1. Governing law and the written bargain
This is predominantly an agreement for an artist's personal services, so common-law contract principles govern rather than the UCC rules for a sale of goods. Sam promised a unique ceiling-border design, and Barn promised $75,000 upon completion. The contract identifies the undertaking and price sufficiently for a contract, even though the scope of public areas and preparation obligations require interpretation.
The mutually drafted handwritten instrument is described as containing the entire written agreement. That supports treating it as an integrated expression of terms, but whether it is a complete integration excluding every consistent additional term remains a legal and factual issue. Its brevity and silence on surface preparation matter. Neither party's unilateral later understanding controls; the court seeks the objective meaning of their agreement in context.
2. Were the bathrooms included?
Barn argues that two public restrooms in the lobby are public areas of the first-floor lobby and thus are expressly included. The word entire also favors a comprehensive undertaking. If that is the only reasonable interpretation and the writing is fully integrated, an earlier oral agreement to omit the restrooms could contradict the written scope and be excluded by the parol evidence rule.
Sam responds that a lobby's public areas can mean the entrance and reception space rather than separate restroom interiors. Before signing, he expressly told Ed that his paints could not be used in the humid restrooms. That discussion can illuminate an ambiguity and the parties' intended boundaries. Evidence used to interpret a term reasonably susceptible to that meaning is different from an attempt to enforce a contradictory prior agreement. The extent to which contextual evidence may be considered to establish ambiguity varies by jurisdiction, and the question does not demand one state's particular formulation.
If the court credits the oral discussion as admissible interpretive evidence, the contract likely excluded bathroom borders. Sam then did not breach by omitting them. If the court instead concludes the clear integrated scope includes them, he has left part of the agreed work unfinished. The writing was mutually drafted, so a presumption against one identified drafter supplies little assistance. His paint-suitability explanation supports his interpretation but does not itself prove impossibility; he knew the issue before signing and cannot simply turn a foreseeable limitation into an unforeseen excuse.
3. Who bears the $3,000 preparation cost?
The contract does not expressly allocate sanding and sealing. Barn's assertion that other artists usually perform surface preparation raises trade usage and implied obligations necessary to achieve the promised result. A binding or interpretive usage generally must be established as sufficiently regular and known, or of a kind the parties had reason to know. Barn's report of recent conversations is not itself conclusive proof of every painter's custom, but competent evidence of an established practice can explain the agreement.
Sam's status as a practicing artist supports an expectation that he understand normal preparation requirements. Promising to paint on newly installed plaster may reasonably include ordinary work necessary for a successful result. If that is part of the original undertaking, he cannot unilaterally increase the fixed price because the job proved more burdensome than expected. Ed did not agree to an extra $3,000; he expressly said preparation was Sam's responsibility. There is no supported contract modification simply because Sam objected and then performed.
If the court instead finds preparation outside the agreed scope, Sam can argue that Barn requested or knowingly accepted an additional non-gratuitous benefit and owes its reasonable value. His bill provides a claim amount, not automatic proof of an agreed price or reasonable cost. Ed's express rejection of additional responsibility makes an implied extra-payment agreement harder to establish. On the supplied evidence, a fixed $75,000 price including customary preparation is the stronger result, assuming the asserted trade practice is proved.
4. Payment and substantial performance
If restrooms were excluded, Sam completed the promised design and Barn's duty to pay $75,000 matured. Barn cannot withhold the entire price based on an obligation the parties did not undertake. Sam likely recovers that amount, subject to any proved extra-work entitlement, allowable interest, and other supported adjustments.
If restrooms were included, the next question is whether the omission is material or whether Sam substantially performed. Substantial performance generally allows recovery of the contract price less damages for incomplete or defective work when the essential bargain has been provided. Relevant considerations include the benefit received, the portion missing, the ease of compensation, prospects of cure, and good faith. A unique design around the main lobby may provide most of the agreed benefit; two bathroom borders might be a relatively small omission. The facts do not give their dimensions or a completion cost, so neither should be invented.
Sam's good-faith belief that bathrooms were excluded favors substantial performance. Deliberate refusal to perform a clearly understood essential requirement would point the other way. The phrase upon completion indicates the expected order of performance, but does not necessarily create an unmistakable express condition demanding perfect performance and forfeiture of all payment for a minor omission. Courts ordinarily distinguish a constructive condition of substantial performance from a clearly stated strict express condition.
If Sam substantially performed, the likely recovery is $75,000 less reasonable completion or other appropriate defect damages, rather than his full unilateral $78,000 bill. If the omission is a material breach, Barn may withhold the contractual payment until the condition is satisfied, subject to other doctrines. Even then, restitution for a net benefit retained may remain available under the governing rules for a breaching performer, offset by Barn's loss. The facts do not justify declaring that an almost completed valuable design necessarily earns zero under every theory.
5. Barn's specific-performance counterclaim
Specific performance ordinarily requires an enforceable definite contract, inadequate damages, and equitable suitability. Sam's rising reputation and one-of-a-kind design make a substitute artist's work imperfectly equivalent, giving Barn a substantial inadequacy argument. But courts ordinarily do not order affirmative performance of personal artistic services. Compulsion raises enforcement, supervision, quality, and personal-liberty concerns that uniqueness does not overcome.
Barn therefore is unlikely to obtain an order forcing Sam to paint the bathrooms, even if they were within the contract and he breached. Barn can seek appropriate damages or a contract-price offset if it proves that obligation. No express negative covenant or competing performance is described that would support a tailored negative injunction, and such an order should not be used as indirect compulsion. Barn also must confront its own refusal to pay and the disputed scope. The principal likely result is payment for the work, with a supported deduction if required, rather than a judicially supervised painting assignment.