test(coverage): add regression tests for issues #192, #206, #204

Additive test coverage across server, editor-ext, client and mcp.

#192 — AiChatService.stream integration (Section 3, against real Postgres):
- new apps/server/test/integration/ai-chat-stream.int-spec.ts drives the real
  streamText through a seeded ai/test MockLanguageModelV3 and a real Node
  ServerResponse, covering: onError persists an assistant error record
  (status 'error' + partial answer + provider cause in metadata); external MCP
  client closed exactly once on BOTH onFinish and onError; anti-tamper —
  history is rebuilt from the DB transcript, not from body.messages.

#206 — red-team findings (most already fixed+tested in #212):
- mdrt-2 (UNFIXED, data loss): turndown.dataloss.test.ts documents that
  pageBreak / transclusionReference / mention are silently dropped on Markdown
  export (characterization + it.fails for the desired survive-export contract).
- persist-6 (UNFIXED, data loss): persistence-store.spec.ts adds an it.failing
  documenting that a momentarily-empty live doc overwrites non-empty content
  (left unfixed — a store-side empty-guard is a behaviour change).

#204 — test-strategy plan, highest-priority subset:
- Phase 1: mcp-clients.lease.spec.ts covers the external MCP client
  lease/refcount/eviction lifecycle (leak / premature-close / double-close).
- Phase 2 data-integrity pure functions: editor-ext table-utils
  (transpose/moveRow/convert round-trip) and math tokenizer false-positive
  guard; client emoji-menu (+ it.fails for the unguarded localStorage
  JSON.parse bug), sort-cells, normalizeTableColumnWidths; mcp htmlEmbed/
  pageBreak markdown data-loss + footnote-diff; server export
  getInternalLinkPageName extensionless-path bug — FIXED (small/clear) + tested.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/editor-ext/src/lib/table/utils/table-utils.test.ts

@@ -0,0 +1,173 @@
+import { describe, it, expect } from "vitest";
+import { Schema } from "@tiptap/pm/model";
+import type { Node as PMNode } from "@tiptap/pm/model";
+import { tableNodes, TableMap } from "@tiptap/pm/tables";
+import { transpose } from "./transpose";
+import { moveRowInArrayOfRows } from "./move-row-in-array-of-rows";
+import { convertTableNodeToArrayOfRows } from "./convert-table-node-to-array-of-rows";
+import { convertArrayOfRowsToTableNode } from "./convert-array-of-rows-to-table-node";
+
+/**
+ * Unit tests for the pure table data-transformation utilities. These functions
+ * drive every drag-to-reorder row/column operation, so a regression here
+ * silently corrupts table content. We test them in isolation against a real
+ * ProseMirror table schema (the same primitives the editor uses).
+ */
+
+// Minimal schema containing real ProseMirror table nodes so TableMap behaves
+// exactly as it does in the editor (merged cells, colspan, etc.).
+const tNodes = tableNodes({
+  tableGroup: "block",
+  cellContent: "inline*",
+  cellAttributes: {},
+});
+const schema = new Schema({
+  nodes: {
+    doc: { content: "block+" },
+    paragraph: { group: "block", content: "inline*", toDOM: () => ["p", 0] },
+    text: { group: "inline" },
+    ...tNodes,
+  },
+  marks: {},
+});
+
+const cell = (txt: string, attrs?: Record<string, unknown>): PMNode =>
+  schema.nodes.table_cell.createChecked(attrs ?? null, schema.text(txt));
+const row = (...cells: PMNode[]): PMNode =>
+  schema.nodes.table_row.createChecked(null, cells);
+const table = (...rows: PMNode[]): PMNode =>
+  schema.nodes.table.createChecked(null, rows);
+
+// Read the text content of each (non-null) cell so we can compare structure
+// without depending on ProseMirror node identity.
+const textGrid = (rows: (PMNode | null)[][]): (string | null)[][] =>
+  rows.map((r) => r.map((c) => (c ? c.textContent : null)));
+
+const tableTextGrid = (t: PMNode): (string | null)[][] =>
+  textGrid(convertTableNodeToArrayOfRows(t));
+
+describe("transpose", () => {
+  it("is its own inverse on a non-square (2x3) matrix", () => {
+    const arr = [
+      ["a1", "a2", "a3"],
+      ["b1", "b2", "b3"],
+    ];
+    const once = transpose(arr);
+    // 2x3 -> 3x2
+    expect(once.length).toBe(3);
+    expect(once[0].length).toBe(2);
+    const twice = transpose(once);
+    expect(twice).toEqual(arr);
+  });
+
+  it("inverts indices: transpose(arr)[j][i] === arr[i][j]", () => {
+    const arr = [
+      ["a1", "a2", "a3"],
+      ["b1", "b2", "b3"],
+    ];
+    const t = transpose(arr);
+    for (let i = 0; i < arr.length; i++) {
+      for (let j = 0; j < arr[0].length; j++) {
+        expect(t[j][i]).toBe(arr[i][j]);
+      }
+    }
+  });
+});
+
+describe("moveRowInArrayOfRows", () => {
+  // Helper: the function mutates `rows` in place (it uses splice), so always
+  // pass a fresh copy and read the returned array.
+  const move = (
+    rows: string[],
+    origin: number[],
+    target: number[],
+    dir: -1 | 0 | 1,
+  ): string[] => moveRowInArrayOfRows([...rows], origin, target, dir);
+
+  it("moves a single row downward to a later index", () => {
+    const result = move(["A", "B", "C", "D"], [0], [2], 0);
+    // A starts at 0, target index 2 -> A lands after C.
+    expect(result).toEqual(["B", "C", "A", "D"]);
+  });
+
+  it("moves a single row upward to an earlier index", () => {
+    const result = move(["A", "B", "C", "D"], [3], [1], 0);
+    expect(result).toEqual(["A", "D", "B", "C"]);
+  });
+
+  it("never drops or duplicates rows (set is preserved) for any pair", () => {
+    const base = ["A", "B", "C", "D", "E"];
+    for (let from = 0; from < base.length; from++) {
+      for (let to = 0; to < base.length; to++) {
+        if (from === to) continue;
+        const result = move(base, [from], [to], 0);
+        expect(result.length).toBe(base.length);
+        expect([...result].sort()).toEqual([...base].sort());
+      }
+    }
+  });
+
+  it("moves an even-sized block (2 rows) preserving block order and full set", () => {
+    // Move the [B,C] block (origin indexes 1,2) toward target index 3 (D,E region).
+    const result = move(["A", "B", "C", "D", "E"], [1, 2], [3], 0);
+    expect(result.length).toBe(5);
+    expect([...result].sort()).toEqual(["A", "B", "C", "D", "E"]);
+    // Block stays contiguous and in original internal order.
+    const bi = result.indexOf("B");
+    expect(result[bi + 1]).toBe("C");
+  });
+
+  it("moves an odd-sized block (3 rows) without dropping rows", () => {
+    const result = move(["A", "B", "C", "D", "E"], [0, 1, 2], [4], 0);
+    expect(result.length).toBe(5);
+    expect([...result].sort()).toEqual(["A", "B", "C", "D", "E"]);
+    // The 3-row block keeps its internal A,B,C order.
+    const ai = result.indexOf("A");
+    expect(result.slice(ai, ai + 3)).toEqual(["A", "B", "C"]);
+  });
+});
+
+describe("convert round-trip: TableNode <-> arrayOfRows", () => {
+  it("preserves a simple 2x3 grid's text content and dimensions", () => {
+    const t = table(
+      row(cell("a1"), cell("b1"), cell("c1")),
+      row(cell("a2"), cell("b2"), cell("c2")),
+    );
+    const before = tableTextGrid(t);
+    expect(before).toEqual([
+      ["a1", "b1", "c1"],
+      ["a2", "b2", "c2"],
+    ]);
+
+    const arr = convertTableNodeToArrayOfRows(t);
+    const rebuilt = convertArrayOfRowsToTableNode(t, arr);
+
+    // Structure (text content + shape) survives the round-trip.
+    expect(tableTextGrid(rebuilt)).toEqual(before);
+    expect(rebuilt.childCount).toBe(t.childCount);
+    const mapA = TableMap.get(t);
+    const mapB = TableMap.get(rebuilt);
+    expect([mapB.width, mapB.height]).toEqual([mapA.width, mapA.height]);
+  });
+
+  it("represents a horizontally merged cell as a null placeholder, and round-trips it", () => {
+    // First cell of row 1 spans 2 columns -> the array form has a null where
+    // the covered column would be.
+    const t = table(
+      row(cell("merged", { colspan: 2 }), cell("c1")),
+      row(cell("a2"), cell("b2"), cell("c2")),
+    );
+
+    const arr = convertTableNodeToArrayOfRows(t);
+    // Row 0: [merged, null, c1] — the null marks the colspan-covered slot.
+    expect(arr[0][0]?.textContent).toBe("merged");
+    expect(arr[0][1]).toBeNull();
+    expect(arr[0][2]?.textContent).toBe("c1");
+
+    const rebuilt = convertArrayOfRowsToTableNode(t, arr);
+    // The merged cell (and its null placeholder) is reconstructed identically.
+    expect(tableTextGrid(rebuilt)).toEqual(tableTextGrid(t));
+    const map = TableMap.get(rebuilt);
+    expect([map.width, map.height]).toEqual([3, 2]);
+  });
+});