Senior Software Engineer Jobs in Maine (NOW HIRING)

Description
Experience: Any career stage. We evaluate demonstrated capability, not years - exceptional recent graduates and seasoned engineers seeking focused project work are equally welcome.
We're looking for a Software Engineer to build a contract-verification framework for Client's AI/ML platform: a system of declarative predicates and invariants that governs how Python code is allowed to change. This is closer to compiler and program-analysis work than to data engineering - you'll turn formal specifications into tooling that verifies code automatically.
Your work will help ensure the reliability of the ML systems that power Client's diagnostic products.
Required: Along with your résumé, include a short paragraph about a time you turned an abstract formalism - a logic, a type system, a grammar, a constraint model - into a tool other people actually used. What it was, what made it hard, and what shipped.
What you'll work on
AI assistants have made writing code dramatically faster. They have not made writing correct code dramatically faster - that gap is widening, and the tooling that closes it matters more than it used to. That's the work this role exists to do.
A common thread runs through everything we build: a formal specification - a schema, a contract, a grammar - is the source of truth, and the tooling we write makes other code conform to that specification automatically. When the specification is the source of truth, code that doesn't match it fails loudly rather than silently - whether that code was written by a human, generated by an AI assistant, or somewhere in between.
Your primary focus:
Predicate & invariant framework for data contracts - the core of the role.
Design and implement declarative contract classes that attach to Python methods (design-by-contract decorators - no relation to the ML data annotations below) and trigger verification of the code inside, using AST-level analysis.
Predicates enforce data contracts: they state what a method must guarantee about the data it produces or consumes, and the verifier checks the implementation against those statements.
Invariants constrain evolution: they state properties of the codebase that must survive change, so that modifications - human- or AI-authored - that would break them fail at verification time, not in production.
You'll shape the vocabulary of predicates and invariants together with the architect, build the verifier and its diagnostics, and make violation messages clear enough that they teach the contract they enforce.
Your secondary focus:
Annotation data platform evolution.
Extend a shipped canonical schema (Avro) and adapter layer that normalize ML annotation data from multiple commercial labeling platforms into a shared representation.
Add adapters for new platforms, evolve the schema under a versioned spec and ADR process, and keep validation utilities and Python typing overlays in sync with the schema.
Key responsibilities
Design and implement the predicate/invariant framework: contract classes, the AST-based verifier, and CI integration.
Turn abstract contract concepts into APIs and diagnostics that working engineers adopt willingly - making the ideas graspable is part of the job, not an afterthought.
Extend and evolve schemas, adapters, and validation layers for the annotation platform under its established change process.
Investigate verification and validation failures and determine whether the fix belongs in the contract, the code, or the source system, documenting your reasoning.
Document the framework thoroughly and transfer knowledge continuously - by the end of the engagement, the team must be able to own and extend it without you.
Work closely with a senior architect on initial designs, then independently own implementation in your areas.
Must-have qualifications
We're flexible on background, but you should be able to demonstrate:
Comfort with formal and abstract structures - logic, type systems, program analysis, algebraic thinking - demonstrated by working software you built from them. Vision and execution together; neither alone is enough.
Deep production Python: decorators, descriptors, metaclasses, type hints, and the standard library.
Strong analytical reasoning: comfort working from ambiguous or underspecified ideas and finding structure.
Ability to communicate technical ideas clearly in writing (design docs, code reviews, documentation, async messaging).
Independence in scoping and delivering work, with the judgment to escalate complex design questions.
Strong pluses (nice to have, not required)
A computer-science degree, or any particular number of years of experience.
Prior data engineering or ML experience (the role is adjacent to ML, not part of model training).
Experience with our exact stack (Avro, Databricks, Spark, dbt, etc. can be learned on the job).
Experience in any of these areas is a genuine plus:
Contracts and verification
Design-by-contract tooling (icontract, deal, Eiffel, JML, Dafny) or other program-verification exposure.
Property-based testing (Hypothesis or similar).
Code-as-data work
Parsing or analyzing source code (Python ast / libcst, tree-sitter, or equivalents); codemods; mypy plugins or typing internals.
Code generation, templating, or compiler back-ends - especially if you've maintained a code generator in production.
Rule and constraint systems
DSLs, OPA/Rego, rule engines, or knowledge-representation/constraint languages (OWL, RDF, SHACL, Datalog).
Translating declarative business rules into executable validation logic.
Schema and validation tooling
Avro, JSON Schema, OpenAPI/Swagger, LinkML, CUE, or similar; Pydantic, Marshmallow, or attrs with validators.
If you're excited about the work but not sure you meet every point, we encourage you to apply - depth in one of these clusters plus strong reasoning can go a long way.
A note on AI tools
OAI coding assistants regularly. We expect you to be comfortable with them and to use them well - they're not a special skill, they're table stakes for tooling work in 2026. What matters is the judgment around them: knowing when the AI's output is wrong, knowing when to direct it more carefully, knowing when to write the code by hand because it's the kind of thing that needs to be right rather than fast. The framework you'll build is itself part of how we keep AI-speed development safe.
What success looks like
In your first 30 days, you'll internalize the contract model and the platform's spec/ADR process, and ship a first working predicate end-to-end - decorator, verification, diagnostics.
By 90 days, the framework core will be enforcing real data contracts in CI on at least one system, and teammates will be writing predicates without your help.
By end of term, the framework will be documented, adopted, and owned by the team; invariants will be guarding codebase evolution; and the extension conversation will be about what to build next, not whether it worked.
We care more about the quality and durability of what you build than lines of code or ticket counts.