gstack/bin/gstack-decision-log

#!/usr/bin/env bun
/**
 * gstack-decision-log — append a durable decision (or supersede/redact/compact it).
 *
 * Usage:
 *   gstack-decision-log '{"decision":"...","rationale":"...","scope":"repo","source":"user"}'
 *   gstack-decision-log --supersede <decision-id>
 *   gstack-decision-log --redact <decision-id>
 *   gstack-decision-log --compact
 *
 * Event-sourced (lib/gstack-decision): every call appends an event and refreshes the
 * bounded active snapshot. NON-INTERACTIVE — never prompts (agents/skills call this;
 * a prompt would hang them). Validation + injection + HIGH-secret rejection happen in
 * validateDecide; a rejected decision exits 1 with a message, nothing persisted.
 */

import { dirname } from "path";
import { mkdirpSync } from "../lib/fs-utils";
import { spawnSync } from "child_process";
import {
  decisionPaths,
  validateDecide,
  makeRefEvent,
  appendEvent,
  rebuildSnapshot,
  compact,
  type DecisionEvent,
} from "../lib/gstack-decision";
import { resolveSlug, gitBranch, flagValue } from "../lib/bin-context";

const HERE = import.meta.dir;

const args = process.argv.slice(2);
const slug = resolveSlug(`${HERE}/gstack-slug`);
const paths = decisionPaths(slug);
// mkdirpSync, not bare mkdirSync: bun on Windows throws EEXIST from a
// recursive mkdir on an existing dir (#2635), and this runs on every log call.
mkdirpSync(dirname(paths.log));

function enqueue(): void {
  // Fire-and-forget cross-machine sync (no-op when artifacts_sync is off).
  spawnSync(`${HERE}/gstack-brain-enqueue`, [`projects/${slug}/decisions.jsonl`], { stdio: "ignore" });
}

if (args.includes("--compact")) {
  const r = compact(paths);
  if (r.skipped) {
    console.log("compact skipped: a concurrent write/compact is in progress; log left intact — re-run");
    process.exit(0);
  }
  console.log(`compacted: ${r.activeCount} active, ${r.archivedCount} archived, ${r.expungedCount} expunged`);
  enqueue();
  process.exit(0);
}

// The payload is identified by its leading `{`, not by "first non-flag arg" — a
// `--supersede <id> '{...}'` call would otherwise mistake the target id for the payload.
const jsonArg = args.find((a) => a.trimStart().startsWith("{"));

/** Parse + validate a decision payload. Exits 1 (nothing persisted) when it's bad. */
function validPayload(raw: string): DecisionEvent {
  let obj: Partial<DecisionEvent>;
  try {
    obj = JSON.parse(raw);
  } catch {
    process.stderr.write("gstack-decision-log: invalid JSON\n");
    process.exit(1);
  }
  if (obj.scope === "branch" && !obj.branch) obj.branch = gitBranch();
  const res = validateDecide(obj);
  if (!res.ok) {
    process.stderr.write(`gstack-decision-log: ${res.error}\n`);
    process.exit(1);
  }
  return res.event;
}

const supersedeId = flagValue(args, "--supersede");
const redactId = flagValue(args, "--redact");
if (supersedeId || redactId) {
  const kind = supersedeId ? "supersede" : "redact";
  const targetId = (supersedeId || redactId) as string;
  if (targetId.trimStart().startsWith("{")) {
    process.stderr.write(`gstack-decision-log: --${kind} needs the target decision id before the replacement JSON\n`);
    process.exit(1);
  }
  if (kind === "redact" && jsonArg) {
    process.stderr.write(
      "gstack-decision-log: --redact expunges and takes no replacement; log the replacement in its own call so it isn't dropped\n",
    );
    process.exit(1);
  }
  // Validate the replacement BEFORE anything is written, then append it FIRST and
  // retire the old one SECOND. Appends are individually atomic, so the only visible
  // interleaving is "both active" (recoverable); the reverse order could retire the
  // old decision and lose the replacement the user was recording.
  const replacement = jsonArg ? { ...validPayload(jsonArg), supersedes: targetId } : undefined;
  if (replacement) appendEvent(paths, replacement);
  appendEvent(paths, makeRefEvent(kind, targetId, { source: "agent" }));
  rebuildSnapshot(paths);
  enqueue();
  console.log(replacement ? `${kind}: ${targetId} -> ${replacement.id}` : `${kind}: ${targetId}`);
  process.exit(0);
}

if (!jsonArg) {
  process.stderr.write(
    "gstack-decision-log: provide a JSON decision, or --supersede/--redact <id>, or --compact\n",
  );
  process.exit(1);
}
const event = validPayload(jsonArg);
appendEvent(paths, event);
rebuildSnapshot(paths);
enqueue();
console.log(event.id);