> ## Documentation Index > Fetch the complete documentation index at: https://docs.lerian.studio/llms.txt > Use this file to discover all available pages before exploring further. # Propose a config-only field-map/dialect mapping for a source sample > Inspects a representative sample of a source file and returns a CONFIG-ONLY mapping/dialect proposal (column→canonical-key suggestions, dialect, per-field confidence and rationale). It is ADVISORY and side-effect-free: producing a proposal PERSISTS NOTHING. The operator reviews the proposal and confirms it through the EXISTING field-map declaration path. The tenant is resolved from the JWT and the context/source from the path — never from the body. The response never carries parsed values, amounts, or transactions. ## OpenAPI ````yaml en/openapi/v3-current/matcher.yaml post /v1/imports/contexts/{contextId}/sources/{sourceId}/mapping-proposal openapi: 3.1.0 info: title: Matcher APIs description: >- Complete API reference for the Matcher reconciliation engine, providing automated transaction matching between Midaz Ledger and external systems. version: 4.1.0 license: name: Elastic License 2.0 url: https://www.elastic.co/licensing/elastic-license servers: - url: https://matcher.sandbox.lerian.net security: [] paths: /v1/imports/contexts/{contextId}/sources/{sourceId}/mapping-proposal: post: tags: - Ingestion summary: Propose a config-only field-map/dialect mapping for a source sample description: >- Inspects a representative sample of a source file and returns a CONFIG-ONLY mapping/dialect proposal (column→canonical-key suggestions, dialect, per-field confidence and rationale). It is ADVISORY and side-effect-free: producing a proposal PERSISTS NOTHING. The operator reviews the proposal and confirms it through the EXISTING field-map declaration path. The tenant is resolved from the JWT and the context/source from the path — never from the body. The response never carries parsed values, amounts, or transactions. operationId: proposeMapping parameters: - description: Context ID in: path name: contextId required: true schema: description: Context ID format: uuid type: string - description: Source ID in: path name: sourceId required: true schema: description: Source ID format: uuid type: string requestBody: content: application/json: schema: $ref: '#/components/schemas/ProposeMappingRequest' required: true responses: '200': content: application/json: schema: $ref: '#/components/schemas/MappingProposalResponse' description: OK default: content: application/problem+json: schema: $ref: '#/components/schemas/Detail' description: Error security: - BearerAuth: [] components: schemas: ProposeMappingRequest: additionalProperties: false properties: format: description: Declared file format hint enum: - csv - json - xml - camt053 examples: - csv type: string hints: additionalProperties: type: string description: >- Optional non-secret operator nudges (e.g. locale=pt-BR, has_header=true) type: object sample: description: Representative source-file sample examples: - | id;value;ccy;posted_at A1;10,50;BRL;2025-06-01 minLength: 1 type: string required: - sample type: object MappingProposalResponse: additionalProperties: false properties: dialect: $ref: '#/components/schemas/DialectResponse' description: >- Proposed source dialect; null when the advisor has no dialect suggestion fields: description: Per-field breakdown backing the proposed mapping items: $ref: '#/components/schemas/FieldProposalResponse' type: - array - 'null' mapping: additionalProperties: {} description: >- Proposed canonical field map (canonical key -> source column); null when the advisor could not propose a mapping type: object required: - fields type: object Detail: additionalProperties: false properties: code: description: >- Stable, machine-readable domain error code scoped to the emitting service (format: -NNNN). examples: - ERR-0001 type: string detail: description: >- A human-readable explanation specific to this occurrence of the problem. examples: - Property foo is required but is missing. type: string errors: description: Optional list of individual error details items: $ref: '#/components/schemas/ErrorDetail' type: - array - 'null' instance: description: >- A URI reference that identifies the specific occurrence of the problem. examples: - https://example.com/error-log/abc123 format: uri type: string status: description: HTTP status code examples: - 400 format: int64 type: integer title: description: >- A short, human-readable summary of the problem type. This value should not change between occurrences of the error. examples: - Bad Request type: string type: default: about:blank description: A URI reference to human-readable documentation for the error. examples: - https://example.com/errors/example format: uri type: string type: object DialectResponse: additionalProperties: false properties: dateStyle: description: >- Detected date convention: iso (YYYY-MM-DD), iso_offset (RFC 3339 with offset), dmy (DD/MM/YYYY), or mdy (MM/DD/YYYY) examples: - iso type: string decimalStyle: description: 'Detected amount decimal convention: dot (1234.56) or comma (1234,56)' examples: - comma type: string delimiter: description: 'Detected CSV field separator: comma, semicolon, tab, or pipe' examples: - semicolon type: string encoding: description: >- Detected file character encoding: utf-8, utf-8-sig (UTF-8 with BOM), cp1252 (Windows Latin-1), or iso-8859-1 examples: - utf-8 type: string required: - encoding - delimiter - decimalStyle - dateStyle type: object FieldProposalResponse: additionalProperties: false properties: canonicalKey: description: Canonical field-map key the proposal targets examples: - amount type: string confidence: description: Advisor confidence in this mapping, 0.0 (none) to 1.0 (certain) examples: - 0.92 format: double maximum: 1 minimum: 0 type: number rationale: description: Short human-readable explanation for the suggestion examples: - numeric column with comma decimal type: string sourceColumn: description: Proposed source column feeding the canonical key examples: - value type: string required: - canonicalKey - sourceColumn - confidence - rationale type: object ErrorDetail: additionalProperties: false properties: location: description: >- Where the error occurred, e.g. 'body.items[3].tags' or 'path.thing-id' type: string message: description: Error message text type: string value: description: The value at the given location type: object securitySchemes: BearerAuth: type: http scheme: bearer bearerFormat: JWT description: 'Bearer token authentication (format: "Bearer {token}")' ````