feat(f8): isAuthorable + widened selectionRejection (file|untitled)

Spec §6.4: replace the scheme!=file / !isUnderRoot rejections with a single
!isAuthorable branch. isUnderRoot retained as a routing input. Per-condition
messaging (#24) kept for no-editor / empty-selection / non-{file,untitled}.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/workspacePath.ts

@@ -20,6 +20,17 @@ export function isUnderRoot(fsPath: string, root: string): boolean {
   return fsPath === root || fsPath.startsWith(root + path.sep);
 }
 
+/**
+ * Documents Cowriting can author on: a saved file OR an unsaved buffer (F8 §6.2).
+ * F8 widened membership from "saved file under the workspace folder" to any
+ * `file:`/`untitled:` doc — the SidecarRouter then routes where its artifact is
+ * stored (repo `.threads/` in-workspace, global storage otherwise). `isUnderRoot`
+ * (above) is retained as that ROUTING input, no longer an authoring gate.
+ */
+export function isAuthorable(scheme: string): boolean {
+  return scheme === "file" || scheme === "untitled";
+}
+
 export interface SelectionContext {
   /** Is there an active text editor at all? */
   hasEditor: boolean;
@@ -27,17 +38,15 @@ export interface SelectionContext {
   selectionEmpty: boolean;
   /** The active document's URI scheme (`file`, `untitled`, …). */
   scheme: string;
-  /** The active document's filesystem path (empty if none). */
-  fsPath: string;
-  /** The workspace folder Cowriting is anchored to. */
-  root: string;
 }
 
 /**
- * Why a selection can't be sent to Claude — or `null` if it can. Each condition
+ * Why a selection can't be sent to Claude — or `null` if it can. F8 widened the
- * gets its OWN message so the user learns the real reason instead of always
+ * membership: any `file:` or `untitled:` document is authorable (in-workspace
- * being told to "select some text" (the reported bug: an out-of-workspace file
+ * files persist to the repo `.threads/` sidecar, out-of-workspace/untitled to
- * was rejected with the no-selection message even though text was selected).
+ * global storage — the router decides). Only a non-{file,untitled} scheme (a
+ * read-only `git:`/`output:` view), a missing editor, or an empty selection is
+ * refused — each with its OWN message (#24's per-condition messaging).
  */
 export function selectionRejection(ctx: SelectionContext): string | null {
   if (!ctx.hasEditor) {
@@ -46,11 +55,8 @@ export function selectionRejection(ctx: SelectionContext): string | null {
   if (ctx.selectionEmpty) {
     return "Cowriting: select some text to send to Claude first.";
   }
-  if (ctx.scheme !== "file") {
+  if (!isAuthorable(ctx.scheme)) {
-    return "Cowriting: save this document to a file first — Cowriting anchors edits to a saved workspace file.";
+    return "Cowriting: this kind of document can't be edited — Cowriting authors on a file or an untitled buffer, not a read-only view.";
-  }
-  if (!isUnderRoot(ctx.fsPath, ctx.root)) {
-    return "Cowriting: this file is outside your workspace folder — open a file inside it to ask Claude to edit (Cowriting anchors edits and attribution to files in the workspace).";
   }
   return null;
 }

test/workspacePath.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from "vitest";
-import { isUnderRoot, selectionRejection } from "../src/workspacePath";
+import { isAuthorable, isUnderRoot, selectionRejection } from "../src/workspacePath";
 
 describe("isUnderRoot", () => {
   const root = "/a/vscode-cowriting-plugin/sandbox";
@@ -24,32 +24,37 @@ describe("isUnderRoot", () => {
   });
 });
 
-describe("selectionRejection", () => {
+describe("isAuthorable", () => {
-  const root = "/ws";
+  it("accepts file: and untitled: schemes", () => {
-  const ok = { hasEditor: true, selectionEmpty: false, scheme: "file", fsPath: "/ws/a.md", root };
+    expect(isAuthorable("file")).toBe(true);
-
+    expect(isAuthorable("untitled")).toBe(true);
-  it("returns null when everything is valid", () => {
-    expect(selectionRejection(ok)).toBeNull();
   });
+  it("rejects read-only / virtual schemes", () => {
+    expect(isAuthorable("git")).toBe(false);
+    expect(isAuthorable("output")).toBe(false);
+    expect(isAuthorable("cowriting-baseline")).toBe(false);
+    expect(isAuthorable("")).toBe(false);
+  });
+});
 
+describe("selectionRejection — F8 widened (accepts out-of-folder + untitled)", () => {
+  const ok = { hasEditor: true, selectionEmpty: false, scheme: "file" };
+
+  it("accepts an in-folder / out-of-folder file (file: scheme)", () => {
+    expect(selectionRejection({ ...ok, scheme: "file" })).toBeNull();
+  });
+  it("accepts an untitled buffer (no longer rejected)", () => {
+    expect(selectionRejection({ ...ok, scheme: "untitled" })).toBeNull();
+  });
   it("names the missing editor", () => {
-    const msg = selectionRejection({ ...ok, hasEditor: false });
+    expect(selectionRejection({ ...ok, hasEditor: false })).toMatch(/focus a text editor/i);
-    expect(msg).toMatch(/focus a text editor/i);
   });
-
   it("names the empty selection (only when there IS an editor)", () => {
-    const msg = selectionRejection({ ...ok, selectionEmpty: true });
+    expect(selectionRejection({ ...ok, selectionEmpty: true })).toMatch(/select some text/i);
-    expect(msg).toMatch(/select some text/i);
   });
-
+  it("rejects a non-{file,untitled} scheme with its own message (not 'select some text')", () => {
-  it("names an unsaved/non-file document", () => {
+    const msg = selectionRejection({ ...ok, scheme: "git" });
-    const msg = selectionRejection({ ...ok, scheme: "untitled" });
+    expect(msg).toMatch(/can.?t be edited|read-only|not a file/i);
-    expect(msg).toMatch(/save this document/i);
-  });
-
-  it("names an out-of-workspace file (the reported bug — NOT a selection problem)", () => {
-    const msg = selectionRejection({ ...ok, fsPath: "/elsewhere/a.md" });
-    expect(msg).toMatch(/outside your workspace folder/i);
     expect(msg).not.toMatch(/select some text/i);
   });
 });