diff --git a/test/e2e/suite-no-workspace/noWorkspace.test.ts b/test/e2e/suite-no-workspace/noWorkspace.test.ts
index e2aecb7..b6c1cb5 100644
--- a/test/e2e/suite-no-workspace/noWorkspace.test.ts
+++ b/test/e2e/suite-no-workspace/noWorkspace.test.ts
@@ -28,8 +28,6 @@ suite("no-workspace activation (#8)", () => {
       "cowriting.acceptProposal",
       "cowriting.rejectProposal",
       "cowriting.proposeAgentEdit",
-      "cowriting.toggleDiffView",
-      "cowriting.pinDiffBaseline",
     ]) {
       assert.ok(all.includes(command), `${command} is registered`);
     }
@@ -39,4 +37,26 @@ suite("no-workspace activation (#8)", () => {
     await vscode.commands.executeCommand("cowriting.editSelection");
     await vscode.commands.executeCommand("cowriting.createThread");
   });
+
+  // F6 (#19) is workspace-INDEPENDENT: its commands are real (not stubs) even
+  // with no folder open, and the toggle works on an untitled buffer.
+  test("F6 toggle works with no folder open (untitled buffer)", async () => {
+    const all = await vscode.commands.getCommands(true);
+    assert.ok(all.includes("cowriting.toggleDiffView"), "toggleDiffView registered");
+    assert.ok(all.includes("cowriting.pinDiffBaseline"), "pinDiffBaseline registered");
+    const untitled = await vscode.workspace.openTextDocument({ content: "no-folder scratch\n", language: "markdown" });
+    await vscode.window.showTextDocument(untitled);
+    await new Promise((r) => setTimeout(r, 300));
+    await vscode.commands.executeCommand("cowriting.toggleDiffView");
+    await new Promise((r) => setTimeout(r, 300));
+    const opened = vscode.window.tabGroups.all.some((g) =>
+      g.tabs.some(
+        (t) =>
+          t.input instanceof vscode.TabInputTextDiff &&
+          t.input.original.scheme === "cowriting-baseline" &&
+          t.input.modified.toString() === untitled.uri.toString(),
+      ),
+    );
+    assert.ok(opened, "a cowriting-baseline diff opened for the untitled buffer with no folder");
+  });
 });
diff --git a/test/e2e/suite/diffView.test.ts b/test/e2e/suite/diffView.test.ts
index 2cc27e6..d694633 100644
--- a/test/e2e/suite/diffView.test.ts
+++ b/test/e2e/suite/diffView.test.ts
@@ -1,11 +1,13 @@
 import * as assert from "assert";
 import * as fs from "fs";
+import * as os from "os";
 import * as path from "path";
 import * as vscode from "vscode";
 import type { CowritingApi } from "../../../src/extension";
 
 const WS = process.env.E2E_WORKSPACE!;
 const DOC_REL = "docs/diffview.md";
+const docUri = () => vscode.Uri.file(path.join(WS, DOC_REL)).toString();
 
 async function openDoc(): Promise<vscode.TextDocument> {
   const uri = vscode.Uri.file(path.join(WS, DOC_REL));
@@ -22,16 +24,17 @@ async function getApi(): Promise<CowritingApi> {
 const settle = () => new Promise((r) => setTimeout(r, 300));
 
 // Order-dependent (F2–F4 pattern): later tests consume earlier state. Owns
-// docs/diffview.md exclusively.
-suite("F6 diff-view toggle (host E2E — programmatic seam ingress, no LLM)", () => {
+// docs/diffview.md exclusively. F6 works on ANY file (#19), so the last two
+// tests use an out-of-workspace file and an untitled buffer.
+suite("F6 diff-view toggle (host E2E — any file, programmatic seam ingress, no LLM)", () => {
   const TARGET = "A target sentence Claude will rewrite via the seam.";
   const REPLACEMENT = "A SENTENCE CLAUDE REWROTE via the seam.";
 
   test("opening a tracked doc captures an `opened` baseline equal to the buffer (INV-18)", async () => {
     const doc = await openDoc();
+    await getApi();
     const api = await getApi();
-    // renderIfOpen on open already called ensureBaseline; assert it captured.
-    const baseline = api.diffViewController.getBaseline(DOC_REL);
+    const baseline = api.diffViewController.getBaseline(docUri());
     assert.ok(baseline, "baseline captured on first sight");
     assert.strictEqual(baseline!.reason, "opened");
     assert.strictEqual(baseline!.text, doc.getText(), "baseline = open-time buffer");
@@ -39,11 +42,10 @@ suite("F6 diff-view toggle (host E2E — programmatic seam ingress, no LLM)", ()
 
   test("toggle opens a diff tab (original scheme cowriting-baseline) over the live doc (PUC-1)", async () => {
     const api = await getApi();
-    assert.strictEqual(api.diffViewController.isDiffOpen(DOC_REL), false, "no diff open yet");
+    assert.strictEqual(api.diffViewController.isDiffOpen(docUri()), false, "no diff open yet");
     await vscode.commands.executeCommand("cowriting.toggleDiffView");
     await settle();
-    assert.strictEqual(api.diffViewController.isDiffOpen(DOC_REL), true, "diff tab open");
-    // The active tab is a TextDiff whose original is the baseline scheme.
+    assert.strictEqual(api.diffViewController.isDiffOpen(docUri()), true, "diff tab open");
     const active = vscode.window.tabGroups.activeTabGroup.activeTab;
     assert.ok(active && active.input instanceof vscode.TabInputTextDiff, "active tab is a diff");
     assert.strictEqual(
@@ -56,12 +58,12 @@ suite("F6 diff-view toggle (host E2E — programmatic seam ingress, no LLM)", ()
   test("typing leaves the baseline unchanged while the buffer diverges", async () => {
     const doc = await openDoc();
     const api = await getApi();
-    const before = api.diffViewController.getBaseline(DOC_REL)!.text;
+    const before = api.diffViewController.getBaseline(docUri())!.text;
     const edit = new vscode.WorkspaceEdit();
     edit.insert(doc.uri, new vscode.Position(0, 0), "OPERATOR ADDED LINE\n");
     assert.ok(await vscode.workspace.applyEdit(edit), "operator edit applied");
     await settle();
-    assert.strictEqual(api.diffViewController.getBaseline(DOC_REL)!.text, before, "baseline unchanged by typing");
+    assert.strictEqual(api.diffViewController.getBaseline(docUri())!.text, before, "baseline unchanged by typing");
     assert.notStrictEqual(doc.getText(), before, "buffer diverged");
   });
 
@@ -82,7 +84,7 @@ suite("F6 diff-view toggle (host E2E — programmatic seam ingress, no LLM)", ()
     assert.ok(id, "propose returns an id");
     assert.ok(await api.proposalController.acceptById(DOC_REL, id!), "accept applies via the seam");
     await settle();
-    const baseline = api.diffViewController.getBaseline(DOC_REL)!;
+    const baseline = api.diffViewController.getBaseline(docUri())!;
     assert.strictEqual(baseline.reason, "machine-landing", "baseline advanced on the landing");
     assert.ok(baseline.text.includes(REPLACEMENT), "landed text is in the baseline (won't show as a change)");
     assert.ok(!baseline.text.includes(TARGET), "old target gone from the baseline too");
@@ -97,7 +99,7 @@ suite("F6 diff-view toggle (host E2E — programmatic seam ingress, no LLM)", ()
     assert.ok(await vscode.workspace.applyEdit(edit));
     await settle();
     assert.notStrictEqual(
-      api.diffViewController.getBaseline(DOC_REL)!.text,
+      api.diffViewController.getBaseline(docUri())!.text,
       doc.getText(),
       "operator changes show against the advanced baseline",
     );
@@ -108,59 +110,82 @@ suite("F6 diff-view toggle (host E2E — programmatic seam ingress, no LLM)", ()
     const api = await getApi();
     await vscode.commands.executeCommand("cowriting.pinDiffBaseline");
     await settle();
-    const baseline = api.diffViewController.getBaseline(DOC_REL)!;
+    const baseline = api.diffViewController.getBaseline(docUri())!;
     assert.strictEqual(baseline.reason, "pinned");
     assert.strictEqual(baseline.text, doc.getText(), "pinned baseline == current buffer (diff empties)");
   });
 
-  test("the baseline is persisted on disk under the storage dir with the expected content (PUC-4)", async () => {
+  test("the baseline is persisted in GLOBAL storage, never the repo (PUC-4, INV-19)", async () => {
+    await openDoc();
     const api = await getApi();
-    const p = api.diffViewController.baselineFilePath(DOC_REL);
-    assert.ok(p, "storage-backed baseline path is available");
+    const p = api.diffViewController.baselineFilePath(docUri());
+    assert.ok(p, "storage-backed baseline path is available for a file: doc");
     assert.ok(fs.existsSync(p!), `baseline file exists at ${p}`);
     const onDisk = JSON.parse(fs.readFileSync(p!, "utf8"));
-    assert.strictEqual(onDisk.docPath, DOC_REL);
+    assert.strictEqual(onDisk.uri, docUri(), "baseline records the document URI");
     assert.strictEqual(onDisk.reason, "pinned", "last epoch (pin) persisted");
-    assert.strictEqual(onDisk.text, api.diffViewController.getBaseline(DOC_REL)!.text, "on-disk == in-memory");
-    // INV-19: nothing leaked into the repo's .threads sidecar tree.
+    assert.strictEqual(onDisk.text, api.diffViewController.getBaseline(docUri())!.text, "on-disk == in-memory");
+    // INV-19: baseline lives under the extension's storage dir, not the repo.
     assert.ok(!p!.includes(`${path.sep}.threads${path.sep}`), "baseline is NOT in the sidecar tree");
+    assert.ok(!p!.startsWith(WS + path.sep), "baseline is NOT under the workspace folder");
+    assert.ok(p!.includes(`${path.sep}baselines${path.sep}`), "baseline lives under <globalStorage>/baselines/");
   });
 
   test("toggle again closes the diff tab and reveals the normal editor (PUC-1)", async () => {
     const api = await getApi();
-    if (!api.diffViewController.isDiffOpen(DOC_REL)) {
+    if (!api.diffViewController.isDiffOpen(docUri())) {
+      await openDoc();
       await vscode.commands.executeCommand("cowriting.toggleDiffView");
       await settle();
     }
-    assert.strictEqual(api.diffViewController.isDiffOpen(DOC_REL), true, "diff open before close");
+    assert.strictEqual(api.diffViewController.isDiffOpen(docUri()), true, "diff open before close");
     await vscode.commands.executeCommand("cowriting.toggleDiffView");
     await settle();
-    assert.strictEqual(api.diffViewController.isDiffOpen(DOC_REL), false, "diff tab closed");
-    // "Normal editor is back": the file is the active text editor, and no
-    // baseline-diff tab for it remains in any group.
+    assert.strictEqual(api.diffViewController.isDiffOpen(docUri()), false, "diff tab closed");
     assert.strictEqual(
       vscode.window.activeTextEditor?.document.uri.toString(),
-      vscode.Uri.file(path.join(WS, DOC_REL)).toString(),
+      docUri(),
       "the normal editor for the doc is active after closing the diff",
     );
   });
 
-  test("toggling on an untracked doc warns and opens no diff (PUC-5)", async () => {
-    await getApi();
-    const untracked = await vscode.workspace.openTextDocument({ content: "scratch", language: "markdown" });
-    await vscode.window.showTextDocument(untracked);
+  test("toggle works on a file OUTSIDE the workspace folder, persisted in global storage (#19)", async () => {
+    const api = await getApi();
+    const outsideDir = fs.mkdtempSync(path.join(os.tmpdir(), "cowriting-outside-"));
+    const outsidePath = path.join(outsideDir, "outside.md");
+    fs.writeFileSync(outsidePath, "# Outside the workspace\n\nThe operator edits this too.\n", "utf8");
+    const outsideUri = vscode.Uri.file(outsidePath);
+    const doc = await vscode.workspace.openTextDocument(outsideUri);
+    await vscode.window.showTextDocument(doc);
     await settle();
+    // Captured on open even though it is NOT under the workspace folder.
+    const baseline = api.diffViewController.getBaseline(outsideUri.toString());
+    assert.ok(baseline, "baseline captured for an out-of-folder file");
+    assert.strictEqual(baseline!.reason, "opened");
     await vscode.commands.executeCommand("cowriting.toggleDiffView");
     await settle();
-    // No baseline-diff tab for an untitled doc anywhere.
-    const anyDiff = vscode.window.tabGroups.all.some((g) =>
-      g.tabs.some(
-        (t) =>
-          t.input instanceof vscode.TabInputTextDiff &&
-          t.input.original.scheme === "cowriting-baseline" &&
-          t.input.modified.toString() === untracked.uri.toString(),
-      ),
-    );
-    assert.strictEqual(anyDiff, false, "no diff opened for the untracked doc");
+    assert.strictEqual(api.diffViewController.isDiffOpen(outsideUri.toString()), true, "diff opens for the outside file");
+    const fp = api.diffViewController.baselineFilePath(outsideUri.toString());
+    assert.ok(fp && fs.existsSync(fp), "outside-file baseline persisted in global storage");
+    assert.ok(!fp!.startsWith(WS + path.sep), "not under the workspace folder");
+    // close it so it doesn't bleed into the untitled test's active-tab checks
+    await vscode.commands.executeCommand("cowriting.toggleDiffView");
+    await settle();
+    fs.rmSync(outsideDir, { recursive: true, force: true });
+  });
+
+  test("toggle works on an UNTITLED buffer, baseline in-memory only (#19)", async () => {
+    const api = await getApi();
+    const untitled = await vscode.workspace.openTextDocument({ content: "scratch line\n", language: "markdown" });
+    await vscode.window.showTextDocument(untitled);
+    await settle();
+    const key = untitled.uri.toString();
+    assert.strictEqual(untitled.uri.scheme, "untitled", "it really is an untitled buffer");
+    const baseline = api.diffViewController.getBaseline(key);
+    assert.ok(baseline, "untitled buffer got an in-memory baseline");
+    assert.strictEqual(api.diffViewController.baselineFilePath(key), undefined, "untitled is NOT persisted to disk");
+    await vscode.commands.executeCommand("cowriting.toggleDiffView");
+    await settle();
+    assert.strictEqual(api.diffViewController.isDiffOpen(key), true, "diff opens for the untitled buffer");
   });
 });