{"id":"package-exists","title":"Package exists on npm, PyPI or crates.io (hallucinated dependency check)","description":"Checks whether up to 10 package names (optionally with a version) exist in the live npm, PyPI or crates.io registry, for coding agents about to add a dependency they may have invented. Per package: exists, latest version, deprecated or yanked flag, and for a missing name the closest names the registry's own search returns (npm, crates.io; PyPI has no search API). Reads registry metadata only: never downloads or runs package code, and says nothing about whether a package is safe or the right one.","roi":"A hallucinated package name is a supply-chain attack waiting to be registered; one call checks the whole install list.","audience":"developer","package":"code-preflight-kit","channels":["x402","mcp"],"endpoint":{"method":"POST","url":"https://agents.writerslogic.com/api/v1/package-exists","path":"/api/v1/package-exists","contentType":"application/json"},"price":{"amount":"0.005","currency":"USDC","network":"base","perCall":true,"failedCallsCharged":false},"inputSchema":{"type":"object","additionalProperties":false,"required":["ecosystem","items"],"properties":{"ecosystem":{"type":"string","enum":["npm","pypi","crates"]},"items":{"type":"array","minItems":1,"maxItems":10,"items":{"type":"object","additionalProperties":false,"required":["name"],"properties":{"name":{"type":"string","maxLength":214},"version":{"type":"string","maxLength":64,"description":"Exact version (npm also accepts a dist-tag)."}}},"description":"At most 5 items for crates.io (its API policy allows one request per second)."}}},"resultSchema":{"type":"object","properties":{"status":{"type":"string","enum":["pass","fail","unknown","unsupported"],"description":"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."},"ecosystem":{"type":"string"},"requests":{"type":"integer","description":"Registry requests made."},"results":{"type":"array","items":{"type":"object","properties":{"name":{"type":"string"},"version":{"type":"string"},"exists":{"type":"boolean"},"versionExists":{"type":"boolean"},"latest":{"type":"string"},"deprecated":{"type":"boolean"},"yanked":{"type":"boolean"},"closest":{"type":"array","items":{"type":"string"}},"note":{"type":"string"}}}},"witnesses":{"type":"array","items":{"type":"object","properties":{"ruleId":{"type":"string"},"detail":{"type":"string"},"path":{"type":"string","description":"JSON pointer or dotted path into the input."},"offset":{"type":"integer"},"index":{"type":"integer"},"expected":{"description":"What the rule required."},"actual":{"description":"What the input had."}}}},"versions":{"type":"object","description":"Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile)."},"limits":{"type":"array","items":{"type":"string"}},"deterministic":{"type":"boolean","description":"Always true: pure code, no model."}}},"outputSchema":{"type":"object","properties":{"data":{"type":"object","properties":{"status":{"type":"string","enum":["pass","fail","unknown","unsupported"],"description":"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."},"ecosystem":{"type":"string"},"requests":{"type":"integer","description":"Registry requests made."},"results":{"type":"array","items":{"type":"object","properties":{"name":{"type":"string"},"version":{"type":"string"},"exists":{"type":"boolean"},"versionExists":{"type":"boolean"},"latest":{"type":"string"},"deprecated":{"type":"boolean"},"yanked":{"type":"boolean"},"closest":{"type":"array","items":{"type":"string"}},"note":{"type":"string"}}}},"witnesses":{"type":"array","items":{"type":"object","properties":{"ruleId":{"type":"string"},"detail":{"type":"string"},"path":{"type":"string","description":"JSON pointer or dotted path into the input."},"offset":{"type":"integer"},"index":{"type":"integer"},"expected":{"description":"What the rule required."},"actual":{"description":"What the input had."}}}},"versions":{"type":"object","description":"Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile)."},"limits":{"type":"array","items":{"type":"string"}},"deterministic":{"type":"boolean","description":"Always true: pure code, no model."}}},"_provenance":{"type":"object","description":"C2PA-aligned manifest and W3C VC 2.0 (eddsa-jcs-2022) issued by the hub DID; verify at POST /api/v1/verify-provenance"}},"required":["data","_provenance"]},"example":{"ecosystem":"npm","items":[{"name":"left-pad"},{"name":"lef-pad"}]},"openapiOperation":{"operationId":"package_exists","summary":"Package exists on npm, PyPI or crates.io (hallucinated dependency check)","description":"Checks whether up to 10 package names (optionally with a version) exist in the live npm, PyPI or crates.io registry, for coding agents about to add a dependency they may have invented. Per package: exists, latest version, deprecated or yanked flag, and for a missing name the closest names the registry's own search returns (npm, crates.io; PyPI has no search API). Reads registry metadata only: never downloads or runs package code, and says nothing about whether a package is safe or the right one.\n\nPrice: 0.005 USDC on Base (x402).","x-x402-price-usdc":"0.005","x-x402-amount":"5000","x-payment-info":{"protocols":["x402"],"price":{"mode":"fixed","currency":"USD","amount":"0.005"}},"x-audience":"developer","x-sample-url":"https://agents.writerslogic.com/api/v1/samples/package-exists","security":[{"x402":[]},{"apiKey":[]}],"requestBody":{"required":true,"content":{"application/json":{"schema":{"type":"object","additionalProperties":false,"required":["ecosystem","items"],"properties":{"ecosystem":{"type":"string","enum":["npm","pypi","crates"]},"items":{"type":"array","minItems":1,"maxItems":10,"items":{"type":"object","additionalProperties":false,"required":["name"],"properties":{"name":{"type":"string","maxLength":214},"version":{"type":"string","maxLength":64,"description":"Exact version (npm also accepts a dist-tag)."}}},"description":"At most 5 items for crates.io (its API policy allows one request per second)."}}},"example":{"ecosystem":"npm","items":[{"name":"left-pad"},{"name":"lef-pad"}]}}}},"responses":{"200":{"description":"Paid result with provenance","content":{"application/json":{"schema":{"type":"object","properties":{"data":{"type":"object","properties":{"status":{"type":"string","enum":["pass","fail","unknown","unsupported"],"description":"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."},"ecosystem":{"type":"string"},"requests":{"type":"integer","description":"Registry requests made."},"results":{"type":"array","items":{"type":"object","properties":{"name":{"type":"string"},"version":{"type":"string"},"exists":{"type":"boolean"},"versionExists":{"type":"boolean"},"latest":{"type":"string"},"deprecated":{"type":"boolean"},"yanked":{"type":"boolean"},"closest":{"type":"array","items":{"type":"string"}},"note":{"type":"string"}}}},"witnesses":{"type":"array","items":{"type":"object","properties":{"ruleId":{"type":"string"},"detail":{"type":"string"},"path":{"type":"string","description":"JSON pointer or dotted path into the input."},"offset":{"type":"integer"},"index":{"type":"integer"},"expected":{"description":"What the rule required."},"actual":{"description":"What the input had."}}}},"versions":{"type":"object","description":"Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile)."},"limits":{"type":"array","items":{"type":"string"}},"deterministic":{"type":"boolean","description":"Always true: pure code, no model."}}},"_provenance":{"type":"object","description":"C2PA-aligned manifest and W3C VC 2.0 (eddsa-jcs-2022) issued by the hub DID; verify at POST /api/v1/verify-provenance"}},"required":["data","_provenance"]}}}},"400":{"description":"Invalid request (no payment consumed)","content":{"application/json":{"schema":{"type":"object","properties":{"error":{"type":"string"},"code":{"type":"string"}}}}}},"401":{"description":"Invalid X-API-KEY","content":{"application/json":{"schema":{"type":"object","properties":{"error":{"type":"string"},"code":{"type":"string"}}}}}},"402":{"description":"Payment required or invalid","content":{"application/json":{"schema":{"type":"object","description":"x402 v2 PaymentRequired (also base64 in the PAYMENT-REQUIRED header)","properties":{"x402Version":{"type":"integer"},"error":{"type":"string"},"code":{"type":"string"},"resource":{"type":"object"},"accepts":{"type":"array","items":{"type":"object"}},"extensions":{"type":"object"}}}}}},"502":{"description":"Upstream failure; the payment is released or not settled","content":{"application/json":{"schema":{"type":"object","properties":{"error":{"type":"string"},"code":{"type":"string"}}}}}}}},"links":{"docs":"https://agents.writerslogic.com/docs/package-exists/","docsJson":"https://agents.writerslogic.com/docs/package-exists.json","sample":"https://agents.writerslogic.com/api/v1/samples/package-exists","openapi":"https://agents.writerslogic.com/openapi.json","catalog":"https://agents.writerslogic.com/api/v1/catalog","verifyProvenance":"https://agents.writerslogic.com/api/v1/verify-provenance","index":"https://agents.writerslogic.com/docs/index.json"}}