Complete reference for .matr language constructs, the Molebyte artifact format, compilation boundaries, and the execution handoff contract between Matter Studio and Material Cloud. This page is designed for authors and agents building production matter programs.
Every .matr file is composed of top-level blocks. The following is the complete set of constructs available in the language. Each block type has required and optional fields, and the compiler enforces structural validity at parse time.
Defines a physical or simulated substance with substrate binding, concentration or quantity, and optional characterization parameters. Multiple materials can be declared per file.
substrate, at least one quantity parameter
metadata, tags, provenance, physical properties
Defines an ordered sequence of operations on materials. Steps execute sequentially. Each step references inputs from material blocks or from previous step outputs. Parallelism is achieved by composing protocols, not by branching.
at least one step with input and duration
step conditions (temperature, pressure, pH, stir_rate), intermediate outputs, annotations
Declares success criteria evaluated at simulation and post-execution. Supports numeric comparisons (>=, <=, ==), range expressions (value ± tolerance), and statistical bounds. Constraint violations are surfaced as signals.
at least one constraint expression
tolerance ranges, comparison operators, statistical bounds
Required on every program. Declares consequence tier, approval chains, escalation behavior, and compliance labels. The compiler validates that governance is consistent with the program's constraint severity.
tier (T0-T4), consequence label
approvals, escalation, compliance labels, audit tags
Configures Material Twin simulation parameters. Defines how many simulation runs to execute, what confidence level is required, which substrate model to use, and what baseline to compare against.
runs, confidence threshold
substrate_model version, baseline reference, timeout, seed
Imports materials, protocols, or constraint sets from other .matr files or from the platform registry. Imports are resolved at compile time and versioned. Circular imports are a compile error.
source path or registry reference
alias, version pin
Declares the expected outputs of the program. Outputs are named, typed, and optionally bounded. They become the signal schema that Material Cloud uses to structure execution results.
at least one named output
format, units, expected range
A Molebyte is the compiled, versioned, immutable artifact produced by the Matter compiler. It is the unit of deployment, execution, audit, and provenance on the Matterforma platform. Molebytes are analogous to container images or compiled binaries, but designed for Material Computing.
{
"format": "molebyte/v1",
"version": "1.2.0",
"hash": "sha256:a3f8e2...",
"source_hash": "sha256:7b1c9d...",
"compiled_at": "2026-02-25T14:30:00Z",
"governance": {
"tier": "T2",
"consequence": "physical-reversible",
"approvals_required": ["domain-lead", "safety-review"]
},
"pep": { /* Protocol Execution Plan */ },
"materials": [ /* resolved material definitions */ ],
"constraints": [ /* constraint expressions */ ],
"simulation": { /* simulation configuration */ },
"outputs": [ /* expected output schema */ ]
}The compiler makes the following guarantees. If compilation succeeds, all of these conditions hold. If any condition cannot be satisfied, compilation fails with a diagnostic.
Source conforms to .matr grammar. All blocks are structurally valid and all required fields are present.
All substrate references resolve to known substrates in the platform registry or simulation catalog.
All constraints are expressible against the declared outputs and do not conflict with each other.
Governance tier is declared, consequence label is present, and approval chain matches organizational policy.
A deterministic Protocol Execution Plan has been generated from the protocol steps and material bindings.
The resulting Molebyte can be simulated in the Material Twin against the declared substrate model. Non-simulatable programs are rejected.
When a Molebyte is submitted to Material Cloud, the following contract governs the boundary between the authoring plane (Matter Studio) and the execution plane (Material Cloud).
No physical execution. Used for testing, learning, and dry runs. No approvals required.
Reversible operations on non-critical substrates. Automated approval sufficient.
Operations with material cost or time investment. Requires domain lead approval.
High-value substrates or irreversible intermediate steps. Requires safety review and domain approval.
Irreversible operations on critical substrates. Requires full approval chain, enhanced simulation, and human-in-the-loop confirmation.