From 6c3e5ae469dc403dc240aef71f3680d752fdfa44 Mon Sep 17 00:00:00 2001
From: Vadim Lazuk <vadimlazuk5@gmail.com>
Date: Tue, 10 Nov 2026 00:22:56 +0300
Subject: [PATCH] feat(database): JSON-aware value editor for json cells
 (#2410)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Refs #2333

Editing json / jsonb / MySQL JSON cells showed one long plain text line, and invalid JSON only failed on Submit. The Value panel and the grid's ⇧Enter window now open the IDE's code editor for JSON cells, pretty-printed (big integers and duplicate keys preserved, large values formatted off the main thread) with highlighting, folding and find; validation as you type blocks Apply only for JSON columns; Reformat; Apply of an unchanged value creates no pending edit, and drafts survive opening the window. XML and bytea modes from #2333 remain.

Co-authored-by: Inf1mum <8135225+Inf1mum@users.noreply.github.com>
---
 e2e/databaseJsonValue.spec.ts               | 149 +++++++++++
 src/editor/core/cm/setup.ts                 |   4 +-
 src/features/database/DataView.tsx          | 124 +++++++--
 src/features/database/Database.module.css   |  31 +++
 src/features/database/ExportDialog.test.tsx |   5 +-
 src/features/database/Grid.test.tsx         | 219 ++++++++++++++-
 src/features/database/Grid.tsx              |  44 ++-
 src/features/database/JsonValueEditor.tsx   | 282 ++++++++++++++++++++
 src/features/database/index.ts              |   2 +
 src/features/database/jsonValue.test.ts     |  83 ++++++
 src/features/database/jsonValue.ts          |  76 ++++++
 src/features/database/jsonValue.worker.ts   |   6 +
 src/features/database/valueEditorActions.ts |  65 +++++
 src/platform/keymaps/eclipse-macos.ts       |   2 +
 src/platform/keymaps/eclipse-windows.ts     |   2 +
 src/platform/keymaps/eclipse.test.ts        |   2 +-
 src/platform/keymaps/intellij-macos.ts      |   3 +
 src/platform/keymaps/intellij-windows.ts    |   3 +
 src/platform/keymaps/vscode-macos.ts        |   3 +
 src/platform/locales/text/en.json           |   3 +
 src/platform/locales/text/zh.json           |   3 +
 21 files changed, 1079 insertions(+), 32 deletions(-)
 create mode 100644 e2e/databaseJsonValue.spec.ts
 create mode 100644 src/features/database/JsonValueEditor.tsx
 create mode 100644 src/features/database/jsonValue.test.ts
 create mode 100644 src/features/database/jsonValue.ts
 create mode 100644 src/features/database/jsonValue.worker.ts
 create mode 100644 src/features/database/valueEditorActions.ts

diff --git a/e2e/databaseJsonValue.spec.ts b/e2e/databaseJsonValue.spec.ts
new file mode 100644
index 000000000..1c75a9f21
--- /dev/null
+++ b/e2e/databaseJsonValue.spec.ts
@@ -0,0 +1,149 @@
+import type { EditorView } from "@codemirror/view";
+import { expect, test } from "./fixtures";
+
+const compact = '{"name":"Ada","tags":["math","code"],"n":9007199254740993}';
+
+for (const type of ["json", "text"]) {
+  test(`JSON value window preserves text and uses ${type} validation rules`, async ({ workbench: page }) => {
+    await page.evaluate(
+      async ({ compact, type }) => {
+        const reactPath = "/node_modules/.vite/deps/react.js";
+        const domPath = "/node_modules/.vite/deps/react-dom_client.js";
+        const viewPath = "/src/features/database/DataView.tsx";
+        const react = await import(reactPath);
+        const dom = await import(domPath);
+        const { createElement, useState } = react.default ?? react;
+        const { createRoot } = dom.default ?? dom;
+        const { DataView } = await import(viewPath);
+        const host = document.createElement("div");
+        host.style.cssText = "position:fixed;inset:100px;z-index:100;display:flex;background:var(--bg-main)";
+        document.body.append(host);
+        function Value() {
+          const [value, setValue] = useState(compact);
+          return createElement(DataView, {
+            columns: [{ name: "payload", type }],
+            rowCount: 1,
+            value: () => value,
+            editable: true,
+            panel: "value",
+            onPanelChange: () => {},
+            onEdit: (_row: number, _col: number, text: string) => setValue(text),
+          });
+        }
+        createRoot(host).render(createElement(Value));
+      },
+      { compact, type },
+    );
+    const cell = page.getByRole("gridcell", { name: compact, exact: true });
+    await cell.click();
+    const panel = page.getByRole("complementary", { name: "Value panel" });
+    const editor = panel.locator(".cm-content");
+    await expect(editor).toContainText("9007199254740993");
+    await expect(panel.getByRole("button", { name: "Apply", exact: true })).toBeDisabled();
+    await cell.press("Shift+Enter");
+    const dialog = page.getByRole("dialog");
+    await expect(dialog.locator(".cm-content")).toBeFocused();
+    await expect
+      .poll(() =>
+        dialog.locator(".cm-editor").evaluate((editor) => {
+          const body = editor.closest("[data-dialog-body]")!;
+          return Math.abs(body.clientHeight - editor.clientHeight);
+        }),
+      )
+      .toBeLessThanOrEqual(4);
+    await expect(dialog.getByRole("button", { name: "Apply", exact: true })).toBeDisabled();
+    await dialog.getByRole("button", { name: "Cancel", exact: true }).click();
+    await expect(cell).toHaveText(compact);
+    await editor.evaluate((element) => {
+      const view = (element as HTMLElement & { cmTile: { view: EditorView } }).cmTile.view;
+      view.dispatch({
+        changes: { from: 0, to: view.state.doc.length, insert: '{"name":"Grace","n":9007199254740993}' },
+      });
+      view.focus();
+    });
+    await page.keyboard.press("Meta+Alt+L");
+    await expect(editor.locator(".cm-line")).toHaveCount(4);
+    await page.keyboard.press("Meta+f");
+    await expect(panel.locator(".cm-search")).toBeVisible();
+    await panel.locator(".cm-search button[name=close]").click();
+    await panel.getByRole("button", { name: "Open in Window", exact: true }).click();
+    await expect(dialog.locator(".cm-content")).toContainText("Grace");
+    await expect(dialog.getByRole("button", { name: "Apply", exact: true })).toBeEnabled();
+    await dialog.locator(".cm-content").evaluate((element) => {
+      const view = (element as HTMLElement & { cmTile: { view: EditorView } }).cmTile.view;
+      view.dispatch({ changes: { from: 0, to: view.state.doc.length, insert: "plain text" } });
+    });
+    const apply = dialog.getByRole("button", { name: "Apply", exact: true });
+    if (type === "json") {
+      await expect(apply).toBeDisabled();
+      await expect(dialog.getByRole("status")).toBeVisible();
+    } else {
+      await expect(apply).toBeEnabled();
+      await apply.click();
+      await expect(page.getByRole("gridcell", { name: "plain text", exact: true })).toBeVisible();
+    }
+  });
+}
+
+test("validates a large JSON value in a worker and applies the exact edited text", async ({ workbench: page }) => {
+  await page.evaluate(async () => {
+    const reactPath = "/node_modules/.vite/deps/react.js";
+    const domPath = "/node_modules/.vite/deps/react-dom_client.js";
+    const viewPath = "/src/features/database/JsonValueEditor.tsx";
+    const react = await import(reactPath);
+    const dom = await import(domPath);
+    const { createElement } = react.default ?? react;
+    const { createRoot } = dom.default ?? dom;
+    const { JsonValueWindow } = await import(viewPath);
+    const host = document.createElement("div");
+    document.body.append(host);
+    const result = document.createElement("output");
+    result.id = "applied-json";
+    document.body.append(result);
+    createRoot(host).render(
+      createElement(JsonValueWindow, {
+        title: "Edit payload",
+        initial: '{"large":"' + "x".repeat(5_000_000) + '"}',
+        validate: true,
+        onClose: () => {},
+        onApply: (text: string) => {
+          result.textContent = text;
+        },
+      }),
+    );
+  });
+  const dialog = page.getByRole("dialog", { name: "Edit payload" });
+  const editor = dialog.locator(".cm-content");
+  await expect(dialog.getByRole("button", { name: "Reformat", exact: true })).toBeEnabled();
+  await dialog.getByRole("button", { name: "Reformat", exact: true }).click();
+  await expect
+    .poll(() =>
+      editor.evaluate(
+        (element) =>
+          (element as HTMLElement & { cmTile: { view: EditorView } }).cmTile.view.state.doc.toString() ===
+          '{\n  "large": "' + "x".repeat(5_000_000) + '"\n}',
+      ),
+    )
+    .toBe(true);
+  await editor.evaluate((element) => {
+    const view = (element as HTMLElement & { cmTile: { view: EditorView } }).cmTile.view;
+    view.dispatch({ changes: { from: view.state.doc.length - 1, to: view.state.doc.length } });
+  });
+  await expect(dialog.getByRole("status")).toBeVisible();
+  await expect(dialog.getByRole("button", { name: "Apply", exact: true })).toBeDisabled();
+  await editor.evaluate((element) => {
+    const view = (element as HTMLElement & { cmTile: { view: EditorView } }).cmTile.view;
+    view.dispatch({
+      changes: { from: 0, to: view.state.doc.length, insert: '{\n "large": "' + "x".repeat(5_000_000) + '"\n}' },
+    });
+  });
+  await expect(dialog.getByRole("button", { name: "Apply", exact: true })).toBeEnabled();
+  await dialog.getByRole("button", { name: "Apply", exact: true }).click();
+  await expect
+    .poll(() =>
+      page
+        .locator("#applied-json")
+        .evaluate((element) => element.textContent === '{\n "large": "' + "x".repeat(5_000_000) + '"\n}'),
+    )
+    .toBe(true);
+});
diff --git a/src/editor/core/cm/setup.ts b/src/editor/core/cm/setup.ts
index 1c01eac6b..a6ee0d556 100644
--- a/src/editor/core/cm/setup.ts
+++ b/src/editor/core/cm/setup.ts
@@ -317,6 +317,8 @@ export interface SetupOptions {
   wrapOverride?: boolean | null;
   /** Extra extensions owned by the slot (update listeners, focus handlers). */
   extra?: Extension;
+  /** Standalone value editors supply their own extensions without file-backed contributions. */
+  contributions?: Extension;
 }
 
 /**
@@ -407,7 +409,7 @@ export function baseExtensions(o: SetupOptions): Extension {
         wrapOverride: o.wrapOverride,
       }),
     ),
-    compartments.contributions.of(contributionExtensions(o.ctx)),
+    compartments.contributions.of(o.contributions ?? contributionExtensions(o.ctx)),
     compartments.distractionFree.of(distractionFreeExtension(o.settings)),
     o.extra ?? [],
   ];
diff --git a/src/features/database/DataView.tsx b/src/features/database/DataView.tsx
index 8c4a41e4f..9a8ab407c 100644
--- a/src/features/database/DataView.tsx
+++ b/src/features/database/DataView.tsx
@@ -26,6 +26,15 @@ import {
 } from "./resultView";
 import { openDialog } from "./store";
 import { hasLineBreak } from "./cellPreview";
+import {
+  initialJsonText,
+  isJsonColumn,
+  isJsonValue,
+  jsonErrorOf,
+  JSON_INLINE_LIMIT,
+  type JsonError,
+} from "./jsonValue";
+import { JsonValueEditor, JsonValueWindow, type JsonEditorApi } from "./JsonValueEditor";
 import styles from "./Database.module.css";
 import { tx } from "@/platform/i18n";
 
@@ -479,8 +488,9 @@ function SidePanel(props: {
           <RecordView key={range.lead.row} {...props} row={range.lead.row} />
         ) : props.panel === "value" ? (
           <ValueView
-            key={`${range.lead.row}:${range.lead.col}`}
-            column={columns[range.lead.col]?.name ?? ""}
+            // A committed value (here or in the grid) starts the editor over.
+            key={`${range.lead.row}:${range.lead.col}\u0000${value(range.lead.row, range.lead.col) ?? "\u0001"}`}
+            column={columns[range.lead.col] ?? { name: "", type: "" }}
             cell={value(range.lead.row, range.lead.col)}
             editable={props.editable}
             onCommit={(v) => props.onEdit(range.lead.row, range.lead.col, v)}
@@ -558,33 +568,109 @@ function RecordField(props: { column: GridColumn; cell: Cell; editable: boolean;
   );
 }
 
-function ValueView(props: { column: string; cell: Cell; editable: boolean; onCommit: (v: Cell) => void }) {
-  const [text, setText] = useState(props.cell ?? "");
-  const dirty = text !== (props.cell ?? "") || (props.cell === null && text !== "");
+/** The Value panel's editor: plain text, or the JSON code editor for JSON cells (#2333). */
+function ValueView(props: { column: GridColumn; cell: Cell; editable: boolean; onCommit: (v: Cell) => void }) {
+  const name = props.column.name;
+  const [json] = useState(() => isJsonValue(props.column.type, props.cell));
+  const validate = isJsonColumn(props.column.type);
+  // JSON opens pretty-printed; the panel applies what the editor shows.
+  const [initial] = useState(() => (json ? initialJsonText(props.cell ?? "") : (props.cell ?? "")));
+  const [text, setText] = useState(initial);
+  const [error, setError] = useState<JsonError | null>(() =>
+    props.cell !== null && validate && initial.length <= JSON_INLINE_LIMIT ? jsonErrorOf(initial) : null,
+  );
+  const [pending, setPending] = useState(json && initial.length > JSON_INLINE_LIMIT);
+  const editor = useRef<JsonEditorApi | null>(null);
+  const dirty = text !== initial;
+  const commit = () => {
+    if (props.editable && dirty && !error && !pending) props.onCommit(text);
+  };
+  const [windowOpen, setWindowOpen] = useState(false);
   return (
     <div className={styles.valueView}>
-      <textarea
-        className={styles.valueText}
-        aria-label={`Value of ${props.column}`}
-        value={text}
-        readOnly={!props.editable}
-        placeholder={props.cell === null ? "<null>" : undefined}
-        spellCheck={false}
-        onChange={(e) => setText(e.target.value)}
-        onKeyDown={(e) => {
-          if (e.key === "Enter" && (e.metaKey || e.ctrlKey) && dirty) props.onCommit(text);
-        }}
-      />
+      {json ? (
+        <>
+          <JsonValueEditor
+            initial={initial}
+            validate={validate}
+            emptyIsNull={props.cell === null}
+            readOnly={!props.editable}
+            ariaLabel={tx`Value of ${name}`}
+            onChange={(t, e, busy) => {
+              setText(t);
+              setError(e);
+              setPending(busy);
+            }}
+            onReady={(api) => (editor.current = api)}
+            onSubmit={commit}
+            onOpenWindow={() => setWindowOpen(true)}
+          />
+          {error && (
+            <div className={styles.valueError} role="status">
+              {error.message}
+            </div>
+          )}
+          <div className={styles.filterButtons}>
+            <Button
+              size="small"
+              disabled={!props.editable || !!error || pending}
+              onClick={() => editor.current?.reformat()}
+            >
+              <T>Reformat</T>
+            </Button>
+            <Button size="small" onClick={() => setWindowOpen(true)}>
+              <T>Open in Window</T>
+            </Button>
+          </div>
+        </>
+      ) : (
+        <textarea
+          className={styles.valueText}
+          aria-label={tx`Value of ${name}`}
+          value={text}
+          readOnly={!props.editable}
+          placeholder={props.cell === null ? "<null>" : undefined}
+          spellCheck={false}
+          onChange={(e) => setText(e.target.value)}
+          onKeyDown={(e) => {
+            if (e.key === "Enter" && (e.metaKey || e.ctrlKey) && dirty) props.onCommit(text);
+          }}
+        />
+      )}
       {props.editable && (
         <div className={styles.filterButtons}>
-          <Button size="small" disabled={!dirty} onClick={() => props.onCommit(text)}>
+          <Button size="small" disabled={!dirty || !!error || pending} onClick={commit}>
             <T>Apply</T>
           </Button>
-          <Button size="small" onClick={() => props.onCommit(null)}>
+          <Button
+            size="small"
+            onClick={() => {
+              if (props.cell !== null) props.onCommit(null);
+            }}
+          >
             <T>Set NULL</T>
           </Button>
         </div>
       )}
+      {windowOpen && (
+        <JsonValueWindow
+          title={tx`Value of ${name}`}
+          initial={text}
+          baseline={initial}
+          validate={validate}
+          emptyIsNull={props.cell === null}
+          readOnly={!props.editable}
+          onClose={() => setWindowOpen(false)}
+          onApply={(t) => {
+            props.onCommit(t);
+            setWindowOpen(false);
+          }}
+          onSetNull={() => {
+            props.onCommit(null);
+            setWindowOpen(false);
+          }}
+        />
+      )}
     </div>
   );
 }
diff --git a/src/features/database/Database.module.css b/src/features/database/Database.module.css
index 4aa6642c9..37ba7524d 100644
--- a/src/features/database/Database.module.css
+++ b/src/features/database/Database.module.css
@@ -951,6 +951,37 @@
   outline: none;
   border-color: var(--focus-ring);
 }
+/* The JSON value editor's host (#2333): the CodeMirror view fills it. */
+.valueEditor {
+  flex: 1;
+  min-height: 120px;
+  border: 1px solid var(--border);
+  border-radius: var(--radius-control);
+  background: var(--bg-input);
+  color: var(--fg-strong);
+  overflow: hidden;
+}
+.valueEditor > :global(.cm-editor) {
+  height: 100%;
+  font-size: var(--fs-code);
+}
+.valueError {
+  color: var(--danger);
+  font-size: var(--fs-code);
+  overflow-wrap: anywhere;
+}
+.valueWindowBody {
+  height: 100%;
+  display: flex;
+  flex-direction: column;
+  flex: 1;
+  min-height: 0;
+  gap: 6px;
+  overflow: hidden;
+}
+.valueWindowBody .valueEditor {
+  min-height: 160px;
+}
 .recordText {
   resize: vertical;
   padding: 3px 6px;
diff --git a/src/features/database/ExportDialog.test.tsx b/src/features/database/ExportDialog.test.tsx
index 3b06fa8c7..ef779bbc6 100644
--- a/src/features/database/ExportDialog.test.tsx
+++ b/src/features/database/ExportDialog.test.tsx
@@ -5,7 +5,10 @@ import { ExportDialog } from "./ExportDialog";
 import { cellPreview } from "./cellPreview";
 
 vi.mock("./store", () => ({ closeDialog: vi.fn() }));
-vi.mock("@/workbench/contributions", () => ({ notifications: () => ({ notify: vi.fn() }) }));
+vi.mock("@/workbench/contributions", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("@/workbench/contributions")>()),
+  notifications: () => ({ notify: vi.fn() }),
+}));
 vi.mock("@tauri-apps/api/path", () => ({ homeDir: async () => "/home/test" }));
 
 describe("large value export", () => {
diff --git a/src/features/database/Grid.test.tsx b/src/features/database/Grid.test.tsx
index 7c8e736a6..fdf5002f0 100644
--- a/src/features/database/Grid.test.tsx
+++ b/src/features/database/Grid.test.tsx
@@ -1,8 +1,10 @@
 import { installKeyboardDispatcher, useKeymap } from "@/platform/keymap";
 import { registerActions } from "@/platform/actions";
-import { fireEvent, render, screen } from "@testing-library/react";
+import { act, fireEvent, render, screen } from "@testing-library/react";
 import { afterEach, describe, expect, it, vi } from "vitest";
 import { useState } from "react";
+import { within } from "@testing-library/react";
+import { EditorView } from "@codemirror/view";
 import { DataView } from "./DataView";
 import { Grid } from "./Grid";
 import { CELL_PREVIEW_LIMIT, cellPreview } from "./cellPreview";
@@ -171,19 +173,22 @@ describe("large database cells", () => {
 
   it("edits the full large value in a dialog and supports cancel and apply", () => {
     const onEdit = vi.fn();
-    render(<Grid columns={columns} rowCount={1} value={() => full} editable onEdit={onEdit} />);
+    const large = "word ".repeat(40_000); // not JSON: the plain multi-line editor
+    render(
+      <Grid columns={[{ name: "note", type: "text" }]} rowCount={1} value={() => large} editable onEdit={onEdit} />,
+    );
     fireEvent.doubleClick(screen.getByRole("gridcell"));
     expect(screen.getByRole("dialog")).toBeTruthy();
     const editor = screen.getByRole("textbox") as HTMLTextAreaElement;
     expect(editor.tagName).toBe("TEXTAREA");
-    expect(editor.value).toBe(full);
-    fireEvent.change(editor, { target: { value: full + "changed" } });
+    expect(editor.value).toBe(large);
+    fireEvent.change(editor, { target: { value: large + "changed" } });
     fireEvent.click(screen.getByRole("button", { name: "Cancel" }));
     expect(onEdit).not.toHaveBeenCalled();
     fireEvent.doubleClick(screen.getByRole("gridcell"));
-    fireEvent.change(screen.getByRole("textbox"), { target: { value: full + "changed" } });
+    fireEvent.change(screen.getByRole("textbox"), { target: { value: large + "changed" } });
     fireEvent.click(screen.getByRole("button", { name: "Apply" }));
-    expect(onEdit).toHaveBeenCalledWith(0, 0, full + "changed");
+    expect(onEdit).toHaveBeenCalledWith(0, 0, large + "changed");
     expect(screen.queryByRole("dialog")).toBeNull();
   });
 
@@ -244,6 +249,208 @@ describe("multi-line database cells", () => {
     expect(onEdit).not.toHaveBeenCalled();
   });
 });
+describe("JSON value editor (#2333)", () => {
+  const json = '{"name":"Ada","tags":["math","code"]}';
+  const pretty = JSON.stringify(JSON.parse(json), null, 2);
+  const payload = [{ name: "payload", type: "jsonb" }];
+  // CodeMirror renders each line in its own element: compare text without layout whitespace.
+  const shown = (text: string) => text.replace(/\s+/g, "");
+
+  /** The mounted CodeMirror view of the open editor. */
+  const view = () => {
+    const content = document.querySelector(".cm-content") as HTMLElement;
+    return EditorView.findFromDOM(content)!;
+  };
+  const editDoc = (insert: string) => {
+    const v = view();
+    act(() => v.dispatch({ changes: { from: 0, to: v.state.doc.length, insert } }));
+  };
+  const openWindow = () => {
+    fireEvent.mouseDown(screen.getByRole("gridcell"), { button: 0 });
+    fireEvent.mouseUp(window);
+    fireEvent.keyDown(screen.getByRole("grid"), { key: "Enter", shiftKey: true });
+  };
+
+  it("opens the JSON window with Shift+Enter, pretty-printed, and applies edits to the grid", () => {
+    const onEdit = vi.fn();
+    render(<Grid columns={payload} rowCount={1} value={() => json} editable onEdit={onEdit} />);
+    openWindow();
+    expect(screen.getByRole("dialog")).toBeTruthy();
+    // The code editor, not the plain textarea: a contenteditable div, pretty-printed.
+    const editor = screen.getByRole("textbox", { name: "Edit payload" });
+    expect(editor.tagName).toBe("DIV");
+    expect(shown(editor.textContent ?? "")).toBe(shown(pretty));
+    editDoc(pretty.replace('"Ada"', '"Grace"'));
+    fireEvent.click(screen.getByRole("button", { name: "Apply" }));
+    expect(onEdit).toHaveBeenCalledWith(0, 0, pretty.replace('"Ada"', '"Grace"'));
+    expect(screen.queryByRole("dialog")).toBeNull();
+  });
+
+  it("opens SQL NULL without an error or a redundant pending edit", () => {
+    const onEdit = vi.fn();
+    render(<Grid columns={payload} rowCount={1} value={() => null} editable onEdit={onEdit} />);
+    openWindow();
+    expect(screen.queryByRole("status")).toBeNull();
+    fireEvent.click(screen.getByRole("button", { name: "Set NULL" }));
+    expect(onEdit).not.toHaveBeenCalled();
+  });
+
+  it("keeps an edited inline draft when maximizing and applies it unchanged", () => {
+    const onEdit = vi.fn();
+    render(<Grid columns={payload} rowCount={1} value={() => json} editable onEdit={onEdit} />);
+    fireEvent.doubleClick(screen.getByRole("gridcell"));
+    const input = screen.getByRole("textbox");
+    const draft = '{"name": "Grace", "n":9007199254740993}';
+    fireEvent.change(input, { target: { value: draft } });
+    fireEvent.keyDown(input, { key: "Enter", shiftKey: true });
+    expect(view().state.doc.toString()).toBe(draft);
+    expect(onEdit).not.toHaveBeenCalled();
+    fireEvent.click(screen.getByRole("button", { name: "Apply" }));
+    expect(onEdit).toHaveBeenCalledWith(0, 0, draft);
+  });
+
+  it("marks invalid JSON and blocks Apply until it parses", () => {
+    const onEdit = vi.fn();
+    render(<Grid columns={payload} rowCount={1} value={() => json} editable onEdit={onEdit} />);
+    openWindow();
+    const apply = () => screen.getByRole("button", { name: "Apply" }) as HTMLButtonElement;
+    expect(apply().disabled).toBe(true); // unchanged
+    editDoc('{"broken": ');
+    expect(apply().disabled).toBe(true);
+    expect(screen.getByRole("status").textContent).toMatch(/JSON/i);
+    fireEvent.click(apply());
+    expect(onEdit).not.toHaveBeenCalled();
+    editDoc('{"ok": 1}');
+    expect(apply().disabled).toBe(false);
+    expect(screen.queryByRole("status")).toBeNull();
+    fireEvent.click(apply());
+    expect(onEdit).toHaveBeenCalledWith(0, 0, '{"ok": 1}');
+  });
+
+  it("allows plain text after JSON highlighting was inferred from text content", () => {
+    const onEdit = vi.fn();
+    render(
+      <Grid columns={[{ name: "payload", type: "text" }]} rowCount={1} value={() => json} editable onEdit={onEdit} />,
+    );
+    openWindow();
+    editDoc("plain text now");
+    fireEvent.click(screen.getByRole("button", { name: "Apply" }));
+    expect(onEdit).toHaveBeenCalledWith(0, 0, "plain text now");
+  });
+
+  it("keeps the compact value unchanged after opening, applying and closing", () => {
+    const onEdit = vi.fn();
+    render(<Grid columns={payload} rowCount={1} value={() => json} editable onEdit={onEdit} />);
+    openWindow();
+    fireEvent.click(screen.getByRole("button", { name: "Apply" }));
+    fireEvent.keyDown(screen.getByRole("textbox"), { key: "Enter", metaKey: true });
+    fireEvent.click(screen.getByRole("button", { name: "Cancel" }));
+    expect(onEdit).not.toHaveBeenCalled();
+  });
+
+  it("reformats the edited text in the window", () => {
+    render(<Grid columns={payload} rowCount={1} value={() => json} editable onEdit={vi.fn()} />);
+    openWindow();
+    editDoc('{"a":1}');
+    fireEvent.click(screen.getByRole("button", { name: "Reformat" }));
+    expect(shown(screen.getByRole("textbox", { name: "Edit payload" }).textContent ?? "")).toBe(
+      shown('{\n  "a": 1\n}'),
+    );
+  });
+
+  it("carries the panel draft into the window and keeps typed text on Apply", () => {
+    const onEdit = vi.fn();
+    render(
+      <DataView
+        columns={payload}
+        rowCount={1}
+        value={() => json}
+        panel="value"
+        onPanelChange={() => {}}
+        editable
+        onEdit={onEdit}
+      />,
+    );
+    fireEvent.mouseDown(screen.getByRole("gridcell"), { button: 0 });
+    const draft = '{"name": "Grace", "n": 9007199254740993}';
+    editDoc(draft);
+    fireEvent.click(screen.getByRole("button", { name: "Open in Window" }));
+    const dialog = screen.getByRole("dialog");
+    const content = dialog.querySelector<HTMLElement>(".cm-content")!;
+    expect(EditorView.findFromDOM(content)!.state.doc.toString()).toBe(draft);
+    fireEvent.click(within(dialog).getByRole("button", { name: "Apply" }));
+    expect(onEdit).toHaveBeenCalledWith(0, 0, draft);
+  });
+
+  it("does not reformat or apply a read-only Value panel", () => {
+    const onEdit = vi.fn();
+    render(
+      <DataView
+        columns={payload}
+        rowCount={1}
+        value={() => json}
+        panel="value"
+        onPanelChange={() => {}}
+        onEdit={onEdit}
+      />,
+    );
+    fireEvent.mouseDown(screen.getByRole("gridcell"), { button: 0 });
+    expect((screen.getByRole("button", { name: "Reformat" }) as HTMLButtonElement).disabled).toBe(true);
+    const v = view();
+    act(() => v.contentDOM.dispatchEvent(new KeyboardEvent("keydown", { key: "Enter", metaKey: true, bubbles: true })));
+    expect(onEdit).not.toHaveBeenCalled();
+    fireEvent.click(screen.getByRole("button", { name: "Open in Window" }));
+    expect(within(screen.getByRole("dialog")).queryByRole("button", { name: "Apply" })).toBeNull();
+  });
+
+  it("treats blank text as invalid for typed JSON and restores the unchanged state when the original text is restored", () => {
+    const onEdit = vi.fn();
+    render(<Grid columns={payload} rowCount={1} value={() => json} editable onEdit={onEdit} />);
+    openWindow();
+    editDoc("");
+    expect((screen.getByRole("button", { name: "Apply" }) as HTMLButtonElement).disabled).toBe(true);
+    editDoc(pretty);
+    expect((screen.getByRole("button", { name: "Apply" }) as HTMLButtonElement).disabled).toBe(true);
+    expect(onEdit).not.toHaveBeenCalled();
+  });
+
+  it("shows formatted JSON in the Value panel with Reformat, Open in Window and guarded Apply", () => {
+    const onEdit = vi.fn();
+    const columns = [
+      { name: "id", type: "int4" },
+      { name: "payload", type: "jsonb" },
+    ];
+    const data = [["1", json]];
+    render(
+      <DataView
+        columns={columns}
+        rowCount={1}
+        value={(r, c) => data[r]![c]!}
+        panel="value"
+        onPanelChange={() => {}}
+        editable
+        onEdit={onEdit}
+      />,
+    );
+    fireEvent.mouseDown(screen.getAllByRole("gridcell")[1]!, { button: 0 });
+    const editor = screen.getByRole("textbox", { name: "Value of payload" });
+    expect(shown(editor.textContent ?? "")).toBe(shown(pretty));
+    const apply = () => screen.getByRole("button", { name: "Apply" }) as HTMLButtonElement;
+    expect(apply().disabled).toBe(true);
+    editDoc(pretty.replace('"Ada"', '"Grace"'));
+    expect(apply().disabled).toBe(false);
+    fireEvent.click(apply());
+    expect(onEdit).toHaveBeenCalledWith(0, 1, pretty.replace('"Ada"', '"Grace"'));
+    // The panel editor restarts on the committed value.
+    expect(shown(editor.textContent ?? "")).toBe(shown(pretty.replace('"Ada"', '"Grace"')));
+    // The same editor in a larger, resizable window.
+    fireEvent.click(screen.getByRole("button", { name: "Open in Window" }));
+    expect(screen.getByRole("dialog", { name: "Value of payload" })).toBeTruthy();
+    fireEvent.click(screen.getByRole("button", { name: "Cancel" }));
+    expect(screen.queryByRole("dialog")).toBeNull();
+  });
+});
+
 describe("result grid search", () => {
   const columns = [
     { name: "city", type: "text" },
diff --git a/src/features/database/Grid.tsx b/src/features/database/Grid.tsx
index a1645500f..c46b7b68a 100644
--- a/src/features/database/Grid.tsx
+++ b/src/features/database/Grid.tsx
@@ -9,6 +9,8 @@ import { useVirtualizer } from "@tanstack/react-virtual";
 import clsx from "clsx";
 import { Dialog, Icon, showContextMenu, type MenuItem } from "@/ui";
 import { parseDelimited, toCsv, toOneRow, toTsv, type Cell } from "./model";
+import { initialJsonText, isJsonColumn, isJsonValue } from "./jsonValue";
+import { JsonValueWindow } from "./JsonValueEditor";
 import styles from "./Database.module.css";
 import { tx } from "@/platform/i18n";
 import { CELL_PREVIEW_LIMIT, cellPreview, hasLineBreak } from "./cellPreview";
@@ -145,7 +147,13 @@ export function Grid(props: GridProps) {
     window.addEventListener("mouseup", stop);
     return () => window.removeEventListener("mouseup", stop);
   }, []);
-  const [editing, setEditing] = useState<{ row: number; col: number; text: string; dialog: boolean } | null>(null);
+  const [editing, setEditing] = useState<{
+    row: number;
+    col: number;
+    text: string;
+    json: boolean;
+    dialog: boolean;
+  } | null>(null);
   /** The inline editor is being swapped for the multi-line one: its blur must not commit. */
   const maximizing = useRef(false);
   useEffect(() => {
@@ -257,13 +265,26 @@ export function Grid(props: GridProps) {
     scrollRef.current?.focus();
   };
 
+  /** The JSON value window's Apply / Set NULL: the same pending-edit pipeline as the inline editor. */
+  const commitJsonWindow = (text: string | null) => {
+    if (!editing) return;
+    if (text !== value(editing.row, editing.col)) onEdit?.(editing.row, editing.col, text);
+    setEditing(null);
+    scrollRef.current?.focus();
+  };
+
   /** `maximized` (⇧Enter): the multi-line editor, which multi-line and long values always use. */
   const startEdit = (row: number, col: number, maximized = false) => {
     if (!editable || props.rowState?.(row) === "deleted") return;
-    const text = value(row, col) ?? "";
-    setEditing({ row, col, text, dialog: maximized || text.length > CELL_PREVIEW_LIMIT || hasLineBreak(text) });
+    const cell = value(row, col);
+    const text = cell ?? "";
+    // JSON cells (type or content) edit in the JSON value editor when the dialog opens (#2333).
+    const json = isJsonValue(columns[col]?.type ?? "", cell);
+    setEditing({ row, col, text, json, dialog: maximized || text.length > CELL_PREVIEW_LIMIT || hasLineBreak(text) });
   };
 
+  const jsonWindowChanged = editing?.dialog && editing.json && editing.text !== (value(editing.row, editing.col) ?? "");
+
   const onKeyDown = (e: KeyboardEvent<HTMLDivElement>) => {
     if (editing) return;
     const mod = e.metaKey || e.ctrlKey;
@@ -408,7 +429,22 @@ export function Grid(props: GridProps) {
       onPaste={onPaste}
       onContextMenu={onContextMenu}
     >
-      {editing?.dialog && (
+      {editing?.dialog && editing.json && (
+        <JsonValueWindow
+          title={tx`Edit ${columns[editing.col]!.name}`}
+          initial={jsonWindowChanged ? editing.text : initialJsonText(editing.text)}
+          baseline={jsonWindowChanged ? (value(editing.row, editing.col) ?? "") : undefined}
+          validate={isJsonColumn(columns[editing.col]!.type)}
+          emptyIsNull={value(editing.row, editing.col) === null}
+          onClose={() => {
+            setEditing(null);
+            scrollRef.current?.focus();
+          }}
+          onApply={(text) => commitJsonWindow(text)}
+          onSetNull={() => commitJsonWindow(null)}
+        />
+      )}
+      {editing?.dialog && !editing.json && (
         <Dialog
           open
           title={tx`Edit ${columns[editing.col]!.name}`}
diff --git a/src/features/database/JsonValueEditor.tsx b/src/features/database/JsonValueEditor.tsx
new file mode 100644
index 000000000..0597a8d71
--- /dev/null
+++ b/src/features/database/JsonValueEditor.tsx
@@ -0,0 +1,282 @@
+import { useEffect, useRef, useState } from "react";
+import { EditorState, Prec } from "@codemirror/state";
+import { EditorView, keymap } from "@codemirror/view";
+import { foldKeymap } from "@codemirror/language";
+import { setDiagnostics } from "@codemirror/lint";
+import { openSearchPanel, searchKeymap } from "@codemirror/search";
+import { findLanguageDescription, loadSupport } from "@/editor/core/cm/languages";
+import { baseExtensions, compartments } from "@/editor/core/cm/setup";
+import { tx } from "@/platform/i18n";
+import { Dialog, T, Button, type DialogButton } from "@/ui";
+import { formatJson, jsonErrorOf, JSON_INLINE_LIMIT, type JsonError } from "./jsonValue";
+import { registerValueEditorActions } from "./valueEditorActions";
+import styles from "./Database.module.css";
+
+export interface JsonEditorApi {
+  reformat(): void;
+  focus(): void;
+}
+
+const jsonLanguage = findLanguageDescription("JSON", "value.json");
+
+/** A standalone value using the same editor setup and JSON support as file editors. */
+export function JsonValueEditor(props: {
+  initial: string;
+  validate: boolean;
+  emptyIsNull?: boolean;
+  readOnly?: boolean;
+  ariaLabel: string;
+  onChange: (text: string, error: JsonError | null, pending: boolean) => void;
+  onReady?: (api: JsonEditorApi | null) => void;
+  onSubmit?: () => void;
+  onOpenWindow?: () => void;
+}) {
+  const hostRef = useRef<HTMLDivElement>(null);
+  const current = useRef(props);
+  current.current = props;
+
+  useEffect(() => {
+    const host = hostRef.current;
+    if (!host) return;
+    let alive = true;
+    let worker: Worker | null = null;
+    const report = (text: string, error: JsonError | null, pending = false) => {
+      current.current.onChange(text, current.current.validate ? error : null, pending && current.current.validate);
+      queueMicrotask(() => {
+        if (!alive || text !== view.state.doc.toString()) return;
+        const from = Math.min(error?.pos ?? 0, Math.max(view.state.doc.length - 1, 0));
+        view.dispatch(
+          setDiagnostics(
+            view.state,
+            error
+              ? [
+                  {
+                    from,
+                    to: Math.min(from + 1, view.state.doc.length),
+                    severity: current.current.validate ? "error" : "warning",
+                    message: error.message,
+                  },
+                ]
+              : [],
+          ),
+        );
+      });
+    };
+    const analyze = (text: string, format = false) => {
+      worker?.terminate();
+      worker = null;
+      if (text === "" && current.current.emptyIsNull) {
+        report(text, null);
+        return;
+      }
+      const done = (result: { text: string; error: JsonError | null }) => {
+        if (!alive || text !== view.state.doc.toString()) return;
+        if (format && result.text !== text && !current.current.readOnly)
+          view.dispatch({ changes: { from: 0, to: view.state.doc.length, insert: result.text } });
+        else report(text, result.error);
+      };
+      if (text.length <= JSON_INLINE_LIMIT) {
+        done({ text: format ? formatJson(text) : text, error: jsonErrorOf(text) });
+      } else {
+        report(text, null, true);
+        worker = new Worker(new URL("./jsonValue.worker.ts", import.meta.url), { type: "module" });
+        const task = worker;
+        worker.onmessage = (event: MessageEvent<{ text: string; error: JsonError | null }>) => {
+          if (worker !== task) return;
+          task.terminate();
+          worker = null;
+          done(event.data);
+        };
+        worker.onerror = () => {
+          if (worker !== task) return;
+          task.terminate();
+          worker = null;
+          report(text, { message: tx("JSON validation failed"), pos: 0 });
+        };
+        worker.postMessage({ text, format });
+      }
+    };
+    const reformat = () => {
+      if (!current.current.readOnly) analyze(view.state.doc.toString(), true);
+      return true;
+    };
+    const view = new EditorView({
+      parent: host,
+      state: EditorState.create({
+        doc: props.initial,
+        extensions: baseExtensions({
+          ctx: {
+            doc: -1,
+            path: "value.json",
+            language: "json",
+            uiMode: "JSON",
+            readOnly: !!props.readOnly,
+            virtual: true,
+          },
+          settings: undefined,
+          info: undefined,
+          language: null,
+          docLength: props.initial.length,
+          indent: { tabSize: 2, insertSpaces: true },
+          wrapOverride: false,
+          contributions: [],
+          extra: [
+            Prec.highest(
+              keymap.of([
+                {
+                  key: "Mod-Enter",
+                  run: () => {
+                    current.current.onSubmit?.();
+                    return true;
+                  },
+                },
+                ...searchKeymap,
+                ...foldKeymap,
+              ]),
+            ),
+            EditorView.editable.of(!props.readOnly),
+            Prec.highest(EditorView.contentAttributes.of({ "aria-label": props.ariaLabel, tabindex: "0" })),
+            EditorView.updateListener.of((update) => {
+              if (update.docChanged) analyze(update.state.doc.toString());
+            }),
+          ],
+        }),
+      }),
+    });
+    if (jsonLanguage)
+      void loadSupport(jsonLanguage).then((support) => {
+        if (alive && support) view.dispatch({ effects: compartments.language.reconfigure(support) });
+      });
+    const unregisterActions = registerValueEditorActions(host, {
+      reformat,
+      find: () => {
+        openSearchPanel(view);
+      },
+      openWindow: props.onOpenWindow ? () => current.current.onOpenWindow?.() : undefined,
+      readOnly: !!props.readOnly,
+    });
+    analyze(props.initial);
+    props.onReady?.({ reformat, focus: () => view.focus() });
+    return () => {
+      alive = false;
+      unregisterActions();
+      worker?.terminate();
+      props.onReady?.(null);
+      view.destroy();
+    };
+    // The parent re-keys the editor when its cell value changes.
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [props.initial]);
+
+  return <div ref={hostRef} className={styles.valueEditor} data-db-value-editor />;
+}
+
+const VALUE_WINDOW_SIZE_KEY = "openidea.database.valueWindowSize";
+
+/** The value window's last size; null on first run, clamped to the window by Dialog. */
+export function loadValueWindowSize(): { w: number; h: number } | null {
+  try {
+    const v = JSON.parse(localStorage.getItem(VALUE_WINDOW_SIZE_KEY) ?? "null") as { w?: unknown; h?: unknown } | null;
+    return typeof v?.w === "number" && typeof v.h === "number" ? { w: v.w, h: v.h } : null;
+  } catch {
+    return null;
+  }
+}
+
+export function saveValueWindowSize(size: { w: number; h: number }) {
+  try {
+    localStorage.setItem(VALUE_WINDOW_SIZE_KEY, JSON.stringify(size));
+  } catch {
+    // Private mode etc. — the size just isn't remembered.
+  }
+}
+
+/** The value editor in a resizable window whose size is remembered between openings. */
+export function JsonValueWindow(props: {
+  title: string;
+  /** The text to open with, already pretty-printed by the caller. */
+  initial: string;
+  baseline?: string;
+  validate: boolean;
+  emptyIsNull?: boolean;
+  readOnly?: boolean;
+  onClose: () => void;
+  /** Applies the editor's text (the caller's pending-edit pipeline); omit for read-only. */
+  onApply?: (text: string) => void;
+  onSetNull?: () => void;
+}) {
+  const [text, setText] = useState(props.initial);
+  const [error, setError] = useState<JsonError | null>(() =>
+    !props.emptyIsNull && props.validate && props.initial.length <= JSON_INLINE_LIMIT
+      ? jsonErrorOf(props.initial)
+      : null,
+  );
+  const [pending, setPending] = useState(props.initial.length > JSON_INLINE_LIMIT);
+  const editor = useRef<JsonEditorApi | null>(null);
+  const [initialSize] = useState(
+    () =>
+      loadValueWindowSize() ?? {
+        w: Math.min(760, globalThis.innerWidth - 64),
+        h: Math.min(520, globalThis.innerHeight - 64),
+      },
+  );
+  const dirty = text !== (props.baseline ?? props.initial);
+  const apply = () => {
+    if (!props.readOnly && dirty && !error && !pending) props.onApply?.(text);
+  };
+  const buttons: DialogButton[] = props.readOnly
+    ? [{ label: "Close", role: "cancel", onClick: props.onClose }]
+    : [
+        ...(props.onSetNull ? [{ label: "Set NULL", onClick: props.onSetNull }] : []),
+        { label: "Cancel", role: "cancel", onClick: props.onClose },
+        { label: "Apply", role: "default", disabled: !dirty || !!error || pending, onClick: apply },
+      ];
+  return (
+    <Dialog
+      open
+      title={props.title}
+      onClose={props.onClose}
+      buttons={buttons}
+      width={760}
+      minWidth={420}
+      minHeight={280}
+      resizable="both"
+      initialSize={initialSize}
+      onResized={saveValueWindowSize}
+      footerStart={
+        props.readOnly ? undefined : (
+          <Button size="small" disabled={!!error || pending} onClick={() => editor.current?.reformat()}>
+            <T>Reformat</T>
+          </Button>
+        )
+      }
+    >
+      <div className={styles.valueWindowBody}>
+        <JsonValueEditor
+          initial={props.initial}
+          validate={props.validate}
+          emptyIsNull={props.emptyIsNull}
+          readOnly={props.readOnly}
+          ariaLabel={props.title}
+          onChange={(t, e, busy) => {
+            setText(t);
+            setError(e);
+            setPending(busy);
+          }}
+          onReady={(api) => {
+            editor.current = api;
+            api?.focus();
+          }}
+          onSubmit={() => {
+            apply();
+          }}
+        />
+        {error && (
+          <div className={styles.valueError} role="status">
+            {error.message}
+          </div>
+        )}
+      </div>
+    </Dialog>
+  );
+}
diff --git a/src/features/database/index.ts b/src/features/database/index.ts
index e9783c53c..65bb28691 100644
--- a/src/features/database/index.ts
+++ b/src/features/database/index.ts
@@ -19,6 +19,7 @@ import {
   setFileDecorations,
   toolWindowService,
 } from "@/workbench/contributions";
+import { installValueEditorActions } from "./valueEditorActions";
 import { SQL_LANGUAGE } from "./sqlLanguage";
 import { TABLE_KIND, tableTitle } from "./tableInput";
 import { nodeTarget, type DbNode } from "./nodes";
@@ -123,6 +124,7 @@ export function activate(): () => void {
     () => setFileDecorations("database", new Map()),
     watchIdleConnections(),
     installTableEditorFocus(),
+    installValueEditorActions(),
     registerDatabaseTreeActions(),
     registerActions([
       {
diff --git a/src/features/database/jsonValue.test.ts b/src/features/database/jsonValue.test.ts
new file mode 100644
index 000000000..27239de4f
--- /dev/null
+++ b/src/features/database/jsonValue.test.ts
@@ -0,0 +1,83 @@
+import { describe, expect, it } from "vitest";
+import { formatJson, initialJsonText, JSON_INLINE_LIMIT, isJsonColumn, isJsonValue, jsonErrorOf } from "./jsonValue";
+
+describe("JSON column detection", () => {
+  it("matches json, jsonb and MySQL JSON types", () => {
+    for (const type of ["json", "jsonb", "JSON", "Json", "MYSQL_TYPE_JSON"]) expect(isJsonColumn(type)).toBe(true);
+    for (const type of ["text", "_json", "jsonb[]", "notjson", "json_config"]) expect(isJsonColumn(type)).toBe(false);
+    expect(isJsonColumn("integer")).toBe(false);
+    expect(isJsonColumn("")).toBe(false);
+  });
+
+  it("edits JSON columns as JSON, including null and invalid values", () => {
+    expect(isJsonValue("jsonb", '{"a":1}')).toBe(true);
+    expect(isJsonValue("json", null)).toBe(true);
+    expect(isJsonValue("JSON", "not json at all")).toBe(true);
+  });
+
+  it("edits text cells as JSON only when they are JSON objects or arrays", () => {
+    expect(isJsonValue("text", '{"a": 1}')).toBe(true);
+    expect(isJsonValue("text", "  [1, 2] ")).toBe(true);
+    expect(isJsonValue("text", '{"a": 1')).toBe(false);
+    expect(isJsonValue("text", "123")).toBe(false);
+    expect(isJsonValue("text", '"quoted"')).toBe(false);
+    expect(isJsonValue("text", "hello {world")).toBe(false);
+    expect(isJsonValue("text", "")).toBe(false);
+    expect(isJsonValue("text", null)).toBe(false);
+  });
+});
+
+describe("JSON validation", () => {
+  it("accepts valid JSON and rejects blank values", () => {
+    expect(jsonErrorOf('{"a": 1}')).toBeNull();
+    expect(jsonErrorOf("[]")).toBeNull();
+    expect(jsonErrorOf("true")).toBeNull();
+    expect(jsonErrorOf("")).not.toBeNull();
+    expect(jsonErrorOf("   ")).not.toBeNull();
+  });
+
+  it("reports the message and offset of the first syntax error", () => {
+    const error = jsonErrorOf('{"a": 1,}');
+    expect(error).not.toBeNull();
+    expect(error!.message).toMatch(/JSON/i);
+    expect(error!.pos).toBeGreaterThan(0);
+    expect(error!.pos).toBeLessThanOrEqual('{"a": 1,}'.length);
+    // An error without a parse position lands at the start.
+    expect(jsonErrorOf("no json here")!.pos).toBe(0);
+  });
+});
+
+describe("formatJson", () => {
+  it("pretty-prints with two spaces and keeps scalars", () => {
+    expect(formatJson('{"a":1,"b":[2,3]}')).toBe('{\n  "a": 1,\n  "b": [\n    2,\n    3\n  ]\n}');
+    expect(formatJson("123")).toBe("123");
+    expect(formatJson('"text"')).toBe('"text"');
+  });
+
+  it("passes invalid text through unchanged", () => {
+    expect(formatJson('{"a": 1')).toBe('{"a": 1');
+    expect(formatJson("")).toBe("");
+  });
+
+  it("is stable over already formatted JSON", () => {
+    const pretty = '{\n  "a": 1,\n  "b": [\n    2\n  ]\n}';
+    expect(formatJson(pretty)).toBe(pretty);
+  });
+});
+
+it("formats without changing large numbers, duplicate keys or number spelling", () => {
+  expect(formatJson('{"n":9007199254740993,"n":1e2}')).toBe('{\n  "n": 9007199254740993,\n  "n": 1e2\n}');
+});
+
+it("bounds automatic formatting and content detection for large values", () => {
+  const text = '{"large":"' + "x".repeat(5_000_000) + '"}';
+  expect(text.length).toBeGreaterThan(JSON_INLINE_LIMIT);
+  expect(initialJsonText(text)).toBe(text);
+  expect(isJsonValue("text", text)).toBe(false);
+  expect(isJsonValue("json", text)).toBe(true);
+});
+
+it("reformats a 5 MB string without dropping any of its content", () => {
+  const value = "x".repeat(5_000_000);
+  expect(formatJson('{"large":"' + value + '"}')).toBe('{\n  "large": "' + value + '"\n}');
+});
diff --git a/src/features/database/jsonValue.ts b/src/features/database/jsonValue.ts
new file mode 100644
index 000000000..df0dcf084
--- /dev/null
+++ b/src/features/database/jsonValue.ts
@@ -0,0 +1,76 @@
+import type { Cell } from "./model";
+
+/** Automatic formatting and content detection are bounded on the UI thread. */
+export const JSON_INLINE_LIMIT = 256_000;
+
+export const isJsonColumn = (type: string) => /^(json|jsonb|MYSQL_TYPE_JSON)$/i.test(type.trim());
+
+export interface JsonError {
+  message: string;
+  pos: number;
+}
+
+export function jsonErrorOf(text: string): JsonError | null {
+  try {
+    JSON.parse(text);
+    return null;
+  } catch (e) {
+    const message = e instanceof Error ? e.message : String(e);
+    const at = /position (\d+)/i.exec(message);
+    return { message, pos: at ? Math.min(Number(at[1]), text.length) : 0 };
+  }
+}
+
+/** Content detection chooses highlighting, never the column's validation rules. */
+export function isJsonValue(columnType: string, cell: Cell): boolean {
+  if (isJsonColumn(columnType)) return true;
+  if (cell === null || cell.length > JSON_INLINE_LIMIT) return false;
+  const text = cell.trim();
+  return (text.startsWith("{") || text.startsWith("[")) && jsonErrorOf(text) === null;
+}
+
+/** Change whitespace only: parsing/stringifying would round integers and discard duplicate keys. */
+export function formatJson(text: string): string {
+  if (jsonErrorOf(text)) return text;
+  const tokens: string[] = [];
+  // Scan strings directly: WebKit can stop a repeated regular expression on a large literal.
+  for (let i = 0; i < text.length;) {
+    const start = i;
+    const char = text[i++]!;
+    if (" \t\r\n".includes(char)) continue;
+    if (char === '"') {
+      while (i < text.length) {
+        const next = text[i++]!;
+        if (next === "\\") i++;
+        else if (next === '"') break;
+      }
+    } else if (!"{}[],:".includes(char)) {
+      while (i < text.length && !" \t\r\n{}[],:".includes(text[i]!)) i++;
+    }
+    tokens.push(text.slice(start, i));
+  }
+  const parts: string[] = [];
+  let depth = 0;
+  let length = 0;
+  const line = () => "\n" + "  ".repeat(Math.min(depth, 100));
+  for (let i = 0; i < tokens.length; i++) {
+    const token = tokens[i]!;
+    let part = token;
+    if (token === "{" || token === "[") {
+      depth++;
+      if (tokens[i + 1] !== (token === "{" ? "}" : "]")) part += line();
+    } else if (token === "}" || token === "]") {
+      depth--;
+      if (tokens[i - 1] !== (token === "}" ? "{" : "[")) part = line() + token;
+    } else if (token === ",") part += line();
+    else if (token === ":") part += " ";
+    length += part.length;
+    if (length > 16_000_000) return text;
+    parts.push(part);
+  }
+  return parts.join("");
+}
+
+export function initialJsonText(text: string): string {
+  return text.length <= JSON_INLINE_LIMIT ? formatJson(text) : text;
+}
diff --git a/src/features/database/jsonValue.worker.ts b/src/features/database/jsonValue.worker.ts
new file mode 100644
index 000000000..5e8d3f686
--- /dev/null
+++ b/src/features/database/jsonValue.worker.ts
@@ -0,0 +1,6 @@
+import { formatJson, jsonErrorOf } from "./jsonValue";
+
+self.onmessage = (event: MessageEvent<{ text: string; format: boolean }>) => {
+  const { text, format } = event.data;
+  self.postMessage({ text: format ? formatJson(text) : text, error: jsonErrorOf(text) });
+};
diff --git a/src/features/database/valueEditorActions.ts b/src/features/database/valueEditorActions.ts
new file mode 100644
index 000000000..f46abdbb9
--- /dev/null
+++ b/src/features/database/valueEditorActions.ts
@@ -0,0 +1,65 @@
+import { registerActions } from "@/platform/actions";
+import { setContext } from "@/platform/context";
+
+interface ValueEditorActions {
+  reformat(): void;
+  find(): void;
+  openWindow?: () => void;
+  readOnly: boolean;
+}
+
+const editors = new WeakMap<Element, ValueEditorActions>();
+let active: ValueEditorActions | null = null;
+
+function update() {
+  setContext("dbJsonValueFocus", !!active);
+  setContext("dbJsonValueEditable", !!active && !active.readOnly);
+  setContext("dbJsonValueCanOpenWindow", !!active?.openWindow);
+}
+
+export function registerValueEditorActions(root: Element, actions: ValueEditorActions): () => void {
+  editors.set(root, actions);
+  return () => {
+    editors.delete(root);
+    if (active === actions) active = null;
+    update();
+  };
+}
+
+export function installValueEditorActions(): () => void {
+  const onFocus = (event: FocusEvent) => {
+    const root = event.target instanceof Element ? event.target.closest("[data-db-value-editor]") : null;
+    active = root ? (editors.get(root) ?? null) : null;
+    update();
+  };
+  document.addEventListener("focusin", onFocus);
+  const dispose = registerActions([
+    {
+      id: "db.reformatValue",
+      title: "Reformat",
+      category: "Database",
+      when: "dbJsonValueFocus && dbJsonValueEditable",
+      run: () => active?.reformat(),
+    },
+    {
+      id: "db.findInValue",
+      title: "Find",
+      category: "Database",
+      when: "dbJsonValueFocus",
+      run: () => active?.find(),
+    },
+    {
+      id: "db.openValueWindow",
+      title: "Open in Window",
+      category: "Database",
+      when: "dbJsonValueCanOpenWindow",
+      run: () => active?.openWindow?.(),
+    },
+  ]);
+  return () => {
+    dispose();
+    document.removeEventListener("focusin", onFocus);
+    active = null;
+    update();
+  };
+}
diff --git a/src/platform/keymaps/eclipse-macos.ts b/src/platform/keymaps/eclipse-macos.ts
index 2671f243d..51ba46f94 100644
--- a/src/platform/keymaps/eclipse-macos.ts
+++ b/src/platform/keymaps/eclipse-macos.ts
@@ -104,6 +104,8 @@ export const eclipseMacos: Record<string, string[]> = {
   "code.quickDocumentation": ["F2"],
   "db.quickDoc": ["F2"],
   "localHistory.recentChanges": [],
+  "db.reformatValue": ["Shift+Meta+F"],
+  "db.findInValue": [],
   "code.reformat": ["Shift+Meta+F"],
   "project.reformatCode": ["Shift+Meta+F"],
   "code.unwrap": [],
diff --git a/src/platform/keymaps/eclipse-windows.ts b/src/platform/keymaps/eclipse-windows.ts
index abc425fe3..ff64a4da8 100644
--- a/src/platform/keymaps/eclipse-windows.ts
+++ b/src/platform/keymaps/eclipse-windows.ts
@@ -108,6 +108,8 @@ export const eclipseWindows: Record<string, string[]> = {
   "code.quickDocumentation": ["Shift+Ctrl+Space", "F2"],
   "db.quickDoc": ["Shift+Ctrl+Space", "F2"],
   "localHistory.recentChanges": [],
+  "db.reformatValue": ["Ctrl+Alt+L", "Shift+Ctrl+F"],
+  "db.findInValue": [],
   "code.reformat": ["Ctrl+Alt+L", "Shift+Ctrl+F"],
   "project.reformatCode": ["Ctrl+Alt+L", "Shift+Ctrl+F"],
   "code.unwrap": ["Alt+R"],
diff --git a/src/platform/keymaps/eclipse.test.ts b/src/platform/keymaps/eclipse.test.ts
index 59aa3517f..eefe5f609 100644
--- a/src/platform/keymaps/eclipse.test.ts
+++ b/src/platform/keymaps/eclipse.test.ts
@@ -47,7 +47,7 @@ const shared = [
   ["find.previous", "find.popup.previousResult"],
   ["find.usages", "project.findUsages"],
   ["code.quickDocumentation", "db.quickDoc", "debug.setValue", "vcs.changelist.edit"],
-  ["code.reformat", "project.reformatCode"],
+  ["code.reformat", "project.reformatCode", "db.reformatValue"],
   ["code.optimizeImports", "project.optimizeImports"],
   ["code.deleteLine", "db.duplicateSource", "project.compareWith", "vcs.showDiff"],
   ["code.moveStatementDown", "find.field.recentSearches", "find.popup.recentSearches"],
diff --git a/src/platform/keymaps/intellij-macos.ts b/src/platform/keymaps/intellij-macos.ts
index 045ba6626..5b909aec9 100644
--- a/src/platform/keymaps/intellij-macos.ts
+++ b/src/platform/keymaps/intellij-macos.ts
@@ -354,6 +354,9 @@ export const intellijMacos: Record<string, string[]> = {
   "http.runRequest": ["Meta+Enter"],
   "graphql.runQuery": ["Meta+Enter"],
   "http.runAll": [],
+  "db.reformatValue": ["Meta+Alt+L"],
+  "db.openValueWindow": [],
+  "db.findInValue": ["Meta+F"],
   "db.execute": ["Meta+Enter"],
   // Table editor with pending changes (after `vcs.rollback`, so ⌥⌘Z reverts the table's edits there).
   "db.goToColumn": ["Meta+F12"],
diff --git a/src/platform/keymaps/intellij-windows.ts b/src/platform/keymaps/intellij-windows.ts
index a049427c4..ee01144a6 100644
--- a/src/platform/keymaps/intellij-windows.ts
+++ b/src/platform/keymaps/intellij-windows.ts
@@ -352,6 +352,9 @@ export const intellijWindows: Record<string, string[]> = {
   "http.runRequest": ["Ctrl+Enter"],
   "graphql.runQuery": ["Ctrl+Enter"],
   "http.runAll": [],
+  "db.reformatValue": ["Ctrl+Alt+L"],
+  "db.openValueWindow": [],
+  "db.findInValue": ["Ctrl+F"],
   "db.execute": ["Ctrl+Enter"],
   // Table editor with pending changes (after `vcs.rollback`, so Ctrl+Alt+Z reverts the table's edits there).
   "db.goToColumn": ["Ctrl+F12"],
diff --git a/src/platform/keymaps/vscode-macos.ts b/src/platform/keymaps/vscode-macos.ts
index 5b6dd9b35..cfd6101f1 100644
--- a/src/platform/keymaps/vscode-macos.ts
+++ b/src/platform/keymaps/vscode-macos.ts
@@ -350,6 +350,9 @@ export const vscodeMacos: Record<string, string[]> = {
   "http.runRequest": ["Meta+Enter"],
   "graphql.runQuery": ["Meta+Enter"],
   "http.runAll": [],
+  "db.reformatValue": ["Alt+Shift+F"],
+  "db.openValueWindow": [],
+  "db.findInValue": ["Meta+F"],
   "db.execute": ["Meta+Enter"],
   "db.showToolWindow": [],
   // Database tool window (when the tree has focus).
diff --git a/src/platform/locales/text/en.json b/src/platform/locales/text/en.json
index 156f35b0d..2c6862143 100644
--- a/src/platform/locales/text/en.json
+++ b/src/platform/locales/text/en.json
@@ -786,6 +786,9 @@
   "Remote of {name}": "Remote of {name}",
   "Target branch of {name}": "Target branch of {name}",
   "Remote project files cannot be shown in {fileManager}": "Remote project files cannot be shown in {fileManager}",
+  "Reformat": "Reformat",
+  "Open in Window": "Open in Window",
+  "JSON validation failed": "JSON validation failed",
   "Download Sources": "Download Sources",
   "Choose Sources…": "Choose Sources…",
   "Source archives": "Source archives",
diff --git a/src/platform/locales/text/zh.json b/src/platform/locales/text/zh.json
index baabab728..05b6b64a2 100644
--- a/src/platform/locales/text/zh.json
+++ b/src/platform/locales/text/zh.json
@@ -7121,6 +7121,9 @@
   "Remote of {name}": "{name} 的远程",
   "Target branch of {name}": "{name} 的目标分支",
   "Remote project files cannot be shown in {fileManager}": "无法在{fileManager}中显示远程项目的文件",
+  "Reformat": "重新格式化",
+  "Open in Window": "在窗口中打开",
+  "JSON validation failed": "JSON 验证失败",
   "Download Sources": "下载源代码",
   "Choose Sources…": "选择源代码…",
   "Source archives": "源代码归档",