diff --git a/packages/plugin-ext/src/common/plugin-api-rpc.ts b/packages/plugin-ext/src/common/plugin-api-rpc.ts
index 1af94682a501f..cedcc7f047c2e 100644
--- a/packages/plugin-ext/src/common/plugin-api-rpc.ts
+++ b/packages/plugin-ext/src/common/plugin-api-rpc.ts
@@ -702,7 +702,7 @@ export interface WorkspaceExt {
     $provideTextDocumentContent(uri: string): Promise<string | undefined | null>;
     $onTextSearchResult(searchRequestId: number, done: boolean, result?: SearchInWorkspaceResult): void;
     $onWorkspaceTrustChanged(trust: boolean | undefined): void;
-    $registerEditSessionIdentityProvider(scheme: string, provider: theia.EditSessionIdentityProvider): theia.Disposable
+    $registerEditSessionIdentityProvider(scheme: string, provider: theia.EditSessionIdentityProvider): theia.Disposable;
 }
 
 export interface TimelineExt {
diff --git a/packages/plugin-ext/src/plugin/plugin-context.ts b/packages/plugin-ext/src/plugin/plugin-context.ts
index 0e7d98ddcfd22..d74040f53ebc5 100644
--- a/packages/plugin-ext/src/plugin/plugin-context.ts
+++ b/packages/plugin-ext/src/plugin/plugin-context.ts
@@ -193,7 +193,8 @@ import {
     TextDiffTabInput,
     TextMergeTabInput,
     WebviewEditorTabInput,
-    DocumentPasteEdit
+    DocumentPasteEdit,
+    EditSessionIdentityMatch
 } from './types-impl';
 import { AuthenticationExtImpl } from './authentication-ext';
 import { SymbolKind } from '../common/plugin-api-rpc-model';
@@ -721,6 +722,15 @@ export function createAPIFactory(
             },
             registerEditSessionIdentityProvider(scheme: string, provider: theia.EditSessionIdentityProvider) {
                 return workspaceExt.$registerEditSessionIdentityProvider(scheme, provider);
+            },
+            /**
+             * @stubbed
+             * This is a stub implementation, lacking a Session Identity server/service, and so the event
+             * should never fire. This should minimally satisfy vscode built-in extensions that decide to 
+             * use this proposed API.
+             */
+            get onWillCreateEditSessionIdentity(): theia.Event<theia.EditSessionIdentityWillCreateEvent> {
+                return workspaceExt.onWillCreateEditSessionIdentityEvent;
             }
         };
 
@@ -1353,7 +1363,8 @@ export function createAPIFactory(
             TabInputTerminal: TerminalEditorTabInput,
             TerminalLocation,
             TerminalExitReason,
-            DocumentPasteEdit
+            DocumentPasteEdit,
+            EditSessionIdentityMatch
         };
     };
 }
diff --git a/packages/plugin-ext/src/plugin/types-impl.ts b/packages/plugin-ext/src/plugin/types-impl.ts
index 7fe67bfc85a84..4efb8836e1932 100644
--- a/packages/plugin-ext/src/plugin/types-impl.ts
+++ b/packages/plugin-ext/src/plugin/types-impl.ts
@@ -3488,3 +3488,11 @@ export class DocumentPasteEdit {
     additionalEdit?: WorkspaceEdit;
 }
 // #endregion
+
+// #region DocumentPaste
+export enum EditSessionIdentityMatch {
+    Complete = 100,
+    Partial = 50,
+    None = 0
+}
+// #endregion
diff --git a/packages/plugin-ext/src/plugin/workspace.ts b/packages/plugin-ext/src/plugin/workspace.ts
index a768cf4006da9..7912d3e905ce0 100644
--- a/packages/plugin-ext/src/plugin/workspace.ts
+++ b/packages/plugin-ext/src/plugin/workspace.ts
@@ -60,6 +60,14 @@ export class WorkspaceExtImpl implements WorkspaceExt {
     private didGrantWorkspaceTrustEmitter = new Emitter<void>();
     public readonly onDidGrantWorkspaceTrust: Event<void> = this.didGrantWorkspaceTrustEmitter.event;
 
+    private willCreateEditSessionIdentityEmitter = new Emitter<theia.EditSessionIdentityWillCreateEvent>();
+    /**
+     * @stubbed
+     * This is a stub implementation, lacking a Session Identity server/service, and so the event
+     * should never fire
+     */
+    public readonly onWillCreateEditSessionIdentityEvent: Event<theia.EditSessionIdentityWillCreateEvent> = this.willCreateEditSessionIdentityEmitter.event;
+
     constructor(rpc: RPCProtocol,
         private editorsAndDocuments: EditorsAndDocumentsExtImpl,
         private messageService: MessageRegistryExt) {
diff --git a/packages/plugin/src/theia-proposed.d.ts b/packages/plugin/src/theia-proposed.d.ts
index 9ce7b3c3db907..c9510d9563ec1 100644
--- a/packages/plugin/src/theia-proposed.d.ts
+++ b/packages/plugin/src/theia-proposed.d.ts
@@ -686,6 +686,10 @@ export module '@theia/plugin' {
 
     // #region SessionIdentityProvider
     export namespace workspace {
+        /**
+         * An event that is emitted when an edit session identity is about to be requested.
+         */
+        export const onWillCreateEditSessionIdentity: Event<EditSessionIdentityWillCreateEvent>;
         /**
          *
          * @param scheme The URI scheme that this provider can provide edit session identities for.
@@ -700,9 +704,46 @@ export module '@theia/plugin' {
          *
          * @param workspaceFolder The workspace folder to provide an edit session identity for.
          * @param token A cancellation token for the request.
-         * @returns An string representing the edit session identity for the requested workspace folder.
+         * @returns An {@link EditSessionIdentityMatch} representing the edit session identity match confidence for the provided identities.
          */
         provideEditSessionIdentity(workspaceFolder: WorkspaceFolder, token: CancellationToken): ProviderResult<string>;
+
+        /**
+         *
+         * @param identity1 An edit session identity.
+         * @param identity2 A second edit session identity to compare to @param identity1.
+         * @param token A cancellation token for the request.
+         * @returns An {@link EditSessionIdentityMatch} representing the edit session identity match confidence for the provided identities.
+         */
+        provideEditSessionIdentityMatch(identity1: string, identity2: string, token: CancellationToken): ProviderResult<EditSessionIdentityMatch>;
+    }
+
+    export enum EditSessionIdentityMatch {
+        Complete = 100,
+        Partial = 50,
+        None = 0
+    }
+
+    export interface EditSessionIdentityWillCreateEvent {
+
+        /**
+         * A cancellation token.
+         */
+        readonly token: CancellationToken;
+
+        /**
+         * The workspace folder to create an edit session identity for.
+         */
+        readonly workspaceFolder: WorkspaceFolder;
+
+        /**
+         * Allows to pause the event until the provided thenable resolves.
+         *
+         * *Note:* This function can only be called during event dispatch.
+         *
+         * @param thenable A thenable that delays saving.
+         */
+        waitUntil(thenable: Thenable<any>): void;
     }
 
     // #endregion