Refactor: PluginController self-manages host customizations

Move host customization management into PluginController so
the IAgent interface no longer needs setHostCustomizations.
PluginController now:
- injects IAgentConfigurationService
- subscribes to onDidRootConfigChange (new event)
- reads + resolves customizations internally
- fires onDidChange so AgentSideEffects can republish

This removes the external poke from AgentSideEffects and the
seed call from AgentService.registerProvider, addressing
Connor's architectural feedback.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: joshspicer

src/vs/platform/agentHost/common/agentService.ts

@@ -483,16 +483,11 @@ export interface IAgent {
 	getProtectedResources(): ProtectedResourceMetadata[];
 
 	/**
-	 * Updates the host-owned customization refs available to this agent.
-	 *
-	 * The list is a full replacement of the remote agent host's configured
-	 * plugins after scope resolution and persistence have been applied.
-	 *
-	 * Implementations can invoke `progress` whenever session-visible status
-	 * for the host customizations changes so callers can republish
-	 * `SessionCustomization` state.
+	 * Fires when the agent's host-owned customizations change
+	 * (loading state, resolution results, etc.), so infrastructure
+	 * can republish {@link AgentInfo} and session customization state.
 	 */
-	setHostCustomizations?(customizations: CustomizationRef[], progress?: () => void): void;
+	readonly onDidCustomizationsChange?: Event<void>;
 
 	/**
 	 * Returns the host-owned customization refs this agent currently exposes.

src/vs/platform/agentHost/node/agentConfigurationService.ts

@@ -4,6 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 
 import * as fs from 'fs';
+import { Emitter, Event } from '../../../base/common/event.js';
 import { Disposable } from '../../../base/common/lifecycle.js';
 import { dirname } from '../../../base/common/path.js';
 import { hasKey } from '../../../base/common/types.js';
@@ -36,6 +37,13 @@ export const IAgentConfigurationService = createDecorator<IAgentConfigurationSer
 export interface IAgentConfigurationService {
 	readonly _serviceBrand: undefined;
 
+	/**
+	 * Fires whenever a {@link ActionType.RootConfigChanged} action is
+	 * processed by the state manager, signalling that callers should
+	 * re-read any root config values they depend on.
+	 */
+	readonly onDidRootConfigChange: Event<void>;
+
 	/**
 	 * Returns the effective value of `key` for `session`, walking the
 	 * `session → parent session → host` chain and returning the first
@@ -92,6 +100,9 @@ export class AgentConfigurationService extends Disposable implements IAgentConfi
 	declare readonly _serviceBrand: undefined;
 	private _rootConfigWrite = Promise.resolve();
 
+	private readonly _onDidRootConfigChange = this._register(new Emitter<void>());
+	readonly onDidRootConfigChange: Event<void> = this._onDidRootConfigChange.event;
+
 	constructor(
 		private readonly _stateManager: AgentHostStateManager,
 		@ILogService private readonly _logService: ILogService,
@@ -110,6 +121,12 @@ export class AgentConfigurationService extends Disposable implements IAgentConfi
 			},
 			values: { ...existing?.values, ...this._loadPersistedRootConfig() },
 		};
+
+		this._register(this._stateManager.onDidEmitEnvelope(envelope => {
+			if (envelope.action.type === ActionType.RootConfigChanged) {
+				this._onDidRootConfigChange.fire();
+			}
+		}));
 	}
 
 	getEffectiveValue<D extends SchemaDefinition, K extends keyof D & string>(

src/vs/platform/agentHost/node/agentService.ts

@@ -14,7 +14,6 @@ import { FileSystemProviderErrorCode, IFileService, toFileSystemProviderErrorCod
 import { InstantiationService } from '../../instantiation/common/instantiationService.js';
 import { ServiceCollection } from '../../instantiation/common/serviceCollection.js';
 import { ILogService } from '../../log/common/log.js';
-import { AgentHostConfigKey, agentHostCustomizationConfigSchema } from '../common/agentHostCustomizationConfig.js';
 import { AgentProvider, AgentSession, IAgent, IAgentCreateSessionConfig, IAgentMessageEvent, IAgentResolveSessionConfigParams, IAgentService, IAgentSessionConfigCompletionsParams, IAgentSessionMetadata, IAgentSubagentStartedEvent, IAgentToolCompleteEvent, IAgentToolStartEvent, AuthenticateParams, AuthenticateResult } from '../common/agentService.js';
 import { ISessionDataService } from '../common/sessionDataService.js';
 import { ActionType, ActionEnvelope, INotification, type IRootConfigChangedAction, type SessionAction, type TerminalAction } from '../common/state/sessionActions.js';
@@ -128,8 +127,6 @@ export class AgentService extends Disposable implements IAgentService {
 		}
 		this._logService.info(`Registering agent provider: ${provider.id}`);
 		this._providers.set(provider.id, provider);
-		const hostCustomizations = this._configurationService.getRootValue(agentHostCustomizationConfigSchema, AgentHostConfigKey.Customizations) ?? [];
-		provider.setHostCustomizations?.([...hostCustomizations]);
 		this._providerSubscriptions.add(this._sideEffects.registerProgressListener(provider));
 		if (!this._defaultProvider) {
 			this._defaultProvider = provider.id;

src/vs/platform/agentHost/node/agentSideEffects.ts

@@ -12,7 +12,6 @@ import { URI } from '../../../base/common/uri.js';
 import { generateUuid } from '../../../base/common/uuid.js';
 import { ILogService } from '../../log/common/log.js';
 import { IInstantiationService } from '../../instantiation/common/instantiation.js';
-import { AgentHostConfigKey, agentHostCustomizationConfigSchema } from '../common/agentHostCustomizationConfig.js';
 import { IAgent, IAgentAttachment, IAgentProgressEvent, type IAgentToolCompleteEvent, type IAgentToolReadyEvent } from '../common/agentService.js';
 import { IDiffComputeService } from '../common/diffComputeService.js';
 import { ISessionDataService } from '../common/sessionDataService.js';
@@ -26,13 +25,11 @@ import {
 	ToolResultContentType,
 	buildSubagentSessionUri,
 	getToolFileEdits,
-	type CustomizationRef,
 	type SessionState,
 	type ToolResultContent,
 	type URI as ProtocolURI,
 } from '../common/state/sessionState.js';
 import { AgentEventMapper } from './agentEventMapper.js';
-import { IAgentConfigurationService } from './agentConfigurationService.js';
 import { AgentHostStateManager } from './agentHostStateManager.js';
 import { NodeWorkerDiffComputeService } from './diffComputeService.js';
 import { computeSessionDiffs, type IIncrementalDiffOptions } from './sessionDiffAggregator.js';
@@ -78,8 +75,6 @@ export class AgentSideEffects extends Disposable {
 	/** Serializes per-session diff computations to avoid races with stale previousDiffs. */
 	private readonly _diffComputationSequencer = new SequencerByKey<string>();
 	private _lastAgentInfos: readonly AgentInfo[] = [];
-	/** Last customizations list passed to agents; compared before each {@link _applyHostCustomizationsToAgents} call to skip no-op updates. */
-	private _lastAppliedCustomizations: readonly CustomizationRef[] = [];
 	/** Per-session debounce timers for mid-turn diff computation. */
 	private readonly _debouncedDiffTimers = this._register(new DisposableMap<string>());
 	private static readonly _DIFF_DEBOUNCE_MS = 5000;
@@ -110,7 +105,6 @@ export class AgentSideEffects extends Disposable {
 		private readonly _options: IAgentSideEffectsOptions,
 		@IInstantiationService instantiationService: IInstantiationService,
 		@ILogService private readonly _logService: ILogService,
-		@IAgentConfigurationService private readonly _configurationService: IAgentConfigurationService,
 	) {
 		super();
 		this._diffComputeService = this._register(new NodeWorkerDiffComputeService(this._logService));
@@ -153,20 +147,6 @@ export class AgentSideEffects extends Disposable {
 		this._stateManager.dispatchServerAction({ type: ActionType.RootAgentsChanged, agents: infos });
 	}
 
-	private _applyHostCustomizationsToAgents(): void {
-		const customizations = this._configurationService.getRootValue(agentHostCustomizationConfigSchema, AgentHostConfigKey.Customizations) ?? [];
-		if (equals(customizations, this._lastAppliedCustomizations)) {
-			return;
-		}
-		this._lastAppliedCustomizations = customizations;
-		for (const agent of this._options.agents.get()) {
-			agent.setHostCustomizations?.([...customizations], () => {
-				this._publishAgentInfos(this._options.agents.get());
-				this._publishSessionCustomizationsForAgent(agent);
-			});
-		}
-	}
-
 	private async _publishSessionCustomizations(agent: IAgent, session: ProtocolURI): Promise<void> {
 		if (!agent.getSessionCustomizations) {
 			return;
@@ -233,6 +213,12 @@ export class AgentSideEffects extends Disposable {
 		disposables.add(agent.onDidSessionProgress(e => {
 			this._handleAgentProgress(agent, agentMapper, e);
 		}));
+		if (agent.onDidCustomizationsChange) {
+			disposables.add(agent.onDidCustomizationsChange(() => {
+				this._publishAgentInfos(this._options.agents.get());
+				this._publishSessionCustomizationsForAgent(agent);
+			}));
+		}
 		return disposables;
 	}
 
@@ -764,7 +750,10 @@ export class AgentSideEffects extends Disposable {
 				break;
 			}
 			case ActionType.RootConfigChanged: {
-				this._applyHostCustomizationsToAgents();
+				// Host customizations are self-managed by each agent's
+				// PluginController via IAgentConfigurationService.onDidRootConfigChange.
+				// Republish agent infos for non-customization schema changes
+				// (e.g. permissions) and session customizations as a catchall.
 				this._publishAgentInfos(this._options.agents.get());
 				this._publishAllSessionCustomizations();
 				break;

src/vs/platform/agentHost/node/copilot/copilotAgent.ts

@@ -7,7 +7,7 @@ import { CopilotClient, ResumeSessionConfig, type CopilotClientOptions, type Ses
 import { rgPath } from '@vscode/ripgrep';
 import * as fs from 'fs/promises';
 import { Limiter, SequencerByKey } from '../../../../base/common/async.js';
-import { Emitter } from '../../../../base/common/event.js';
+import { Emitter, Event } from '../../../../base/common/event.js';
 import { appendEscapedMarkdownInlineCode } from '../../../../base/common/htmlContent.js';
 import { Disposable, DisposableMap } from '../../../../base/common/lifecycle.js';
 import { ResourceMap } from '../../../../base/common/map.js';
@@ -22,7 +22,7 @@ import { IParsedPlugin, parsePlugin } from '../../../agentPlugins/common/pluginP
 import { IFileService } from '../../../files/common/files.js';
 import { IInstantiationService } from '../../../instantiation/common/instantiation.js';
 import { ILogService } from '../../../log/common/log.js';
-import { customizationMatchesDirectory } from '../../common/agentHostCustomizationConfig.js';
+import { customizationMatchesDirectory, AgentHostConfigKey, agentHostCustomizationConfigSchema } from '../../common/agentHostCustomizationConfig.js';
 import { IAgentPluginManager, ISyncedCustomization } from '../../common/agentPluginManager.js';
 import { AgentSession, IAgent, IAgentAttachment, IAgentCreateSessionConfig, IAgentCreateSessionResult, IAgentDescriptor, IAgentDeltaEvent, IAgentMessageEvent, IAgentModelInfo, IAgentProgressEvent, IAgentResolveSessionConfigParams, IAgentSessionConfigCompletionsParams, IAgentSessionMetadata, IAgentSessionProjectInfo, IAgentSubagentStartedEvent, IAgentToolCompleteEvent, IAgentToolStartEvent } from '../../common/agentService.js';
 import { AutoApproveLevel, ISchemaProperty, createSchema, platformSessionSchema, schemaProperty } from '../../common/agentHostSchema.js';
@@ -33,6 +33,7 @@ import { ProtectedResourceMetadata, SessionCustomizationSource, type ConfigSchem
 import { AHP_AUTH_REQUIRED, ProtocolError } from '../../common/state/sessionProtocol.js';
 import { CustomizationStatus, CustomizationRef, SessionInputResponseKind, type PendingMessage, type SessionInputAnswer, type ToolCallResult, type PolicyState } from '../../common/state/sessionState.js';
 import { IAgentHostGitService } from '../agentHostGitService.js';
+import { IAgentConfigurationService } from '../agentConfigurationService.js';
 import { IAgentHostTerminalManager } from '../agentHostTerminalManager.js';
 import { CopilotAgentSession, SessionWrapperFactory, type IActiveClientSnapshot } from './copilotAgentSession.js';
 import { ICopilotSessionContext, projectFromCopilotContext } from './copilotGitProject.js';
@@ -179,6 +180,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 	private readonly _sessionSequencer = new SequencerByKey<string>();
 	private _shutdownPromise: Promise<void> | undefined;
 	private readonly _plugins: PluginController;
+	readonly onDidCustomizationsChange: Event<void>;
 	/** Per-session active client state for tools + plugin snapshot tracking. */
 	private readonly _activeClients = new ResourceMap<ActiveClient>();
 
@@ -191,7 +193,8 @@ export class CopilotAgent extends Disposable implements IAgent {
 		@IAgentHostTerminalManager private readonly _terminalManager: IAgentHostTerminalManager,
 	) {
 		super();
-		this._plugins = this._instantiationService.createInstance(PluginController);
+		this._plugins = this._register(this._instantiationService.createInstance(PluginController));
+		this.onDidCustomizationsChange = this._plugins.onDidChange;
 	}
 
 	protected _createCopilotClient(options: CopilotClientOptions): ICopilotClient {
@@ -228,10 +231,6 @@ export class CopilotAgent extends Disposable implements IAgent {
 		return this._plugins.getSessionCustomizations(entry?.customizationDirectory ?? metadata?.customizationDirectory ?? metadata?.workingDirectory);
 	}
 
-	setHostCustomizations(customizations: CustomizationRef[], progress?: () => void): void {
-		this._plugins.setHostCustomizations(customizations, progress);
-	}
-
 	async authenticate(resource: string, token: string): Promise<boolean> {
 		if (resource !== 'https://api.github.com') {
 			return false;
@@ -1216,20 +1215,33 @@ interface IResolvedCustomization {
 	readonly plugin?: IParsedPlugin;
 }
 
-class PluginController {
+class PluginController extends Disposable {
+	private readonly _onDidChange = this._register(new Emitter<void>());
+	readonly onDidChange = this._onDidChange.event;
+
 	private readonly _enablement = new Map<string, boolean>();
 	private _clientCustomizations: readonly IResolvedCustomization[] = [];
 	private _hostCustomizations: readonly IResolvedCustomization[] = [];
 	private _clientSync: Promise<readonly IResolvedCustomization[]> = Promise.resolve([]);
 	private _hostSync: Promise<readonly IResolvedCustomization[]> = Promise.resolve([]);
 	private _clientRevision = 0;
 	private _hostRevision = 0;
+	private _lastAppliedRefs: readonly CustomizationRef[] = [];
 
 	constructor(
 		@IAgentPluginManager private readonly _pluginManager: IAgentPluginManager,
 		@ILogService private readonly _logService: ILogService,
 		@IFileService private readonly _fileService: IFileService,
-	) { }
+		@IAgentConfigurationService private readonly _configurationService: IAgentConfigurationService,
+	) {
+		super();
+
+		// Seed from current root config and subscribe to future changes.
+		this._applyHostCustomizations();
+		this._register(this._configurationService.onDidRootConfigChange(() => {
+			this._applyHostCustomizations();
+		}));
+	}
 
 	public getConfiguredHostCustomizations(): readonly CustomizationRef[] {
 		return this._hostCustomizations.map(item => item.customization.customization);
@@ -1276,7 +1288,18 @@ class PluginController {
 		this._enablement.set(pluginProtocolUri, enabled);
 	}
 
-	public setHostCustomizations(customizations: CustomizationRef[], progress?: () => void): void {
+	/**
+	 * Reads the current host customizations from the root config and
+	 * resolves them. Skips the update when the configured refs have not
+	 * changed since the last application.
+	 */
+	private _applyHostCustomizations(): void {
+		const customizations = this._configurationService.getRootValue(agentHostCustomizationConfigSchema, AgentHostConfigKey.Customizations) ?? [];
+		if (equals(customizations, this._lastAppliedRefs)) {
+			return;
+		}
+		this._lastAppliedRefs = customizations;
+
 		const revision = ++this._hostRevision;
 		this._hostCustomizations = customizations.map(customization => ({
 			customization: {
@@ -1286,15 +1309,15 @@ class PluginController {
 				status: CustomizationStatus.Loading,
 			},
 		}));
-		progress?.();
+		this._onDidChange.fire();
 		this._hostSync = Promise.all(customizations.map(customization => this._resolveConfiguredCustomization(customization, SessionCustomizationSource.Host))).then(resolved => {
 			if (revision === this._hostRevision) {
 				this._hostCustomizations = resolved;
 			}
 			return resolved;
 		}).finally(() => {
 			if (revision === this._hostRevision) {
-				progress?.();
+				this._onDidChange.fire();
 			}
 		});
 	}

src/vs/platform/agentHost/test/node/agentService.test.ts

@@ -21,7 +21,7 @@ import { AgentSession } from '../../common/agentService.js';
 import { ISessionDatabase, ISessionDataService } from '../../common/sessionDataService.js';
 import { SessionDatabase } from '../../node/sessionDatabase.js';
 import { ActionType, ActionEnvelope } from '../../common/state/sessionActions.js';
-import { SessionActiveClient, ResponsePartKind, SessionLifecycle, ToolCallConfirmationReason, ToolCallStatus, ToolResultContentType, TurnState, buildSubagentSessionUri, type CustomizationRef, type MarkdownResponsePart, type ToolCallCompletedState, type ToolCallResponsePart } from '../../common/state/sessionState.js';
+import { SessionActiveClient, ResponsePartKind, SessionLifecycle, ToolCallConfirmationReason, ToolCallStatus, ToolResultContentType, TurnState, buildSubagentSessionUri, type MarkdownResponsePart, type ToolCallCompletedState, type ToolCallResponsePart } from '../../common/state/sessionState.js';
 import { IProductService } from '../../../product/common/productService.js';
 import { AgentService } from '../../node/agentService.js';
 import { MockAgent } from './mockAgent.js';
@@ -131,11 +131,6 @@ suite('AgentService (node dispatcher)', () => {
 				const rootConfigResource = joinPath(tempDir, 'agent-host-config.json');
 				const svc = disposables.add(new AgentService(new NullLogService(), fileService, createNullSessionDataService(), { _serviceBrand: undefined } as IProductService, rootConfigResource));
 				const agent = new MockAgent('copilot');
-				const hostCustomizationCalls: CustomizationRef[][] = [];
-				agent.setHostCustomizations = customizations => {
-					hostCustomizationCalls.push([...customizations]);
-					agent.customizations = [...customizations];
-				};
 				disposables.add(toDisposable(() => agent.dispose()));
 				svc.registerProvider(agent);
 
@@ -147,26 +142,23 @@ suite('AgentService (node dispatcher)', () => {
 
 				let persisted = false;
 				for (let attempt = 0; attempt < 20; attempt++) {
-					if (hostCustomizationCalls.length > 1) {
-						try {
-							const parsed = JSON.parse(readFileSync(rootConfigResource.fsPath, 'utf8'));
-							assert.deepStrictEqual(
-								parsed.customizations,
-								[customization],
-							);
-							persisted = true;
-							break;
-						} catch {
-							// Wait for the serialized root-config write to complete.
-						}
+					try {
+						const parsed = JSON.parse(readFileSync(rootConfigResource.fsPath, 'utf8'));
+						assert.deepStrictEqual(
+							parsed.customizations,
+							[customization],
+						);
+						persisted = true;
+						break;
+					} catch {
+						// Wait for the serialized root-config write to complete.
 					}
 					if (attempt === 19) {
 						break;
 					}
 					await new Promise(resolve => setTimeout(resolve, 5));
 				}
 
-				assert.deepStrictEqual(hostCustomizationCalls.at(-1), [customization]);
 				assert.ok(persisted, 'should persist the root config change');
 			} finally {
 				rmSync(tempDir.fsPath, { recursive: true, force: true });

src/vs/platform/agentHost/test/node/agentSideEffects.test.ts

@@ -735,9 +735,7 @@ suite('AgentSideEffects', () => {
 		test('republishes agent and session customizations for existing sessions', async () => {
 			setupSession('file:///workspace');
 			const customization = { uri: 'file:///plugin-a', displayName: 'Plugin A' };
-			agent.setHostCustomizations = customizations => {
-				agent.customizations = [...customizations];
-			};
+			agent.customizations = [customization];
 			agent.getSessionCustomizations = async () => [{
 				customization,
 				source: SessionCustomizationSource.Host,