Prompt files provider API local caching #286466

pwang347 · 2026-01-08T01:33:41Z

No description provided.

…ptsServiceImpl.ts Co-authored-by: Copilot <[email protected]>

… into pawang/cacheV2

Copilot

Pull request overview

This PR adds local caching support for prompt file provider APIs, allowing VS Code to display extension-provided prompt files (agents, instructions, and prompt files) before the extension activates. The implementation introduces an isCacheable boolean property that defaults to true, enabling extensions to opt out of caching for dynamic content.

Key Changes:

Added isCacheable property to prompt file resource APIs for controlling cache behavior
Made isEditable property readonly in API definitions for consistency
Implemented persistent storage-based caching of provider resources using profile-scoped storage
Added cache invalidation when extensions are uninstalled

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/vscode-dts/vscode.proposed.chatPromptFiles.d.ts	Adds `isCacheable` property to CustomAgentOptions, InstructionsOptions, and PromptFileOptions interfaces; makes `isEditable` readonly
src/vs/workbench/contrib/chat/common/promptSyntax/service/promptsService.ts	Adds `isCacheable` property to IPromptFileResource interface
src/vs/workbench/contrib/chat/common/promptSyntax/service/promptsServiceImpl.ts	Implements caching logic with storage persistence, cache retrieval for unactivated extensions, and cache invalidation
src/vs/workbench/api/common/extHostTypes.ts	Adds `isCacheable` property to CustomAgentChatResource, InstructionsChatResource, and PromptFileChatResource classes
src/vs/workbench/contrib/chat/test/common/promptSyntax/service/promptsService.test.ts	Adds comprehensive test suite covering caching, non-caching, cache updates, cache clearing, and pre-activation scenarios

Copilot · 2026-01-08T01:44:15Z

src/vs/workbench/contrib/chat/test/common/promptSyntax/service/promptsService.test.ts

+			if (cachedValue) {
+				const cached = JSON.parse(cachedValue);
+				assert.strictEqual(cached.length, 0, 'Should not have cached non-cacheable resources');
+			}


The test assertion logic is incomplete. When a provider returns only non-cacheable resources, the cache should either not exist or be an empty array. The current implementation writes an empty array when all resources are non-cacheable (line 176 in promptsServiceImpl.ts stores an empty array). The test should assert that the cache is undefined OR contains an empty array, not just check if it's an empty array when it exists. Consider changing to: "assert.ok(!cachedValue || JSON.parse(cachedValue).length === 0, 'Should not have cached non-cacheable resources');"

Suggested change

if (cachedValue) {

const cached = JSON.parse(cachedValue);

assert.strictEqual(cached.length, 0, 'Should not have cached non-cacheable resources');

}

assert.ok(!cachedValue || JSON.parse(cachedValue).length === 0, 'Should not have cached non-cacheable resources');

Copilot · 2026-01-08T01:44:16Z

src/vs/workbench/contrib/chat/common/promptSyntax/service/promptsServiceImpl.ts

+		// Filter out cached resources from extensions that now have active providers
+		// (the provider's resources replace the cached ones, even if URIs differ due to dynamic content)
+		const cachedExtensionIds = new Set(cachedResources.map(c => (c as IExtensionPromptPath).extension.identifier.value));
+		return result.filter(r => {
+			if (r.storage !== PromptsStorage.extension) {
+				return true;
+			}
+			const extensionPath = r as IExtensionPromptPath;
+			const extensionId = extensionPath.extension.identifier.value;
+			// If this is a cached resource and the extension now has an active provider, filter it out
+			if (cachedExtensionIds.has(extensionId) && activeProviderExtensionIds.has(extensionId)) {
+				// Keep only if it came from the provider (not from cache)
+				// Cached resources were added first, provider resources added after
+				// We can identify cached ones by checking if they're in the original cachedResources array
+				return !cachedResources.some(c => c.uri.toString() === r.uri.toString());
+			}
+			return true;
+		});


The filtering logic at line 486 uses a nested loop (filter + some) which results in O(n*m) complexity where n is the number of results and m is the number of cached resources. For extensions with many resources, this could be inefficient. Consider creating a Set of cached URIs before the filter operation to make the lookup O(1): "const cachedUris = new Set(cachedResources.map(c => c.uri.toString()));" and then use "cachedUris.has(r.uri.toString())" instead of the some() call.

Copilot · 2026-01-08T01:44:16Z

src/vs/workbench/contrib/chat/common/promptSyntax/service/promptsServiceImpl.ts

+	 */
+	private setCachedProviderResources(extensionId: string, type: PromptsType, resources: IPromptFileResource[]): void {
+		const key = `${this.cachedProviderResourcesStorageKeyPrefix}${extensionId}.${type}`;
+		this.logger.info(`[setCachedProviderResources] Setting cache for ${extensionId}/${type}, input resources:`, JSON.stringify(resources.map(r => ({ name: r.name, description: r.description, uri: r.uri?.toString(), isEditable: r.isEditable, isCacheable: r.isCacheable }))));


The logging at line 165 uses optional chaining (r.uri?.toString()) but the actual mapping at line 172 uses non-optional access (r.uri.toString()). This inconsistency could cause a runtime error if a resource is provided without a URI. Since IPromptFileResource.uri is marked as required (not optional) in the interface, the logging should match the code and use r.uri.toString() without the optional chaining operator.

Suggested change

this.logger.info(`[setCachedProviderResources] Setting cache for ${extensionId}/${type}, input resources:`, JSON.stringify(resources.map(r => ({ name: r.name, description: r.description, uri: r.uri?.toString(), isEditable: r.isEditable, isCacheable: r.isCacheable }))));

this.logger.info(`[setCachedProviderResources] Setting cache for ${extensionId}/${type}, input resources:`, JSON.stringify(resources.map(r => ({ name: r.name, description: r.description, uri: r.uri.toString(), isEditable: r.isEditable, isCacheable: r.isCacheable }))));

Copilot · 2026-01-08T01:44:16Z

src/vs/workbench/contrib/chat/common/promptSyntax/service/promptsService.ts

 	readonly isEditable?: boolean;
+
+	/**
+	 * Indicates whether the editor should cache the URI on startup before activation. Defaults to true.


The documentation says "cache the URI on startup" but the implementation actually caches the entire resource metadata (name, description, uri, isEditable), not just the URI. Consider updating the documentation to say "cache the resource metadata on startup before activation" for accuracy.

Suggested change

* Indicates whether the editor should cache the URI on startup before activation. Defaults to true.

* Indicates whether the editor should cache the resource metadata on startup before activation. Defaults to true.

Copilot · 2026-01-08T01:44:16Z

src/vs/workbench/contrib/chat/common/promptSyntax/service/promptsServiceImpl.ts

+	private setCachedProviderResources(extensionId: string, type: PromptsType, resources: IPromptFileResource[]): void {
+		const key = `${this.cachedProviderResourcesStorageKeyPrefix}${extensionId}.${type}`;
+		this.logger.info(`[setCachedProviderResources] Setting cache for ${extensionId}/${type}, input resources:`, JSON.stringify(resources.map(r => ({ name: r.name, description: r.description, uri: r.uri?.toString(), isEditable: r.isEditable, isCacheable: r.isCacheable }))));
+		// Filter to only cacheable resources (isCacheable defaults to true)
+		const cacheableResources: ICachedPromptFileResource[] = resources
+			.filter(r => r.isCacheable !== false)
+			.map(r => ({
+				name: r.name,
+				description: r.description,
+				uri: r.uri.toString(),
+				isEditable: r.isEditable
+			}));
+		this.logger.info(`[setCachedProviderResources] Storing ${cacheableResources.length} cacheable resources for key=${key}:`, JSON.stringify(cacheableResources));
+		this.storageService.store(key, JSON.stringify(cacheableResources), StorageScope.PROFILE, StorageTarget.MACHINE);
+
+		// Track that this extension has registered a provider for this type
+		this.addCachedProviderExtension(extensionId, type);


When all resources from a provider are non-cacheable (isCacheable=false), the implementation still stores an empty array in storage and tracks the extension as having cached resources. This is somewhat inefficient as it creates storage entries and tracks extensions even when there's nothing useful to cache. Consider only storing cache data and tracking extensions when there is at least one cacheable resource (e.g., check if cacheableResources.length > 0 before storing).

Copilot · 2026-01-08T01:44:17Z

src/vs/workbench/contrib/chat/common/promptSyntax/service/promptsServiceImpl.ts

 		const result: IPromptPath[] = [];

+		// First, get cached resources for extensions that haven't activated yet
+		const cachedResources = await this.getCachedResourcesForUnactivatedExtensions(type);


Cached resources loaded before extension activation (line 419) are not having their readonly state applied via filesConfigService.updateReadonly(), unlike provider resources (lines 448-455). This means if a cached resource has isEditable=false, the file won't be marked as readonly until the extension activates and the provider returns it. Consider applying the readonly state to cached resources as well if they have isEditable=false stored in the cache.

Suggested change

const cachedResources = await this.getCachedResourcesForUnactivatedExtensions(type);

const cachedResources = await this.getCachedResourcesForUnactivatedExtensions(type);

for (const cached of cachedResources) {

const cachedExtensionPath = cached as IExtensionPromptPath & { isEditable?: boolean };

if (cachedExtensionPath.isEditable === false) {

try {

await this.filesConfigService.updateReadonly(cached.uri, true);

} catch (e) {

const msg = e instanceof Error ? e.message : String(e);

this.logger.error(`[listFromProviders] Failed to make cached file readonly: ${cached.uri}`, msg);

}

}

}

pwang347 and others added 4 commits January 7, 2026 15:43

cache prompt ext files

4bca3d7

Update src/vs/workbench/contrib/chat/common/promptSyntax/service/prom…

ad09e8d

…ptsServiceImpl.ts Co-authored-by: Copilot <[email protected]>

fix

9cef5b7

Merge branch 'pawang/extPromptCaching' of github.com:microsoft/vscode…

ca9fd6b

… into pawang/cacheV2

Copilot AI review requested due to automatic review settings January 8, 2026 01:33

pwang347 changed the base branch from main to pawang/providerV2 January 8, 2026 01:33

Copilot started reviewing on behalf of pwang347 January 8, 2026 01:34 View session

pwang347 mentioned this pull request Jan 8, 2026

Add proposed API for prompt files providers #280426

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Prompt files provider API local caching #286466

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	this.logger.info(`[setCachedProviderResources] Setting cache for ${extensionId}/${type}, input resources:`, JSON.stringify(resources.map(r => ({ name: r.name, description: r.description, uri: r.uri?.toString(), isEditable: r.isEditable, isCacheable: r.isCacheable }))));
	this.logger.info(`[setCachedProviderResources] Setting cache for ${extensionId}/${type}, input resources:`, JSON.stringify(resources.map(r => ({ name: r.name, description: r.description, uri: r.uri.toString(), isEditable: r.isEditable, isCacheable: r.isCacheable }))));

	* Indicates whether the editor should cache the URI on startup before activation. Defaults to true.
	* Indicates whether the editor should cache the resource metadata on startup before activation. Defaults to true.

-		const cachedResources = await this.getCachedResourcesForUnactivatedExtensions(type);
+		const cachedResources = await this.getCachedResourcesForUnactivatedExtensions(type);
+		for (const cached of cachedResources) {
+			const cachedExtensionPath = cached as IExtensionPromptPath & { isEditable?: boolean };
+			if (cachedExtensionPath.isEditable === false) {
+				try {
+					await this.filesConfigService.updateReadonly(cached.uri, true);
+				} catch (e) {
+					const msg = e instanceof Error ? e.message : String(e);
+					this.logger.error(`[listFromProviders] Failed to make cached file readonly: ${cached.uri}`, msg);
+				}
+			}
+		}

Prompt files provider API local caching #286466

Prompt files provider API local caching #286466

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