[Bug]: Tool-output file uploads fail with EACCES because scratch files are written into the installed package (dist/.tmp) #286

What happens

Every tool-output file the bot tries to deliver to Telegram is dropped with EACCES when the package is installed globally and the bot runs as an unprivileged user:

[2026-10-23T08:39:45.128Z] [ERROR] [ToolBatcher] Failed to send tool file message: session=ses_..., reason=enqueue_file Error: EACCES: permission denied, mkdir '/usr/lib/node_modules/@grinev/opencode-telegram-bot/dist/.tmp'

The assistant's reply is still delivered, but the attached file (write/edit summary, diff) never reaches the chat.

Environment

• opencode-telegram-bot 0.26.5 (npm i -g @grinev/opencode-telegram-bot)
• Node.js v24.21.0, Linux x64
• Bot started from a systemd unit as an unprivileged user (srv)
• Global npm prefix is root-owned: /usr/lib/node_modules/@grinev/opencode-telegram-bot is drwxr-xr-x root root

Root cause

src/bot/events/telegram-event-delivery.ts:19:

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const TEMP_DIR = path.join(__dirname, "..", "..", ".tmp");

In the built package that resolves to <package>/dist/.tmp. sendDocument() then calls fs.mkdir(TEMP_DIR, { recursive: true }) and fs.writeFile(...), which requires write access inside the installed package. That is true for a root install (npm i -g, Docker image, distro package), so the very first upload fails.

The same code path is fine only when the bot is started from a writable source checkout or as root — which is why this does not show up in local development.

Expected

Scratch files for outgoing documents should be written to a directory the bot process owns, e.g. under os.tmpdir(), regardless of how the package was installed.

Workaround

sudo mkdir -p /usr/lib/node_modules/@grinev/opencode-telegram-bot/dist/.tmp
sudo chown "$USER" /usr/lib/node_modules/@grinev/opencode-telegram-bot/dist/.tmp

This restores uploads until the next npm update -g, which recreates the package directory and drops the permission fix.

Proposed fix

Use the OS temp directory instead of the package directory:

const TEMP_DIR = path.join(os.tmpdir(), "opencode-telegram-bot");

os.tmpdir() is writable for the process (and honours TMPDIR), so no installation layout or ownership can break it. I have a PR ready: #287.