Check that numbers, units, part numbers, tolerance signs, dates, placeholders and URLs survive translation

$0.005 USDC per call · Agent infrastructure · POST /api/v1/translation-invariants · Id translation-invariants

For aligned source and target segments, extracts the tokens a translation must not change (numbers with attached units or %, ISO dates, part numbers and versions, tolerance and comparison operators such as ± ≤ ≥, placeholders like {0} or %s, URLs and emails) and reports any that are missing, added or altered, with offsets in both texts in UTF-16, code points, UTF-8 bytes and graphemes. Numbers are compared by value across decimal and thousands conventions (1,234.5 vs 1.234,5), digits of other scripts count as ASCII digits, and a separator that could be either is reported as ambiguous unless sourceDecimal/targetDecimal says which. Does not read number words, check grammar or translate; units are compared only when attached to the number or a symbol such as %.

What you get

Catches the dropped decimal, the lost ± and the broken placeholder before a translation ships. 200 segments per $0.005 call.

Call it

Send the JSON body below to https://agents.writerslogic.com/api/v1/translation-invariants. An unpaid request answers 402 with the price and how to pay; a request that fails with a 5xx status is not charged.

curl -i -X POST https://agents.writerslogic.com/api/v1/translation-invariants \
  -H 'content-type: application/json' \
  -d '{"segments":[{"id":"s1","source":"Tighten to 25 Nm ±2 (part PN-4471-B), see https://x.example/a.","target":"Mit 25 Nm anziehen (Teil PN-4471-B), siehe https://x.example/a."}],"targetDecimal":","}'

Input

Field	Type	Required	Description
`segments`	array<object>; max 200 items	yes	Up to 200; 100000 characters in total.
`sourceDecimal`	string; one of ".", ",", "auto"	no	Decimal mark of the source locale. Default auto (both readings tried).
`targetDecimal`	string; one of ".", ",", "auto"	no	Decimal mark of the target locale. Default auto.
`kinds`	array<string; one of "number", "identifier", "operator", "placeholder", "url", "date">; max 6 items	no	Token kinds to check. Default all.

Example request body

{
  "segments": [
    {
      "id": "s1",
      "source": "Tighten to 25 Nm ±2 (part PN-4471-B), see https://x.example/a.",
      "target": "Mit 25 Nm anziehen (Teil PN-4471-B), siehe https://x.example/a."
    }
  ],
  "targetDecimal": ","
}

Result

The response is { "data": ..., "_provenance": ... }. data carries these fields; _provenance is a signed W3C Verifiable Credential with a C2PA-style manifest, checked free at POST /api/v1/verify-provenance.

Field	Type	Required	Description
`status`	string; one of "pass", "fail", "unknown", "unsupported"	no	pass: every rule held. fail: a rule was violated (see witnesses). unknown: the input lacks the evidence to decide. unsupported: outside what this engine covers. Missing evidence is never a pass.
`segments`	array<object>; max 200 items	no
`witnesses`	array<object>	no
`versions`	object	no	Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile).
`limits`	array<string>	no
`deterministic`	boolean	no	Always true: pure code, no model.

Pay and connect

Available through: x402 (USDC on Base), MCP. MCP clients reach it through the context-evidence-kit package.

Machine-readable

This agent as JSON (schemas, example, OpenAPI operation)
Free signed sample response
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