diff --git a/src/editor/api.ts b/src/editor/api.ts
index 5efdae59..f4581b3f 100644
--- a/src/editor/api.ts
+++ b/src/editor/api.ts
@@ -590,6 +590,8 @@ export interface DocumentAttachment {
   doc: number;
   /** Current document text; build the view's state from it. */
   text(): string;
+  /** The document's language mode name (backend-assigned, as the editor tabs use). */
+  uiMode(): string | null;
   readOnly: boolean;
   /** Add to the view (one view at a time). */
   extension: Extension;
diff --git a/src/editor/core/model/attachment.ts b/src/editor/core/model/attachment.ts
index cbd61f57..652f5538 100644
--- a/src/editor/core/model/attachment.ts
+++ b/src/editor/core/model/attachment.ts
@@ -85,6 +85,7 @@ export async function attachDocument(manager: DocumentManager, path: string): Pr
     path,
     doc: model.doc,
     text: () => model.sync.localText.toString(),
+    uiMode: () => model.getMeta().uiMode,
     readOnly: model.getMeta().readOnly || model.virtual,
     extension: [
       model.manager.workspaceHistory.extension(historyTarget),
diff --git a/src/features/todo/PreviewEditor.test.tsx b/src/features/todo/PreviewEditor.test.tsx
new file mode 100644
index 00000000..5653cf0e
--- /dev/null
+++ b/src/features/todo/PreviewEditor.test.tsx
@@ -0,0 +1,128 @@
+import { afterEach, describe, expect, it } from "vitest";
+import { render, screen, waitFor } from "@testing-library/react";
+import { EditorView } from "@codemirror/view";
+import { _provideDocumentAttacher, type DocumentAttachment } from "@/editor/api";
+import { PreviewEditor, heldAttachment } from "./PreviewEditor";
+import { previewText } from "./ipc";
+
+/**
+ * Stubs of the document attachment: edits dispatch real CodeMirror
+ * transactions, so the dirty/held/release logic runs against the view.
+ */
+function stubAttacher(docs: Map<string, { text: string; dirty?: boolean; readOnly?: boolean }>) {
+  const released: string[] = [];
+  _provideDocumentAttacher((path) => {
+    const att: DocumentAttachment = {
+      path,
+      doc: 1,
+      text: () => docs.get(path)!.text,
+      dirty: () => !!docs.get(path)!.dirty,
+      uiMode: () => null,
+      readOnly: !!docs.get(path)!.readOnly,
+      extension: EditorView.updateListener.of((u) => {
+        for (const tr of u.transactions)
+          if (tr.docChanged) {
+            docs.get(path)!.text = u.state.doc.toString();
+            docs.get(path)!.dirty = true;
+          }
+      }),
+      save: async () => {
+        docs.get(path)!.dirty = false;
+      },
+      synced: () => Promise.resolve(),
+      undo: () => false,
+      redo: () => false,
+      edit: () => {},
+      release: () => released.push(path),
+    };
+    return Promise.resolve(att);
+  });
+  return { released };
+}
+
+describe("PreviewEditor", () => {
+  afterEach(() => _provideDocumentAttacher(null));
+
+  it("shows the document as an editable CodeMirror view", async () => {
+    const docs = new Map([["/p/a.ts", { text: "// TODO: fix\n" }]]);
+    stubAttacher(docs);
+    render(<PreviewEditor path="/p/a.ts" line={0} col={3} fallbackLoad={previewText} />);
+    await waitFor(() => expect(document.querySelector(".cm-editor")).toBeTruthy());
+    expect(document.querySelector(".cm-content")?.textContent).toContain("TODO: fix");
+  });
+
+  it("moves the caret to another item of the same file without a new view", async () => {
+    const docs = new Map([["/p/two.ts", { text: "// TODO: one\nconst x = 1;\n// TODO: two\n" }]]);
+    stubAttacher(docs);
+    const { rerender } = render(<PreviewEditor path="/p/two.ts" line={0} col={3} fallbackLoad={previewText} />);
+    const content = await waitFor(() => {
+      const el = document.querySelector<HTMLElement>(".cm-content");
+      expect(el).toBeTruthy();
+      return el!;
+    });
+    const view = EditorView.findFromDOM(content)!;
+    expect(view.state.selection.main.head).toBe(3);
+    rerender(<PreviewEditor path="/p/two.ts" line={2} col={3} fallbackLoad={previewText} />);
+    expect(EditorView.findFromDOM(document.querySelector<HTMLElement>(".cm-content")!)).toBe(view);
+    expect(view.state.doc.lineAt(view.state.selection.main.head).number).toBe(3);
+    expect(view.state.selection.main.head - view.state.doc.line(3).from).toBe(3);
+  });
+
+  it("falls back to the read-only preview for read-only documents", async () => {
+    const docs = new Map([["/p/ro.ts", { text: "// TODO\n", readOnly: true }]]);
+    const { released } = stubAttacher(docs);
+    render(<PreviewEditor path="/p/ro.ts" line={0} col={0} fallbackLoad={previewText} />);
+    // No editor, no attach error: the read-only SourcePreview shows instead.
+    await waitFor(() => expect(document.querySelector(".cm-editor")).toBeNull());
+    expect(screen.queryByText("editor not started")).toBeNull();
+    expect(released).toEqual(["/p/ro.ts"]);
+  });
+
+  it("releases a clean document on unmount", async () => {
+    const docs = new Map([["/p/clean.ts", { text: "// TODO\n" }]]);
+    const { released } = stubAttacher(docs);
+    const { unmount } = render(<PreviewEditor path="/p/clean.ts" line={0} col={0} fallbackLoad={previewText} />);
+    await waitFor(() => expect(document.querySelector(".cm-editor")).toBeTruthy());
+    unmount();
+    expect(released).toEqual(["/p/clean.ts"]);
+    expect(heldAttachment("/p/clean.ts")).toBeNull();
+  });
+
+  it("holds a dirty document instead of releasing, and previewText reads its text", async () => {
+    const docs = new Map([["/p/dirty.ts", { text: "// TODO: edit me\n", dirty: false }]]);
+    const { released } = stubAttacher(docs);
+    const { unmount } = render(<PreviewEditor path="/p/dirty.ts" line={0} col={7} fallbackLoad={previewText} />);
+    const content = await waitFor(() => {
+      const el = document.querySelector<HTMLElement>(".cm-content");
+      expect(el).toBeTruthy();
+      return el!;
+    });
+    // Edit through the real view: dispatch a transaction (the stub marks dirty).
+    const view = EditorView.findFromDOM(content)!;
+    view.dispatch({ changes: { from: 0, to: view.state.doc.length, insert: "// TODO: edited" } });
+    unmount();
+    expect(released).toEqual([]);
+    const held = heldAttachment("/p/dirty.ts");
+    expect(held).toBeTruthy();
+    await expect(previewText("/p/dirty.ts")).resolves.toBe("// TODO: edited");
+    // Once saved (clean), the held attachment is released on next lookup.
+    docs.get("/p/dirty.ts")!.dirty = false;
+    expect(heldAttachment("/p/dirty.ts")).toBeNull();
+    expect(released).toEqual(["/p/dirty.ts"]);
+  });
+
+  it("falls back to disk text when nothing holds the document", async () => {
+    expect(heldAttachment("/p/gone.ts")).toBeNull();
+    // Not open anywhere: previewText goes to the backend (fails in tests) —
+    // the read order is covered by the held case above.
+    const docs = new Map([["/p/held.ts", { text: "kept", dirty: true }]]);
+    const { released } = stubAttacher(docs);
+    // Fake a held attachment through a mounted-then-edited view.
+    const { unmount } = render(<PreviewEditor path="/p/held.ts" line={0} col={0} fallbackLoad={previewText} />);
+    await waitFor(() => expect(document.querySelector(".cm-content")).toBeTruthy());
+    docs.get("/p/held.ts")!.dirty = true;
+    unmount();
+    await expect(previewText("/p/held.ts")).resolves.toBe("kept");
+    expect(released).toEqual([]);
+  });
+});
diff --git a/src/features/todo/PreviewEditor.tsx b/src/features/todo/PreviewEditor.tsx
new file mode 100644
index 00000000..a2c634bd
--- /dev/null
+++ b/src/features/todo/PreviewEditor.tsx
@@ -0,0 +1,157 @@
+/**
+ * The TODO preview as an editor, like IntelliJ's: a CodeMirror view attached
+ * to the real document (attachDocument), so edits share the buffer with the
+ * editor tabs and are saved by Save All. There is no editing switch.
+ *
+ * Read-only files (and no selection) fall back to the read-only `SourcePreview`.
+ *
+ * Dirty buffers are never released: releasing a document nobody else shows
+ * would either auto-save it or close it and drop the edits. Instead they are
+ * held here (an invisible open document — Save All still reaches them), and
+ * `previewText` reads them so the read-only preview shows the edited text.
+ */
+import { useEffect, useRef, useState } from "react";
+import { EditorView, highlightActiveLine, keymap, lineNumbers } from "@codemirror/view";
+import { Compartment, EditorState } from "@codemirror/state";
+import { history, historyKeymap, defaultKeymap } from "@codemirror/commands";
+import { search, searchKeymap } from "@codemirror/search";
+import { syntaxHighlighting } from "@codemirror/language";
+import { openideaTheme } from "@/editor/core/cm/theme";
+import { openideaHighlightStyle } from "@/editor/core/cm/highlight";
+import { findLanguageDescription, loadSupport } from "@/editor/core/cm/languages";
+import { attachDocument, embeddedEditorExtensions, type DocumentAttachment } from "@/editor/api";
+import { SourcePreview, T, type SourceHighlight } from "@/ui";
+import styles from "./TodoView.module.css";
+
+/** Dirty attachments kept alive after their view unmounted (see header note). */
+const heldDirty = new Map<string, DocumentAttachment>();
+
+/** The held attachment for `path`, if it is still dirty; releases it otherwise. */
+export function heldAttachment(path: string): DocumentAttachment | null {
+  const att = heldDirty.get(path) ?? null;
+  if (att && !att.dirty()) {
+    heldDirty.delete(path);
+    att.release();
+    return null;
+  }
+  return att;
+}
+
+/**
+ * The editable pane for one TODO item's file: mounts a CodeMirror view over
+ * the attached document and centres the item's line; read-only files show the
+ * read-only preview instead. Switching files holds or releases the previous
+ * attachment (see the cleanup below).
+ */
+export function PreviewEditor({
+  path,
+  line,
+  col,
+  highlights = [],
+  fallbackLoad,
+}: {
+  path: string | null;
+  line: number;
+  col: number;
+  highlights?: readonly SourceHighlight[];
+  /** Loader of the read-only fallback (the held-dirty-aware `previewText`). */
+  fallbackLoad: (path: string) => Promise<string>;
+}) {
+  const hostRef = useRef<HTMLDivElement>(null);
+  const viewRef = useRef<EditorView | null>(null);
+  const [error, setError] = useState<string | null>(null);
+  const [readOnly, setReadOnly] = useState(false);
+
+  useEffect(() => {
+    if (!path) return;
+    let alive = true;
+    let view: EditorView | null = null;
+    let att: DocumentAttachment | null = null;
+    void (async () => {
+      try {
+        att = await attachDocument(path);
+        if (!alive) return void att.release();
+        if (att.readOnly) {
+          // Read-only files (disk flag, virtual docs) show the plain preview.
+          att.release();
+          if (alive) setReadOnly(true);
+          return;
+        }
+        const language = new Compartment();
+        view = new EditorView({
+          state: EditorState.create({
+            doc: att.text(),
+            extensions: [
+              openideaTheme,
+              syntaxHighlighting(openideaHighlightStyle),
+              lineNumbers(),
+              highlightActiveLine(),
+              history(),
+              search({ top: true }),
+              // Mod-S is intentionally not bound: the global keymap's
+              // `file.save` (Save All) runs on capture before CodeMirror and
+              // saves the attached document together with the rest — same as
+              // the diff viewer's editable side.
+              keymap.of([...historyKeymap, ...searchKeymap, ...defaultKeymap]),
+              att.extension,
+              embeddedEditorExtensions(path),
+              language.of([]),
+            ],
+          }),
+          parent: hostRef.current!,
+        });
+        viewRef.current = view;
+        // Centre the TODO item; the view starts at its line.
+        const at = Math.min(view.state.doc.lines, line + 1);
+        const text = view.state.doc.line(at);
+        const pos = Math.min(text.from + col, text.to);
+        view.dispatch({
+          selection: { anchor: pos },
+          effects: EditorView.scrollIntoView(pos, { y: "center" }),
+        });
+        // Language loads async, like the notebook cells. The mode comes from the
+        // document (backend-assigned): filename guessing inside
+        // findLanguageDescription is disabled once the backend language table
+        // has loaded, so passing null would leave the view uncoloured.
+        const desc = findLanguageDescription(att.uiMode(), path);
+        if (desc)
+          void loadSupport(desc).then((support) => {
+            if (alive && support && view) view.dispatch({ effects: language.reconfigure(support) });
+          });
+      } catch (e) {
+        // Editor core not started (tests) or the document failed to open.
+        if (alive) setError(String((e as Error)?.message ?? e));
+      }
+    })();
+    return () => {
+      alive = false;
+      viewRef.current = null;
+      view?.destroy();
+      setReadOnly(false);
+      // Hold dirty buffers (see header); release clean ones.
+      if (att) {
+        if (att.dirty()) heldDirty.set(path, att);
+        else att.release();
+      }
+    };
+    // `line`/`col` only place the initial caret; the view itself is per path.
+  }, [path]); // eslint-disable-line react-hooks/exhaustive-deps
+
+  // Another item of the same file: move the caret there (the view stays).
+  useEffect(() => {
+    const view = viewRef.current;
+    if (!view) return;
+    const text = view.state.doc.line(Math.min(view.state.doc.lines, line + 1));
+    const pos = Math.min(text.from + col, text.to);
+    view.dispatch({ selection: { anchor: pos }, effects: EditorView.scrollIntoView(pos, { y: "center" }) });
+  }, [line, col]);
+
+  if (!path || readOnly) return <SourcePreview path={path} line={line} highlights={highlights} load={fallbackLoad} />;
+  if (error)
+    return (
+      <div className={styles.previewError}>
+        <T>{error}</T>
+      </div>
+    );
+  return <div ref={hostRef} className={styles.previewEditor} />;
+}
diff --git a/src/features/todo/TodoView.module.css b/src/features/todo/TodoView.module.css
index 35b8bf54..d841e020 100644
--- a/src/features/todo/TodoView.module.css
+++ b/src/features/todo/TodoView.module.css
@@ -107,3 +107,15 @@
   flex: 1;
   min-height: 0;
 }
+.previewEditor,
+.previewError {
+  flex: 1;
+  min-height: 0;
+}
+.previewError {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  color: var(--fg-faint);
+  font-family: var(--font-ui);
+}
diff --git a/src/features/todo/TodoView.test.tsx b/src/features/todo/TodoView.test.tsx
index af16084a..2407abe2 100644
--- a/src/features/todo/TodoView.test.tsx
+++ b/src/features/todo/TodoView.test.tsx
@@ -68,4 +68,24 @@ describe("TodoView", () => {
     expect(screen.queryByText("Select an item to preview")).toBeNull();
     act(() => useTodoViewOptions.setState({ preview: true }));
   });
+
+  it("previews the selected item as an editable editor, without a switch", async () => {
+    act(() =>
+      useTodos.setState({
+        scannedOnce: true,
+        scanned: new Map([
+          ["/p/src/a.ts", [{ path: "/p/src/a.ts", line: 4, col: 3, keyword: "TODO", text: "TODO: x" }]],
+        ]),
+      }),
+    );
+    render(<TodoView />);
+    // Select the file group so the preview has an item (trees select on mousedown).
+    fireEvent.mouseDown(screen.getByText("a.ts").closest("[role=treeitem]")!);
+    await screen.findByText("(5, 4)");
+    // No editing switch: the preview is simply an editor, like IntelliJ's.
+    expect(screen.queryByLabelText("Allow editing")).toBeNull();
+    // No document attacher in tests: the editable pane degrades to its error
+    // state ("editor not started") instead of crashing.
+    await screen.findByText("editor not started");
+  });
 });
diff --git a/src/features/todo/TodoView.tsx b/src/features/todo/TodoView.tsx
index 5d7895b9..0dbc87f3 100644
--- a/src/features/todo/TodoView.tsx
+++ b/src/features/todo/TodoView.tsx
@@ -13,7 +13,6 @@ import {
   IconButton,
   Menu,
   Select,
-  SourcePreview,
   SplitGroup,
   SplitHandle,
   SplitPanel,
@@ -27,6 +26,7 @@ import {
   T,
 } from "@/ui";
 import { previewText } from "./ipc";
+import { PreviewEditor } from "./PreviewEditor";
 import {
   BUILTIN_TODO_SCOPES,
   activePatterns,
@@ -530,5 +530,15 @@ export function TodoView() {
 function TodoPreview({ node }: { node: Node | null }) {
   const item = node?.kind === "item" ? node.item : (node?.group.items[0] ?? null);
   const highlights = item ? [{ line: item.line, ranges: [[item.col, item.col + item.text.length] as const] }] : [];
-  return <SourcePreview path={item?.path ?? null} line={item?.line ?? 0} highlights={highlights} load={previewText} />;
+  // IDEA's TODO preview is simply an editor on the file: editable in place,
+  // with read-only files falling back to the read-only preview (in PreviewEditor).
+  return (
+    <PreviewEditor
+      path={item?.path ?? null}
+      line={item?.line ?? 0}
+      col={item?.col ?? 0}
+      highlights={highlights}
+      fallbackLoad={previewText}
+    />
+  );
 }
diff --git a/src/features/todo/ipc.ts b/src/features/todo/ipc.ts
index 11490261..b1380f39 100644
--- a/src/features/todo/ipc.ts
+++ b/src/features/todo/ipc.ts
@@ -1,6 +1,7 @@
 import { editorsFor } from "@/editor/api";
 import { call, commands } from "@/platform/ipc";
 import type { RequestId } from "@/platform/ipc";
+import { heldAttachment } from "./PreviewEditor";
 
 export { call, commands, isTauri, nextRequestId, onIdeEvent } from "@/platform/ipc";
 
@@ -12,8 +13,14 @@ export function cancelRequestSafe(id: RequestId) {
   }
 }
 
-/** File text for the preview pane: the open buffer, else the file on disk. */
+/**
+ * File text for the preview pane: the open buffer, else the file on disk.
+ * Held dirty attachments first — a buffer edited in the preview then unmounted
+ * is no longer in `editorsFor`, but its edits must still show (see PreviewEditor).
+ */
 export function previewText(path: string): Promise<string> {
+  const held = heldAttachment(path);
+  if (held) return Promise.resolve(held.text());
   const view = editorsFor(path)[0]?.view;
   return view ? Promise.resolve(view.state.doc.toString()) : call(commands.fsReadText(path));
 }