v1.0.0

First version: AWS Signature Version 4 signing for every AWS service.

• getAuthHeaders(request, credentials) returns the headers to send, for S3 and, with request.service, any other service. It never modifies the request or its URL.
• presign(request, credentials) returns a presigned URL.
• getAuthHeadersV4a and presignV4a sign with SigV4a (ECDSA P-256) for the regions in request.regionSet.
• chunkSigner(authHeaders, credentials) signs aws-chunked uploads, with signed trailing headers; eventSigner(authHeaders, credentials) signs event-stream messages.
• Session tokens (credentials.sessionToken) and unsigned payloads (request.unsignedPayload).
• Path and query encoding, query sorting and header trimming follow the specification; a raw + in an S3 path is a space, as S3 reads it. Other services normalise the path and encode it twice.
• Input that cannot be signed correctly throws: signHeaders that name x-amz-date, authorization or __proto__ or hold a line break, a presigned URL that is not http or https or is already presigned, an expires outside 1 to 604800 seconds, and the headers of a SigV4a signature given to chunkSigner or eventSigner. An empty chunk is not signed, because it would end the upload.
• No dependencies. Node.js 22.12 and later, Bun, Deno and Cloudflare Workers; the signing-key cache is shared by an entry's signers.
• Each signer is its own module and export, so a bundle holds only what it imports. Node and Bun load one built file (dist/) instead of six modules (the node condition resolves to dist/node.js); the workerd, worker and browser conditions resolve to src/web.js and default to src/node.js, which keep the per-signer modules.
• Cloudflare Workers and browsers get a WebCrypto implementation through the workerd, worker and browser export conditions, with or without nodejs_compat. There every signer returns a promise (the chunk and event signers' methods do); the types are x | Promise<x>, so always await. sigflint/web imports that implementation directly.
• Speed, memory and size are measured against six other libraries (docs/benchmarks.md, bench/).