feat: crossrung-reply stand-in writer — validate, append, stable-serialize (F5 SLICE-4, #14)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-10 23:04:17 -07:00
parent 452f5d193f
commit e0c127c4d9
2 changed files with 186 additions and 0 deletions
@@ -0,0 +1,116 @@
+#!/usr/bin/env node
+// crossrung-reply — the Gitea-rung STAND-IN writer (F5 spec §6.2, fork e):
+// exactly what a forge-side surface does to the record, as a local process.
+// Conforming-writer behavior per the contract (vscode-cowriting-plugin-content/
+// specs/coauthoring-sidecar-contract.md §5): validate → refuse newer majors →
+// append a Message (fresh uuid, ISO-8601 UTC, identity w/ email) →
+// stable-serialize (known-key order, unknowns after sorted, 2-space, trailing
+// newline) → validate again → write.
+//
+// This deliberately RE-IMPLEMENTS the contract's serialization instead of
+// importing the extension's serializer: it is executable documentation of how
+// a second rung behaves. test/crossrungReply.test.ts pins byte-fidelity
+// against the reference serializer — the contract-drift tripwire.
+//
+// usage:
+//   node scripts/crossrung-reply.mjs <sidecar.json> <threadId> <body> \
+//     [--author-id id] [--author-email email]
+import { readFileSync, writeFileSync } from "node:fs";
+import { randomUUID } from "node:crypto";
+import { fileURLToPath } from "node:url";
+import path from "node:path";
+import Ajv from "ajv/dist/2020.js";
+
+const here = path.dirname(fileURLToPath(import.meta.url));
+const schema = JSON.parse(readFileSync(path.join(here, "..", "schemas", "coauthoring-sidecar.schema.json"), "utf8"));
+const ajv = new Ajv({ allErrors: true });
+const checks = ajv.compile(schema);
+
+function fail(msg) {
+  console.error(`crossrung-reply: ${msg}`);
+  process.exit(1);
+}
+function validateOrFail(data, when) {
+  if (!checks(data)) {
+    fail(
+      `${when} validation failed:\n` +
+        (checks.errors ?? []).map((e) => `  ${e.instancePath || "/"} ${e.message}`).join("\n"),
+    );
+  }
+}
+
+// --- args ---
+const [file, threadId, body] = process.argv.slice(2, 5);
+if (!file || !threadId || body === undefined) {
+  console.error("usage: crossrung-reply.mjs <sidecar.json> <threadId> <body> [--author-id id] [--author-email email]");
+  process.exit(2);
+}
+const flags = process.argv.slice(5);
+const flagVal = (name) => {
+  const i = flags.indexOf(name);
+  return i >= 0 ? flags[i + 1] : undefined;
+};
+const authorId = flagVal("--author-id") ?? "crossrung";
+const authorEmail = flagVal("--author-email");
+
+// --- contract serialization (independent implementation: contract §2) ---
+const ORDER = {
+  root: ["schemaVersion", "document", "anchors", "threads", "attributions", "proposals"],
+  document: ["path"],
+  anchor: ["fingerprint"],
+  fingerprint: ["text", "before", "after", "lineHint"],
+  thread: ["id", "anchorId", "status", "messages"],
+  message: ["id", "author", "body", "createdAt"],
+  provenance: ["kind", "id", "email", "agent"],
+  agent: ["sdk", "model", "sessionId", "onBehalfOf"],
+  onBehalfOf: ["id", "email"],
+  attribution: ["id", "anchorId", "author", "createdAt", "updatedAt", "turnId"],
+  proposal: ["id", "anchorId", "replacement", "author", "createdAt", "turnId", "instruction"],
+};
+// known keys first (contract order, present ones only), unknown keys after, sorted
+function ordered(obj, kind, mapKnown = {}) {
+  const out = {};
+  const known = ORDER[kind] ?? [];
+  for (const k of known) if (k in obj) out[k] = k in mapKnown ? mapKnown[k](obj[k]) : obj[k];
+  for (const k of Object.keys(obj).filter((k) => !known.includes(k)).sort()) out[k] = obj[k];
+  return out;
+}
+const provenance = (p) =>
+  ordered(p, "provenance", {
+    agent: (ag) => ordered(ag, "agent", { onBehalfOf: (o) => ordered(o, "onBehalfOf") }),
+  });
+function canonicalize(a) {
+  return ordered(a, "root", {
+    document: (d) => ordered(d, "document"),
+    anchors: (anchors) =>
+      Object.fromEntries(
+        Object.keys(anchors)
+          .sort()
+          .map((k) => [k, ordered(anchors[k], "anchor", { fingerprint: (fp) => ordered(fp, "fingerprint") })]),
+      ),
+    threads: (ts) =>
+      ts.map((t) => ordered(t, "thread", { messages: (ms) => ms.map((m) => ordered(m, "message", { author: provenance })) })),
+    attributions: (ats) => ats.map((at) => ordered(at, "attribution", { author: provenance })),
+    proposals: (ps) => ps.map((p) => ordered(p, "proposal", { author: provenance })),
+  });
+}
+const serialize = (a) => JSON.stringify(canonicalize(a), null, 2) + "\n";
+
+// --- the write (contract §5 checklist) ---
+const data = JSON.parse(readFileSync(file, "utf8"));
+validateOrFail(data, "pre-write");
+if (data.schemaVersion > 1) {
+  fail(`schemaVersion ${data.schemaVersion} is newer than this writer understands (1) — refusing to write (INV-16)`);
+}
+const thread = data.threads.find((t) => t.id === threadId);
+if (!thread) fail(`no thread ${threadId} in ${file}`);
+thread.messages.push({
+  id: `m_${randomUUID()}`,
+  author: { kind: "human", id: authorId, ...(authorEmail ? { email: authorEmail } : {}) },
+  body,
+  createdAt: new Date().toISOString(),
+});
+const out = serialize(data);
+validateOrFail(JSON.parse(out), "post-write");
+writeFileSync(file, out, "utf8");
+console.log(`appended reply to ${threadId} in ${file}`);
@@ -0,0 +1,70 @@
+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 { execFileSync } from "node:child_process";
+import { emptyArtifact, serializeArtifact, type Artifact } from "../src/model";
+import { validateSidecar } from "./helpers/validateSidecar";
+
+const SCRIPT = path.resolve(__dirname, "../scripts/crossrung-reply.mjs");
+let dir: string;
+let sidecar: string;
+
+beforeEach(() => {
+  dir = fs.mkdtempSync(path.join(os.tmpdir(), "cowriting-crossrung-"));
+  sidecar = path.join(dir, "sample.md.json");
+  const a = emptyArtifact("docs/sample.md");
+  a.anchors["a_1"] = { fingerprint: { text: "alpha", before: "", after: "", lineHint: 0 } };
+  a.threads.push({
+    id: "t_1",
+    anchorId: "a_1",
+    status: "open",
+    messages: [{ id: "m_1", author: { kind: "human", id: "ben" }, body: "hi", createdAt: "2026-06-10T00:00:00.000Z" }],
+  });
+  // INV-15 must hold through a FOREIGN writer too
+  (a as unknown as Record<string, unknown>).futureSection = [{ id: "f_1" }];
+  fs.writeFileSync(sidecar, serializeArtifact(a), "utf8");
+});
+afterEach(() => fs.rmSync(dir, { recursive: true, force: true }));
+
+function run(...args: string[]): string {
+  return execFileSync(process.execPath, [SCRIPT, ...args], { encoding: "utf8" });
+}
+
+describe("crossrung-reply stand-in (F5 SLICE-4, PUC-2)", () => {
+  it("appends a conforming reply, preserves unknowns, byte-identical to the reference serializer", () => {
+    run(sidecar, "t_1", "Reply from the forge", "--author-id", "gitea", "--author-email", "forge@example.org");
+    const raw = fs.readFileSync(sidecar, "utf8");
+    const parsed = JSON.parse(raw) as Artifact;
+    expect(parsed.threads[0].messages).toHaveLength(2);
+    const reply = parsed.threads[0].messages[1];
+    expect(reply.body).toBe("Reply from the forge");
+    expect(reply.author).toEqual({ kind: "human", id: "gitea", email: "forge@example.org" });
+    expect(reply.id).toMatch(/^m_/);
+    expect((parsed as unknown as Record<string, unknown>).futureSection).toEqual([{ id: "f_1" }]);
+    expect(validateSidecar(parsed).valid).toBe(true);
+    // the stand-in's independent serialization is byte-identical to the
+    // editor's (INV-2 across writers) — the contract-drift tripwire.
+    expect(serializeArtifact(parsed)).toBe(raw);
+  });
+
+  it("refuses an unknown thread id and leaves the file untouched", () => {
+    const before = fs.readFileSync(sidecar, "utf8");
+    expect(() => run(sidecar, "t_nope", "x")).toThrow();
+    expect(fs.readFileSync(sidecar, "utf8")).toBe(before);
+  });
+
+  it("refuses an invalid sidecar (validates BEFORE writing)", () => {
+    fs.writeFileSync(sidecar, '{"schemaVersion":1}\n', "utf8");
+    expect(() => run(sidecar, "t_1", "x")).toThrow();
+  });
+
+  it("refuses a newer-major sidecar (INV-16 holds for foreign writers too)", () => {
+    const v2 = JSON.parse(fs.readFileSync(sidecar, "utf8"));
+    v2.schemaVersion = 2;
+    fs.writeFileSync(sidecar, JSON.stringify(v2, null, 2) + "\n", "utf8");
+    const before = fs.readFileSync(sidecar, "utf8");
+    expect(() => run(sidecar, "t_1", "x")).toThrow();
+    expect(fs.readFileSync(sidecar, "utf8")).toBe(before);
+  });
+});