diff --git a/README.md b/README.md
index 038cb87..12b3aa3 100644
--- a/README.md
+++ b/README.md
@@ -48,6 +48,47 @@ If using the `language-server.js` distribution, it is necessary to retain the en
 Communication with the language server typically happens over stdio with `--stdio`. The `language-server.js`
 distribution additionally supports Node IPC with `--node-ipc`.
 
+## Agent Client Protocol (ACP) (Preview)
+
+The Copilot Language Server also supports the [Agent Client Protocol (ACP)](https://agentclientprotocol.com/),
+enabling integration with ACP-compatible editors like [JetBrains AI Assistant](https://www.jetbrains.com/help/ai-assistant/acp.html), [Zed](https://zed.dev/), and more.
+
+### Running in ACP Mode
+
+To start the language server in ACP mode:
+
+```sh
+npx -y @github/copilot-language-server --acp
+```
+
+Or if installed locally:
+
+```sh
+node ./node_modules/@github/copilot-language-server/dist/language-server.js --acp
+```
+
+Communication happens over stdin/stdout.
+
+### JetBrains AI Assistant
+
+To use Copilot as an ACP agent in JetBrains AI Assistant, add the following to your `~/.jetbrains/acp.json`:
+
+```json
+{
+  "agent_servers": {
+    "GitHub Copilot": {
+      "command": "npx",
+      "args": [
+        "@github/copilot-language-server@latest",
+        "--acp"
+      ]
+    }
+  }
+}
+```
+
+See the [ACP specification](https://agentclientprotocol.com/) for full protocol details.
+
 ## Communication Protocol
 
 The [Language Server Protocol](https://microsoft.github.io/language-server-protocol/) (LSP) is used to communicate with
@@ -154,12 +195,14 @@ status bar icon or other UI affordance.
 
 Notification includes the following fields:
 
+- `busy` - boolean indicating whether a task is in progress
 - `message` - a string describing the status (can be empty)
 - `kind` - status of the language server:
    - `'Normal'` - When everything is working normally.
    - `'Error'` - When not authorized and authenticated.
    - `'Warning'` - When there is a temporary issue, such as a failed HTTP request.
    - `'Inactive'` - When the current file is ignored due to file size or content exclusions.
+- `command` - an optional LSP `Command` object providing an actionable command for the client to offer the user (e.g., sign in, learn more about quota limits)
 
 ## Authentication
 
@@ -279,6 +322,73 @@ item, plus the length (in UTF-16 codepoints) of the completion that was accepted
 Note that the `acceptedLength` includes everything from the start of `insertText` to the end of the accepted text. It is
 *not* the length of the accepted text itself.
 
+## Next Edit Suggestions
+
+`textDocument/copilotInlineEdit` is a custom method used to retrieve "next edit"
+suggestions which are inline completions that may include deletions or
+modifications to existing text and may not be positioned at the cursor. These
+are similar to inline completions and the API shape is similar as well. But it
+is a separate method to allow opting into the feature and distinguishing between
+the two kinds of suggestions.
+
+The request parameters are similar to
+[`TextDocumentPositionParams`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.18/specification/#textDocumentPositionParams)
+but with a `textDocument.version` field required as in as
+[`VersionedTextDocumentIdentifier`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.18/specification/#versionedTextDocumentIdentifier):
+
+```json
+{
+    "textDocument": {
+        "uri": "file:///path/to/file",
+        "version": 0
+    },
+    "position": {"line": 1, "character": 2}
+}
+```
+
+The result is an object containing an `edits` array:
+
+```json
+{
+    "edits": [
+        {
+            "text": "an edit suggestion",
+            "textDocument": {
+                "uri": "file:///path/to/file",
+                "version": 0
+            },
+            "range": {
+                "start": {"line": 1, "character": 0},
+                "end": {"line": 1, "character": 5}
+            },
+            "command": {
+                "title": "Accept inline edit",
+                "command": "github.copilot.didAcceptCompletionItem",
+                "arguments": ["some-id"]
+            }
+        }
+    ]
+}
+```
+
+The `command` field, per the LSP spec, is called via
+[`workspace/executeCommand`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#workspace_executeCommand)
+*after* the user accepts the edit. Copilot uses this for acceptance telemetry.
+
+The LSP spec does not provide an event for showing the edit, so a custom
+`textDocument/didShowInlineEdit` is used. Call it with an `item` parameter
+containing the item shown from the `edits` array (note only the first argument is required):
+
+```json
+{
+    "item": {
+        "command": {
+            "arguments": ["some-id"]
+        }
+    }
+}
+```
+
 ## Panel Completions
 
 Panel completions are used for "Open Copilot" style completions. They are similar to inline completions, but are shown