Worker output validation

A successful worker exchange reports completion; it does not make the worker's paths or files trustworthy. metewand-runtime validates materializer, implementation, and evaluator output in the private directory assigned by the executor before any artifact can be accepted or published.

WorkerOutputValidator takes the offline schema catalog from a checked repository. It also loads Metewand's embedded public schemas, so validation does not read schemas from the worker's output or retrieve them from the network.

Paths and filesystem inventory

Materializer and implementation responses name their manifest relative to the assigned output root. Returned paths must be nonempty, normalized UTF-8 relative paths using / separators. Absolute POSIX and Windows drive paths, . and .. components, repeated or trailing separators, and backslashes are rejected before the path is joined to the root.

The runtime walks the output without following links. Regular files and the directories needed to contain them are the only accepted entry types. Symbolic links, sockets, FIFOs, devices, and other special entries fail validation. The same walk rejects files absent from the manifest and directories that contain no declared file. A result or dataset manifest cannot declare itself because a self-hash cannot be completed.

Each declared payload path must be unique. The runtime checks that it names a regular file, compares its exact byte length, streams it through SHA-256, and detects length or type changes during the read. Validated file records are returned in UTF-8 byte order, independent of their order in the worker's JSON.

Evaluator output uses the same containment rules. Its assigned metrics document must be the only regular file in its private output; only directories needed to contain that document are permitted.

Document and scientific contracts

Every document is parsed through Metewand's restricted canonical JSON domain, which rejects malformed input, duplicate keys, invalid Unicode, non-finite or out-of-range numbers, and trailing input. Materialized datasets must satisfy the public artifact-manifest schema—including its complete: true marker—and the dataset definition's output schema.

Implementation results must satisfy the public result-manifest schema. The manifest's optional schema field must exactly name the result schema selected by the checked problem contract. When omitted, Metewand uses the selected schema, including an inline declaration. Its data object is always validated against that schema. Evaluator metrics follow the analogous rule for the public metrics envelope and the selected metric schema. A worker cannot redirect validation by naming a different repository schema in its output.

The validator returns typed ValidatedDataset, ValidatedResult, and ValidatedMetrics values. Failures retain the rejected relative path, selected schema, expected and observed size or digest, or underlying JSON and schema diagnostics as appropriate. Artifact publication and attempt-outcome mapping remain later runtime layers; neither protocol success nor an unvalidated path is evidence of a valid result.