A worked SynthID-Text fixture
Follow one public reference profile from fixed probability masses to an exact token-trace score. The values and contracts come from Declawd v0.2.0, and the interaction runs locally.
This is not Claude’s watermark, Anthropic’s detector or Google’s production implementation.
It cannot test arbitrary text or establish AI use. It uses a public educational key and fixed data.
Do not use it to judge a person.
Four fixed token candidates
The fixture starts with context token IDs 11 22 33 44. Its four candidate masses are integers out of 1000; they are not model logits or captured model output.
Each public key produces a binary g-value for a candidate. The first six keyed columns are shown because the registered tournament uses depths zero to five.
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| Candidate | Token ID | Probability mass | g0 | g1 | g2 | g3 | g4 | g5 |
|---|---|---|---|---|---|---|---|---|
| cedar | 101 | 400/1000 (40%) | 1 | 1 | 1 | 1 | 1 | 0 |
| fern | 202 | 300/1000 (30%) | 0 | 0 | 0 | 0 | 0 | 1 |
| moss | 303 | 200/1000 (20%) | 1 | 1 | 1 | 0 | 0 | 1 |
| reed | 404 | 100/1000 (10%) | 0 | 0 | 1 | 0 | 1 | 0 |
Six registered tournament rounds
Each row compares two fixed draws at one key depth. A higher g-value wins; a tie keeps the first draw. The fixture records the draws, so there is no random choice in this page.
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| Depth | First draw | Second draw | Winner |
|---|---|---|---|
0 | cedar (1) | fern (0) | cedar |
1 | moss (1) | reed (0) | moss |
2 | fern (0) | reed (1) | reed |
3 | cedar (1) | moss (0) | cedar |
4 | reed (1) | fern (0) | reed |
5 | moss (1) | cedar (0) | moss |
One prepared token trace
The scorer hashes five-token windows with 64-bit wrapping arithmetic. Repeated four-token contexts and positions at or after the first end token are excluded. This prepared trace has 8 valid contexts and no exclusions.
The raw score counts set g-bits. The weighted score applies the published integer weights. Both stay as unreduced fractions and use integer round-half-to-even for the 12-place decimal.
- 0
101 - 1
202 - 2
303 - 3
404 - 4
505 - 5
606 - 6
707 - 7
808 - 8
909 - 9
1010 - 10
1111 - 11
1212
- Valid contexts
- 8
- Raw score
131/2400.545833333333- Weighted score
19846/382800.518443051202
Each mask below lists candidate position zero first. A 1 means that the position is included. All eight prepared positions survive the repetition and end-token checks; the digest pins each one-byte LSB0 mask.
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| Mask | Position bits | Packed SHA-256 |
|---|---|---|
| Repetition | 11111111 | a8100ae6aa1940d0b663bb31cd466142ebbdbd5187131b92d93818987832eb89 |
| End token | 11111111 | a8100ae6aa1940d0b663bb31cd466142ebbdbd5187131b92d93818987832eb89 |
| Valid | 11111111 | a8100ae6aa1940d0b663bb31cd466142ebbdbd5187131b92d93818987832eb89 |
The fixed values remain readable without JavaScript. Switching among the registered substitutions needs JavaScript because the exact score is recalculated in this browser.
Original prepared trace Scored
- Valid contexts
- Raw score
- Weighted score
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| Edit | Token index | Change | Raw score | Weighted score |
|---|---|---|---|---|
| edit-a | 4 | 505 → 506 | 134/2400.558333333333 | 20770/382800.542580982236 |
| edit-b | 7 | 808 → 818 | 118/2400.491666666667 | 17804/382800.465099268548 |
| edit-c | 10 | 1111 → 1112 | 136/2400.566666666667 | 21188/382800.553500522466 |
No detector threshold or text verdict
A raw reference score is not a detector result. This page has no private production key, compatible tokenizer, calibration set, decision rule or false-positive and false-negative measurements for Claude.
Anthropic says Claude uses a version of SynthID-Text. That family relationship does not make this public profile interoperable with Claude.
The browser accepts no prose and makes no network request. The same fixed trace can be scored with declawd lab synthid score from the immutable v0.2.0 release.
The four JSON Schemas are published under Contracts. Their vendored bytes are checked against the release source contract during every site build.