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spacetax

confirmedPython · llama.cppModel behavior & reasoningJuly 7, 2026

the question

What does a single trailing space on a prompt do?

what came out

It changes a byte-level-BPE model's tokenization and greedy output on 100% of prompts, and flips a third of factual answers wrong -- on a real llama.cpp server. One trailing space. Pre-registered, independently verified.

method & receipts

  • Result: confirmed
  • Pre-registered the prediction was written down and committed before the run.
  • Reproducible one script re-runs the whole thing from scratch.
  • Independently reviewed an adversarial review pass, kept in the repo.
  • Machine-readable claims every reported number, in a checkable file.
  • Tested — a correctness/benchmark suite ships alongside the code.

→ read the code and re-run it

github.com/v-code01/spacetax