writeAtomic, everywhere a file lands

the .part-then-rename rule was applied at two upload routes yesterday and
by this morning the platform had a dozen other writes putting files in the
same folders — an OCR result beside its image, a TTS clip, a download
landing, a save from the editor — every one straight to the final name. a
guarantee that holds for two of fourteen paths is not a guarantee, and the
next person adding a fifteenth had nothing to copy.

so it is a function now, and every durable write goes through it: the file
browser, sendoff, task definitions, skill and tool files, bug reports,
scraped attachments, the chat provider config.

the failure it prevents is silent rather than loud. a truncated m4a decodes
fine, it is simply short — a commander transcribing recordings as they land
would produce a clean transcript of the first few seconds of a two-minute
memo and report success.

two things learned writing it. Bun.write creates the parent chain itself,
so the mkdir option i added was dead weight and several callers were doing
it twice. and Parameters<typeof Bun.write>[1] resolves to the first
overload only — BunFile — which rejects the string and Buffer every caller
actually passes.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Officer-Session: 656f5c85-e49a-4f1f-b9f3-042a04b4d043

src/servers/api/item-router.ts

@@ -2,6 +2,7 @@ import { createRouter } from '../create-router';
 import { readdir, mkdir, rm } from 'node:fs/promises';
 import { join, dirname } from 'node:path';
 import { itemsDir, type ItemType } from '../data-path';
+import { writeAtomic } from '@@/write-atomic';
 
 // Shared router for the flat, file-based item types (skills, tools, processes). Each item is a
 // directory under $OFFICER_ITEMS_DIR/<type>/<dirName>/ holding a single markdown file (SKILL.md /
@@ -114,8 +115,8 @@ export function createItemRouter({ type, fileName, label }: ItemRouterConfig) {
     const { sessionId, messages } = await ctx.req.json<{ sessionId: string; messages: unknown[] }>();
 
     await mkdir(chatDir, { recursive: true });
-    await Bun.write(join(chatDir, 'messages.json'), JSON.stringify(messages));
-    if (sessionId) await Bun.write(join(chatDir, 'meta.json'), JSON.stringify({ id: sessionId }));
+    await writeAtomic(join(chatDir, 'messages.json'), JSON.stringify(messages));
+    if (sessionId) await writeAtomic(join(chatDir, 'meta.json'), JSON.stringify({ id: sessionId }));
 
     return ctx.json({ ok: true });
   });
@@ -140,7 +141,7 @@ export function createItemRouter({ type, fileName, label }: ItemRouterConfig) {
     if (await Bun.file(filePath).exists()) return ctx.text(`${label} already exists`, 409);
 
     await mkdir(dirname(filePath), { recursive: true });
-    await Bun.write(filePath, `---\nname: ${name.trim()}\ndescription: \n---\n`);
+    await writeAtomic(filePath, `---\nname: ${name.trim()}\ndescription: \n---\n`);
 
     return ctx.json({ name: name.trim(), dirName, filePath });
   });