Add private app extension APIs

nodejs/docs/extensions.md

@@ -74,6 +74,36 @@ An approval is remembered against the exact set of names the user saw, so an ext
 
 An approved extension can pass a granted value to anything it starts, so ask only for what the extension genuinely needs.
 
+## Contributing app session badges
+
+App hosts can retain a hidden, non-conversational session for executable extensions that contribute branch or pull request badges. Use `joinAppSessionBadges()` to opt in explicitly:
+
+```js
+import { joinAppSessionBadges } from "@github/copilot-sdk/extension";
+
+const badges = await joinAppSessionBadges();
+
+badges.onSnapshot(async (snapshot) => {
+    await badges.setBadges(
+        snapshot.sessions.map((target) => ({
+            workspaceId: target.workspaceId,
+            sessionId: target.sessionId,
+            badge: {
+                state: "open",
+                label: target.branch,
+            },
+        }))
+    );
+});
+```
+
+`setBadges()` validates the complete ordered batch before sending one
+`extensions.appSessionBadges.setBadges` JSON-RPC request. Duplicate workspace and session target
+pairs reject the complete batch. Use `badge: null` to clear a target. An empty batch is a local
+no-op. `setBadge()` and `clearBadge()` remain available for individual updates.
+
+Each snapshot is a full replacement of the sessions that the app considers eligible. The app owns hidden-session lifecycle, visibility filtering, and repository inspection. Native GitHub pull request badges remain authoritative, and the app can reject an update when a native badge appears after the snapshot. Extensions can publish only `draft`, `open`, `merged`, or `closed` states with an optional label; arbitrary markup, icons, colors, and URLs are not supported.
+
 ## Further Reading
 
 - `examples.md` — Practical code examples for tools, hooks, events, and complete extensions

nodejs/package.json

@@ -29,6 +29,16 @@
                 "types": "./dist/extension.d.ts",
                 "default": "./dist/cjs/extension.js"
             }
+        },
+        "./private/app-extension": {
+            "import": {
+                "types": "./dist/appExtension.d.ts",
+                "default": "./dist/appExtension.js"
+            },
+            "require": {
+                "types": "./dist/appExtension.d.ts",
+                "default": "./dist/cjs/appExtension.js"
+            }
         }
     },
     "type": "module",