Paste a Stack Trace, Get a Minimal Patch: Coding Workflow

Why stack-first beats code-first

When you paste a React or Node stack trace into a coding model, put the error block above the source. Models latch onto the first failure signal. If you dump a whole file first, they often invent a different bug. On spacebunny.me the one-click demo “Paste error → patch” already orders the prompt this way: role, stack, related snippet, then parent call-site notes.

A reproducible TypeScript example

A common free-tier win: TypeError on users.map when users is still undefined during the first render. Ask for three root-cause bullets and a minimal unified diff — not a rewrite of the component tree. Temperature 0.2–0.4 keeps the patch boring and correct. Watch the live credit estimate; a stack + 40-line snippet usually costs a few credits, not dozens.

What to demand in the answer

• Root cause in ≤3 bullets tied to the stack frames you pasted.
• A unified diff or surgical patch — avoid full-file regenerations unless you ask for them.
• One sentence on the regression test you should add (render with undefined props).
• No pep talk. If the model starts explaining React lifecycle from scratch, tighten the prompt.

Credits and when to stop

If the first reply misses the null-guard, reply with “still crashes on first paint — only change the map line” instead of pasting more files. Extra context burns tokens; clarifying constraints is cheaper. When the estimate exceeds your balance, the playground blocks send and links to /pricing#topup so you are not surprised mid-stream.