Definition

Once semantic intent is allowed to participate in execution, the absence of an explicit instruction boundary renders task behavior opaque, non-replayable, and structurally unaccountable.

Semantic ISA (Instruction Set Architecture) defines an intermediate execution layer in which semantic constructs are transformed into constrained, inspectable instructions.

It specifies the minimal instruction surface required for semantic commitments to participate in execution under deterministic and auditable conditions.

Semantic ISA is neither a language for expression nor a prompt format. It functions as a semantic–execution boundary, not as an application interface.

Role in the Execution Stack

Natural language is expressive but inherently ambiguous. Direct execution from language collapses semantic intent and operational behavior into an opaque step that cannot be reliably inspected, replayed, or constrained.

Semantic ISA introduces a stable intermediate layer that:

  • separates semantic intent from execution mechanics,
  • allows semantic inputs to be compiled rather than interpreted at runtime,
  • produces instructions that map to concrete execution substrates.

This layer exists independently of implementation language, model choice, or runtime environment.

Motivation

As language-driven systems move into execution-, coordination-, and governance-adjacent domains, failure modes increasingly arise from structural ambiguity rather than incorrect content.

Common failure patterns include:

  • non-replayable behavior under identical inputs,
  • hidden assumptions embedded in fluent output,
  • inability to trace or attribute responsibility,
  • tight coupling between intent expression and specific models or vendors.

Semantic ISA addresses these issues by formally separating intent articulation from execution commitment.

Architectural Position

Semantic ISA occupies a role analogous to instruction set architectures in computing systems.

Just as CPU ISAs abstract hardware differences while enforcing operational constraints, Semantic ISA abstracts linguistic variability while enforcing semantic constraints required for execution.

Key properties include:

  • Determinism Equivalent semantic instructions yield equivalent executable behavior under defined conditions.
  • Portability Semantic intent expressed in any natural language can be normalized into a common instruction layer.
  • Auditability Each instruction is inspectable, traceable, and attributable prior to execution.
  • Composability Instructions can be combined into larger execution graphs without reinterpreting raw language.

Semantic ISA does not replace natural language. It constrains language precisely at the point where execution begins to matter.

Scope

Semantic ISA concerns:

  • admissible instruction forms between semantics and execution,
  • the minimum structure required for replayability and traceability,
  • preservation of semantic accountability across execution steps.

It does not prescribe concrete syntax, tooling, or optimization strategies. Those are downstream concerns.

What This Work Is Not

Semantic ISA is not:

  • a programming language competing with existing languages,
  • a prompt framework or model-specific API,
  • a reasoning model,
  • an agent scripting or workflow description system.

Such systems may embed or rely on an ISA layer, but they are not equivalent to it.

Relationship to Executable Semantic Order

Executable Semantic Order defines when semantic descriptions are allowed to enter execution.

Semantic ISA defines how this transition is realized once it is allowed.

The former specifies conditions of admissibility. The latter specifies the mechanism of realization.

Neither replaces the other.

Status

This concept is considered stable.

Ongoing work focuses on concrete instruction schemas, execution mappings, and integration with runtime and governance systems, rather than revision of the architectural boundary defined here.