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03 — Auditing · Assurance guide

Manual circuit and constraint review

Human review

In one paragraph

Manual circuit and constraint review: Human review. Layer: Circuit. Characteristic finds: Underconstraint, missing range checks, composition errors, and application-semantic bugs no tool models. Blind to: Large repetitive constraint sets where attention degrades; anything outside the read scope. Coverage claim: None — unmeasurable. Cost profile: High, reviewer-limited. Choose it when: Every engagement, as the backbone. Highest value on novel application logic, custom gadgets, and cross-component composition — anywhere a specification exists to check against.

By MarketComp Updated v1.3 About the authors Changelog
Layer
Circuit
Characteristic finds
Underconstraint, missing range checks, composition errors, and application-semantic bugs no tool models
Blind to
Large repetitive constraint sets where attention degrades; anything outside the read scope
Coverage claim
None — unmeasurable
Cost profile
High, reviewer-limited
Assurance matrix · see the row in context

What it is

Line-by-line review of the arithmetisation by reviewers fluent in the DSL and proof system: is every witness value constrained, are ranges enforced, are components composed with their preconditions satisfied, is every public input actually bound. In practice the reviewer builds a model of what the constraint system permits and then searches for a satisfying assignment the developer did not intend.

Strengths and tradeoffs

Strengths
  • Covers arbitrary bug classes, including application-semantic ones no tool models
  • Works on any DSL and arithmetisation, including new ones with no tooling
  • Produces design feedback and explanations, not just alerts
  • Can identify security properties the specification forgot to require
Tradeoffs
  • Quality varies enormously with the individual reviewer's ZK experience
  • Does not scale to large repetitive constraint sets such as zkVM chip tables
  • Point-in-time: invalidated by any constraint change
  • No coverage metric — you cannot measure what was not read
  • Reviewer supply is scarce, and scarcer still for the less common DSLs

Choose it whenEvery engagement, as the backbone. Highest value on novel application logic, custom gadgets, and cross-component composition — anywhere a specification exists to check against.

Failure modes that involve it
Maintained implementations

Not recorded for this entry.

Maturity: Production standard · License: Service · github.com ↗

How to decide
Other assurance guides in §03
ZK security consultanciesAutomated underconstraint detectionFormal verification of ZK circuitsDifferential and fuzz testingCryptographic review of the protocol and proof systemVerifier and integration reviewAudit contestsBug bountiesLLM-assisted review

Sources cited on this page · 1

  1. 0xPARC ZK Bug Tracker — bug taxonomy (frozen since late 2024; Circom/application-circuit skew)reference

All 48 sources for §03 are listed on the section page →

Cite this page 
MarketComp (2026). Manual circuit and constraint review. The ZK Field Manual (Version 1.3). MarketComp. https://zkpick.com/audit/manual-circuit-review/
@misc{zkfieldmanual-manual-circuit-and-constraint-review,
  title        = {Manual circuit and constraint review — The ZK Field Manual},
  author       = {MarketComp},
  year         = {2026},
  version      = {1.3},
  howpublished = {\url{https://zkpick.com/audit/manual-circuit-review/}},
  note         = {Accessed: YYYY-MM-DD}
}