From b4e90b1a76bcb6e9b07adbee522d75a7fa4a5b1d Mon Sep 17 00:00:00 2001
From: TylerLeonhardt <2644648+TylerLeonhardt@users.noreply.github.com>
Date: Tue, 8 Sep 2026 19:57:00 -0700
Subject: [PATCH] agentHost: refresh expiring GitHub credentials (#334418)

Propagate authentication session lifetimes through AHP and use the Copilot SDK token provider for renewable Entra-backed GitHub sessions. Centralize static and provider-backed credential behavior behind one owner and reuse shared expiry helpers throughout authentication replay.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 extensions/github-authentication/package.json |   3 +-
 .../github-authentication/src/github.ts       |  52 +++++--
 .../src/test/github.test.ts                   |  85 +++++++++-
 .../github-authentication/tsconfig.json       |   3 +-
 src/vs/base/common/date.ts                    |  25 +++
 src/vs/base/test/common/date.test.ts          |  21 ++-
 .../browser/agentHostProtocolClient.ts        |  19 ++-
 src/vs/platform/agentHost/common/agent.ts     |   4 +-
 .../common/state/protocol/.ahp-version        |   2 +-
 .../common/state/protocol/common/commands.ts  |  20 ++-
 .../state/protocol/common/notifications.ts    |  10 +-
 .../node/agentHostAuthenticationService.ts    |  27 +++-
 .../agentHost/node/copilot/copilotAgent.ts    |  84 +++++-----
 .../node/copilot/copilotAgentSession.ts       |  40 +++--
 .../node/copilot/copilotGitHubCredentials.ts  | 145 ++++++++++++++++++
 .../node/copilot/copilotSessionLauncher.ts    |  12 +-
 .../agentHostProtocolClient.test.ts           |   4 +-
 .../agentHost/test/node/agentService.test.ts  |   4 +-
 .../agentHost/test/node/copilotAgent.test.ts  |  80 +++++++++-
 .../test/node/copilotAgentSession.test.ts     |  14 +-
 .../node/copilotGitHubCredentials.test.ts     |  93 +++++++++++
 .../test/node/copilotSessionLauncher.test.ts  |  19 +--
 .../platform/agentHost/test/node/mockAgent.ts |   6 +-
 .../common/extensionsApiProposals.ts          |   3 +
 .../agentSessions/agentHost/agentHostAuth.ts  | 107 +++++++------
 .../agentSessions/agentHostAuth.test.ts       |  43 ++++--
 .../authentication/common/authentication.ts   |   1 +
 ...vscode.proposed.authSessionExpiration.d.ts |  18 +++
 28 files changed, 744 insertions(+), 200 deletions(-)
 create mode 100644 src/vs/platform/agentHost/node/copilot/copilotGitHubCredentials.ts
 create mode 100644 src/vs/platform/agentHost/test/node/copilotGitHubCredentials.test.ts
 create mode 100644 src/vscode-dts/vscode.proposed.authSessionExpiration.d.ts

diff --git a/extensions/github-authentication/package.json b/extensions/github-authentication/package.json
index eb0e7f2b6184..a835d1c03c26 100644
--- a/extensions/github-authentication/package.json
+++ b/extensions/github-authentication/package.json
@@ -20,7 +20,8 @@
   "enabledApiProposals": [
     "authIssuers",
     "authProviderSpecific",
-    "authSessionAccountIcon"
+    "authSessionAccountIcon",
+    "authSessionExpiration"
   ],
   "activationEvents": [],
   "capabilities": {
diff --git a/extensions/github-authentication/src/github.ts b/extensions/github-authentication/src/github.ts
index 5d8ff26b966c..5250aeb743b6 100644
--- a/extensions/github-authentication/src/github.ts
+++ b/extensions/github-authentication/src/github.ts
@@ -42,6 +42,8 @@ interface ITransientSession {
 	readonly expiresAt: number;
 }
 
+const TOKEN_RENEWAL_WINDOW_MS = 60 * 60 * 1000;
+
 export enum AuthProviderType {
 	github = 'github',
 	githubEnterprise = 'github-enterprise'
@@ -267,7 +269,10 @@ export class GitHubAuthenticationProvider implements vscode.AuthenticationProvid
 
 	/** Every session held only by this process, whether or not its token is still any good. */
 	private get transientSessions(): vscode.AuthenticationSession[] {
-		return [...this._transientSessions.values()].map(held => held.session);
+		return [...this._transientSessions.values()].map(held => ({
+			...held.session,
+			expiresIn: held.expiresAt > Date.now() ? Math.ceil((held.expiresAt - Date.now()) / 1000) : undefined
+		}));
 	}
 
 	get onDidChangeSessions() {
@@ -397,8 +402,7 @@ export class GitHubAuthenticationProvider implements vscode.AuthenticationProvid
 			return undefined;
 		}
 
-		const session = this.sessionFor(renewed.account, renewed.token, [...renewed.scopes]);
-		this._transientSessions.set(session.id, { session, expiresAt: Date.now() + renewed.expiresIn * 1000 });
+		const session = this.storeTransientSession(this.sessionFor(renewed.account, renewed.token, [...renewed.scopes]), renewed.expiresIn);
 		this.afterSessionLoad(session);
 		return session;
 	}
@@ -422,7 +426,7 @@ export class GitHubAuthenticationProvider implements vscode.AuthenticationProvid
 		for (const session of wanted) {
 			// No transient entry means a persisted session, and nothing persisted carries an expiry.
 			const held = this._transientSessions.get(session.id);
-			if (!held || held.expiresAt > now) {
+			if (!held || held.expiresAt > now + TOKEN_RENEWAL_WINDOW_MS) {
 				usable.push(session);
 			} else {
 				stale.push(session);
@@ -437,8 +441,26 @@ export class GitHubAuthenticationProvider implements vscode.AuthenticationProvid
 		}
 
 		const renewed = await Promise.all(stale.map(session => this.renew(session)));
-		this.evict(stale.filter((_, index) => !renewed[index]), 'their token ran out and could not be renewed');
-		return [...usable, ...renewed.filter(<T>(session?: T): session is T => Boolean(session))];
+		const expired: vscode.AuthenticationSession[] = [];
+		const retained: vscode.AuthenticationSession[] = [];
+		for (let index = 0; index < stale.length; index++) {
+			if (renewed[index]) {
+				continue;
+			}
+
+			const held = this._transientSessions.get(stale[index].id);
+			const remainingLifetime = held ? held.expiresAt - Date.now() : 0;
+			if (held && remainingLifetime > 0) {
+				retained.push({
+					...held.session,
+					expiresIn: Math.ceil(remainingLifetime / 1000)
+				});
+			} else {
+				expired.push(stale[index]);
+			}
+		}
+		this.evict(expired, 'their token ran out and could not be renewed');
+		return [...usable, ...retained, ...renewed.filter(<T>(session?: T): session is T => Boolean(session))];
 	}
 
 	/**
@@ -531,8 +553,7 @@ export class GitHubAuthenticationProvider implements vscode.AuthenticationProvid
 
 		// The same session with a new token, so it keeps its id and is reported as changed rather
 		// than as one session going away and another arriving.
-		const next: vscode.AuthenticationSession = { ...session, accessToken: renewed.token };
-		this._transientSessions.set(next.id, { session: next, expiresAt: Date.now() + renewed.expiresIn * 1000 });
+		const next = this.storeTransientSession({ ...session, accessToken: renewed.token }, renewed.expiresIn);
 		this._logger.info(`Renewed session ${session.id}.`);
 		this._sessionChangeEmitter.fire({ added: [], removed: [], changed: [next] });
 		return next;
@@ -794,20 +815,19 @@ export class GitHubAuthenticationProvider implements vscode.AuthenticationProvid
 		const exchanged = await this._githubServer.loginWithMicrosoft(scopes, {
 			microsoftAccount: await this.rememberedMicrosoftAccount(gitHubAccountLabel)
 		});
-		const session = this.sessionFor(exchanged.account, exchanged.token, scopes);
+		const session = this.storeTransientSession(this.sessionFor(exchanged.account, exchanged.token, scopes), exchanged.expiresIn);
 		this.afterSessionLoad(session);
 
-		this._transientSessions.set(session.id, {
-			session,
-			// The exchange reports what GitHub said the token is good for; when that runs out is
-			// this side's question, since it is the side that has to hold the session until then.
-			expiresAt: Date.now() + exchanged.expiresIn * 1000
-		});
-
 		this._sessionChangeEmitter.fire({ added: [session], removed: [], changed: [] });
 		return session;
 	}
 
+	private storeTransientSession(session: vscode.AuthenticationSession, expiresIn: number): vscode.AuthenticationSession {
+		const result = { ...session, expiresIn };
+		this._transientSessions.set(result.id, { session: result, expiresAt: Date.now() + expiresIn * 1000 });
+		return result;
+	}
+
 	/**
 	 * A session for a GitHub identity that has already been resolved, so nothing here needs a
 	 * lookup.
diff --git a/extensions/github-authentication/src/test/github.test.ts b/extensions/github-authentication/src/test/github.test.ts
index b8b2a07c1ff8..54c110098f38 100644
--- a/extensions/github-authentication/src/test/github.test.ts
+++ b/extensions/github-authentication/src/test/github.test.ts
@@ -8,7 +8,8 @@ import * as vscode from 'vscode';
 import { AccountLinks } from '../common/accountLinks';
 import { IGitHubUserInfo } from '../common/gitHubAccount';
 import { Log } from '../common/logger';
-import { EntraTokenExchangeError, EntraTokenExchangeFailure, IEntraRenewal, IEntraRenewedToken } from '../entraTokenExchange';
+import { EntraTokenExchangeError, EntraTokenExchangeFailure, IEntraExchangedToken, IEntraLoginOptions, IEntraRenewal, IEntraRenewedToken } from '../entraTokenExchange';
+import { GitHubSignInProvider } from '../flows';
 import { AuthProviderType, GitHubAuthenticationProvider } from '../github';
 import { TestMemento } from './testMemento';
 
@@ -128,6 +129,7 @@ suite('GitHub Microsoft-brokered sessions', () => {
 		_microsoftGeneration: number;
 		_microsoft: { getAccounts(): Promise<vscode.AuthenticationSessionAccountInformation[]> };
 		_githubServer: {
+			loginWithMicrosoft(scopes: readonly string[], options?: IEntraLoginOptions): Promise<IEntraExchangedToken>;
 			renewWithMicrosoft(renewal: IEntraRenewal): Promise<IEntraRenewedToken>;
 			sendAdditionalTelemetryInfo(session: vscode.AuthenticationSession): Promise<void>;
 		};
@@ -140,6 +142,8 @@ suite('GitHub Microsoft-brokered sessions', () => {
 		readonly accountLinks: AccountLinks;
 		/** Every renewal the provider put on the wire, in order. */
 		readonly renewals: IEntraRenewal[];
+		/** Every interactive Microsoft exchange the provider put on the wire, in order. */
+		readonly logins: Array<{ readonly scopes: readonly string[]; readonly options: IEntraLoginOptions | undefined }>;
 		/** What the provider told VS Code changed, as `verb account` for each session. */
 		readonly announced: string[];
 		/** The sessions still held in memory, as `account until` for each. */
@@ -163,8 +167,10 @@ suite('GitHub Microsoft-brokered sessions', () => {
 		/** Sessions already held in memory, and how long each has left in milliseconds. */
 		transient?: readonly (readonly [vscode.AuthenticationSession, number])[];
 		microsoftAccounts?: (call: number) => vscode.AuthenticationSessionAccountInformation[];
+		login?: (call: number, scopes: readonly string[], options: IEntraLoginOptions | undefined) => Promise<IEntraExchangedToken>;
 		renew?: (call: number, renewal: IEntraRenewal) => Promise<IEntraRenewedToken>;
 	} = {}): IHarness {
+		const logins: Array<{ scopes: readonly string[]; options: IEntraLoginOptions | undefined }> = [];
 		const renewals: IEntraRenewal[] = [];
 		const announced: string[] = [];
 		const accountLinks = new AccountLinks(new TestMemento(), STORAGE_KEY, logger);
@@ -186,6 +192,12 @@ suite('GitHub Microsoft-brokered sessions', () => {
 				getAccounts: async () => overrides.microsoftAccounts?.(microsoftReads++) ?? [MICROSOFT_ACCOUNT]
 			},
 			_githubServer: {
+				loginWithMicrosoft: async (scopes, options) => {
+					logins.push({ scopes, options });
+					return overrides.login
+						? await overrides.login(logins.length - 1, scopes, options)
+						: { token: `gho_login_${logins.length}`, expiresIn: 7200, account: GITHUB_ACCOUNT };
+				},
 				renewWithMicrosoft: async renewal => {
 					renewals.push(renewal);
 					return overrides.renew
@@ -210,6 +222,7 @@ suite('GitHub Microsoft-brokered sessions', () => {
 			provider: provider as GitHubAuthenticationProvider,
 			state: provider as IProviderState,
 			accountLinks,
+			logins,
 			renewals,
 			announced,
 			heldSessions: () => [...transientSessions.values()]
@@ -218,6 +231,24 @@ suite('GitHub Microsoft-brokered sessions', () => {
 		};
 	}
 
+	test('publishes the lifetime reported by an interactive Microsoft exchange', async () => {
+		const harness = createHarness();
+
+		const session = await harness.provider.createSession(SCOPES, { provider: GitHubSignInProvider.Microsoft });
+
+		assert.deepStrictEqual({
+			token: session.accessToken,
+			expiresIn: session.expiresIn,
+			logins: harness.logins,
+			announced: harness.announced,
+		}, {
+			token: 'gho_login_1',
+			expiresIn: 7200,
+			logins: [{ scopes: SCOPES, options: { microsoftAccount: undefined } }],
+			announced: ['added mona_contoso'],
+		});
+	});
+
 	async function withLink(harness: IHarness): Promise<IHarness> {
 		await harness.accountLinks.link(MICROSOFT_ACCOUNT.label, { id: GITHUB_ACCOUNT.id, label: GITHUB_ACCOUNT.accountName });
 		return harness;
@@ -235,16 +266,29 @@ suite('GitHub Microsoft-brokered sessions', () => {
 			scopes: sessions.map(session => session.scopes),
 			renewals: harness.renewals,
 			announced: harness.announced,
-			held: harness.heldSessions()
+			held: harness.heldSessions(),
+			expiresIn: sessions.map(session => session.expiresIn),
 		}, {
 			accounts: ['mona_contoso'],
 			scopes: [SCOPES],
 			renewals: [{ scopes: SCOPES, gitHubAccountId: '42', microsoftAccount: MICROSOFT_ACCOUNT }],
 			announced: ['added mona_contoso'],
-			held: ['mona_contoso live']
+			held: ['mona_contoso live'],
+			expiresIn: [3600]
 		});
 	});
 
+	test('recomputes the remaining lifetime of a cached Microsoft-brokered session', async () => {
+		const session = sessionFor('mona_contoso', 'cached', 'gho_cached');
+		const harness = createHarness({
+			transient: [[session, 2 * 60 * 60 * 1000]]
+		});
+
+		const [resolved] = await harness.provider.getSessions(SCOPES);
+
+		assert.ok(resolved.expiresIn !== undefined && resolved.expiresIn > 3600 && resolved.expiresIn <= 7200);
+	});
+
 	test('keeps what the user agreed to when a restore fails for a reason that says nothing about who they are', async () => {
 		const ambiguous = async (failure: EntraTokenExchangeFailure) => {
 			const harness = await withLink(createHarness({
@@ -315,29 +359,54 @@ suite('GitHub Microsoft-brokered sessions', () => {
 		});
 	});
 
-	test('settles every session whose token has run out, not only when there is nothing to hand back', async () => {
+	test('renews every session in the renewal window, not only when there is nothing else to hand back', async () => {
 		const harness = await withLink(createHarness({
 			// Another account, signed in the ordinary way, so it has no expiry and is always usable.
 			persisted: [sessionFor('hubot', 'persisted', 'gho_persisted')],
-			transient: [[sessionFor('mona_contoso', 'expired', 'gho_stale'), -1000]]
+			transient: [[sessionFor('mona_contoso', 'expiring', 'gho_stale'), 60 * 60 * 1000]]
 		}));
 
 		const sessions = await harness.provider.getSessions(SCOPES);
 
 		assert.deepStrictEqual({
 			accounts: sessions.map(session => session.account.label).sort(),
-			// An expired session left unprocessed is never handed out, never renewed and never
+			// A stale session left unprocessed is never handed out, never renewed and never
 			// reported as removed, but stays a candidate on every read for the life of the window.
 			held: harness.heldSessions(),
 			// Renewed in place, so it keeps its id and is reported as changed rather than as one
 			// account going away and another arriving.
 			announced: harness.announced,
-			tokens: sessions.map(session => session.accessToken).sort()
+			tokens: sessions.map(session => session.accessToken).sort(),
+			expirations: sessions.map(session => [session.account.label, session.expiresIn]).sort(),
 		}, {
 			accounts: ['hubot', 'mona_contoso'],
 			held: ['mona_contoso live'],
 			announced: ['changed mona_contoso'],
-			tokens: ['gho_1', 'gho_persisted']
+			tokens: ['gho_1', 'gho_persisted'],
+			expirations: [['hubot', undefined], ['mona_contoso', 3600]]
+		});
+	});
+
+	test('keeps a still-valid session when proactive renewal fails', async () => {
+		const harness = await withLink(createHarness({
+			transient: [[sessionFor('mona_contoso', 'expiring', 'gho_still_valid'), 60 * 60 * 1000]],
+			renew: async () => { throw new EntraTokenExchangeError(EntraTokenExchangeFailure.Network, 'offline'); }
+		}));
+
+		const sessions = await harness.provider.getSessions(SCOPES);
+
+		assert.deepStrictEqual({
+			tokens: sessions.map(session => session.accessToken),
+			hasUsableLifetime: sessions.every(session => session.expiresIn !== undefined && session.expiresIn > 0 && session.expiresIn <= 3600),
+			held: harness.heldSessions(),
+			announced: harness.announced,
+			renewals: harness.renewals.length
+		}, {
+			tokens: ['gho_still_valid'],
+			hasUsableLifetime: true,
+			held: ['mona_contoso live'],
+			announced: [],
+			renewals: 1
 		});
 	});
 });
diff --git a/extensions/github-authentication/tsconfig.json b/extensions/github-authentication/tsconfig.json
index ff8545f48547..836b5861933f 100644
--- a/extensions/github-authentication/tsconfig.json
+++ b/extensions/github-authentication/tsconfig.json
@@ -20,6 +20,7 @@
 		"../../src/vscode-dts/vscode.d.ts",
 		"../../src/vscode-dts/vscode.proposed.authIssuers.d.ts",
 		"../../src/vscode-dts/vscode.proposed.authProviderSpecific.d.ts",
-		"../../src/vscode-dts/vscode.proposed.authSessionAccountIcon.d.ts"
+		"../../src/vscode-dts/vscode.proposed.authSessionAccountIcon.d.ts",
+		"../../src/vscode-dts/vscode.proposed.authSessionExpiration.d.ts"
 	]
 }
diff --git a/src/vs/base/common/date.ts b/src/vs/base/common/date.ts
index 6562ab5a7d95..aa43c9474696 100644
--- a/src/vs/base/common/date.ts
+++ b/src/vs/base/common/date.ts
@@ -14,6 +14,31 @@ const week = day * 7;
 const month = day * 30;
 const year = day * 365;
 
+/**
+ * Returns the absolute expiration time for a relative lifetime in seconds.
+ */
+export function getExpirationTime(expiresIn: number | undefined, now = Date.now()): number | undefined {
+	return expiresIn === undefined ? undefined : now + expiresIn * 1000;
+}
+
+/**
+ * Returns whether a known expiration time has passed.
+ */
+export function isExpired(expiresAt: number | undefined, now = Date.now()): boolean {
+	return expiresAt !== undefined && expiresAt <= now;
+}
+
+/**
+ * Returns the positive number of whole seconds until `expiresAt`, rounded up.
+ */
+export function getRemainingTimeInSeconds(expiresAt: number | undefined, now = Date.now()): number | undefined {
+	if (expiresAt === undefined) {
+		return undefined;
+	}
+	const remaining = Math.ceil((expiresAt - now) / 1000);
+	return remaining > 0 ? remaining : undefined;
+}
+
 /**
  * Create a localized difference of the time between now and the specified date.
  * @param date The date to generate the difference from.
diff --git a/src/vs/base/test/common/date.test.ts b/src/vs/base/test/common/date.test.ts
index 70a725552f98..ef67204bf5d7 100644
--- a/src/vs/base/test/common/date.test.ts
+++ b/src/vs/base/test/common/date.test.ts
@@ -4,13 +4,32 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { strictEqual } from 'assert';
-import { fromNow, fromNowByDay, getDurationString, safeIntl } from '../../common/date.js';
+import { fromNow, fromNowByDay, getDurationString, getExpirationTime, getRemainingTimeInSeconds, isExpired, safeIntl } from '../../common/date.js';
 import { ensureNoDisposablesAreLeakedInTestSuite } from './utils.js';
 import { LANGUAGE_DEFAULT } from '../../common/platform.js';
 
 suite('Date', () => {
 	ensureNoDisposablesAreLeakedInTestSuite();
 
+	test('getRemainingTimeInSeconds', () => {
+		strictEqual(getRemainingTimeInSeconds(undefined, 1000), undefined);
+		strictEqual(getRemainingTimeInSeconds(1000, 1000), undefined);
+		strictEqual(getRemainingTimeInSeconds(1001, 1000), 1);
+		strictEqual(getRemainingTimeInSeconds(2001, 1000), 2);
+	});
+
+	test('getExpirationTime', () => {
+		strictEqual(getExpirationTime(undefined, 1000), undefined);
+		strictEqual(getExpirationTime(0, 1000), 1000);
+		strictEqual(getExpirationTime(2, 1000), 3000);
+	});
+
+	test('isExpired', () => {
+		strictEqual(isExpired(undefined, 1000), false);
+		strictEqual(isExpired(1000, 1000), true);
+		strictEqual(isExpired(1001, 1000), false);
+	});
+
 	suite('fromNow', () => {
 		test('appendAgoLabel', () => {
 			strictEqual(fromNow(Date.now() - 35000), '35 secs');
diff --git a/src/vs/platform/agentHost/browser/agentHostProtocolClient.ts b/src/vs/platform/agentHost/browser/agentHostProtocolClient.ts
index 35f1b47a29df..37ebc1c65a9f 100644
--- a/src/vs/platform/agentHost/browser/agentHostProtocolClient.ts
+++ b/src/vs/platform/agentHost/browser/agentHostProtocolClient.ts
@@ -37,6 +37,7 @@ import { AhpErrorCodes, JsonRpcErrorCodes } from '../common/state/protocol/error
 import { ChatSourceKind, ContentEncoding, ResourceRequestParams, type CompletionsParams, type CompletionsResult, type CreateTerminalParams, type ResolveSessionConfigResult, type SessionConfigCompletionsResult } from '../common/state/protocol/commands.js';
 import type { InvokeChangesetOperationParams, InvokeChangesetOperationResult } from '../common/state/protocol/channels-changeset/commands.js';
 import { decodeBase64, encodeBase64 } from '../../../base/common/buffer.js';
+import { getExpirationTime, getRemainingTimeInSeconds, isExpired } from '../../../base/common/date.js';
 import type { FetchAutomationRunsParams, FetchAutomationRunsResult, ListAutomationTriggerDefinitionsParams, ListAutomationTriggerDefinitionsResult, RunAutomationParams, RunAutomationResult } from '../common/state/protocol/channels-automation/commands.js';
 import { ILoadEstimator, LoadEstimator } from '../../../base/parts/ipc/common/ipc.net.js';
 import { ITelemetryService, TelemetryLevel, TELEMETRY_CRASH_REPORTER_SETTING_ID, TELEMETRY_OLD_SETTING_ID, TELEMETRY_SETTING_ID } from '../../telemetry/common/telemetry.js';
@@ -275,7 +276,7 @@ export class AgentHostProtocolClient extends Disposable implements IAgentConnect
 
 	/** Pending JSON-RPC requests keyed by request id. */
 	private readonly _pendingRequests = new Map<number, IPendingRequest>();
-	private readonly _authentication = new Map<string, AuthenticateParams>();
+	private readonly _authentication = new Map<string, { readonly params: AuthenticateParams; readonly expiresAt: number | undefined }>();
 	private _nextRequestId = 1;
 
 	/**
@@ -1008,7 +1009,8 @@ export class AgentHostProtocolClient extends Disposable implements IAgentConnect
 				if (initialAuthentication) {
 					const normalizedParams = this._normalizeAuthenticationParams(initialAuthentication);
 					initialAuthenticationKey = this._authenticationKey(normalizedParams);
-					this._authentication.set(initialAuthenticationKey, normalizedParams);
+					const expiresAt = getExpirationTime(normalizedParams.expiresIn);
+					this._authentication.set(initialAuthenticationKey, { params: normalizedParams, expiresAt });
 				}
 			} catch (error) {
 				throw new InitialAuthenticationError(error);
@@ -1017,12 +1019,20 @@ export class AgentHostProtocolClient extends Disposable implements IAgentConnect
 				return;
 			}
 		}
-		await Promise.all([...this._authentication.entries()].map(async ([key, params]) => {
+		await Promise.all([...this._authentication.entries()].map(async ([key, authentication]) => {
+			const now = Date.now();
+			if (isExpired(authentication.expiresAt, now)) {
+				this._authentication.delete(key);
+				return;
+			}
+			const expiresIn = getRemainingTimeInSeconds(authentication.expiresAt, now);
+			const params = authentication.params;
 			try {
 				await this._dispatchRequest<CommandMap['authenticate']['result']>('authenticate', {
 					channel: ROOT_STATE_URI,
 					...params,
 					scopes: params.scopes ? [...params.scopes] : undefined,
+					...(expiresIn === undefined ? {} : { expiresIn }),
 				}, this._state.kind === AgentHostClientState.Connecting
 					? { bypassInitializeQueue: true, bypassReconnectGate: true }
 					: { bypassReconnectGate: true });
@@ -1411,6 +1421,7 @@ export class AgentHostProtocolClient extends Disposable implements IAgentConnect
 	 */
 	async authenticate(params: AuthenticateParams): Promise<AuthenticateResult> {
 		const normalizedParams = this._normalizeAuthenticationParams(params);
+		const expiresAt = getExpirationTime(params.expiresIn);
 		await this._sendRequest('authenticate', {
 			channel: ROOT_STATE_URI,
 			...normalizedParams,
@@ -1418,7 +1429,7 @@ export class AgentHostProtocolClient extends Disposable implements IAgentConnect
 		});
 		const key = this._authenticationKey(normalizedParams);
 		if (params.token) {
-			this._authentication.set(key, normalizedParams);
+			this._authentication.set(key, { params: normalizedParams, expiresAt });
 		} else {
 			this._authentication.delete(key);
 		}
diff --git a/src/vs/platform/agentHost/common/agent.ts b/src/vs/platform/agentHost/common/agent.ts
index a9c5caf83bba..7dcbe0c11611 100644
--- a/src/vs/platform/agentHost/common/agent.ts
+++ b/src/vs/platform/agentHost/common/agent.ts
@@ -295,6 +295,8 @@ export interface AuthenticateParams {
 
 	/** The bearer token value (RFC 6750). */
 	readonly token: string;
+	/** The access token's remaining lifetime in seconds, when known. */
+	readonly expiresIn?: number;
 }
 
 /** Request for a previously accepted bearer token. */
@@ -1279,7 +1281,7 @@ export interface IAgent {
 	getProtectedResources(): ProtectedResourceMetadata[];
 
 	/** An empty token revokes the credential previously forwarded for this resource. */
-	authenticate(resource: string, token: string): Promise<boolean>;
+	authenticate(resource: string, token: string, expiresIn?: number): Promise<boolean>;
 
 	/** Optional token consumer for provider-owned resources such as MCP servers. */
 	handleAuthenticationToken?(params: AuthenticateParams): Promise<boolean>;
diff --git a/src/vs/platform/agentHost/common/state/protocol/.ahp-version b/src/vs/platform/agentHost/common/state/protocol/.ahp-version
index 6110301d110e..7dc5824dd8a3 100644
--- a/src/vs/platform/agentHost/common/state/protocol/.ahp-version
+++ b/src/vs/platform/agentHost/common/state/protocol/.ahp-version
@@ -1 +1 @@
-60706330
+fd0471d4
diff --git a/src/vs/platform/agentHost/common/state/protocol/common/commands.ts b/src/vs/platform/agentHost/common/state/protocol/common/commands.ts
index 5ac6b4778a52..f20293b34fe5 100644
--- a/src/vs/platform/agentHost/common/state/protocol/common/commands.ts
+++ b/src/vs/platform/agentHost/common/state/protocol/common/commands.ts
@@ -1130,7 +1130,8 @@ export interface ResourceMkdirResult {
  * ```jsonc
  * // Client → Server
  * { "jsonrpc": "2.0", "id": 3, "method": "authenticate",
- *   "params": { "channel": "ahp-root://", "resource": "https://api.github.com", "token": "gho_xxxx" } }
+ *   "params": { "channel": "ahp-root://", "resource": "https://api.github.com",
+ *     "token": "gho_xxxx", "expiresIn": 3540 } }
  *
  * // Server → Client (success)
  * { "jsonrpc": "2.0", "id": 3, "result": {} }
@@ -1150,6 +1151,23 @@ export interface AuthenticateParams extends BaseParams {
 	resource: string;
 	/** Bearer token obtained from the resource's authorization server */
 	token: string;
+	/**
+	 * The access token's remaining lifetime, in seconds, when this
+	 * `authenticate` request is sent. This corresponds to `expires_in` in an
+	 * OAuth 2.0 token response (RFC 6749 section 5.1).
+	 *
+	 * If the client retained the original token response, it MUST subtract the
+	 * elapsed time before forwarding this value. Omit this field when the
+	 * authorization server did not supply an expiry or the expiry is otherwise
+	 * unknown. When supplied, the value MUST be a positive integer.
+	 *
+	 * This field is irrelevant when `token` is empty to revoke authentication
+	 * and SHOULD be omitted in that case.
+	 *
+	 * @integer
+	 * @minimum 1
+	 */
+	expiresIn?: number;
 	/**
 	 * OAuth scopes the token grants, when known. Lets the server determine
 	 * whether a specific challenge — e.g. the `requiredScopes` on a live
diff --git a/src/vs/platform/agentHost/common/state/protocol/common/notifications.ts b/src/vs/platform/agentHost/common/state/protocol/common/notifications.ts
index caff18926682..dbf91000407e 100644
--- a/src/vs/platform/agentHost/common/state/protocol/common/notifications.ts
+++ b/src/vs/platform/agentHost/common/state/protocol/common/notifications.ts
@@ -17,7 +17,10 @@ import type { ProtectedResourceMetadata, URI } from './state.js';
 export const enum AuthRequiredReason {
 	/** The client has not yet authenticated for the resource */
 	Required = 'required',
-	/** A previously valid token has expired or been revoked */
+	/**
+	 * A previously valid token has expired or been revoked. The client must
+	 * acquire or renew the credential rather than replaying the challenged token.
+	 */
 	Expired = 'expired',
 }
 
@@ -32,8 +35,9 @@ export const enum AuthRequiredReason {
  * to; the `resource` field carries the complete OAuth protected resource
  * metadata (per RFC 9728).
  *
- * Clients should obtain a fresh token and push it via the `authenticate`
- * command.
+ * Clients should obtain or renew the credential and push the resulting token
+ * via the `authenticate` command. When `reason` is `expired`, clients MUST NOT
+ * blindly replay the challenged token.
  *
  * @category Protocol Notifications
  * @method auth/required
diff --git a/src/vs/platform/agentHost/node/agentHostAuthenticationService.ts b/src/vs/platform/agentHost/node/agentHostAuthenticationService.ts
index fb3aabd25aab..2ba34954ba6e 100644
--- a/src/vs/platform/agentHost/node/agentHostAuthenticationService.ts
+++ b/src/vs/platform/agentHost/node/agentHostAuthenticationService.ts
@@ -3,6 +3,7 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
+import { getExpirationTime, getRemainingTimeInSeconds, isExpired } from '../../../base/common/date.js';
 import { Emitter, Event } from '../../../base/common/event.js';
 import { Disposable } from '../../../base/common/lifecycle.js';
 import { createDecorator } from '../../instantiation/common/instantiation.js';
@@ -34,6 +35,7 @@ interface IStoredAuthToken {
 	readonly resource: string;
 	readonly scopes: readonly string[];
 	readonly token: string;
+	readonly expiresAt: number | undefined;
 }
 
 export class AgentHostAuthenticationService extends Disposable implements IAgentHostAuthenticationService, IAgentHostAuthenticationController {
@@ -51,6 +53,7 @@ export class AgentHostAuthenticationService extends Disposable implements IAgent
 
 	async authenticate(params: AuthenticateParams, providers: Iterable<IAgent>): Promise<AuthenticateResult> {
 		this._logService.trace(`[AgentHostAuthenticationService] authenticate called: resource=${params.resource}`);
+		const expiresAt = getExpirationTime(params.expiresIn);
 		const providerList = [...providers];
 		// Multiple providers may share the same protected resource (e.g.
 		// both Copilot CLI and Claude consume the Copilot-scoped OAuth credential).
@@ -63,7 +66,7 @@ export class AgentHostAuthenticationService extends Disposable implements IAgent
 			p => p.getProtectedResources().some(r => r.resource === params.resource),
 		);
 		const settled = await Promise.allSettled(
-			matching.map(p => p.authenticate(params.resource, params.token)),
+			matching.map(p => p.authenticate(params.resource, params.token, params.expiresIn)),
 		);
 		let authenticated = false;
 		let rejected = false;
@@ -106,7 +109,7 @@ export class AgentHostAuthenticationService extends Disposable implements IAgent
 			// while clearing its own live state.
 			this._tokens.delete(key);
 		} else if (authenticated) {
-			this._tokens.set(key, { resource: params.resource, scopes, token: params.token });
+			this._tokens.set(key, { resource: params.resource, scopes, token: params.token, expiresAt });
 		}
 		const token = this._tokens.get(key)?.token;
 		if (previousToken !== token) {
@@ -117,11 +120,17 @@ export class AgentHostAuthenticationService extends Disposable implements IAgent
 
 	async replay(provider: IAgent): Promise<void> {
 		const protectedResources = new Set(provider.getProtectedResources().map(resource => resource.resource));
-		for (const stored of this._tokens.values()) {
-			const params: AuthenticateParams = { resource: stored.resource, scopes: stored.scopes, token: stored.token };
+		for (const [key, stored] of this._tokens) {
+			const now = Date.now();
+			if (isExpired(stored.expiresAt, now)) {
+				this._tokens.delete(key);
+				continue;
+			}
+			const expiresIn = getRemainingTimeInSeconds(stored.expiresAt, now);
+			const params: AuthenticateParams = { resource: stored.resource, scopes: stored.scopes, token: stored.token, expiresIn };
 			if (protectedResources.has(stored.resource)) {
 				try {
-					await provider.authenticate(stored.resource, stored.token);
+					await provider.authenticate(stored.resource, stored.token, expiresIn);
 				} catch (error) {
 					this._logService.error(error, `[AgentHostAuthenticationService] Provider '${provider.id}' rejected replayed authentication for resource=${stored.resource}`);
 				}
@@ -139,7 +148,7 @@ export class AgentHostAuthenticationService extends Disposable implements IAgent
 	getAuthToken(request: IAgentHostAuthTokenRequest): string | undefined {
 		const scopes = this._normalizeScopes(request.scopes);
 		const exact = this._tokens.get(this._key(request.resource, scopes));
-		if (exact) {
+		if (exact && !isExpired(exact.expiresAt)) {
 			return exact.token;
 		}
 		if (scopes.length === 0) {
@@ -149,7 +158,7 @@ export class AgentHostAuthenticationService extends Disposable implements IAgent
 		const requested = new Set(scopes);
 		let best: IStoredAuthToken | undefined;
 		for (const candidate of this._tokens.values()) {
-			if (candidate.resource !== request.resource || candidate.scopes.length === 0) {
+			if (candidate.resource !== request.resource || candidate.scopes.length === 0 || isExpired(candidate.expiresAt)) {
 				continue;
 			}
 			if (!this._containsAll(candidate.scopes, requested)) {
@@ -165,7 +174,8 @@ export class AgentHostAuthenticationService extends Disposable implements IAgent
 
 		// Compatibility for clients that resolved the right token before scopes
 		// were forwarded through the authenticate command.
-		return this._tokens.get(this._key(request.resource, []))?.token;
+		const unscoped = this._tokens.get(this._key(request.resource, []));
+		return unscoped && !isExpired(unscoped.expiresAt) ? unscoped.token : undefined;
 	}
 
 	private _containsAll(scopes: readonly string[], requested: ReadonlySet<string>): boolean {
@@ -184,4 +194,5 @@ export class AgentHostAuthenticationService extends Disposable implements IAgent
 	private _normalizeScopes(scopes: readonly string[] | undefined): readonly string[] {
 		return scopes ? [...new Set(scopes)].sort() : [];
 	}
+
 }
diff --git a/src/vs/platform/agentHost/node/copilot/copilotAgent.ts b/src/vs/platform/agentHost/node/copilot/copilotAgent.ts
index 794858eb56fa..5d66841eb254 100644
--- a/src/vs/platform/agentHost/node/copilot/copilotAgent.ts
+++ b/src/vs/platform/agentHost/node/copilot/copilotAgent.ts
@@ -83,6 +83,7 @@ import { createCopilotCliEnvironment } from './copilotCliEnvironment.js';
 import { ICopilotSessionContext, projectFromCopilotContext } from './copilotGitProject.js';
 import { parsedPluginsEqual, toChildCustomizations } from './copilotPluginConverters.js';
 import { CopilotGitHubTelemetryForwarder } from './copilotGitHubTelemetryForwarder.js';
+import { CopilotGitHubCredentials } from './copilotGitHubCredentials.js';
 import { CopilotSecondaryAssignmentContext } from './copilotSecondaryAssignmentContext.js';
 import { CopilotSessionLauncher, AutoTierConfigKey, ContextSizeConfigKey, ThinkingLevelConfigKey, getCopilotContextTier, isCopilotReasoningEffort, resolveCopilotAutoTier, resolveCopilotReasoningEffort, type CopilotSessionLaunchPlan, type IActiveClientSnapshot } from './copilotSessionLauncher.js';
 import { CopilotAgentStartupConfig } from './copilotAgentStartupConfig.js';
@@ -842,7 +843,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 	private _closedConnectionRecovery: { readonly clientFailureId: string; readonly promise: Promise<ICopilotClosedConnectionRecoveryResult> } | undefined;
 	private readonly _authenticationSequencer = new Sequencer();
 	private _updatingGitHubCredentials = false;
-	private _githubToken: string | undefined;
+	private readonly _githubCredentials = this._register(new CopilotGitHubCredentials());
 	private _serverToolHost: IAgentServerToolHost | undefined;
 
 	setServerToolHost(host: IAgentServerToolHost): void {
@@ -963,6 +964,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 		@IAgentHostWorktreeIsolation worktree: IAgentHostWorktreeIsolation,
 	) {
 		super();
+		this._register(this._githubCredentials.onDidRequestRefresh(() => this._handleCopilotSessionAuthRequired()));
 		this._worktree = worktree;
 		this._lastStartupConfig = this._readClientStartupConfig();
 		this._plugins = this._register(this._instantiationService.createInstance(PluginController, () => this._ensureClient()));
@@ -1362,9 +1364,9 @@ export class CopilotAgent extends Disposable implements IAgent {
 
 	async getNetworkDiagnosticsEndpoints(): Promise<readonly IAgentHostNetworkEndpoint[]> {
 		let capiUrl = process.env['VSCODE_AGENT_HOST_CAPI_URL_OVERRIDE'] || COPILOT_CAPI_URL;
-		if (this._githubToken) {
+		if (this._githubCredentials.token) {
 			try {
-				capiUrl = await this._copilotApiService.resolveApiEndpoint(this._githubToken) || capiUrl;
+				capiUrl = await this._copilotApiService.resolveApiEndpoint(this._githubCredentials.token) || capiUrl;
 			} catch (error) {
 				this._logService.debug(`[Copilot] CAPI endpoint discovery for network diagnostics failed; using ${capiUrl}: ${error instanceof Error ? error.message : String(error)}`);
 			}
@@ -1378,7 +1380,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 	}
 
 	async getNetworkDiagnosticsAccount(): Promise<string | undefined> {
-		return this._githubToken ? this._copilotApiService.resolveUserLogin?.(this._githubToken) : undefined;
+		return this._githubCredentials.token ? this._copilotApiService.resolveUserLogin?.(this._githubCredentials.token) : undefined;
 	}
 
 	async getManagedSettingsDiagnostics(): Promise<IAgentHostManagedSettingsSnapshot> {
@@ -1403,7 +1405,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 			stage = 'querying native MDM and GitHub managed settings';
 			return getCopilotManagedSettingsDiagnostics(
 				runtimeSdk,
-				this._githubToken,
+				this._githubCredentials.token,
 				this._gitHubEndpointService.getEnterpriseUri() ?? 'https://github.com',
 				AbortSignal.timeout(COPILOT_MANAGED_SETTINGS_DIAGNOSTICS_TIMEOUT_MS),
 				COPILOT_MANAGED_SETTINGS_QUERY_TIMEOUT_MS,
@@ -1718,7 +1720,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 		};
 	}
 
-	async authenticate(resource: string, token: string): Promise<boolean> {
+	async authenticate(resource: string, token: string, expiresIn?: number): Promise<boolean> {
 		if (resource === this._gitHubEndpointService.getRepoResource().resource) {
 			return true;
 		}
@@ -1733,18 +1735,18 @@ export class CopilotAgent extends Disposable implements IAgent {
 			if (token) {
 				this._authenticationRequired.set(undefined, undefined);
 			}
-			await this._applyGitHubToken(token || undefined);
+			await this._applyGitHubToken(token || undefined, expiresIn);
 		});
 		return true;
 	}
 
-	private async _applyGitHubToken(token: string | undefined): Promise<void> {
-		if (this._githubToken === token) {
+	private async _applyGitHubToken(token: string | undefined, expiresIn: number | undefined): Promise<void> {
+		const { tokenChanged, modeChanged: tokenProviderModeChanged } = this._githubCredentials.update(token, expiresIn);
+		if (!tokenChanged && !tokenProviderModeChanged) {
 			return;
 		}
 		this._logService.info(`[Copilot] Auth token ${token ? 'updated' : 'cleared'}`);
 		this._telemetryService.setCommonProperty('copilotSku', undefined);
-		this._githubToken = token;
 		this._updateRestrictedTelemetry(token);
 		this._refreshProxy();
 		if (!token) {
@@ -1765,21 +1767,27 @@ export class CopilotAgent extends Disposable implements IAgent {
 			return;
 		}
 		const host = this._gitHubEndpointService.getEnterpriseUri() ?? 'https://github.com';
-		let restartRequired = false;
+		let restartRequired = tokenProviderModeChanged;
 		this._updatingGitHubCredentials = true;
 		try {
-			for (const session of this._allLiveSessions()) {
-				try {
-					const result = await session.updateGitHubCredentials(host, token);
-					if (!result.success) {
-						restartRequired = true;
-						this._logService.warn(`[Copilot:${session.sessionId}] GitHub credential update was rejected; scheduling a safe CopilotClient restart`);
-					} else if (result.copilotUserResolved === false) {
-						this._logService.warn(`[Copilot:${session.sessionId}] GitHub credentials were updated, but Copilot user metadata could not be resolved; plan, quota, and billing metadata may be degraded. Reauthenticate to restore it.`);
+			if (!tokenProviderModeChanged) {
+				for (const session of this._allLiveSessions()) {
+					// Provider-backed SDK sessions receive this token through their registered callback.
+					if (!session.usesStaticGitHubToken) {
+						continue;
+					}
+					try {
+						const result = await session.updateGitHubCredentials(host, token);
+						if (!result.success) {
+							restartRequired = true;
+							this._logService.warn(`[Copilot:${session.sessionId}] GitHub credential update was rejected; scheduling a safe CopilotClient restart`);
+						} else if (result.copilotUserResolved === false) {
+							this._logService.warn(`[Copilot:${session.sessionId}] GitHub credentials were updated, but Copilot user metadata could not be resolved; plan, quota, and billing metadata may be degraded. Reauthenticate to restore it.`);
+						}
+					} catch (error) {
+						restartRequired = true;
+						this._logService.warn(`[Copilot:${session.sessionId}] Failed to update GitHub credentials; scheduling a safe CopilotClient restart: ${getErrorMessage(error)}`);
 					}
-				} catch (error) {
-					restartRequired = true;
-					this._logService.warn(`[Copilot:${session.sessionId}] Failed to update GitHub credentials; scheduling a safe CopilotClient restart: ${getErrorMessage(error)}`);
 				}
 			}
 		} finally {
@@ -1787,7 +1795,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 			await this._applyPendingClientRestart();
 		}
 		if (restartRequired) {
-			await this._requestClientRestart('GitHub credential update failed');
+			await this._requestClientRestart(tokenProviderModeChanged ? 'GitHub credential mode changed' : 'GitHub credential update failed');
 		}
 		await this._resolveCopilotSku(token);
 		void this._scheduleModelRefresh();
@@ -1803,7 +1811,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 	private async _resolveCopilotSku(githubToken: string): Promise<void> {
 		try {
 			const copilotSku = await this._copilotApiService.resolveCopilotSku?.(githubToken);
-			if (copilotSku && this._githubToken === githubToken) {
+			if (copilotSku && this._githubCredentials.token === githubToken) {
 				this._telemetryService.setCommonProperty('copilotSku', copilotSku);
 			}
 		} catch (err) {
@@ -1832,7 +1840,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 	private async _resolveRestrictedTelemetry(githubToken: string): Promise<void> {
 		try {
 			const ctx = await this._copilotApiService.resolveRestrictedTelemetryContext(githubToken);
-			if (this._githubToken !== githubToken) {
+			if (this._githubCredentials.token !== githubToken) {
 				return; // token changed while resolving; a newer call owns the state
 			}
 			this._applyRestrictedTelemetry({
@@ -1882,7 +1890,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 		}
 
 		const sessionId = notification.sessionId;
-		const githubToken = this._githubToken;
+		const githubToken = this._githubCredentials.token;
 		if (!githubToken) {
 			await router.route(notification, undefined, additionalProperties);
 			return;
@@ -1890,7 +1898,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 
 		try {
 			const context = await this._copilotApiService.resolveRestrictedTelemetryContext(githubToken);
-			if (this._githubToken !== githubToken) {
+			if (this._githubCredentials.token !== githubToken) {
 				return;
 			}
 			await router.route(notification, {
@@ -2014,7 +2022,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 			return;
 		}
 
-		const tokenAtRefreshStart = this._githubToken;
+		const tokenAtRefreshStart = this._githubCredentials.token;
 		if (!tokenAtRefreshStart) {
 			this._capiModels = [];
 			this._publishModels();
@@ -2022,7 +2030,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 		}
 		try {
 			const models = await this._listModels(tokenAtRefreshStart);
-			if (this._githubToken === tokenAtRefreshStart && this._modelCatalogGeneration === generation) {
+			if (this._githubCredentials.token === tokenAtRefreshStart && this._modelCatalogGeneration === generation) {
 				this._capiModels = models;
 				this._publishModels();
 			}
@@ -2030,7 +2038,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 			// Token rotated mid-flight — a newer refresh owns the result — or
 			// teardown began while the request was in flight, in which case a
 			// retry would just resurrect the client we are tearing down.
-			if (this._githubToken !== tokenAtRefreshStart || this._modelCatalogGeneration !== generation || this._shutdownPromise) {
+			if (this._githubCredentials.token !== tokenAtRefreshStart || this._modelCatalogGeneration !== generation || this._shutdownPromise) {
 				return;
 			}
 			if (/\b401\b/.test(getErrorMessage(err))) {
@@ -3958,7 +3966,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 				disabledRootMcpServers: await this._disabledRootMcpServers(sessionUri, sdkSessionId, snapshot),
 				activeClientToolSet: activeClient.toolSet,
 				shellManager,
-				githubToken: this._githubToken,
+				githubCredentials: this._githubCredentials.forSession(),
 				model: provisional.model,
 				longContextWindow: this._longContextWindowFor(provisional.model?.id),
 				freeLongContext: this._isFreeLongContext(provisional.model?.id),
@@ -4480,7 +4488,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 					disabledRootMcpServers: await this._disabledRootMcpServers(session, sdkSessionId, snapshot),
 					activeClientToolSet: activeClient.toolSet,
 					shellManager,
-					githubToken: this._githubToken,
+					githubCredentials: this._githubCredentials.forSession(),
 					fallback: { model, longContextWindow: this._longContextWindowFor(model?.id), freeLongContext: this._isFreeLongContext(model?.id) },
 				};
 			} else {
@@ -4495,7 +4503,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 					disabledRootMcpServers: await this._disabledRootMcpServers(session, chatSdkId, snapshot),
 					activeClientToolSet: activeClient.toolSet,
 					shellManager,
-					githubToken: this._githubToken,
+					githubCredentials: this._githubCredentials.forSession(),
 					model,
 					longContextWindow: this._longContextWindowFor(model?.id),
 					freeLongContext: this._isFreeLongContext(model?.id),
@@ -4939,7 +4947,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 					disabledRootMcpServers: await this._disabledRootMcpServers(configurationResource, info.sdkSessionId, snapshot),
 					activeClientToolSet: activeClient.toolSet,
 					shellManager,
-					githubToken: this._githubToken,
+					githubCredentials: this._githubCredentials.forSession(),
 					fallback: { model: info.model, longContextWindow: this._longContextWindowFor(info.model?.id), freeLongContext: this._isFreeLongContext(info.model?.id) },
 				};
 				agentSession = this._createAgentSession(launchPlan, workingDirectory, activeClient, { sessionUri: configurationResource, chatChannelUri: chat, resource: context.resource });
@@ -5099,6 +5107,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 		if (!this._shutdownPromise) {
 			this._isShuttingDown = true;
 			this._sessionsPendingRegistration.clearAndDisposeAll();
+			this._githubCredentials.shutdown();
 			for (const lifetime of this._sessionLifetimes.values()) {
 				void lifetime.close();
 			}
@@ -5213,9 +5222,9 @@ export class CopilotAgent extends Disposable implements IAgent {
 		}
 
 		let capiUrl = env['VSCODE_AGENT_HOST_CAPI_URL_OVERRIDE'] || COPILOT_CAPI_URL;
-		if (this._githubToken) {
+		if (this._githubCredentials.token) {
 			try {
-				const discovered = await this._copilotApiService.resolveApiEndpoint(this._githubToken);
+				const discovered = await this._copilotApiService.resolveApiEndpoint(this._githubCredentials.token);
 				if (discovered) {
 					capiUrl = discovered;
 				}
@@ -5316,7 +5325,6 @@ export class CopilotAgent extends Disposable implements IAgent {
 				// MCP reconcile has no host call of its own, so read the retained host snapshot lazily.
 				hostCustomizations: () => this._retainedHostCustomizations(sessionUri),
 				serverToolHost: this._serverToolHost,
-				isLaunchTokenCurrent: () => this._githubToken === launchPlan.githubToken,
 				onTurnEnded: () => this._onChatTurnEnded(),
 			},
 		);
@@ -5496,7 +5504,7 @@ export class CopilotAgent extends Disposable implements IAgent {
 			disabledRootMcpServers: await this._disabledRootMcpServers(sessionUri, sessionId, snapshot),
 			activeClientToolSet: activeClient.toolSet,
 			shellManager,
-			githubToken: this._githubToken,
+			githubCredentials: this._githubCredentials.forSession(),
 			workspaceless: storedMetadata.workspaceless,
 			fallback: {
 				model: storedMetadata.model,
diff --git a/src/vs/platform/agentHost/node/copilot/copilotAgentSession.ts b/src/vs/platform/agentHost/node/copilot/copilotAgentSession.ts
index aa040dd4c92a..7e7047829c3d 100644
--- a/src/vs/platform/agentHost/node/copilot/copilotAgentSession.ts
+++ b/src/vs/platform/agentHost/node/copilot/copilotAgentSession.ts
@@ -481,8 +481,6 @@ export interface ICopilotAgentSessionOptions {
 	 * the future) and exposes SDK tool handlers that execute them in-process.
 	 */
 	readonly serverToolHost?: IAgentServerToolHost;
-	/** Returns whether the token that launched this session is still the active account token. */
-	readonly isLaunchTokenCurrent?: () => boolean;
 	/** Overrides source-launch detection for deterministic tests. */
 	readonly enableDevelopmentErrorInjection?: boolean;
 
@@ -932,6 +930,7 @@ export class CopilotAgentSession extends Disposable {
 	 * non-destructive idle release to avoid disconnecting mid-turn.
 	 */
 	get hasActiveTurn(): boolean { return this._currentTurn.value !== undefined; }
+	get usesStaticGitHubToken(): boolean { return this._launchPlan.githubCredentials.usesStaticToken; }
 	get chatUri(): URI { return this._chatChannelUri; }
 	get currentTurnId(): string | undefined { return this._currentTurn.value?.id; }
 
@@ -1094,7 +1093,6 @@ export class CopilotAgentSession extends Disposable {
 	private readonly _shellInitScriptInstanceId = generateUuid().substring(0, 8);
 	private readonly _launchPlan: CopilotSessionLaunchPlan;
 	private _detectInterruptedTurnOnRestore: boolean;
-	private readonly _isLaunchTokenStillCurrent: () => boolean;
 	/** Notifies the agent that this chat's turn ended. See {@link ICopilotAgentSessionOptions.onTurnEnded}. */
 	private readonly _onTurnEnded: () => void;
 	private readonly _shellManager: ShellManager | undefined;
@@ -1150,6 +1148,7 @@ export class CopilotAgentSession extends Disposable {
 	private readonly _repoInfoTelemetry: AgentHostRepoInfoTelemetry;
 	private _activeRepoInfoTurn: {
 		readonly telemetryMessageId: string;
+		readonly githubToken: string | undefined;
 		cancelled: boolean;
 		begin: Promise<{ readonly context: IAgentHostRestrictedTelemetryContext; readonly baseBranch: string | undefined } | undefined>;
 	} | undefined;
@@ -1182,7 +1181,6 @@ export class CopilotAgentSession extends Disposable {
 		this._sessionLauncher = options.sessionLauncher;
 		this._launchPlan = options.launchPlan;
 		this._detectInterruptedTurnOnRestore = options.launchPlan.kind === 'resume';
-		this._isLaunchTokenStillCurrent = options.isLaunchTokenCurrent ?? (() => true);
 		this._onTurnEnded = options.onTurnEnded ?? (() => { });
 		this._shellManager = options.shellManager;
 		this._nonPtyShellTerminals = this._register(this._instantiationService.createInstance(NonPtyShellTerminalStreams, options.sessionUri, options.chatChannelUri));
@@ -2260,9 +2258,13 @@ export class CopilotAgentSession extends Disposable {
 
 	/** Updates the GitHub credentials used by this live SDK session. */
 	async updateGitHubCredentials(host: string, token: string): Promise<GitHubCredentialsUpdateResult> {
-		return this._wrapper.session.rpc.gitHubAuth.setCredentials({
+		const result = await this._wrapper.session.rpc.gitHubAuth.setCredentials({
 			credentials: { type: 'token', host, token },
 		});
+		if (result.success) {
+			this._launchPlan.githubCredentials.updateStaticToken(token);
+		}
+		return result;
 	}
 
 	private _setPromptCacheState(promptCache: ISessionPromptCacheState | undefined): void {
@@ -2383,7 +2385,7 @@ export class CopilotAgentSession extends Disposable {
 	}
 
 	private async _initialGitHubMcpToken(request: McpAuthRequest): Promise<string | undefined> {
-		const githubToken = this._launchPlan.githubToken;
+		const githubToken = this._currentGitHubToken;
 		const requestUrl = normalizeMcpServerUrl(request.serverUrl);
 		if (!githubToken || requestUrl === undefined) {
 			return undefined;
@@ -4705,10 +4707,10 @@ export class CopilotAgentSession extends Disposable {
 		}
 	}
 
-	private async _beginRepoInfoTelemetry(telemetryMessageId: string, clientType: AgentHostClientType, isCurrent: () => boolean): Promise<{ readonly context: IAgentHostRestrictedTelemetryContext; readonly baseBranch: string | undefined } | undefined> {
+	private async _beginRepoInfoTelemetry(telemetryMessageId: string, clientType: AgentHostClientType, githubToken: string | undefined, isCurrent: () => boolean): Promise<{ readonly context: IAgentHostRestrictedTelemetryContext; readonly baseBranch: string | undefined } | undefined> {
 		let resolved: { readonly context: IAgentHostRestrictedTelemetryContext; readonly baseBranch: string | undefined } | undefined;
 		try {
-			resolved = await this._resolveRepoInfoTelemetryContext();
+			resolved = await this._resolveRepoInfoTelemetryContext(githubToken);
 		} catch (error) {
 			this._logService.warn(`[Copilot:${this.sessionId}] Failed to resolve repository info telemetry context: ${getErrorMessage(error)}`);
 			return undefined;
@@ -4733,10 +4735,18 @@ export class CopilotAgentSession extends Disposable {
 			return;
 		}
 		this._activeRepoInfoTurn = undefined;
-		const isCurrent = () => !turn.cancelled && this._isLaunchTokenCurrent();
+		const isCurrent = () => !turn.cancelled && turn.githubToken !== undefined && this._isGitHubTokenCurrent(turn.githubToken);
 		void turn.begin.then(resolved => this._endRepoInfoTelemetry(turn.telemetryMessageId, resolved, isCurrent));
 	}
 
+	private _isGitHubTokenCurrent(token: string): boolean {
+		return this._launchPlan.githubCredentials.isCurrentToken(token);
+	}
+
+	private get _currentGitHubToken(): string | undefined {
+		return this._launchPlan.githubCredentials.token;
+	}
+
 	private _cancelActiveRepoInfoTelemetry(): void {
 		const turn = this._activeRepoInfoTurn;
 		if (!turn) {
@@ -4747,11 +4757,10 @@ export class CopilotAgentSession extends Disposable {
 		void turn.begin.finally(() => this._repoInfoTelemetry.clearTurn(turn.telemetryMessageId));
 	}
 
-	private async _resolveRepoInfoTelemetryContext(): Promise<{ readonly context: IAgentHostRestrictedTelemetryContext; readonly baseBranch: string | undefined } | undefined> {
+	private async _resolveRepoInfoTelemetryContext(githubToken: string | undefined): Promise<{ readonly context: IAgentHostRestrictedTelemetryContext; readonly baseBranch: string | undefined } | undefined> {
 		if (this._configurationService.getRootValue(platformRootSchema, AgentHostDisableRepoInfoTelemetryConfigKey) === true) {
 			return undefined;
 		}
-		const githubToken = this._launchPlan.githubToken;
 		if (!githubToken) {
 			return undefined;
 		}
@@ -4765,10 +4774,6 @@ export class CopilotAgentSession extends Disposable {
 		return { context: this._toRepoInfoTelemetryContext(rawContext), baseBranch };
 	}
 
-	private _isLaunchTokenCurrent(): boolean {
-		return this._launchPlan.githubToken !== undefined && this._isLaunchTokenStillCurrent();
-	}
-
 	private _toRepoInfoTelemetryContext(context: IRestrictedTelemetryContext): IAgentHostRestrictedTelemetryContext {
 		return {
 			restrictedTelemetryEnabled: context.restrictedTelemetryEnabled,
@@ -6535,11 +6540,12 @@ export class CopilotAgentSession extends Disposable {
 				this._cancelActiveRepoInfoTelemetry();
 				const turn: NonNullable<CopilotAgentSession['_activeRepoInfoTurn']> = {
 					telemetryMessageId,
+					githubToken: this._currentGitHubToken,
 					cancelled: false,
 					begin: Promise.resolve(undefined),
 				};
-				const isCurrent = () => !turn.cancelled && this._isLaunchTokenCurrent();
-				turn.begin = this._beginRepoInfoTelemetry(telemetryMessageId, this._currentTurn.value?.clientType ?? AgentHostClientType.Unknown, isCurrent);
+				const isCurrent = () => !turn.cancelled && turn.githubToken !== undefined && this._isGitHubTokenCurrent(turn.githubToken);
+				turn.begin = this._beginRepoInfoTelemetry(telemetryMessageId, this._currentTurn.value?.clientType ?? AgentHostClientType.Unknown, turn.githubToken, isCurrent);
 				this._activeRepoInfoTurn = turn;
 			}
 		}));
diff --git a/src/vs/platform/agentHost/node/copilot/copilotGitHubCredentials.ts b/src/vs/platform/agentHost/node/copilot/copilotGitHubCredentials.ts
new file mode 100644
index 000000000000..1e6ce8a83af1
--- /dev/null
+++ b/src/vs/platform/agentHost/node/copilot/copilotGitHubCredentials.ts
@@ -0,0 +1,145 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import type { GitHubTokenProvider } from '@github/copilot-sdk';
+import { DeferredPromise, timeout } from '../../../../base/common/async.js';
+import { getExpirationTime, getRemainingTimeInSeconds } from '../../../../base/common/date.js';
+import { Emitter, Event } from '../../../../base/common/event.js';
+import { Disposable } from '../../../../base/common/lifecycle.js';
+
+const COPILOT_GITHUB_TOKEN_REFRESH_THRESHOLD_SECONDS = 60 * 60;
+const COPILOT_GITHUB_TOKEN_REFRESH_TIMEOUT_MS = 30_000;
+
+type CopilotGitHubSdkSessionOptions =
+	| { readonly gitHubToken: string | undefined; readonly gitHubTokenProvider?: never }
+	| { readonly gitHubToken?: never; readonly gitHubTokenProvider: GitHubTokenProvider };
+
+/**
+ * The GitHub credential configuration captured when an SDK session launches.
+ */
+export class CopilotGitHubSessionCredentials {
+	private constructor(
+		private _staticToken: string | undefined,
+		private readonly _provider: CopilotGitHubCredentials | undefined,
+	) { }
+
+	static fromToken(token: string | undefined): CopilotGitHubSessionCredentials {
+		return new CopilotGitHubSessionCredentials(token, undefined);
+	}
+
+	static fromProvider(provider: CopilotGitHubCredentials): CopilotGitHubSessionCredentials {
+		return new CopilotGitHubSessionCredentials(undefined, provider);
+	}
+
+	get usesStaticToken(): boolean {
+		return this._provider === undefined;
+	}
+
+	get token(): string | undefined {
+		return this._provider?.token ?? this._staticToken;
+	}
+
+	get sdkSessionOptions(): CopilotGitHubSdkSessionOptions {
+		return this._provider
+			? { gitHubTokenProvider: this._provider.tokenProvider }
+			: { gitHubToken: this._staticToken };
+	}
+
+	isCurrentToken(token: string): boolean {
+		return this.token === token;
+	}
+
+	updateStaticToken(token: string): void {
+		if (!this.usesStaticToken) {
+			throw new Error('Cannot update provider-backed GitHub credentials as a static token');
+		}
+		this._staticToken = token;
+	}
+}
+
+/**
+ * Owns the current GitHub credential mode and supplies refreshable credentials to SDK sessions.
+ */
+export class CopilotGitHubCredentials extends Disposable {
+	private _token: string | undefined;
+	private _expiresAt: number | undefined;
+	private _usesTokenProvider = false;
+	private _pendingRefresh: DeferredPromise<void> | undefined;
+	private _isShutdown = false;
+
+	constructor(
+		private readonly _now = Date.now,
+		private readonly _refreshTimeoutMs = COPILOT_GITHUB_TOKEN_REFRESH_TIMEOUT_MS,
+	) {
+		super();
+	}
+
+	private readonly _onDidRequestRefresh = this._register(new Emitter<void>());
+	readonly onDidRequestRefresh: Event<void> = this._onDidRequestRefresh.event;
+
+	get token(): string | undefined {
+		return this._token;
+	}
+
+	readonly tokenProvider: GitHubTokenProvider = async ({ reason }) => {
+		let expiresIn = getRemainingTimeInSeconds(this._expiresAt, this._now());
+		if (!this._isShutdown && this._usesTokenProvider && (reason === 'refresh' || expiresIn === undefined || expiresIn <= COPILOT_GITHUB_TOKEN_REFRESH_THRESHOLD_SECONDS)) {
+			await this._requestRefresh();
+			expiresIn = getRemainingTimeInSeconds(this._expiresAt, this._now());
+		}
+		if (this._isShutdown || !this._usesTokenProvider || !this._token || expiresIn === undefined || expiresIn <= COPILOT_GITHUB_TOKEN_REFRESH_THRESHOLD_SECONDS) {
+			return { kind: 'cancelled' };
+		}
+		return { kind: 'token', accessToken: this._token, expiresIn };
+	};
+
+	forSession(): CopilotGitHubSessionCredentials {
+		return this._usesTokenProvider
+			? CopilotGitHubSessionCredentials.fromProvider(this)
+			: CopilotGitHubSessionCredentials.fromToken(this._token);
+	}
+
+	update(token: string | undefined, expiresIn: number | undefined): { readonly tokenChanged: boolean; readonly modeChanged: boolean } {
+		const tokenChanged = this._token !== token;
+		const usesTokenProvider = token !== undefined && expiresIn !== undefined;
+		const modeChanged = this._usesTokenProvider !== usesTokenProvider;
+		this._token = token;
+		this._expiresAt = usesTokenProvider ? getExpirationTime(expiresIn, this._now()) : undefined;
+		this._usesTokenProvider = usesTokenProvider;
+		this._completePendingRefresh();
+		return { tokenChanged, modeChanged };
+	}
+
+	shutdown(): void {
+		this._isShutdown = true;
+		this.update(undefined, undefined);
+	}
+
+	private async _requestRefresh(): Promise<void> {
+		let pending = this._pendingRefresh;
+		if (!pending) {
+			pending = new DeferredPromise<void>();
+			this._pendingRefresh = pending;
+			this._onDidRequestRefresh.fire();
+		}
+		const refreshTimeout = timeout(this._refreshTimeoutMs);
+		try {
+			await Promise.race([pending.p, refreshTimeout]);
+		} finally {
+			refreshTimeout.cancel();
+		}
+	}
+
+	private _completePendingRefresh(): void {
+		const pending = this._pendingRefresh;
+		this._pendingRefresh = undefined;
+		pending?.complete();
+	}
+
+	override dispose(): void {
+		this.shutdown();
+		super.dispose();
+	}
+}
diff --git a/src/vs/platform/agentHost/node/copilot/copilotSessionLauncher.ts b/src/vs/platform/agentHost/node/copilot/copilotSessionLauncher.ts
index 97a48a9e125f..52e2687145e4 100644
--- a/src/vs/platform/agentHost/node/copilot/copilotSessionLauncher.ts
+++ b/src/vs/platform/agentHost/node/copilot/copilotSessionLauncher.ts
@@ -30,6 +30,7 @@ import { IAgentHostSessionOpenTelemetry } from '../agentHostSessionOpenTelemetry
 import { IByokLmBridgeRegistry } from '../byokLmBridgeRegistry.js';
 import { IByokLmProxyService, type IByokLmProxyHandle } from './byokLmProxyService.js';
 import type { ICopilotMcpServerInfo, ICopilotPluginInfo } from './copilotAgent.js';
+import { CopilotGitHubSessionCredentials } from './copilotGitHubCredentials.js';
 import { toSdkHooks, toSdkInstructionDirectories, toSdkMcpServers, toSdkMcpServersFromConfigMap, toSdkSessionCustomAgents, toSdkSkillDirectories } from './copilotPluginConverters.js';
 import { CopilotSessionWrapper } from './copilotSessionWrapper.js';
 import { ShellManager, createShellTools, type IUnsandboxedCommandConfirmationRequest } from './copilotShellTools.js';
@@ -252,7 +253,7 @@ interface ICopilotSessionLaunchBase {
 	 */
 	readonly activeClientToolSet: ActiveClientToolSet;
 	readonly shellManager: ShellManager | undefined;
-	readonly githubToken: string | undefined;
+	readonly githubCredentials: CopilotGitHubSessionCredentials;
 
 	/**
 	 * Whether this is a workspace-less session. Threaded into the
@@ -1024,14 +1025,7 @@ export class CopilotSessionLauncher implements ICopilotSessionLauncher {
 			pluginDirectories: coalesce(plugins.map(p => p.pluginDir))
 				.filter(d => d.scheme === Schemas.file).map(d => d.fsPath),
 			tools: promptOverrides.tools,
-			// Pass the GitHub token at the session level. The SDK's
-			// client-level `gitHubToken` authenticates the CLI process,
-			// but each session also needs its own token resolved into a
-			// GitHub identity (login, Copilot plan, endpoints) to drive
-			// model routing and quota — without this the session
-			// errors with "Session was not created with authentication
-			// info or custom provider" on first send. See #318693.
-			gitHubToken: plan.githubToken,
+			...plan.githubCredentials.sdkSessionOptions,
 			// Enable infinite sessions so the SDK provisions a workspace
 			// directory (containing `plan.md`, `checkpoints/`, `files/`).
 			// The workspace is required for plan mode to work — without
diff --git a/src/vs/platform/agentHost/test/electron-browser/agentHostProtocolClient.test.ts b/src/vs/platform/agentHost/test/electron-browser/agentHostProtocolClient.test.ts
index 19fa407d8180..14669157ffd2 100644
--- a/src/vs/platform/agentHost/test/electron-browser/agentHostProtocolClient.test.ts
+++ b/src/vs/platform/agentHost/test/electron-browser/agentHostProtocolClient.test.ts
@@ -2915,7 +2915,7 @@ suite('AgentHostProtocolClient', () => {
 				jsonrpc: '2.0', id: initialAnnotationsSubscribe.id,
 				result: { snapshot: { resource: annotationsUri.toString(), state: { annotations: [] }, fromSeq: 5 } },
 			});
-			const authentication = client.authenticate({ resource: 'https://api.github.com', token: 'token' });
+			const authentication = client.authenticate({ resource: 'https://api.github.com', token: 'token', expiresIn: 3600 });
 			const initialAuthenticate = await waitForRequest(transports[0], 'authenticate');
 			transports[0].fireMessage({ jsonrpc: '2.0', id: initialAuthenticate.id, result: {} });
 			await authentication;
@@ -2961,6 +2961,8 @@ suite('AgentHostProtocolClient', () => {
 			});
 
 			const restoredAuthenticate = await waitForRequestAt(reconnectTransport, 'authenticate', 0);
+			const restoredExpiresIn = (restoredAuthenticate.params as { expiresIn?: number }).expiresIn;
+			assert.ok(restoredExpiresIn !== undefined && restoredExpiresIn > 0 && restoredExpiresIn <= 3600);
 			const managedSettings = reconnectTransport.sentMessages.find(message => hasKey(message, { method: true }) && message.method === 'setClientManagedSettingsPermissions');
 			assert.ok(managedSettings, 'managed settings should be restored after fresh initialization');
 			assert.ok(
diff --git a/src/vs/platform/agentHost/test/node/agentService.test.ts b/src/vs/platform/agentHost/test/node/agentService.test.ts
index 89cb67b5aee9..b2ac738d993a 100644
--- a/src/vs/platform/agentHost/test/node/agentService.test.ts
+++ b/src/vs/platform/agentHost/test/node/agentService.test.ts
@@ -7178,10 +7178,10 @@ suite('AgentService (node dispatcher)', () => {
 		test('routes token to provider matching the resource', async () => {
 			registerTestAgentProvider(service, copilotAgent);
 
-			const result = await service.authenticate({ resource: 'https://api.github.com', token: 'ghp_test123' });
+			const result = await service.authenticate({ resource: 'https://api.github.com', token: 'ghp_test123', expiresIn: 3600 });
 
 			assert.deepStrictEqual(result, { authenticated: true });
-			assert.deepStrictEqual(copilotAgent.authenticateCalls, [{ resource: 'https://api.github.com', token: 'ghp_test123' }]);
+			assert.deepStrictEqual(copilotAgent.authenticateCalls, [{ resource: 'https://api.github.com', token: 'ghp_test123', expiresIn: 3600 }]);
 		});
 
 		test('returns not authenticated for unknown resource', async () => {
diff --git a/src/vs/platform/agentHost/test/node/copilotAgent.test.ts b/src/vs/platform/agentHost/test/node/copilotAgent.test.ts
index 05a1ab1b6480..f549b2ef24f9 100644
--- a/src/vs/platform/agentHost/test/node/copilotAgent.test.ts
+++ b/src/vs/platform/agentHost/test/node/copilotAgent.test.ts
@@ -49,7 +49,7 @@ import { AgentHostClientConnectionKind, AgentHostLaunchKind, AgentHostTransportK
 import { ISessionDataService } from '../../common/sessionDataService.js';
 import { buildDefaultChatUri, buildChatUri, buildSubagentChatUri, buildSubagentSessionUri, parseRequiredSessionUriFromChatUri, CustomizationLoadStatus, MessageKind, readSessionEhcliAdoptable, ResponsePartKind, ROOT_STATE_URI, ToolResultContentType, TurnState, customizationId, AH_META_IS_ARCHIVED_DB_KEY, AH_META_IS_READ_DB_KEY, type ClientPluginCustomization, type Customization, type PluginCustomization, type ToolCallResult, type Turn, RuleCustomization } from '../../common/state/sessionState.js';
 import { ChatOriginKind, CustomizationEnablementKind, CustomizationType, SessionStatus, ToolCallContributorKind, type AgentSelection, type ModelSelection, type ProtectedResourceMetadata, type ToolDefinition } from '../../common/state/protocol/state.js';
-import { ActionType, type ChatAction, type SessionAction } from '../../common/state/sessionActions.js';
+import { ActionType, AuthRequiredReason, type ChatAction, type SessionAction } from '../../common/state/sessionActions.js';
 
 import { AgentConfigurationService, IAgentConfigurationService } from '../../node/agentConfigurationService.js';
 import { AgentHostAuthenticationService, IAgentHostAuthenticationService } from '../../node/agentHostAuthenticationService.js';
@@ -63,6 +63,7 @@ import { IAgentHostTerminalManager } from '../../node/agentHostTerminalManager.j
 import { IAgentHostOTelService } from '../../common/otel/agentHostOTelService.js';
 import { AgentHostCompletions, IAgentHostCompletions } from '../../node/agentHostCompletions.js';
 import { COPILOT_AGENT_HOST_SYSTEM_MESSAGE, CopilotAgent, getCopilotManagedSettingsDiagnostics, rebaseUnder, REFRESH_DEBOUNCE_MS, resolveCopilotOtlpMetricsEndpoint } from '../../node/copilot/copilotAgent.js';
+import { CopilotGitHubSessionCredentials } from '../../node/copilot/copilotGitHubCredentials.js';
 import { GITHUB_MCP_SERVER_NAME } from '../../node/shared/githubMcpServer.js';
 import { AGENT_HOST_FILE_LINK_INSTRUCTIONS } from '../../node/shared/fileLinkInstructions.js';
 import { COPILOT_AGENT_HOST_LARGE_OUTPUT_TOOL_INSTRUCTION } from '../../node/copilot/prompts/toolInstructions.js';
@@ -200,11 +201,13 @@ function setDefaultSessionStub(agent: CopilotAgent, sessionId: string, stub: unk
 		sessionUri?: URI;
 		resourceUri?: URI;
 		chatChannelUri?: URI;
+		usesStaticGitHubToken?: boolean;
 		bindChatChannel?: (uri: URI) => void;
 		destroySession?: () => Promise<void>;
 	};
 	typed.sessionId ??= sessionId;
 	typed.sessionUri ??= sessionUri;
+	typed.usesStaticGitHubToken ??= true;
 	// A session-backed (default) chat's host-chosen persistence scope is the
 	// session itself; that is how the agent identifies it without rebuilding a
 	// default-chat URI (see `CopilotAgent._findSessionChat`).
@@ -767,6 +770,7 @@ interface IFakeAgentSession {
 
 interface ICredentialUpdateSession {
 	readonly hasActiveTurn: boolean;
+	readonly usesStaticGitHubToken?: boolean;
 	updateGitHubCredentials(host: string, token: string): Promise<{ readonly success: boolean; readonly copilotUserResolved?: boolean }>;
 	dispose(): void;
 }
@@ -777,6 +781,7 @@ class MockCopilotSession {
 	readonly workingDirectoryCalls: string[] = [];
 	readonly workingDirectoryErrors: Array<Error | undefined> = [];
 	readonly workingDirectoryResults: string[] = [];
+	readonly gitHubCredentialUpdates: Array<{ credentials: { type: 'token'; host: string; token: string } }> = [];
 	readonly rpc = {
 		eventLog: {
 			registerInterest: async () => ({ handle: 'sampling-interest' }),
@@ -786,7 +791,10 @@ class MockCopilotSession {
 			update: async () => ({ success: true }),
 		},
 		gitHubAuth: {
-			setCredentials: async () => ({ success: true, copilotUserResolved: true }),
+			setCredentials: async (params: { credentials: { type: 'token'; host: string; token: string } }) => {
+				this.gitHubCredentialUpdates.push(params);
+				return { success: true, copilotUserResolved: true };
+			},
 		},
 		permissions: {
 			setMode: async ({ mode }: { mode: PermissionMode }) => ({ success: true, mode }),
@@ -1196,7 +1204,7 @@ function createAgentSessionThroughAgent(agent: CopilotAgent, instantiationServic
 		resolvedAgentName: undefined,
 		snapshot: options?.snapshot ?? { tools: [], plugins: [], mcpServers: {} },
 		shellManager,
-		githubToken: 'token',
+		githubCredentials: CopilotGitHubSessionCredentials.fromToken('token'),
 		model: undefined,
 	};
 	return { session: agentInternals._createAgentSession(launchPlan, options?.workingDirectory, activeClient), activeClient, createOptions: () => createOptions };
@@ -2618,7 +2626,7 @@ suite('CopilotAgent', () => {
 			await waitForState(agent.models, models => models.length === 0);
 
 			assert.deepStrictEqual({
-				githubToken: agent['_githubToken'],
+				githubToken: agent['_githubCredentials'].token,
 				models: agent.models.get(),
 			}, {
 				githubToken: undefined,
@@ -2658,7 +2666,7 @@ suite('CopilotAgent', () => {
 		}
 	});
 
-	test('updates every live session after a changed auth token without restarting an unchanged proxy', async () => {
+	test('updates live sessions and restarts only when the credential mode changes', async () => {
 		const client = new TestCopilotClient([], [{
 			id: 'gpt-4o',
 			name: 'GPT-4o',
@@ -2666,6 +2674,7 @@ suite('CopilotAgent', () => {
 		const agent = createTestAgent(disposables, { copilotClient: client });
 		const first = {
 			hasActiveTurn: false,
+			usesStaticGitHubToken: true,
 			updates: [] as Array<{ host: string; token: string }>,
 			async updateGitHubCredentials(host: string, token: string) {
 				this.updates.push({ host, token });
@@ -2675,6 +2684,7 @@ suite('CopilotAgent', () => {
 		} satisfies ICredentialUpdateSession & { updates: Array<{ host: string; token: string }> };
 		const second = {
 			hasActiveTurn: false,
+			usesStaticGitHubToken: true,
 			updates: [] as Array<{ host: string; token: string }>,
 			async updateGitHubCredentials(host: string, token: string) {
 				this.updates.push({ host, token });
@@ -2688,15 +2698,20 @@ suite('CopilotAgent', () => {
 			setDefaultSessionStub(agent, 'second', second);
 			await agent.authenticate('https://api.github.com', 'model-token-a');
 			await agent.authenticate('https://api.github.com', 'model-token-a');
+			await agent.authenticate('https://api.github.com', 'model-token-a', 7200);
 
 			assert.deepStrictEqual({
 				firstUpdates: first.updates,
 				secondUpdates: second.updates,
 				stops: client.stopCallCount,
 			}, {
-				firstUpdates: [{ host: 'https://github.com', token: 'model-token-a' }],
-				secondUpdates: [{ host: 'https://github.com', token: 'model-token-a' }],
-				stops: 0,
+				firstUpdates: [
+					{ host: 'https://github.com', token: 'model-token-a' },
+				],
+				secondUpdates: [
+					{ host: 'https://github.com', token: 'model-token-a' },
+				],
+				stops: 1,
 			});
 		} finally {
 			await disposeAgent(agent);
@@ -10194,8 +10209,57 @@ suite('CopilotAgent', () => {
 
 				assert.deepStrictEqual({
 					configToken: capturedConfig?.gitHubToken,
+					hasTokenProvider: capturedConfig?.gitHubTokenProvider !== undefined,
 				}, {
 					configToken: 'gh-token-abc',
+					hasTokenProvider: false,
+				});
+			} finally {
+				await disposeAgent(agent);
+			}
+		});
+
+		test('materialization uses refreshable GitHub credentials when the lifetime is known', async () => {
+			const sessionDataService = disposables.add(new TestSessionDataService());
+			const client = new TestCopilotClient([]);
+			const mockSession = new MockCopilotSession();
+			let capturedConfig: Parameters<ITestCopilotClient['createSession']>[0] | undefined;
+			const agent = createTestAgent(disposables, { sessionDataService, copilotClient: client });
+			client.createSession = async config => {
+				capturedConfig = config;
+				return mockSession as unknown as CopilotSession;
+			};
+
+			try {
+				await agent.authenticate('https://api.github.com', 'initial-token', 3600);
+				const result = await provisionSession(agent, {
+					session: AgentSession.uri('copilotcli', 'refreshable-token-session'),
+					workingDirectories: [URI.file('/workspace')],
+				});
+				await agent.chats.sendMessage(defaultChatUri(result.session), 'hello', undefined, undefined, undefined, undefined, exactChatContext(result.session, defaultChatUri(result.session), result.session));
+
+				const provider = capturedConfig?.gitHubTokenProvider;
+				assert.ok(provider);
+				const refresh = provider({ host: 'github.com', sessionId: 'refreshable-token-session', reason: 'refresh' });
+				const authenticationRequired = agent.authenticationRequired.get();
+				await agent.authenticate('https://api.github.com', 'refreshed-token', 7200);
+				await refresh;
+
+				assert.deepStrictEqual({
+					gitHubToken: capturedConfig?.gitHubToken,
+					hasTokenProvider: capturedConfig?.gitHubTokenProvider !== undefined,
+					authenticationRequired,
+					credentialUpdates: mockSession.gitHubCredentialUpdates,
+					clientStops: client.stopCallCount,
+				}, {
+					gitHubToken: undefined,
+					hasTokenProvider: true,
+					authenticationRequired: {
+						resource: GITHUB_COPILOT_PROTECTED_RESOURCE,
+						reason: AuthRequiredReason.Expired,
+					},
+					credentialUpdates: [],
+					clientStops: 0,
 				});
 			} finally {
 				await disposeAgent(agent);
diff --git a/src/vs/platform/agentHost/test/node/copilotAgentSession.test.ts b/src/vs/platform/agentHost/test/node/copilotAgentSession.test.ts
index 84ec7b614163..fd824962673a 100644
--- a/src/vs/platform/agentHost/test/node/copilotAgentSession.test.ts
+++ b/src/vs/platform/agentHost/test/node/copilotAgentSession.test.ts
@@ -45,6 +45,7 @@ import { toHostSnapshotAttachmentMeta } from '../../common/meta/agentSnapshotAtt
 import { STREAMING_TOOL_DISPLAY_INTERVAL_MS } from '../../common/streamingToolCallDisplay.js';
 import { CustomizationEnablementKind, CustomizationType, McpAuthRequiredReason, McpServerStatus, type Customization, type McpServerCustomization } from '../../common/state/protocol/channels-session/state.js';
 import { CopilotAgentSession, type ICopilotWorkingDirectoryChangeTransaction } from '../../node/copilot/copilotAgentSession.js';
+import { CopilotGitHubCredentials, CopilotGitHubSessionCredentials } from '../../node/copilot/copilotGitHubCredentials.js';
 import { buildNonPtyShellTerminalUri } from '../../node/copilot/copilotNonPtyShellTerminals.js';
 import { ShellManager } from '../../node/copilot/copilotShellTools.js';
 import { buildMcpChannel } from '../../node/shared/mcpCustomizationController.js';
@@ -807,12 +808,12 @@ async function createAgentSession(disposables: DisposableStore, options?: {
 	/** Platform used to compute the SDK sandbox policy. Defaults to `'linux'` so sandbox tests are deterministic. */
 	platform?: NodeJS.Platform;
 	githubToken?: string;
+	githubCredentials?: CopilotGitHubSessionCredentials;
 	copilotApiEndpoint?: string;
 	gitService?: IAgentHostGitService;
 	gitHubEndpointService?: IAgentHostGitHubEndpointService;
 	restrictedTelemetryContext?: IRestrictedTelemetryContext;
 	restrictedTelemetryContextError?: Error;
-	isLaunchTokenCurrent?: () => boolean;
 	onTurnEnded?: () => void;
 	modelId?: string;
 	enableDevelopmentErrorInjection?: boolean;
@@ -879,7 +880,7 @@ async function createAgentSession(disposables: DisposableStore, options?: {
 		resolvedAgentName: undefined,
 		snapshot: options?.clientSnapshot ?? { tools: [], plugins: [], mcpServers: {} },
 		shellManager: options?.shellManager,
-		githubToken: options?.githubToken,
+		githubCredentials: options?.githubCredentials ?? CopilotGitHubSessionCredentials.fromToken(options?.githubToken),
 		isEphemeral: options?.isEphemeral,
 		hasScopedEditSurface: options?.hasScopedEditSurface,
 	};
@@ -1104,7 +1105,6 @@ async function createAgentSession(disposables: DisposableStore, options?: {
 			customizationDirectory: options?.customizationDirectory,
 			serverToolHost: options?.serverToolHost,
 			platform: options?.platform ?? 'linux',
-			isLaunchTokenCurrent: options?.isLaunchTokenCurrent,
 			onTurnEnded: options?.onTurnEnded,
 			enableDevelopmentErrorInjection: options?.enableDevelopmentErrorInjection ?? true,
 			realpath: options?.realpath,
@@ -13205,9 +13205,10 @@ Use the attached image as context.
 		});
 
 		test('drops an in-flight capture when the launch token is no longer current', async () => {
-			let tokenCurrent = true;
 			const workingDirectory = URI.file('/repo');
 			const telemetryService = new CapturingRestrictedTelemetryService();
+			const githubCredentials = disposables.add(new CopilotGitHubCredentials());
+			githubCredentials.update('github-token', 7200);
 			const gitService: IAgentHostGitService = {
 				...createNoopGitService(),
 				getRepositoryRoot: async () => workingDirectory,
@@ -13222,8 +13223,7 @@ Use the attached image as context.
 				workingDirectory,
 				gitService,
 				telemetryService,
-				githubToken: 'github-token',
-				isLaunchTokenCurrent: () => tokenCurrent,
+				githubCredentials: githubCredentials.forSession(),
 				restrictedTelemetryContext: {
 					restrictedTelemetryEnabled: true,
 					trackingId: 'tracking-id',
@@ -13235,7 +13235,7 @@ Use the attached image as context.
 				},
 			});
 			mockSession.fire('assistant.turn_start', { turnId: 'root-turn' });
-			tokenCurrent = false;
+			githubCredentials.update('replacement-token', 7200);
 			await timeout(0);
 
 			assert.deepStrictEqual(telemetryService.events.filter(event => event.eventName === 'request.repoInfo'), []);
diff --git a/src/vs/platform/agentHost/test/node/copilotGitHubCredentials.test.ts b/src/vs/platform/agentHost/test/node/copilotGitHubCredentials.test.ts
new file mode 100644
index 000000000000..d246dc59bd99
--- /dev/null
+++ b/src/vs/platform/agentHost/test/node/copilotGitHubCredentials.test.ts
@@ -0,0 +1,93 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import assert from 'assert';
+import { ensureNoDisposablesAreLeakedInTestSuite } from '../../../../base/test/common/utils.js';
+import { CopilotGitHubCredentials } from '../../node/copilot/copilotGitHubCredentials.js';
+
+suite('CopilotGitHubCredentials', () => {
+	const disposables = ensureNoDisposablesAreLeakedInTestSuite();
+
+	test('coalesces refreshes and refreshes short-lived tokens before returning them', async () => {
+		let now = 1_000_000;
+		const credentials = disposables.add(new CopilotGitHubCredentials(() => now));
+		credentials.update('initial-token', 7200);
+		let refreshRequests = 0;
+		disposables.add(credentials.onDidRequestRefresh(() => refreshRequests++));
+
+		const firstRefresh = credentials.tokenProvider({ host: 'github.com', sessionId: 'session', reason: 'refresh' });
+		const secondRefresh = credentials.tokenProvider({ host: 'github.com', sessionId: 'session', reason: 'refresh' });
+		assert.strictEqual(refreshRequests, 1);
+
+		now += 1000;
+		credentials.update('refreshed-token', 7200);
+		const refreshedTokens = await Promise.all([firstRefresh, secondRefresh]);
+		credentials.update('short-token', 3600);
+		const preflightRefresh = credentials.tokenProvider({ host: 'github.com', sessionId: 'session', reason: 'initial' });
+		assert.strictEqual(refreshRequests, 2);
+		credentials.update('preflight-refreshed-token', 7200);
+
+		assert.deepStrictEqual({
+			refreshedTokens,
+			preflightToken: await preflightRefresh,
+		}, {
+			refreshedTokens: [
+				{ kind: 'token', accessToken: 'refreshed-token', expiresIn: 7200 },
+				{ kind: 'token', accessToken: 'refreshed-token', expiresIn: 7200 },
+			],
+			preflightToken: { kind: 'token', accessToken: 'preflight-refreshed-token', expiresIn: 7200 },
+		});
+	});
+
+	test('cancels a refresh that does not complete in time', async () => {
+		const credentials = disposables.add(new CopilotGitHubCredentials(() => 1_000_000, 0));
+		credentials.update('expiring-token', 3600);
+		let refreshRequests = 0;
+		disposables.add(credentials.onDidRequestRefresh(() => refreshRequests++));
+
+		const token = await credentials.tokenProvider({ host: 'github.com', sessionId: 'session', reason: 'initial' });
+
+		assert.deepStrictEqual({ refreshRequests, token }, {
+			refreshRequests: 1,
+			token: { kind: 'cancelled' },
+		});
+	});
+
+	test('captures credential mode for each SDK session', () => {
+		const credentials = disposables.add(new CopilotGitHubCredentials());
+		credentials.update('static-token', undefined);
+		const staticSession = credentials.forSession();
+		const modeChange = credentials.update('provider-token', 7200);
+		const providerSession = credentials.forSession();
+
+		staticSession.updateStaticToken('updated-static-token');
+
+		assert.deepStrictEqual({
+			modeChange,
+			staticSession: {
+				usesStaticToken: staticSession.usesStaticToken,
+				token: staticSession.token,
+				options: staticSession.sdkSessionOptions,
+			},
+			providerSession: {
+				usesStaticToken: providerSession.usesStaticToken,
+				token: providerSession.token,
+				hasProvider: providerSession.sdkSessionOptions.gitHubTokenProvider !== undefined,
+			},
+		}, {
+			modeChange: { tokenChanged: true, modeChanged: true },
+			staticSession: {
+				usesStaticToken: true,
+				token: 'updated-static-token',
+				options: { gitHubToken: 'updated-static-token' },
+			},
+			providerSession: {
+				usesStaticToken: false,
+				token: 'provider-token',
+				hasProvider: true,
+			},
+		});
+	});
+});
diff --git a/src/vs/platform/agentHost/test/node/copilotSessionLauncher.test.ts b/src/vs/platform/agentHost/test/node/copilotSessionLauncher.test.ts
index 57e92020cf1e..7fdc6a01416f 100644
--- a/src/vs/platform/agentHost/test/node/copilotSessionLauncher.test.ts
+++ b/src/vs/platform/agentHost/test/node/copilotSessionLauncher.test.ts
@@ -33,6 +33,7 @@ import type { IAgentHostTerminalManager } from '../../node/agentHostTerminalMana
 import { ByokLmBridgeRegistry, IByokLmBridgeRegistry } from '../../node/byokLmBridgeRegistry.js';
 import { ByokLmProxyService, IByokLmProxyService, type IByokLmProxyHandle } from '../../node/copilot/byokLmProxyService.js';
 import { resolveCopilotMcpServerInfo, type ICopilotPluginInfo } from '../../node/copilot/copilotAgent.js';
+import { CopilotGitHubSessionCredentials } from '../../node/copilot/copilotGitHubCredentials.js';
 import { CopilotSessionLauncher, filterClientToolNames, getCopilotAutoTier, getCopilotReasoningEffort, isCopilotReasoningEffort, resolveByokSessionConfig, normalizeToolFilterPatterns, resolveConfiguredReasoningEffortOverride, resolveCopilotAutoTier, resolveCopilotReasoningEffort, toSdkToolFilterPatterns, type CopilotSessionLaunchPlan, type ICopilotSessionRuntime } from '../../node/copilot/copilotSessionLauncher.js';
 import { buildDefaultChatUri } from '../../common/state/sessionState.js';
 import type { IAgentHostSessionOpenTelemetry } from '../../node/agentHostSessionOpenTelemetry.js';
@@ -511,7 +512,7 @@ suite('CopilotSessionLauncher shared session config', () => {
 			disabledRootMcpServers: ['github', 'azure'],
 			activeClientToolSet: new ActiveClientToolSet(),
 			shellManager: undefined,
-			githubToken: undefined,
+			githubCredentials: CopilotGitHubSessionCredentials.fromToken(undefined),
 		};
 		const createPlan: CopilotSessionLaunchPlan = {
 			...basePlan,
@@ -678,7 +679,7 @@ suite('CopilotSessionLauncher resume fallback', () => {
 				snapshot: { tools: [], plugins: [], mcpServers: {} },
 				activeClientToolSet: new ActiveClientToolSet(),
 				shellManager: undefined,
-				githubToken: undefined,
+				githubCredentials: CopilotGitHubSessionCredentials.fromToken(undefined),
 				kind: 'resume',
 				fallback: { model: undefined },
 			},
@@ -902,7 +903,7 @@ suite('CopilotSessionLauncher GPT-5.6 customizations', () => {
 			snapshot: { tools: [], plugins: [], mcpServers: {} },
 			activeClientToolSet: new ActiveClientToolSet(),
 			shellManager: undefined,
-			githubToken: undefined,
+			githubCredentials: CopilotGitHubSessionCredentials.fromToken(undefined),
 			model: { id: 'claude-sonnet-4.5', config: {} },
 		};
 
@@ -933,7 +934,7 @@ suite('CopilotSessionLauncher GPT-5.6 customizations', () => {
 			snapshot: { tools: [], plugins: [], mcpServers: {} },
 			activeClientToolSet: new ActiveClientToolSet(),
 			shellManager: undefined,
-			githubToken: undefined,
+			githubCredentials: CopilotGitHubSessionCredentials.fromToken(undefined),
 			model: { id: 'claude-sonnet-4.5', config: {} },
 		};
 
@@ -963,7 +964,7 @@ suite('CopilotSessionLauncher GPT-5.6 customizations', () => {
 			snapshot: { tools: [], plugins: [], mcpServers: {} },
 			activeClientToolSet: new ActiveClientToolSet(),
 			shellManager: undefined,
-			githubToken: undefined,
+			githubCredentials: CopilotGitHubSessionCredentials.fromToken(undefined),
 			model: { id: 'claude-sonnet-4.5', config: {} },
 		};
 
@@ -993,7 +994,7 @@ suite('CopilotSessionLauncher GPT-5.6 customizations', () => {
 			snapshot: { tools: [], plugins: [], mcpServers: {} },
 			activeClientToolSet: new ActiveClientToolSet(),
 			shellManager: undefined,
-			githubToken: undefined,
+			githubCredentials: CopilotGitHubSessionCredentials.fromToken(undefined),
 			model: { id: 'claude-sonnet-4.5', config: {} },
 		};
 
@@ -1020,7 +1021,7 @@ suite('CopilotSessionLauncher GPT-5.6 customizations', () => {
 			snapshot: { tools: [], plugins: [], mcpServers: {} },
 			activeClientToolSet: new ActiveClientToolSet(),
 			shellManager: undefined,
-			githubToken: undefined,
+			githubCredentials: CopilotGitHubSessionCredentials.fromToken(undefined),
 			fallback: { model: { id: 'gpt-5.6-sol', config: {} } },
 		};
 
@@ -1333,7 +1334,7 @@ suite('CopilotSessionLauncher resume config', () => {
 			snapshot,
 			activeClientToolSet: new ActiveClientToolSet(),
 			shellManager: undefined,
-			githubToken: 'token',
+			githubCredentials: CopilotGitHubSessionCredentials.fromToken('token'),
 			fallback: { model },
 		};
 		const runtime = { createClientSdkTools, createServerSdkTools: () => [] };
@@ -1565,7 +1566,7 @@ suite('CopilotSessionLauncher auto tier', () => {
 			snapshot: { tools: [], plugins: [], mcpServers: {} },
 			activeClientToolSet: new ActiveClientToolSet(),
 			shellManager: undefined,
-			githubToken: undefined,
+			githubCredentials: CopilotGitHubSessionCredentials.fromToken(undefined),
 		};
 		const plan: CopilotSessionLaunchPlan = kind === 'create'
 			? { ...base, kind: 'create', model }
diff --git a/src/vs/platform/agentHost/test/node/mockAgent.ts b/src/vs/platform/agentHost/test/node/mockAgent.ts
index fe321991e33c..e7f189b5c525 100644
--- a/src/vs/platform/agentHost/test/node/mockAgent.ts
+++ b/src/vs/platform/agentHost/test/node/mockAgent.ts
@@ -85,7 +85,7 @@ export class MockAgent implements IAgent {
 	readonly respondToPermissionCalls: { requestId: string; approved: boolean }[] = [];
 	readonly changeModelCalls: { session: URI; model: ModelSelection; chat?: URI }[] = [];
 	readonly changeAgentCalls: { session: URI; agent: AgentSelection | undefined; chat?: URI }[] = [];
-	readonly authenticateCalls: { resource: string; token: string }[] = [];
+	readonly authenticateCalls: { resource: string; token: string; expiresIn?: number }[] = [];
 	readonly setClientCustomizationsCalls: { clientId: string; customizations: ClientPluginCustomization[] }[] = [];
 	readonly setClientToolsCalls: { clientId: string; tools: readonly ToolDefinition[] }[] = [];
 	readonly removeActiveClientCalls: { chat: URI; clientId: string }[] = [];
@@ -401,8 +401,8 @@ export class MockAgent implements IAgent {
 
 	async materializeChat(_chat: URI, _context: URI | IAgentChatContext, _providerData: string | undefined): Promise<IAgentCreateChatResult | void> { }
 
-	async authenticate(resource: string, token: string): Promise<boolean> {
-		this.authenticateCalls.push({ resource, token });
+	async authenticate(resource: string, token: string, expiresIn?: number): Promise<boolean> {
+		this.authenticateCalls.push({ resource, token, ...(expiresIn === undefined ? {} : { expiresIn }) });
 		return true;
 	}
 
diff --git a/src/vs/platform/extensions/common/extensionsApiProposals.ts b/src/vs/platform/extensions/common/extensionsApiProposals.ts
index bfc17bad459a..77ae2c267cee 100644
--- a/src/vs/platform/extensions/common/extensionsApiProposals.ts
+++ b/src/vs/platform/extensions/common/extensionsApiProposals.ts
@@ -48,6 +48,9 @@ const _allApiProposals = {
 	authSessionAudience: {
 		proposal: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.authSessionAudience.d.ts',
 	},
+	authSessionExpiration: {
+		proposal: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.authSessionExpiration.d.ts',
+	},
 	authenticationChallenges: {
 		proposal: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.authenticationChallenges.d.ts',
 	},
diff --git a/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostAuth.ts b/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostAuth.ts
index 81db903d83b9..837e0001e8df 100644
--- a/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostAuth.ts
+++ b/src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostAuth.ts
@@ -166,8 +166,8 @@ export class AgentHostAuthTokenCache {
 	}
 }
 
-type AuthenticationTokenResolution =
-	| { readonly kind: 'resolved'; readonly token: string }
+type AuthenticationSessionResolution =
+	| { readonly kind: 'resolved'; readonly session: AuthenticationSession }
 	| { readonly kind: 'signedOut' }
 	| { readonly kind: 'unavailable' };
 
@@ -217,7 +217,7 @@ export class AgentHostAuthenticationRecovery {
 		const commandService = accessor.get(ICommandService);
 		const logService = accessor.get(ILogService);
 		const scopes = resource.scopes_supported ?? [];
-		const resolution = await resolveAuthenticationTokenForResource(
+		const resolution = await resolveAuthenticationSessionForResource(
 			URI.parse(resource.resource),
 			resource.authorization_servers ?? [],
 			scopes,
@@ -227,23 +227,23 @@ export class AgentHostAuthenticationRecovery {
 		);
 		throwIfAuthenticationStale(options);
 		if (resolution.kind !== 'resolved') {
-			logAuthenticationTokenResolution(logService, options.logPrefix, resource.resource, resolution);
+			logAuthenticationSessionResolution(logService, options.logPrefix, resource.resource, resolution);
 			if (resolution.kind === 'signedOut') {
 				this._resentTokens.delete(key);
 			}
 			return;
 		}
-		const token = resolution.token;
+		const session = resolution.session;
 
 		const previousToken = this._resentTokens.get(key);
-		if (previousToken !== undefined && previousToken === token) {
+		if (previousToken !== undefined && previousToken === session.accessToken) {
 			options.authTokenCache?.clear(resource.resource, resource.scopes_supported);
 			throwIfAuthenticationStale(options);
-			const interactiveToken = await forceAuthenticationInteractively(authenticationService, commandService, logService, resource, options);
+			const interactiveSession = await forceAuthenticationInteractively(authenticationService, commandService, logService, resource, options);
 			throwIfAuthenticationStale(options);
-			if (interactiveToken) {
-				this._resentTokens.set(key, interactiveToken);
-				if (interactiveToken === token) {
+			if (interactiveSession) {
+				this._resentTokens.set(key, interactiveSession.accessToken);
+				if (interactiveSession.accessToken === session.accessToken) {
 					logService.info(`${options.logPrefix} Interactive authentication completed without a new token for ${resource.resource}`);
 				}
 			}
@@ -251,28 +251,28 @@ export class AgentHostAuthenticationRecovery {
 		}
 
 		options.authTokenCache?.clear(resource.resource, resource.scopes_supported);
-		if (await forwardAuthenticationToken(options, resource.resource, resource.scopes_supported ?? [], token)) {
-			this._resentTokens.set(key, token);
+		if (await forwardAuthenticationToken(options, resource.resource, resource.scopes_supported ?? [], session)) {
+			this._resentTokens.set(key, session.accessToken);
 			logService.info(`${options.logPrefix} Authenticating for resource: ${resource.resource}`);
 		}
 	}
 }
 
 /**
- * Resolves a bearer token for a protected resource by trying each
+ * Resolves an authentication session for a protected resource by trying each
  * authorization server in order. First attempts an exact scope match,
  * then falls back to finding the session whose scopes are the narrowest
  * superset of the requested scopes.
  */
-export async function resolveTokenForResource(
+export async function resolveSessionForResource(
 	resourceServer: URI,
 	authorizationServers: readonly string[],
 	scopes: readonly string[],
 	authenticationService: IAuthenticationService,
 	logService: ILogService,
 	logPrefix: string,
-): Promise<string | undefined> {
-	const resolution = await resolveAuthenticationTokenForResource(
+): Promise<AuthenticationSession | undefined> {
+	const resolution = await resolveAuthenticationSessionForResource(
 		resourceServer,
 		authorizationServers,
 		scopes,
@@ -280,17 +280,17 @@ export async function resolveTokenForResource(
 		logService,
 		logPrefix,
 	);
-	return resolution.kind === 'resolved' ? resolution.token : undefined;
+	return resolution.kind === 'resolved' ? resolution.session : undefined;
 }
 
-async function resolveAuthenticationTokenForResource(
+async function resolveAuthenticationSessionForResource(
 	resourceServer: URI,
 	authorizationServers: readonly string[],
 	scopes: readonly string[],
 	authenticationService: IAuthenticationService,
 	logService: ILogService,
 	logPrefix: string,
-): Promise<AuthenticationTokenResolution> {
+): Promise<AuthenticationSessionResolution> {
 	let hasUnavailableProvider = false;
 	for (const server of authorizationServers) {
 		const serverUri = URI.parse(server);
@@ -328,7 +328,7 @@ async function resolveAuthenticationTokenForResource(
 		}
 		const exactSession = sessions[0];
 		if (exactSession) {
-			return { kind: 'resolved', token: exactSession.accessToken };
+			return { kind: 'resolved', session: exactSession };
 		}
 
 		let allSessions: readonly AuthenticationSession[];
@@ -341,7 +341,7 @@ async function resolveAuthenticationTokenForResource(
 			continue;
 		}
 		const requestedSet = new Set(scopes);
-		let bestToken: string | undefined;
+		let bestSession: AuthenticationSession | undefined;
 		let bestExtraScopes = Infinity;
 		for (const session of allSessions) {
 			const sessionScopes = new Set(session.scopes);
@@ -356,12 +356,12 @@ async function resolveAuthenticationTokenForResource(
 				const extraScopes = sessionScopes.size - requestedSet.size;
 				if (extraScopes < bestExtraScopes) {
 					bestExtraScopes = extraScopes;
-					bestToken = session.accessToken;
+					bestSession = session;
 				}
 			}
 		}
-		if (bestToken) {
-			return { kind: 'resolved', token: bestToken };
+		if (bestSession) {
+			return { kind: 'resolved', session: bestSession };
 		}
 	}
 	return hasUnavailableProvider ? { kind: 'unavailable' } : { kind: 'signedOut' };
@@ -372,6 +372,8 @@ export interface IAgentHostAuthenticateRequest {
 	readonly scopes?: readonly string[];
 	/** An empty token revokes the credential previously forwarded for this resource and scope set. */
 	readonly token: string;
+	/** The access token's remaining lifetime in seconds, when known. */
+	readonly expiresIn?: number;
 }
 
 export interface IAgentHostAuthenticationOptions {
@@ -406,12 +408,19 @@ async function forwardAuthenticationToken(
 	options: Pick<IAgentHostAuthenticationOptions, 'authTokenCache' | 'authenticate' | 'isCurrent'>,
 	resource: string,
 	scopes: readonly string[] | undefined,
-	token: string,
+	session: Pick<AuthenticationSession, 'accessToken' | 'expiresIn'> | undefined,
 ): Promise<boolean> {
 	throwIfAuthenticationStale(options);
-	const request = { resource, scopes, token };
+	const token = session?.accessToken ?? '';
+	const expiresIn = session?.expiresIn;
+	const request: IAgentHostAuthenticateRequest = {
+		resource,
+		scopes,
+		token,
+		...(expiresIn !== undefined && Number.isInteger(expiresIn) && expiresIn > 0 ? { expiresIn } : {}),
+	};
 	if (options.authTokenCache) {
-		return options.authTokenCache.authenticate(resource, scopes, token, () => options.authenticate(request));
+		return options.authTokenCache.authenticate(resource, scopes ?? [], token, () => options.authenticate(request));
 	}
 	await options.authenticate(request);
 	return true;
@@ -457,7 +466,7 @@ export async function authenticateProtectedResourcesWithToken(
 	options: Pick<IAgentHostAuthenticationOptions, 'authTokenCache' | 'authenticate' | 'isCurrent'>,
 ): Promise<void> {
 	for (const resource of protectedResources) {
-		await forwardAuthenticationToken(options, resource.resource, resource.scopes_supported, token);
+		await forwardAuthenticationToken(options, resource.resource, resource.scopes_supported, { accessToken: token });
 	}
 }
 
@@ -504,24 +513,24 @@ export async function revokeAuthenticationForRemovedSessions(
 			}
 			reconciledResources.add(key);
 
-			const resolution = await resolveTokenForProtectedResource(authenticationService, logService, resource, options);
+			const resolution = await resolveSessionForProtectedResource(authenticationService, logService, resource, options);
 			throwIfAuthenticationStale(options);
 			if (resolution.kind === 'unavailable') {
-				logAuthenticationTokenResolution(logService, options.logPrefix, resource.resource, resolution);
+				logAuthenticationSessionResolution(logService, options.logPrefix, resource.resource, resolution);
 				continue;
 			}
 			if (resolution.kind === 'resolved') {
 				// Another account still covers this resource; forward it so the host
 				// swaps credentials instead of losing them. Unchanged tokens are
 				// deduped by the cache.
-				if (await forwardAuthenticationToken(options, resource.resource, scopes, resolution.token)) {
+				if (await forwardAuthenticationToken(options, resource.resource, scopes, resolution.session)) {
 					logService.info(`${options.logPrefix} Authenticating for resource after session removal: ${resource.resource}`);
 				}
 				continue;
 			}
 
 			options.authTokenCache?.clear(resource.resource, scopes);
-			if (await forwardAuthenticationToken(options, resource.resource, scopes, '')) {
+			if (await forwardAuthenticationToken(options, resource.resource, scopes, undefined)) {
 				logService.info(`${options.logPrefix} Clearing authentication for resource after session removal: ${resource.resource}`);
 			}
 		}
@@ -576,14 +585,14 @@ async function authenticateProtectedResourceWithServices(
 	options: IAgentHostAuthenticationOptions,
 ): Promise<boolean> {
 	throwIfAuthenticationStale(options);
-	const resolution = await resolveTokenForProtectedResource(authenticationService, logService, resource, options);
+	const resolution = await resolveSessionForProtectedResource(authenticationService, logService, resource, options);
 	throwIfAuthenticationStale(options);
 	if (resolution.kind !== 'resolved') {
-		logAuthenticationTokenResolution(logService, options.logPrefix, resource.resource, resolution);
+		logAuthenticationSessionResolution(logService, options.logPrefix, resource.resource, resolution);
 		return false;
 	}
 
-	const authenticated = await forwardAuthenticationToken(options, resource.resource, resource.scopes_supported ?? [], resolution.token);
+	const authenticated = await forwardAuthenticationToken(options, resource.resource, resource.scopes_supported ?? [], resolution.session);
 	if (!authenticated) {
 		logService.trace(`${options.logPrefix} Authentication state for ${resource.resource} unchanged; skipping authenticate RPC`);
 		return false;
@@ -592,13 +601,13 @@ async function authenticateProtectedResourceWithServices(
 	return true;
 }
 
-async function resolveTokenForProtectedResource(
+async function resolveSessionForProtectedResource(
 	authenticationService: IAuthenticationService,
 	logService: ILogService,
 	resource: ProtectedResourceMetadata,
 	options: Pick<IAgentHostAuthenticationOptions, 'logPrefix'>,
-): Promise<AuthenticationTokenResolution> {
-	return resolveAuthenticationTokenForResource(
+): Promise<AuthenticationSessionResolution> {
+	return resolveAuthenticationSessionForResource(
 		URI.parse(resource.resource),
 		resource.authorization_servers ?? [],
 		resource.scopes_supported ?? [],
@@ -608,11 +617,11 @@ async function resolveTokenForProtectedResource(
 	);
 }
 
-function logAuthenticationTokenResolution(
+function logAuthenticationSessionResolution(
 	logService: ILogService,
 	logPrefix: string,
 	resource: string,
-	resolution: Exclude<AuthenticationTokenResolution, { readonly kind: 'resolved' }>,
+	resolution: Exclude<AuthenticationSessionResolution, { readonly kind: 'resolved' }>,
 ): void {
 	if (resolution.kind === 'unavailable') {
 		logService.info(`${logPrefix} Authentication provider is not ready for resource: ${resource}; deferring authentication`);
@@ -637,7 +646,7 @@ export async function resolveAuthenticationInteractively(
 		throwIfAuthenticationStale(options);
 		const resourceUri = URI.parse(resource.resource);
 		const scopes = resource.scopes_supported ?? [];
-		const existingToken = await resolveTokenForResource(
+		const existingSession = await resolveSessionForResource(
 			resourceUri,
 			resource.authorization_servers ?? [],
 			scopes,
@@ -646,8 +655,8 @@ export async function resolveAuthenticationInteractively(
 			options.logPrefix,
 		);
 		throwIfAuthenticationStale(options);
-		if (existingToken) {
-			await forwardAuthenticationToken(options, resource.resource, scopes, existingToken);
+		if (existingSession) {
+			await forwardAuthenticationToken(options, resource.resource, scopes, existingSession);
 			logService.info(`${options.logPrefix} Interactive authentication succeeded for ${resource.resource}`);
 			return true;
 		}
@@ -664,7 +673,7 @@ async function forceAuthenticationInteractively(
 	logService: ILogService,
 	resource: ProtectedResourceMetadata,
 	options: IAgentHostAuthenticationOptions,
-): Promise<string | undefined> {
+): Promise<AuthenticationSession | undefined> {
 	throwIfAuthenticationStale(options);
 	const scopes = resource.scopes_supported ?? [];
 	const setupResult = await commandService.executeCommand<IChatSetupResult>(CHAT_SETUP_ACTION_ID, undefined, {
@@ -681,7 +690,7 @@ async function forceAuthenticationInteractively(
 	if (!setupResult.success) {
 		throw setupResult.error ?? new Error(localize('agentHost.signInFailed', "Failed to sign in to use GitHub Copilot."));
 	}
-	const token = await resolveTokenForResource(
+	const session = await resolveSessionForResource(
 		URI.parse(resource.resource),
 		resource.authorization_servers ?? [],
 		scopes,
@@ -690,16 +699,16 @@ async function forceAuthenticationInteractively(
 		options.logPrefix,
 	);
 	throwIfAuthenticationStale(options);
-	if (!token) {
+	if (!session) {
 		logService.info(`${options.logPrefix} Interactive authentication did not provide a token for ${resource.resource}`);
 		return undefined;
 	}
 	options.authTokenCache?.clear(resource.resource, scopes);
-	if (!await forwardAuthenticationToken(options, resource.resource, scopes, token)) {
+	if (!await forwardAuthenticationToken(options, resource.resource, scopes, session)) {
 		return undefined;
 	}
 	logService.info(`${options.logPrefix} Interactive authentication completed for ${resource.resource}`);
-	return token;
+	return session;
 }
 
 export async function resolveMcpServerAuthentication(
@@ -884,7 +893,7 @@ async function authenticateMcpSession(
 	updateAccess: boolean,
 	agentHost: { readonly authority: string; readonly label: string } | undefined,
 ): Promise<void> {
-	await forwardAuthenticationToken(options, options.mcpServerUrl, scopes, session.accessToken);
+	await forwardAuthenticationToken(options, options.mcpServerUrl, scopes, session);
 	if (updateAccess) {
 		authenticationMcpAccessService.updateAllowedMcpServers(providerId, session.account.label, [{ id: options.mcpServerId, name: options.mcpServerName, allowed: true, url: options.mcpServerUrl, agentHost }]);
 		authenticationMcpService.updateAccountPreference(options.mcpServerId, providerId, session.account);
diff --git a/src/vs/workbench/contrib/chat/test/browser/agentSessions/agentHostAuth.test.ts b/src/vs/workbench/contrib/chat/test/browser/agentSessions/agentHostAuth.test.ts
index edbdee0d59a0..e4d2fb8c5a40 100644
--- a/src/vs/workbench/contrib/chat/test/browser/agentSessions/agentHostAuth.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/agentSessions/agentHostAuth.test.ts
@@ -21,7 +21,7 @@ import { IAuthenticationMcpUsageService } from '../../../../../services/authenti
 import { IAuthenticationService, type AuthenticationSession, type IAuthenticationProvider } from '../../../../../services/authentication/common/authentication.js';
 import { IDynamicAuthenticationProviderStorageService } from '../../../../../services/authentication/common/dynamicAuthenticationProviderStorage.js';
 import { CHAT_SETUP_ACTION_ID } from '../../../browser/actions/chatActions.js';
-import { AgentHostAuthenticationRecovery, authenticateProtectedResources, resolveAuthenticationInteractively, resolveTokenForResource, AgentHostAuthTokenCache, agentHostMcpServerId, resolveMcpServerAuthentication, modelRequiresAgentAuthentication, revokeAuthenticationForRemovedSessions, type IAgentHostAuthenticationOptions } from '../../../browser/agentSessions/agentHost/agentHostAuth.js';
+import { AgentHostAuthenticationRecovery, authenticateProtectedResources, resolveAuthenticationInteractively, resolveSessionForResource, AgentHostAuthTokenCache, agentHostMcpServerId, resolveMcpServerAuthentication, modelRequiresAgentAuthentication, revokeAuthenticationForRemovedSessions, type IAgentHostAuthenticationOptions } from '../../../browser/agentSessions/agentHost/agentHostAuth.js';
 import { createAgentModelByokMeta } from '../../../../../../platform/agentHost/common/agentModelByokMeta.js';
 
 class TestCommandService extends mock<ICommandService>() {
@@ -46,7 +46,7 @@ function createAuthInstantiationService(disposables: Pick<DisposableStore, 'add'
 
 function createMockAuthService(overrides: {
 	getOrActivateProviderIdForServer?: (serverUri: URI, resourceUri: URI) => Promise<string | undefined>;
-	getSessions?: (providerId: string, scopes: string[] | undefined, options: any, activate: boolean) => Promise<readonly { scopes: string[]; accessToken: string }[]>;
+	getSessions?: (providerId: string, scopes: string[] | undefined, options: any, activate: boolean) => Promise<readonly { scopes: string[]; accessToken: string; expiresIn?: number }[]>;
 	createSession?: (providerId: string, scopes: string[], options: any) => Promise<{ accessToken: string }>;
 	createDynamicAuthenticationProvider?: (...args: Parameters<IAuthenticationService['createDynamicAuthenticationProvider']>) => Promise<{ readonly id: string } | undefined>;
 	getProvider?: IAuthenticationService['getProvider'];
@@ -93,7 +93,7 @@ suite('agentHostMcpServerId', () => {
 	});
 });
 
-suite('resolveTokenForResource', () => {
+suite('resolveSessionForResource', () => {
 
 	const log = new NullLogService();
 	const resource = URI.parse('https://api.example.com');
@@ -102,7 +102,7 @@ suite('resolveTokenForResource', () => {
 
 	test('returns undefined when no authorization servers provided', async () => {
 		const authService = createMockAuthService({});
-		const token = await resolveTokenForResource(resource, [], ['read'], authService, log, 'test');
+		const token = (await resolveSessionForResource(resource, [], ['read'], authService, log, 'test'))?.accessToken;
 		assert.strictEqual(token, undefined);
 	});
 
@@ -110,7 +110,7 @@ suite('resolveTokenForResource', () => {
 		const authService = createMockAuthService({
 			getOrActivateProviderIdForServer: () => Promise.resolve(undefined),
 		});
-		const token = await resolveTokenForResource(resource, ['https://auth.example.com'], ['read'], authService, log, 'test');
+		const token = (await resolveSessionForResource(resource, ['https://auth.example.com'], ['read'], authService, log, 'test'))?.accessToken;
 		assert.strictEqual(token, undefined);
 	});
 
@@ -124,7 +124,7 @@ suite('resolveTokenForResource', () => {
 				return Promise.resolve([]);
 			},
 		});
-		const token = await resolveTokenForResource(resource, ['https://auth.example.com'], ['read'], authService, log, 'test');
+		const token = (await resolveSessionForResource(resource, ['https://auth.example.com'], ['read'], authService, log, 'test'))?.accessToken;
 		assert.strictEqual(token, 'exact-token');
 	});
 
@@ -143,7 +143,7 @@ suite('resolveTokenForResource', () => {
 				]);
 			},
 		});
-		const token = await resolveTokenForResource(resource, ['https://auth.example.com'], ['read'], authService, log, 'test');
+		const token = (await resolveSessionForResource(resource, ['https://auth.example.com'], ['read'], authService, log, 'test'))?.accessToken;
 		assert.strictEqual(token, 'narrow-token');
 	});
 
@@ -160,7 +160,7 @@ suite('resolveTokenForResource', () => {
 				]);
 			},
 		});
-		const token = await resolveTokenForResource(resource, ['https://auth.example.com'], ['read'], authService, log, 'test');
+		const token = (await resolveSessionForResource(resource, ['https://auth.example.com'], ['read'], authService, log, 'test'))?.accessToken;
 		assert.strictEqual(token, undefined);
 	});
 
@@ -176,11 +176,11 @@ suite('resolveTokenForResource', () => {
 			},
 			getSessions: () => Promise.resolve([{ scopes: ['read'], accessToken: 'server2-token' }]),
 		});
-		const token = await resolveTokenForResource(
+		const token = (await resolveSessionForResource(
 			resource,
 			['https://auth1.example.com', 'https://auth2.example.com'],
 			['read'], authService, log, 'test',
-		);
+		))?.accessToken;
 		assert.strictEqual(token, 'server2-token');
 		assert.strictEqual(calls.length, 2);
 	});
@@ -1137,14 +1137,14 @@ suite('authenticateProtectedResources', () => {
 			getOrActivateProviderIdForServer: () => Promise.resolve('provider-1'),
 			getSessions: (_providerId, scopes) => {
 				if (scopes) {
-					return Promise.resolve([{ scopes: ['read'], accessToken: 'cached-token' }]);
+					return Promise.resolve([{ scopes: ['read'], accessToken: 'cached-token', expiresIn: 3600 }]);
 				}
 
 				return Promise.resolve([]);
 			},
 		});
 		const cache = new AgentHostAuthTokenCache();
-		const requests: { resource: string; scopes?: readonly string[]; token: string }[] = [];
+		const requests: { resource: string; scopes?: readonly string[]; token: string; expiresIn?: number }[] = [];
 		const agents = [{ protectedResources: [protectedResource] }] as unknown as readonly AgentInfo[];
 		const instantiationService = createAuthInstantiationService(disposables, authService);
 
@@ -1163,6 +1163,25 @@ suite('authenticateProtectedResources', () => {
 			},
 		});
 
+		assert.deepStrictEqual(requests, [{ resource: protectedResource.resource, scopes: ['read'], token: 'cached-token', expiresIn: 3600 }]);
+	});
+
+	test('forwards a token without a malformed session expiry', async () => {
+		const authService = createMockAuthService({
+			getOrActivateProviderIdForServer: () => Promise.resolve('provider-1'),
+			getSessions: (_providerId, scopes) => Promise.resolve(scopes ? [{ scopes: ['read'], accessToken: 'cached-token', expiresIn: 0 }] : []),
+		});
+		const requests: { resource: string; scopes?: readonly string[]; token: string; expiresIn?: number }[] = [];
+		const agents = [{ protectedResources: [protectedResource] }] as unknown as readonly AgentInfo[];
+		const instantiationService = createAuthInstantiationService(disposables, authService);
+
+		await instantiationService.invokeFunction(authenticateProtectedResources, agents, {
+			logPrefix: '[AgentHost]',
+			authenticate: async request => {
+				requests.push(request);
+			},
+		});
+
 		assert.deepStrictEqual(requests, [{ resource: protectedResource.resource, scopes: ['read'], token: 'cached-token' }]);
 	});
 
diff --git a/src/vs/workbench/services/authentication/common/authentication.ts b/src/vs/workbench/services/authentication/common/authentication.ts
index bd9683498b33..04c67d5c86b3 100644
--- a/src/vs/workbench/services/authentication/common/authentication.ts
+++ b/src/vs/workbench/services/authentication/common/authentication.ts
@@ -34,6 +34,7 @@ export interface AuthenticationSession {
 	account: AuthenticationSessionAccount;
 	scopes: ReadonlyArray<string>;
 	idToken?: string;
+	expiresIn?: number;
 }
 
 export interface AuthenticationSessionsChangeEvent {
diff --git a/src/vscode-dts/vscode.proposed.authSessionExpiration.d.ts b/src/vscode-dts/vscode.proposed.authSessionExpiration.d.ts
new file mode 100644
index 000000000000..4d183777a704
--- /dev/null
+++ b/src/vscode-dts/vscode.proposed.authSessionExpiration.d.ts
@@ -0,0 +1,18 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+declare module 'vscode' {
+
+	export interface AuthenticationSession {
+		/**
+		 * The access token's remaining lifetime, in seconds, when the authentication provider returns the session.
+		 *
+		 * This corresponds to `expires_in` in an OAuth 2.0 token response. Providers returning
+		 * cached sessions must recompute this value. This is undefined when the authentication
+		 * provider does not know the access token's expiry. When defined, this must be a positive integer.
+		 */
+		readonly expiresIn?: number;
+	}
+}