diff --git a/README.md b/README.md
index ad23fce..0e86b0a 100644
--- a/README.md
+++ b/README.md
@@ -133,9 +133,16 @@ webview to the sidebar. MCP speaks all three of its pillars rather than tools al
 MCP resources and prompts are offered to the agent, not just listed in a panel.
 
 Where it is still thin, specifically: a `WorkspaceEdit` cannot create, delete or rename
-files, and the shim has no `TextEditor` decorations, no custom editors, and no debug adapter
-API. Each of those throws rather than returning an empty value, so an extension that needs
-one fails loudly instead of quietly doing nothing.
+files, and the shim has no custom editors and no debug adapter API. Those three fail loudly —
+`WorkspaceEdit` throws, and the other two are absent from the API object, so calling one is a
+`TypeError` rather than a quiet nothing.
+
+One gap does not behave that way, and saying otherwise here was worse than the gap itself:
+**`createTextEditorDecorationType` returns a working-looking handle and `setDecorations`
+accepts ranges, and nothing is ever drawn.** An extension doing inline blame or coverage
+highlighting gets a successful answer and no pixels. It is the one place left with the shape
+this project spent a release removing; it is named here until it is built rather than
+described as something it is not.
 
 ## Contributing
 
diff --git a/ide/src/ext/vscodeShim.ts b/ide/src/ext/vscodeShim.ts
index 74775aa..4297d61 100644
--- a/ide/src/ext/vscodeShim.ts
+++ b/ide/src/ext/vscodeShim.ts
@@ -757,7 +757,22 @@ export function makeVscodeApi(deps: ShimDeps, ext: { id: string; name: string; c
   const api: any = {
     version: "1.85.0",
     commands, window: window_, languages, workspace,
-    env: { appName: "Schutz", language: getLang(), machineId: "schutz", openExternal: () => Promise.resolve(true), clipboard: { writeText: () => Promise.resolve(), readText: () => Promise.resolve("") } },
+    // env 셋이 전부 성공을 답하고 아무것도 안 했다. openExternal 은 true 를 돌려주며
+    // 브라우저를 열지 않았고(그 IPC 는 진작 있었다), 클립보드는 어디에도 쓰지 않고
+    // 늘 빈 문자열을 읽었다. 확장 입장에서는 "썼는데 비어 있다" 라 자기 버그로 보인다.
+    env: {
+      appName: "Schutz", language: getLang(), machineId: "schutz",
+      openExternal: async (target: any) => {
+        const url = String(target?.toString?.() ?? target ?? "");
+        if (!url) return false;
+        const r = await window.schutz?.openExternal(url);
+        return !!r?.ok;   // 메인이 http/https/mailto 만 연다 — 거절도 그대로 전한다
+      },
+      clipboard: {
+        writeText: (text: string) => navigator.clipboard.writeText(String(text ?? "")),
+        readText: () => navigator.clipboard.readText(),
+      },
+    },
     Uri: UriShim, Position, Range, Selection, Location, Disposable, EventEmitter,
     MarkdownString, CompletionItem, CompletionItemKind, Hover, ThemeIcon, ThemeColor,
     WorkspaceEdit, CodeAction, CodeActionKind,