Change default state of proposals exp

src/vs/workbench/services/extensions/common/extensions.ts

@@ -395,6 +395,11 @@ let _proposedApiEnabledResolver: ProposedApiEnabledResolver | undefined;
  */
 export const enabledApiProposalsFallbackExperimentName = 'extensionEnabledApiProposalsFallback';
 
+/**
+ * Experiment value that explicitly blocks all proposals reaching the fallback.
+ */
+export const enabledApiProposalsFallbackNone = 'none';
+
 /**
  * Resolves the value of the {@link enabledApiProposalsFallbackExperimentName}-experiment, or
  * `undefined` when it does not apply (non-`stable` quality) or cannot be read in time.
@@ -424,31 +429,32 @@ export async function resolveEnabledApiProposalsFallbackExperiment(assignmentSer
  *
  * @param value A comma-separated list of `publisher.extension:proposalName` entries. Any combination
  * that appears here will have {@link isProposedApiEnabled} return `true` even when the extension has
- * not declared that particular proposal.
+ * not declared that particular proposal. When unset, all proposals are allowed;
+ * {@link enabledApiProposalsFallbackNone} blocks all proposals that reach the fallback.
  * @param quality The product quality. The experiment only takes effect when this is `stable`.
  */
 export function setEnabledApiProposalsFallbackExperiment(value: string | undefined, quality: string | undefined): IDisposable {
-	if (quality !== 'stable' || !value) {
+	if (quality !== 'stable') {
 		return Disposable.None;
 	}
 
 	const allowed = new Set<string>();
-	for (const entry of value.split(',')) {
-		const trimmed = entry.trim();
-		const idx = trimmed.indexOf(':');
-		if (idx <= 0 || idx === trimmed.length - 1) {
-			continue;
+	if (value !== undefined && value !== enabledApiProposalsFallbackNone) {
+		for (const entry of value.split(',')) {
+			const trimmed = entry.trim();
+			const idx = trimmed.indexOf(':');
+			if (idx <= 0 || idx === trimmed.length - 1) {
+				continue;
+			}
+			const extensionId = ExtensionIdentifier.toKey(trimmed.slice(0, idx));
+			const proposal = trimmed.slice(idx + 1);
+			allowed.add(`${extensionId}:${proposal}`);
 		}
-		const extensionId = ExtensionIdentifier.toKey(trimmed.slice(0, idx));
-		const proposal = trimmed.slice(idx + 1);
-		allowed.add(`${extensionId}:${proposal}`);
-	}
-
-	if (allowed.size === 0) {
-		return Disposable.None;
 	}
 
-	const resolver: ProposedApiEnabledResolver = (extension, proposal) => allowed.has(`${ExtensionIdentifier.toKey(extension.identifier)}:${proposal}`);
+	const resolver: ProposedApiEnabledResolver = value === undefined
+		? () => true
+		: (extension, proposal) => allowed.has(`${ExtensionIdentifier.toKey(extension.identifier)}:${proposal}`);
 	_proposedApiEnabledResolver = resolver;
 	return toDisposable(() => {
 		if (_proposedApiEnabledResolver === resolver) {

src/vs/workbench/services/extensions/test/common/extensions.test.ts

@@ -8,7 +8,7 @@ import { URI } from '../../../../../base/common/uri.js';
 import { ensureNoDisposablesAreLeakedInTestSuite } from '../../../../../base/test/common/utils.js';
 import { ExtensionIdentifier, IExtensionDescription, TargetPlatform } from '../../../../../platform/extensions/common/extensions.js';
 import { ApiProposalName } from '../../../../../platform/extensions/common/extensionsApiProposals.js';
-import { isProposedApiEnabled, setEnabledApiProposalsFallbackExperiment } from '../../common/extensions.js';
+import { enabledApiProposalsFallbackNone, isProposedApiEnabled, setEnabledApiProposalsFallbackExperiment } from '../../common/extensions.js';
 
 suite('isProposedApiEnabled (extensionEnabledApiProposalsFallback experiment)', () => {
 
@@ -63,6 +63,29 @@ suite('isProposedApiEnabled (extensionEnabledApiProposalsFallback experiment)',
 		assert.strictEqual(isProposedApiEnabled(noProposals, 'someProposal' as ApiProposalName), false);
 	});
 
+	test('missing experiment allows all proposals on stable by default', () => {
+		const withProposals = desc('test.withProposals', ['unrelatedProposal']);
+		const withoutProposals = desc('test.withoutProposals', undefined);
+		store.add(setEnabledApiProposalsFallbackExperiment(undefined, 'stable'));
+
+		assert.deepStrictEqual(
+			{
+				withProposals: isProposedApiEnabled(withProposals, 'someProposal' as ApiProposalName),
+				withoutProposals: isProposedApiEnabled(withoutProposals, 'someProposal' as ApiProposalName),
+			},
+			{
+				withProposals: true,
+				withoutProposals: false,
+			}
+		);
+	});
+
+	test('none experiment blocks all proposals that reach the fallback', () => {
+		const missing = desc('test.missing', ['unrelatedProposal']);
+		store.add(setEnabledApiProposalsFallbackExperiment(enabledApiProposalsFallbackNone, 'stable'));
+		assert.strictEqual(isProposedApiEnabled(missing, 'someProposal' as ApiProposalName), false);
+	});
+
 	test('experiment has no effect on non-stable builds', () => {
 		const missing = desc('test.missing', ['unrelatedProposal']);
 		store.add(setEnabledApiProposalsFallbackExperiment('test.missing:someProposal', 'insider'));