new·The score now tells you which way it movedA brain's exam only ever grows: its own material writes questions, and so does every question a real caller asked and did not get answered. The score is a percentage over that growing set, so a brain that learned more could post a smaller number — and this week three did. One of them answered two MORE questions than the week before and showed eighteen points less. Printed as a single percentage, that reads as decline to a reader and as punishment to anyone who contributes material.all news →
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explore / Backend & APIs / mozg / Bun

Bun · Runtime

Answer questions about the Bun runtime exactly as specified: Bun.serve, Bun.file and file I/O, Bun.$ shell, SQLite, WebSockets, TCP, transpiler and every other Bun.* API with its arguments and options, plus Node compatibility details.

1,522 notes · updated 2026-08-14 · trained 76%

since last sitting: +47 newly passed — this brain is learning · the verified changelog →

use this brain
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$ claude mcp add --transport http mozg \
https://mozg.sh/mcp --header "Authorization: Bearer …"
> use mozg/bun-runtime — …
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Ask it things like

answers 47/59 on its latest exam · anti-bluff 0/1
What is the fetch handler signature in Bun.serve?Bun.serve HTTP server✓
How do you set up TLS/HTTPS in Bun.serve?Bun.serve HTTP server✓
What are the key methods on BunFile?File I/O✓
What does Database.query() execute and what does it return?SQLite Database✓
What comparison APIs does Bun provide?Advanced APIs✓
What are the supported TypedArray classes?Binary Data✓
What methods does DataView provide?Binary Data✓
How do you write a string to a file with Bun?File I/O✓

What it can answer

59 coverage checks
76%
Answers 47 of the exam's 60 questionsIt answers 47 questions, 47 more than last time, out of an exam that grew by 60.Nothing it used to answer has stopped working.
✓TCP Sockets5 / 5
✓Utilities5 / 5
▲Binary Data4 / 6
✓File I/O4 / 4
✓Module Resolution4 / 4
▲Shell & Child Processes4 / 5
✓Advanced APIs3 / 3
▲Bun.serve HTTP server3 / 4
▲Hashing & Cryptography3 / 4
✓Routing & File System Router3 / 3
▲WebSockets3 / 5
✓Node Compatibility2 / 2
▲SQLite Database2 / 5
▲Transpiler2 / 4
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Attacks survived

re-run weekly · 2026-08-11
✓gate-battery12/12 known hostile payloads caught by the ingest gate
✓injection-corpusevery active note scanned — no steering language
✕secret-corpusConnection string with password: "MySQL connection with new SQL()" · Connection string with password: "MySQL connection with new SQL()" · Connection string with password: "MySQL connection string formats" · Connection string with password: "MySQL connection string formats" · Connection string with password: "MySQL connection string formats"

heuristic scans against known attack classes — measured and dated, not a promise of unpoisonability

Inside

  • Basic WebSocket server example pattern in Bun · websockets
  • WebSocket unsubscribe method · websockets
  • WebSocket data property typing in TypeScript · websockets
  • Bun.serve() returns server object with hostname and port · bun.serve http server
  • WebSocket pub-sub subscribe method · websockets
  • WebSocket pub-sub publish method · websockets
  • WebSocket message handler lifecycle · websockets
  • WebSocket open handler lifecycle · websockets
  • WebSocket close handler lifecycle · websockets
  • WebSocket upgrade in Bun.serve fetch handler · websockets
  • WebSocket upgrade example with contextual data · websockets
  • WebSocket contextual data pattern with cookies and headers · websockets
  • WebSocket contextual data with authentication example · websockets
  • server.upgrade() data parameter for WebSocket context · websockets

Licence

CC BY-NC-SA 4.0

Use it, copy it, build on it, with credit. Selling it is not allowed.