Limitations
Every execution model defines guarantees.
A trustworthy execution model also defines its boundaries.
Forge intentionally separates documented execution guarantees from properties that depend on infrastructure, workload characteristics, external systems, or domain-specific assumptions.
Understanding these boundaries is part of understanding the execution model itself.
Limitations are therefore not exceptions to the execution doctrine.
They are part of the doctrine.
Why Explicit Boundaries Matter
Execution guarantees only remain meaningful while their scope is explicitly defined.
Undocumented assumptions eventually become operational surprises.
The purpose of this document is therefore not to describe weaknesses.
Its purpose is to define the exact scope of the Forge execution model.
By documenting both guarantees and intentional non-guarantees, Forge allows engineers to evaluate the platform using clearly defined expectations rather than implicit assumptions.
Execution Guarantees
Within the documented execution model, Forge is designed to preserve:
- execution contract identity
- primitive and profile identity
- deterministic execution planning
- deterministic reduction semantics
- controlled seed discipline
- replay compatibility
- execution evidence
- verification policies
- workload reproducibility within the documented execution semantics
These guarantees define computational behavior.
They do not imply identical infrastructure behavior.
Infrastructure Boundaries
Forge intentionally does not require homogeneous infrastructure.
Execution may legitimately occur across:
- different processor architectures
- different operating systems
- different cloud providers
- different geographic regions
- different virtualization environments
- different execution agents
- different transport paths
Operational diversity is considered part of normal execution rather than an exceptional condition.
The execution model therefore preserves computational identity instead of infrastructure identity.
Performance Boundaries
Forge does not guarantee:
- identical execution latency
- identical throughput
- identical scheduling decisions
- identical resource allocation
- linear horizontal scaling
- benchmark portability across all environments
Observed performance depends on many external factors, including workload characteristics, infrastructure composition, scheduling policy, hardware capabilities, and network conditions.
Benchmark results should therefore always be interpreted within the context in which they were measured.
Numerical Boundaries
Certain workload classes rely on floating-point arithmetic.
Floating-point behavior may legitimately differ across processors, compiler implementations, instruction sets, or aggregation order.
Forge therefore distinguishes between:
- computational correctness
- numerical representation
- implementation-specific precision
Where strict numerical stability is required, workload definitions, reducers, and execution policies must explicitly account for those requirements.
Forge intentionally does not guarantee universal bit-for-bit equality across heterogeneous execution environments.
Statistical Boundaries
Probabilistic workloads require different correctness criteria than deterministic workloads.
Execution may therefore be evaluated using statistical properties such as:
- convergence behavior
- expected value stability
- distribution consistency
- variance stability
- confidence intervals
- entropy characteristics
Equivalent statistical behavior should not be confused with identical individual samples.
Forge preserves execution semantics appropriate to each workload class rather than enforcing identical statistical outputs across fundamentally probabilistic computations.
Verification Boundaries
Verification establishes execution integrity.
It does not establish domain correctness.
Verification demonstrates that execution faithfully followed the documented execution contract and verification policy.
It does not determine:
- whether a scientific model is valid
- whether business assumptions are correct
- whether an optimization objective is appropriate
- whether an input dataset is accurate
- whether a probabilistic model reflects reality
Those questions remain the responsibility of workload authors and domain experts.
Replay Boundaries
Replay reproduces execution semantics.
Replay does not reproduce operational history.
Replay intentionally does not require:
- identical execution agents
- identical processor models
- identical infrastructure topology
- identical network conditions
- identical execution timing
Instead, replay evaluates whether the original execution contract continues to produce equivalent computational behavior under the documented execution model.
Security Boundaries
Security and execution trust address different concerns.
Security determines:
- who may execute workloads
- who may access artifacts
- who may manage execution resources
Execution trust determines:
- whether execution followed the documented contract
- whether execution evidence is preserved
- whether computational integrity can later be evaluated
Authentication, authorization, and verification therefore remain independent responsibilities.
Economic Boundaries
Forge associates economic settlement with verified computational contribution rather than declared participation.
Economic accounting may incorporate:
- verified shard completion
- execution evidence
- verification outcomes
- replay references
- measured computational contribution
Economic correctness therefore depends on documented execution evidence rather than self-reported activity.
Current Implementation Boundaries
The Forge execution doctrine intentionally distinguishes architectural principles from implementation maturity.
Specific execution capabilities may evolve over time as new verification policies, scheduling strategies, execution primitives, or replay mechanisms are introduced.
The documented execution model should therefore be interpreted according to the currently implemented runtime behavior rather than anticipated future capabilities.
Implementation maturity may change.
Execution doctrine should remain stable.
Non-Goals
Forge is intentionally not designed to:
- replace scientific validation
- validate business assumptions
- prove mathematical correctness
- eliminate floating-point behavior
- remove statistical uncertainty
- replace domain expertise
- guarantee optimal scheduling
- guarantee universal workload performance
- eliminate every possible infrastructure failure
These problems belong to different layers of the computational stack.
Forge focuses on preserving execution integrity, computational evidence, and reproducible execution semantics.
Practical Mental Model
A useful way to understand the execution boundaries is:
Execution Contract
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Execution Guarantees
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Execution Boundaries
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Operational Expectations
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Correct System InterpretationExecution guarantees define what Forge preserves.
Execution boundaries define where those guarantees intentionally end.
Both are essential to understanding the execution model.
Relationship to the Trust Layer
The Trust Layer is composed of complementary responsibilities.
Trust Layer explains why computational trust exists.
Verification explains how execution integrity is established.
Heterogeneous Execution explains which execution properties remain invariant across diverse infrastructure.
Limitations defines the precise boundaries of those guarantees.
Together these documents describe the complete execution doctrine of the Forge runtime.
Final Note
Forge does not become more trustworthy by promising more.
It becomes more trustworthy by precisely defining:
- what remains invariant
- what intentionally varies
- what evidence is preserved
- where execution guarantees begin
- where execution guarantees end
Explicit boundaries are part of computational trust.
Systems become dependable not because they claim certainty, but because they define uncertainty with precision.