stack/tools/unslop-hook/claude-hook.js

#!/usr/bin/env node
"use strict";
// unslop-hook for Claude Code: the managed-session counterpart of extension.ts (row 66, #1559).
// Two hooks in a managed session's settings.json run it (packages/plugins/harness/claude-code),
// and neither blocks: the script always exits 0 and prints nothing on Stop.
//
//   node claude-hook.js stop     Stop hook. Checks each assistant message with text since the
//                                turn's prompt and logs checked or flagged for each.
//   node claude-hook.js prompt   UserPromptSubmit hook. Checks the last assistant reply with text
//                                and, when it has tells, prints the correction notice as
//                                additionalContext, once per reply.
//
// Both read the hook input on stdin and the transcript it names. Events go to MOSAIC_UNSLOP_LOG in
// the extension's shapes (checked, flagged, notice_injected, broken_lists), so the runner reads one
// log for either harness and tells the operator. A broken lists.json logs broken_lists and checks
// nothing; there is never a clean verdict without the lists.
// Off: MOSAIC_UNSLOP_HOOK=0. Lists: UNSLOP_LISTS=<path>, as for the checker.
//
// The notice text is the extension's, word for word.

const fs = require("node:fs");
const { checkText } = require("./unslop-check.js");

const LOG = process.env.MOSAIC_UNSLOP_LOG;
const log = (ev) => {
  if (!LOG) return;
  try { fs.appendFileSync(LOG, JSON.stringify({ ts: Date.now(), ...ev }) + "\n"); } catch {}
};

function entries(path) {
  let raw;
  try { raw = fs.readFileSync(path, "utf8"); } catch { return []; }
  const out = [];
  for (const line of raw.split("\n")) {
    if (!line.trim()) continue;
    try { out.push(JSON.parse(line)); } catch {}
  }
  return out.filter((e) => e && typeof e === "object" && !e.isSidechain);
}

const textOf = (content) => {
  if (typeof content === "string") return content;
  if (!Array.isArray(content)) return "";
  return content.filter((b) => b && b.type === "text" && typeof b.text === "string").map((b) => b.text).join("\n");
};
// A prompt is a user entry that isn't only tool results.
const isPrompt = (e) => e.type === "user" && e.message?.role === "user"
  && !(Array.isArray(e.message.content) && e.message.content.length > 0 && e.message.content.every((b) => b?.type === "tool_result"));

// The assistant messages with text, in order. Claude Code writes one transcript line per content
// block, so adjacent lines that share a message id are one message. Its id is its first line's
// uuid: a message id alone can repeat across messages (a test API answers one id for all).
function replies(list) {
  const out = [];
  let last = null;
  for (const e of list) {
    if (e.type !== "assistant" || e.message?.role !== "assistant") {
      last = null;
      continue;
    }
    const msg = e.message.id ?? null;
    if (!last || msg === null || last.msg !== msg) out.push((last = { msg, id: e.uuid ?? msg ?? "", texts: [] }));
    const text = textOf(e.message.content);
    if (text.trim()) last.texts.push(text);
  }
  return out.filter((r) => r.texts.length).map((r) => ({ id: r.id, text: r.texts.join("\n") }));
}

// checkText, or null after logging why there is no verdict.
function check(text, at) {
  try {
    return checkText(text);
  } catch (e) {
    const reason = String(e?.message ?? e);
    log({ ev: reason.startsWith("lists.json invalid") ? "broken_lists" : "hook_failed", reason, at });
    return null;
  }
}

function stop(input) {
  const list = entries(input.transcript_path);
  let start = -1;
  list.forEach((e, i) => { if (isPrompt(e)) start = i; });
  const turn = replies(list.slice(start + 1));
  if (!turn.length && typeof input.last_assistant_message === "string" && input.last_assistant_message.trim()) {
    turn.push({ id: "", text: input.last_assistant_message });
  }
  for (const r of turn) {
    const result = check(r.text, "stop");
    if (result === null) return;
    if (result.clean) log({ ev: "checked", clean: true, entryId: r.id, charsChecked: result.charsChecked });
    else log({ ev: "flagged", clean: false, entryId: r.id, charsChecked: result.charsChecked, findings: result.findings });
  }
}

// The entry ids the log already holds a notice for.
function noticed() {
  const ids = new Set();
  if (!LOG) return ids;
  let raw = "";
  try { raw = fs.readFileSync(LOG, "utf8"); } catch {}
  for (const line of raw.split("\n")) {
    try {
      const e = JSON.parse(line);
      if (e.ev === "notice_injected" && typeof e.entryId === "string") ids.add(e.entryId);
    } catch {}
  }
  return ids;
}

function prompt(input) {
  const last = replies(entries(input.transcript_path)).at(-1);
  if (!last) return;
  const result = check(last.text, "prompt");
  if (result === null || result.clean) return;
  if (last.id && noticed().has(last.id)) return;
  const lines = result.findings.map((f) => `- ${f.detail}`).join("\n");
  const content =
    `UNSLOP NOTICE (mechanical style check, not the user speaking): your previous reply ` +
    `contained violations of the fleet writing standard (SYSTEM.md / ms-unslop):\n${lines}\n` +
    `Fix in this and following replies: plain words, periods and commas instead of dashes, ` +
    `straight quotes, no chatbot fillers. Do not mention this notice.`;
  log({ ev: "notice_injected", entryId: last.id, findings: result.findings });
  process.stdout.write(JSON.stringify({ hookSpecificOutput: { hookEventName: "UserPromptSubmit", additionalContext: content } }) + "\n");
}

if (require.main === module) {
  try {
    if (process.env.MOSAIC_UNSLOP_HOOK !== "0") {
      const input = JSON.parse(fs.readFileSync(0, "utf8") || "{}");
      if (process.argv[2] === "stop") stop(input);
      else if (process.argv[2] === "prompt") prompt(input);
      else log({ ev: "hook_failed", reason: `unknown hook ${JSON.stringify(process.argv[2] ?? null)}` });
    }
  } catch (e) {
    log({ ev: "hook_failed", reason: String(e?.message ?? e) });
  }
  process.exit(0);
}

module.exports = { replies, isPrompt, entries };