownDeprecationMessage` so
+ * the deprecated entry's tags don't win.
  */
 suite('PROVIDER_METADATA package.json consistency', () => {
 
@@ -43,7 +38,6 @@ suite('PROVIDER_METADATA package.json consistency', () => {
 	}
 
 	const authPkg = readPackageJson('package.json');
-	const assistantPkg = readPackageJson('..', 'positron-assistant', 'package.json');
 
 	test('every authentication contribution has a PROVIDER_METADATA entry', () => {
 		// `label` (Accounts menu) and `displayName` (model picker) are deliberately
@@ -60,8 +54,8 @@ suite('PROVIDER_METADATA package.json consistency', () => {
 	});
 
 	test('settingName and status match the provider enable settings', () => {
-		// Collect every `provider.<name>.enable`/`.enabled` setting across both
-		// manifests, mapping the name to its maturity status (derived from tags).
+		// Collect every `provider.<name>.enable`/`.enabled` setting in the
+		// manifest, mapping the name to its maturity status (derived from tags).
 		// `status` in PROVIDER_METADATA must mirror that exactly.
 		const enableSettings: Record<string, 'preview' | 'experimental' | undefined> = {};
 		const collect = (pkg: any) => {
@@ -80,7 +74,6 @@ suite('PROVIDER_METADATA package.json consistency', () => {
 			}
 		};
 		collect(authPkg);
-		collect(assistantPkg);
 
 		const fromMetadata: Record<string, 'preview' | 'experimental' | undefined> = {};
 		for (const entry of Object.values(PROVIDER_METADATA)) {

extensions/copilot/.esbuild.mts

@@ -32,6 +32,9 @@ const baseNodeBuildOptions = {
 	external: [
 		'./package.json',
 		'./.vscode-test.mjs',
+		// Positron: the `positron` module is provided by the Positron extension
+		// host at runtime, so leave it external rather than bundling it.
+		'positron',
 		'playwright',
 		'keytar',
 		'@azure/functions-core',
@@ -206,6 +209,7 @@ const webExtHostBuildOptions = {
 	format: 'cjs', // Necessary to export activate function from bundle for extension
 	external: [
 		'vscode',
+		'positron', // Positron: provided by the Positron extension host at runtime
 		'http',
 	]
 } satisfies esbuild.BuildOptions;

extensions/copilot/src/extension/prompts/node/base/positronAssistant.tsx

@@ -5,7 +5,7 @@
 
 import { PromptElement, PromptSizing, SystemMessage, TextChunk } from '@vscode/prompt-tsx';
 import type { ChatResponsePart } from '@vscode/prompt-tsx/dist/base/vscodeTypes.js';
-import * as vscode from 'vscode';
+import type * as vscode from 'vscode';
 import type { GenericBasePromptElementProps } from '../../../context/node/resolvers/genericPanelIntentInvocation';
 import type { IBuildPromptContext } from '../../../prompt/common/intents.js';
 
@@ -25,22 +25,22 @@ export class PositronAssistant extends PromptElement<GenericBasePromptElementPro
 		progress?: vscode.Progress<ChatResponsePart>,
 		token?: vscode.CancellationToken): Promise<any> {
 
-		// The Positron Assistant extension supplies the Positron-specific context
-		// for this prompt. When Copilot Chat is used on its own, that extension may
-		// be disabled or not installed; skip this element in that case rather than
-		// failing the whole chat request.
-		const extension = vscode.extensions.getExtension('positron.positron-assistant');
-		if (!extension) {
+		const request = this.context.request;
+		if (!request) {
 			return undefined;
 		}
 
-		// Activate the extension if needed so its API is available, then generate
-		// the content element.
-		const api = await extension.activate();
-		if (typeof api?.generateAssistantPrompt !== 'function') {
+		// Positron supplies the Positron-specific context for this prompt via the
+		// `positron` API, provided by the Positron extension host at runtime. It
+		// is absent when Copilot Chat runs outside Positron (or in simulation
+		// tests), so guard the lookup and skip this element rather than failing
+		// the whole chat request.
+		try {
+			const positron = require('positron') as typeof import('positron');
+			return await positron.ai.generateAssistantPrompt(request);
+		} catch {
 			return undefined;
 		}
-		return await api.generateAssistantPrompt(this.context.request);
 	}
 
 	/**