1import { stat, readdir } from "node:fs/promises";
2import { homedir } from "node:os";
3import path from "node:path";
4import { GenError } from "./types.ts";
5import type { ToolCall } from "./types.ts";
6import { hasImageGenInvocation } from "./parser.ts";
7 
8const PNG_MAGIC = Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]);
9 
10export function codexHome(): string {
11  return process.env.CODEX_HOME ?? path.join(homedir(), ".codex");
12}
13 
14export async function verifyImageGenWasInvoked(threadId: string | null): Promise<{ ok: boolean; reason?: string }> {
15  if (!threadId) return { ok: false, reason: "no thread id" };
16  const dir = path.join(codexHome(), "generated_images", threadId);
17  try {
18    const entries = await readdir(dir);
19    const pngs = entries.filter((e) => e.toLowerCase().endsWith(".png"));
20    if (pngs.length === 0) return { ok: false, reason: `no PNG in ${dir}` };
21    return { ok: true };
22  } catch (e: any) {
23    return { ok: false, reason: `cannot read ${dir}: ${e?.code ?? e?.message}` };
24  }
25}
26 
27// Real evidence that image_gen ran in THIS thread. Codex's image_gen tool does
28// not surface as a stream item, so a successful run shows only reasoning/shell/
29// agent_message — `dirHasImage` (a PNG in this thread's generated_images dir) is
30// what proves it. The stream check is kept as a forward-compatible signal in
31// case a future Codex version emits the item. The #185 shortcut (copying an
32// unrelated history image, which lives under a different thread id) yields
33// neither, so it is correctly rejected.
34export function hasImageGenEvidence(toolCalls: ToolCall[], dirHasImage: boolean): boolean {
35  return dirHasImage || hasImageGenInvocation(toolCalls);
36}
37 
38export async function verifyOutput(outputPath: string): Promise<{ bytes: number }> {
39  let s;
40  try {
41    s = await stat(outputPath);
42  } catch {
43    throw new GenError("output_missing", `Output file not created: ${outputPath}`);
44  }
45  if (s.size < 1000) {
46    throw new GenError("invalid_png", `Output file too small (${s.size} bytes)`);
47  }
48  const file = Bun.file(outputPath);
49  const head = new Uint8Array(await file.slice(0, 8).arrayBuffer());
50  for (let i = 0; i < PNG_MAGIC.length; i++) {
51    if (head[i] !== PNG_MAGIC[i]) {
52      throw new GenError("invalid_png", `Output is not a valid PNG (magic mismatch)`);
53    }
54  }
55  return { bytes: s.size };
56}
57