scripts/append-log.js

#!/usr/bin/env node
/**
 * append-log.js — concurrency-safe append tool for the shared team log (and,
 * generically, any "top-insert or bottom-append a line" markdown file).
 *
 * Ported from a production teamlog module, deployed at `91-team-tools/teamlog/append-teamlog.js`, +
 * a production concurrency module, deployed at `91-team-tools/concurrency/safe-append.js`, merged into one tool and
 * desensitized. Same core guarantee as both originals: atomic lock-file
 * queueing + atomic temp-file-then-rename replace + read-back verification —
 * this is what makes "many agents append to one shared log concurrently"
 * safe instead of a corruption risk (the production deployment this was
 * distilled from hit real concurrent-write corruption before this existed —
 * see scripts/README.md).
 *
 * Deliberate difference from the production append-teamlog.js: THIS tool does
 * NOT enforce a specific entry format (no forced `- 【YYYY-MM-DD】@name:`
 * pattern). A portable template can't assume every deployment's team log uses
 * that exact convention — team-skeleton.md only specifies "append-only,
 * reverse-chronological", not a literal entry grammar. Format discipline is
 * the caller's responsibility (same design choice as production's
 * concurrency/safe-append.js, which this tool's --mode/--anchor options are
 * ported from).
 *
 * Usage (target file resolution: --target overrides > team-config.json's
 * shared_paths.team_log resolved from the team root found by walking up from
 * cwd):
 *   node append-log.js "<entry text>" [--target <path>] [--mode top|bottom] [--anchor <regex>]
 *   node append-log.js --file <entry-file-path> [--target <path>] [--mode top|bottom] [--anchor <regex>]
 *   node append-log.js --stdin [--target <path>] [--mode top|bottom] [--anchor <regex>]
 *
 * Modes:
 *   --mode top (default):
 *     - no --anchor: classic team-log insert point — right after the title
 *       line (line 1); if line 2 is blank, insert after that blank line
 *       instead (preserves a "title, blank line, newest entry" shape).
 *     - --anchor "<regex>": insert after the FIRST line matching the regex
 *       (e.g. inserting under a specific "## Unread" heading in an inbox
 *       file). No match = hard error, never silently falls back elsewhere.
 *   --mode bottom: append a line at end of file (adds a trailing newline
 *     first if the file didn't already end with one, without touching the
 *     existing last line's content).
 *
 * Behavior:
 *   - Entry content with embedded newlines gets collapsed to one line (a
 *     multi-line entry would break the "one line = one entry" convention).
 *   - Atomically creates `<target>.lock` to queue writers; a lock older than
 *     30s is treated as a crashed holder's leftover and force-cleared.
 *   - After acquiring the lock: read file → insert per mode → write to a
 *     temp file → atomic rename → read back and verify the entry is actually
 *     there + line count is consistent with the insert.
 *   - Any failure: non-zero exit code + a stderr message. No silent failures.
 */
'use strict';
const fs = require('fs');
const path = require('path');
const flock = require('./lib/file-lock');
const cfg = require('./lib/config');

/**
 * die() THROWS rather than calling process.exit() directly — this is
 * deliberate, not an oversight. Several die() call sites (notably
 * computeTopInsertIndex on an --anchor miss) run *after* the lock has already
 * been acquired, inside a try/finally whose finally block releases it. A bare
 * process.exit() would skip that finally entirely and leak the lock file,
 * wedging every subsequent writer until the 30s stale-lock self-heal kicks in.
 * Throwing lets the existing try/finally run normally; main() below has a
 * single top-level catch that turns a DieError back into the same
 * "[append-log] failed: ...; non-zero exit" contract callers expect.
 */
class DieError extends Error {
  constructor(message, code) {
    super(message);
    this.name = 'DieError';
    this.code = code || 1;
  }
}
function die(msg, code) {
  throw new DieError(msg, code);
}

function parseArgs(argv) {
  const args = { targetFile: null, mode: 'top', anchor: null, entry: null, entryFile: null, useStdin: false };
  const rest = [];
  for (let i = 0; i < argv.length; i++) {
    const a = argv[i];
    if (a === '--target') args.targetFile = argv[++i];
    else if (a === '--mode') args.mode = argv[++i];
    else if (a === '--anchor') args.anchor = argv[++i];
    else if (a === '--file') args.entryFile = argv[++i];
    else if (a === '--stdin') args.useStdin = true;
    else rest.push(a);
  }
  if (!args.entry && rest.length) args.entry = rest.join(' ');
  return args;
}

function readEntry(args) {
  if (args.entryFile) {
    if (!fs.existsSync(args.entryFile)) die('--file points to a file that does not exist: ' + args.entryFile);
    return cfg.readTextFileStripBOM(args.entryFile).trim();
  }
  if (args.useStdin) {
    try {
      return fs.readFileSync(0, 'utf8').trim();
    } catch (e) {
      die('failed to read stdin: ' + e.message);
    }
  }
  if (args.entry != null) return args.entry.trim();
  die('no entry content given. Use one of: "<text>" as a positional arg / --file <path> / --stdin');
}

function normalizeEntry(entry) {
  if (!entry) die('entry content is empty');
  if (entry.includes('\n')) {
    entry = entry.split('\n').map((s) => s.trim()).filter(Boolean).join(' ');
  }
  return entry;
}

/** top-mode insert index: returns the index to splice the new line in before. */
function computeTopInsertIndex(lines, anchorPattern) {
  if (anchorPattern) {
    const re = new RegExp(anchorPattern);
    for (let i = 0; i < lines.length; i++) {
      if (re.test(lines[i])) return i + 1;
    }
    die('--anchor "' + anchorPattern + '" matched no line in the target file — refusing to silently insert elsewhere');
  }
  let insertAt = 1;
  if (lines[1] !== undefined && lines[1].trim() === '') insertAt = 2;
  return insertAt;
}

/** Resolve the target file: --target (as-is if absolute, else relative to cwd) > team-config.json shared_paths.team_log. */
function resolveTargetFile(args) {
  if (args.targetFile) return path.resolve(args.targetFile);
  const cwd = process.cwd();
  const teamRoot = cfg.resolveTeamRoot(cwd);
  const config = cfg.loadTeamConfig(teamRoot);
  const p = cfg.resolveSharedPath(teamRoot, config, 'team_log');
  if (!p) {
    die(
      'no --target given, and could not resolve shared_paths.team_log from team-config.json ' +
        '(team root search started at ' + cwd + '). Pass --target explicitly, or run this from ' +
        'somewhere under the team root / an agent home.'
    );
  }
  return p;
}

function runMain() {
  const args = parseArgs(process.argv.slice(2));
  if (args.mode !== 'top' && args.mode !== 'bottom') die('--mode only supports top or bottom, got: ' + args.mode);

  const targetFile = resolveTargetFile(args);
  if (!fs.existsSync(targetFile)) die('target file does not exist: ' + targetFile);

  const entry = normalizeEntry(readEntry(args));
  const lockPath = targetFile + '.lock';

  flock.acquireLockSync(lockPath, {
    onWait: () => process.stderr.write('[append-log] someone else is writing ' + path.basename(targetFile) + ', waiting...\n'),
    onStaleClear: (age) =>
      process.stderr.write('[append-log] cleared a ' + Math.round(age / 1000) + 's-old stale lock (holder likely crashed)\n'),
  });

  try {
    const before = fs.readFileSync(targetFile, 'utf8');
    const hadTrailingNewline = before.endsWith('\n');
    const lines = before.split('\n');

    let after;
    if (args.mode === 'bottom') {
      if (before.length === 0) after = entry + '\n';
      else if (hadTrailingNewline) after = before + entry + '\n';
      else after = before + '\n' + entry + '\n';
    } else {
      const insertAt = computeTopInsertIndex(lines, args.anchor);
      lines.splice(insertAt, 0, entry);
      after = lines.join('\n');
    }

    flock.atomicWriteSync(targetFile, after);

    const verify = fs.readFileSync(targetFile, 'utf8');
    if (!verify.includes(entry)) die('read-back after write did not find the entry just written — file may have been corrupted by a race, please check manually!', 3);
    const linesBefore = before.split('\n').length;
    const linesAfter = verify.split('\n').length;
    if (linesAfter < linesBefore) die('line count decreased after write (before ' + linesBefore + ', after ' + linesAfter + ') — please check manually!', 3);

    process.stdout.write(
      '[append-log] OK ' + (args.mode === 'top' ? 'inserted' : 'appended') + ' into ' + path.basename(targetFile) +
        ': ' + entry.slice(0, 60) + (entry.length > 60 ? '...' : '') + '\n'
    );
  } finally {
    flock.releaseLock(lockPath);
  }
}

/** Top-level error boundary: turns a DieError/LockError back into "[append-log] failed: ...; non-zero exit". */
function main() {
  try {
    runMain();
  } catch (e) {
    if (e instanceof DieError) {
      process.stderr.write('[append-log] failed: ' + e.message + '\n');
      process.exitCode = e.code;
      return;
    }
    if (e instanceof flock.LockError) {
      process.stderr.write('[append-log] failed: ' + e.message + '\n');
      process.exitCode = e.code === 'LOCK_TIMEOUT' ? 2 : 1;
      return;
    }
    throw e; // genuinely unexpected — surface the real stack trace, don't swallow it
  }
}

if (require.main === module) {
  main();
}

module.exports = { computeTopInsertIndex, normalizeEntry, resolveTargetFile };