Exact multipart form body encoder
WHEN TO USE: Construct exact inert multipart/form-data bytes from ordered supplied text or binary file parts, preserving repeated field names. Caller supplies a collision-checked boundary; explicit utf8 or canonical padded Base64 output and decoded wire byte count. Strict ASCII names prevent header injection; no upload, custom headers, nested multipart, automatic field flattening or API acceptance claim.
structured · Operation ID: multipart-form-encode
Choose this operation when
- Encode ordered multipart form-data upload bodies with binary files and repeated field names
- Measure exact multipart request bytes with deterministic collision-checked boundaries
Outside this profile
- Performing HTTP requests or uploads, headers beyond Content-Disposition and Content-Type, nested multipart or endpoint compatibility
- Non-ASCII field names or filenames, path filenames, filename*, or implicit charset guessing
- Uploading, executing artifacts, contacting agents or registries, publishing, or changing remote state
- Verifying semantic truth, source authenticity, permissions, target API acceptance or signatures
Exact release references
Static JSON contract · Markdown reference · Fixed example response
Complete input schema
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"type": "object",
"properties": {
"boundary": {
"type": "string",
"minLength": 1,
"maxLength": 60,
"pattern": "^[A-Za-z0-9_-]+$"
},
"outputEncoding": {
"type": "string",
"enum": [
"utf8",
"base64"
]
},
"parts": {
"minItems": 1,
"maxItems": 32,
"type": "array",
"items": {
"type": "object",
"properties": {
"name": {
"type": "string",
"minLength": 1,
"maxLength": 64,
"pattern": "^[\\x20-\\x21\\x23-\\x2e\\x30-\\x5b\\x5d-\\x7e]+$"
},
"filename": {
"type": "string",
"minLength": 1,
"maxLength": 128,
"pattern": "^[\\x20-\\x21\\x23-\\x2e\\x30-\\x5b\\x5d-\\x7e]+$"
},
"mediaType": {
"type": "string",
"minLength": 3,
"maxLength": 127,
"pattern": "^[A-Za-z0-9][A-Za-z0-9!#$&^_.+\\-]*\\/[A-Za-z0-9][A-Za-z0-9!#$&^_.+\\-]*$"
},
"encoding": {
"type": "string",
"enum": [
"utf8",
"base64"
]
},
"data": {
"type": "string",
"maxLength": 80000
}
},
"required": [
"name",
"mediaType",
"encoding",
"data"
],
"additionalProperties": false
}
}
},
"required": [
"boundary",
"outputEncoding",
"parts"
],
"additionalProperties": false
}
Complete output-envelope schema
{
"type": "object",
"required": [
"operation",
"version",
"result",
"provenance"
],
"properties": {
"operation": {
"const": "multipart-form-encode",
"type": "string"
},
"version": {
"const": "0.29.0",
"type": "string"
},
"result": {
"$schema": "https://json-schema.org/draft/2020-12/schema",
"type": "object",
"properties": {
"contentType": {
"type": "string",
"minLength": 31,
"maxLength": 100
},
"encoding": {
"type": "string",
"enum": [
"utf8",
"base64"
]
},
"body": {
"type": "string",
"maxLength": 133336
},
"byteLength": {
"type": "integer",
"minimum": 1,
"maximum": 100000
},
"partCount": {
"type": "integer",
"minimum": 1,
"maximum": 32
}
},
"required": [
"contentType",
"encoding",
"body",
"byteLength",
"partCount"
],
"additionalProperties": false
},
"provenance": {
"type": "object",
"required": [
"inputSha256",
"outputSha256",
"deterministic",
"externalRequests"
],
"properties": {
"inputSha256": {
"type": "string",
"pattern": "^[a-f0-9]{64}$"
},
"outputSha256": {
"type": "string",
"pattern": "^[a-f0-9]{64}$"
},
"deterministic": {
"const": true
},
"externalRequests": {
"const": 0
}
}
}
},
"additionalProperties": false
}
Fixed example
One accepted fixed example, not a custom-input trial. No operation runs when this static page is requested.
Example input
{
"boundary": "b42",
"outputEncoding": "utf8",
"parts": [
{
"name": "file",
"filename": "notes.txt",
"mediaType": "text/plain",
"encoding": "utf8",
"data": "abc"
}
]
}
Example response
{
"operation": "multipart-form-encode",
"version": "0.29.0",
"result": {
"contentType": "multipart/form-data; boundary=b42",
"encoding": "utf8",
"body": "--b42\r\nContent-Disposition: form-data; name=\"file\"; filename=\"notes.txt\"\r\nContent-Type: text/plain\r\n\r\nabc\r\n--b42--\r\n",
"byteLength": 116,
"partCount": 1
},
"provenance": {
"inputSha256": "e22407bb1d5d4451adb5676aab25633a52b61787a22e1f399b608e6643546d39",
"outputSha256": "dfa67a8c7d10639911e78caf05010359fbc718ebbbc7a4983d3f907c154ed739",
"deterministic": true,
"externalRequests": 0
}
}
Bounds and precision
JavaScript IEEE-754 numbers; use strings for large integer IDs/exact decimals where the schema accepts strings. No lossless numeric parsing.
{
"global": {
"requestBytes": 131072,
"responseBytes": 524288,
"jsonDepth": 32,
"jsonNodes": 20000,
"requestsPerMinute": 60,
"paidAttemptsPerMinute": 20,
"idempotencyHours": 24
},
"operation": {
"inputBytes": 100000,
"outputBytes": 400000,
"jsonNodes": 12000,
"depth": 20,
"profile": "rfc7578-bounded-body-v1",
"parts": 32,
"nameBytes": 64,
"filenameBytes": 128,
"mediaTypeBytes": 127,
"boundaryBytes": 60,
"payloadBytes": 60000,
"wireBytes": 100000,
"mediaTypeProfile": "RFC6838 restricted ASCII type/subtype; no parameters"
}
}
Complete schemas, descriptions and cross-field validation may impose additional limits.
Proposed price and protocol definitions
{
"unit": "one successful operation call",
"proposedNominalUsd": "0.005",
"sixDecimalTokenBaseUnits": "5000",
"subscription": false,
"includesPayerWalletOrNetworkFees": false,
"liveQuoteVerified": false,
"condition": "Actual SDK challenge is authoritative only within the caller's explicit authorization; configured six-decimal token peg is an operator assertion, not a conversion guarantee."
}
Protocol definitions: x402, mpp. MPP uses Tempo charge. Paid MCP execution is unsupported. All runtime readiness is not evaluated in this build.
API path templates, not endpoints on this documentation host
{
"x402": "/v1/x402/multipart-form-encode",
"mpp": "/v1/mpp/multipart-form-encode"
}
Required headers
{
"Content-Type": "application/json",
"Idempotency-Key": "random 16–128 character operation identifier"
}
Actual SDK challenge amount, asset, network, recipient and wallet costs must pass independent authorization. Preserve identical key, body, protocol and credential on retries; on PAYMENT_UNCERTAIN stop and reconcile.
Execution profile and provider conditions
{
"deterministic": true,
"externalRequests": 0,
"maxExternalRequests": 0,
"resultSnapshotPersisted": false,
"fixedExampleIsIllustrativeSnapshot": false,
"requiresPayment": true,
"supportsMcpExecution": false
}
Deterministic supplied-input operation with no external requests or stored request/result bodies. Payment infrastructure retains payment metadata and hashes.
Failure handling
- HTTP 400: Malformed JSON, missing/invalid idempotency key, or payment identifier mismatch Correct the request before payment
- HTTP 402: Payment challenge or rejected payment Use official protocol SDK; inspect payment outcome before another payment
- HTTP 409: Idempotency conflict, duplicate proof, or PAYMENT_UNCERTAIN Keep original key, body, and proof; reconcile uncertainty with operator; never blindly repay
- HTTP 413: Input or generated output too large Reduce input; no payment attempted for validation failure
- HTTP 415: Unsupported media type or compression Send uncompressed application/json
- HTTP 422: Schema or service-specific semantic validation failure Correct input using returned error code; no payment attempted
- HTTP 429: Request/payment-attempt rate exceeded Wait for rate limit window; preserve existing payment identity
- HTTP 503: Payment configuration/provider/state unavailable, or live DNS preparation failed before settlement Check readiness; DNS preparation failures may retry the identical key/body/credential only; uncertainty requires reconciliation
Declared requirements
Before any paid call, refresh the live operation contract and POST the complete bounded budgeted plan to the separate API's /preflight. Unknown requirements block selection; compatible preflight is not permission to spend.