vscode-cowriting-plugin/test/store.test.ts

import { describe, it, expect, beforeEach, afterEach } from "vitest";
import * as fs from "node:fs";
import * as os from "node:os";
import * as path from "node:path";
import { CoauthorStore } from "../src/store";
import { emptyArtifact, newId, serializeArtifact, type Artifact } from "../src/model";

let root: string;

beforeEach(() => {
  root = fs.mkdtempSync(path.join(os.tmpdir(), "coauthor-store-"));
});
afterEach(() => {
  fs.rmSync(root, { recursive: true, force: true });
});

function withThread(): Artifact {
  const a = emptyArtifact("docs/spec.md");
  a.anchors["a1"] = { fingerprint: { text: "hello", before: "", after: "", lineHint: 0 } };
  a.threads.push({
    id: "t1",
    anchorId: "a1",
    status: "open",
    messages: [{ id: newId("m"), author: { kind: "human", id: "ben" }, body: "note", createdAt: "2026-06-10T00:00:00.000Z" }],
  });
  return a;
}

describe("CoauthorStore", () => {
  it("returns null for a document with no sidecar", () => {
    const store = new CoauthorStore(root);
    expect(store.load("docs/spec.md")).toBeNull();
  });

  it("computes the sidecar path as .threads/<docPath>.json", () => {
    const store = new CoauthorStore(root);
    expect(store.sidecarPath("docs/spec.md")).toBe(path.join(root, ".threads", "docs", "spec.md.json"));
  });

  it("save then load round-trips the artifact", () => {
    const store = new CoauthorStore(root);
    const a = withThread();
    store.save("docs/spec.md", a);
    expect(store.load("docs/spec.md")).toEqual(a);
  });

  it("writes byte-stable, pretty JSON (re-save is identical)", () => {
    const store = new CoauthorStore(root);
    const a = withThread();
    store.save("docs/spec.md", a);
    const first = fs.readFileSync(store.sidecarPath("docs/spec.md"), "utf8");
    store.save("docs/spec.md", store.load("docs/spec.md")!);
    const second = fs.readFileSync(store.sidecarPath("docs/spec.md"), "utf8");
    expect(second).toBe(first);
    expect(first).toBe(serializeArtifact(a));
  });

  it("update(): two writers merge sections instead of clobbering (F3 §6.2)", () => {
    const store = new CoauthorStore(root);
    store.update("d.md", (a) => {
      a.anchors["a_t"] = { fingerprint: { text: "t", before: "", after: "", lineHint: 0 } };
      a.threads.push({ id: "t1", anchorId: "a_t", status: "open", messages: [] });
    });
    store.update("d.md", (a) => {
      a.anchors["a_at"] = { fingerprint: { text: "x", before: "", after: "", lineHint: 0 } };
      a.attributions.push({
        id: "at1", anchorId: "a_at", author: { kind: "human", id: "ben" },
        createdAt: "2026-06-10T00:00:00.000Z", updatedAt: "2026-06-10T00:00:00.000Z",
      });
    });
    const loaded = store.load("d.md")!;
    expect(loaded.threads).toHaveLength(1);
    expect(loaded.attributions).toHaveLength(1);
    expect(Object.keys(loaded.anchors).sort()).toEqual(["a_at", "a_t"]);
  });

  it("update() prunes anchors no longer referenced by threads or attributions", () => {
    const store = new CoauthorStore(root);
    store.update("d.md", (a) => {
      a.anchors["a_old"] = { fingerprint: { text: "o", before: "", after: "", lineHint: 0 } };
      a.attributions.push({
        id: "at1", anchorId: "a_old", author: { kind: "human", id: "ben" },
        createdAt: "2026-06-10T00:00:00.000Z", updatedAt: "2026-06-10T00:00:00.000Z",
      });
    });
    store.update("d.md", (a) => {
      a.attributions = [];
    });
    expect(Object.keys(store.load("d.md")!.anchors)).toEqual([]);
  });

  it("consumeSelfWrite counts multiple writes to the same sidecar (double-save suppression)", () => {
    const store = new CoauthorStore(root);
    store.update("d.md", (a) => {
      a.anchors["a_t"] = { fingerprint: { text: "t", before: "", after: "", lineHint: 0 } };
      a.threads.push({ id: "t1", anchorId: "a_t", status: "open", messages: [] });
    });
    store.update("d.md", (a) => {
      a.attributions.push({
        id: "at1", anchorId: "a_t", author: { kind: "human", id: "ben" },
        createdAt: "2026-06-10T00:00:00.000Z", updatedAt: "2026-06-10T00:00:00.000Z",
      });
    });
    const p = store.sidecarPath("d.md");
    expect(store.consumeSelfWrite(p)).toBe(true);
    expect(store.consumeSelfWrite(p)).toBe(true);
    expect(store.consumeSelfWrite(p)).toBe(false);
  });
});

describe("newer-major write refusal (F5 SLICE-2, INV-16 backstop)", () => {
  it("update REFUSES to write a sidecar from a newer major, leaving bytes untouched", () => {
    const store = new CoauthorStore(root);
    const p = store.sidecarPath("docs/v2.md");
    fs.mkdirSync(path.dirname(p), { recursive: true });
    const v2 = { ...emptyArtifact("docs/v2.md"), schemaVersion: 2 };
    fs.writeFileSync(p, serializeArtifact(v2), "utf8");
    const before = fs.readFileSync(p, "utf8");
    expect(() =>
      store.update("docs/v2.md", (a) => {
        a.threads = [];
      }),
    ).toThrow(/INV-16/);
    expect(fs.readFileSync(p, "utf8")).toBe(before);
  });
});