writer model fingerprint · v0.3.2

· Public eight-cell reference analysis

writer/palmyra-x5 behavioral LLM fingerprint

This page breaks down the exact reference that VerifyLLMAPI uses for writer/palmyra-x5: 119 normalized answers across eight low-entropy probes, plus its nearest enrolled models by mean Jensen–Shannon divergence.

Fingerprint summary

Reference answers
119
Samples per cell
14–15
Nearest mean JSD
0.249720

The most concentrated cell was animal-random|en: elephant held 93.3% of its answers and entropy measured 0.353 bits. The broadest cell was letter-random|zh at 2.340 bits.

Against the closest enrolled model, color-random|zh contributed the largest cell distance at JSD 0.402387. This is a descriptive comparison, not proof that either API route serves a named checkpoint.

Completeness: the author dataset allows up to 15 valid answers per selected cell in reference half A. This model contains 119/120 across the eight cells. We show the actual denominator for every share.

The eight test requests

The research pipeline sent each user prompt with a one-answer system constraint, temperature 1, a 16-token output cap, and reasoning disabled. VerifyLLMAPI uses the same prompt text and normalization target.

CellTaskExact request textNormalization and n
animal-random|en Random animal · English Name a random animal.
System constraintAnswer with a single word or a single number only. Output nothing else: no explanation, no punctuation, no quotation marks.
word · 15/15 reference samples
word-random|en Random word · English Name a random word.
System constraintAnswer with a single word or a single number only. Output nothing else: no explanation, no punctuation, no quotation marks.
word · 15/15 reference samples
animal-random|ru Random animal · Russian Назови случайное животное.
System constraintОтвечай только одним словом или одним числом. Не выводи ничего больше: без объяснений, без знаков препинания, без кавычек.
word · 15/15 reference samples
animal-random|ar Random animal · Arabic اذكر حيواناً عشوائياً.
System constraintأجب بكلمة واحدة أو رقم واحد فقط. لا تكتب أي شيء آخر: لا شرح ولا علامات ترقيم ولا علامات اقتباس.
word · 15/15 reference samples
letter-random|zh Random character · Chinese 说出一个随机的汉字。
System constraint只用一个词或一个数字回答。不要输出任何其他内容:不要解释,不要标点符号,不要引号。
grapheme · 15/15 reference samples
animal-random|zh Random animal · Chinese 说出一个随机的动物。
System constraint只用一个词或一个数字回答。不要输出任何其他内容:不要解释,不要标点符号,不要引号。
word · 15/15 reference samples
letter-random|ar Random letter · Arabic اذكر حرفاً عشوائياً من الحروف الأبجدية.
System constraintأجب بكلمة واحدة أو رقم واحد فقط. لا تكتب أي شيء آخر: لا شرح ولا علامات ترقيم ولا علامات اقتباس.
grapheme · 14/15 reference samples
color-random|zh Random color · Chinese 说出一个随机的颜色。
System constraint只用一个词或一个数字回答。不要输出任何其他内容:不要解释,不要标点符号,不要引号。
word · 15/15 reference samples

Response distributions

These are normalized reference-half counts from the published OpenRouter dataset. The tables contain aggregate values, not user data or a live VerifyLLMAPI scan.

1. animal-random|en

Random animal, English. 15 valid reference answers produced 2 normalized values. The mode was elephant at 14/15 (93.3%); entropy was 0.353 bits.

writer/palmyra-x5 response distribution for animal-random|en
Normalized responseCountShare
elephant 14 93.3%
lion 1 6.7%

2. word-random|en

Random word, English. 15 valid reference answers produced 6 normalized values. The mode was apple at 9/15 (60.0%); entropy was 1.872 bits.

writer/palmyra-x5 response distribution for word-random|en
Normalized responseCountShare
apple 9 60.0%
sunflower 2 13.3%
butterfly 1 6.7%
elephant 1 6.7%
ocean 1 6.7%
unicorn 1 6.7%

3. animal-random|ru

Random animal, Russian. 15 valid reference answers produced 2 normalized values. The mode was лев at 12/15 (80.0%); entropy was 0.722 bits.

writer/palmyra-x5 response distribution for animal-random|ru
Normalized responseCountShare
лев 12 80.0%
слон 3 20.0%

4. animal-random|ar

Random animal, Arabic. 15 valid reference answers produced 5 normalized values. The mode was فيل at 9/15 (60.0%); entropy was 1.738 bits.

writer/palmyra-x5 response distribution for animal-random|ar
Normalized responseCountShare
فيل 9 60.0%
فهد 2 13.3%
نمر 2 13.3%
النمر 1 6.7%
فأر 1 6.7%

5. letter-random|zh

Random character, Chinese. 15 valid reference answers produced 7 normalized values. The mode was at 6/15 (40.0%); entropy was 2.340 bits.

writer/palmyra-x5 response distribution for letter-random|zh
Normalized responseCountShare
6 40.0%
4 26.7%
1 6.7%
1 6.7%
1 6.7%
1 6.7%
1 6.7%

6. animal-random|zh

Random animal, Chinese. 15 valid reference answers produced 2 normalized values. The mode was 老虎 at 9/15 (60.0%); entropy was 0.971 bits.

writer/palmyra-x5 response distribution for animal-random|zh
Normalized responseCountShare
老虎 9 60.0%
狮子 6 40.0%

7. letter-random|ar

Random letter, Arabic. 14 valid reference answers produced 4 normalized values. The mode was ج at 5/14 (35.7%); entropy was 1.809 bits.

writer/palmyra-x5 response distribution for letter-random|ar
Normalized responseCountShare
ج 5 35.7%
س 5 35.7%
خ 3 21.4%
ك 1 7.1%

8. color-random|zh

Random color, Chinese. 15 valid reference answers produced 3 normalized values. The mode was 蓝色 at 12/15 (80.0%); entropy was 0.906 bits.

writer/palmyra-x5 response distribution for color-random|zh
Normalized responseCountShare
蓝色 12 80.0%
紫色 2 13.3%
靛蓝 1 6.7%

Three nearest enrolled references

We compute base-2 JSD for each of the eight categorical distributions, then average the eight distances. A lower value means more similar answer frequencies within this product reference. It does not identify an unknown route by itself.

RankReference modelMean 8-cell JSD
1 qwen/qwen3-235b-a22b-2507 0.249720
2 qwen/qwen3-30b-a3b-instruct-2507 0.388091
3 openai/gpt-3.5-turbo-0613 0.458167

How many live requests does verification use?

ProfileCells × samplesFresh model requestsSame-data EER
Quick, default complete check4 × 52011.8%
Standard8 × 5408.1%
Paper budget8 × 151206.7%

The current-Agent workflow starts with quick. Each answer comes from a fresh Codex or Claude Code process that reuses host-managed login. These requests can consume host allowance or provider balance.

What this fingerprint can and cannot show

  • The reference records behavior observed through OpenRouter in the author dataset. Provider wrappers, model updates, decoding, and date can move a distribution.
  • The author collection set temperature 1 and disabled reasoning. Current-Agent mode labels sampling as a host default because supported Agent CLIs expose no temperature flag.
  • The eight high-gap cells and product thresholds use the same public cohort. Their EER values are calibration results, not an independent production accuracy claim.
  • A nearest reference is a similarity result. VerifyLLMAPI returns INCONCLUSIVE when the claimed route lacks an enrolled fingerprint.

Primary sources, license, and reproducibility

  1. Tomas Bruckner, One Token Is Enough: Fingerprinting and Verifying Large Language Models from Single-Token Output Distributions, arXiv:2607.10252v1.
  2. Author dataset and derived results, DOI 10.5281/zenodo.21278557, CC BY 4.0.
  3. Author collection and analysis software, DOI 10.5281/zenodo.21278793, MIT.
  4. VerifyLLMAPI atlas JSON, built from reference pamela-openrouter-2026-07-8cell-ref-a, SHA-256 51f3f63cbcfb56b151055d2d10e36a9cc2f0644cc68b580784853d68951fa866.

Page evidence SHA-256: 8d3277299ea1bdfef4f5296b8e9ddab2c1622636b9366f52f14cb4b89e6d1090. This hash covers the model ID, eight cell metrics, nearest references, and strongest cell difference in the generated atlas.

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