Jev anti-patterns
An anti-pattern here is a shape of system that keeps failing even when individual calls look fine. The common mistakes page is the punch list; this page is the architecture review. Independent. docs.typesafe.ai.
Independent angle (cover, do not clone)
Win delta: named anti-patterns with “replace with” (decide-then-draft, regex-then-Jev, fail-closed). We do not clone a myth-FAQ cluster or a rival “Jev limitations” essay.
Question and context
System One is a function-call model: state in, typed answers out, code acts. Anti-patterns try to turn it into a chatbot, a warehouse, a lawyer, or a silent cron that mutates production without traces.
Core concepts (named patterns)
The oracle
One mega-Choice (“what should we do with this customer?”) with criteria that restate your entire handbook. Replace with atomic questions and a graph in code. Official how-to: snap judgments, decompose.
The dump truck
POST the CRM, EHR, or lake “in case it helps.” jev-1.13 is documented to degrade with distractors; you also pay input tokens (vendor $0.042 / M — confirm models page). Replace with an input contract.
The ghost writer
Use System One as the email/ticket generator. Wrong job; you lose a typed audit of the decision. Replace with decide-then-draft (Jev enum → LLM prose).
The silent alias
Thresholds fitted on Monday’s jev-latest, traffic on Thursday’s new resolve. Replace with version pinning and a canary on response.model.
The confidence laundering
Copy one τ everywhere (read vs irreversible, Noul vs Choice). Replace with per-action floors and evaluation.
The unauditable irreversible
Auto-refund, auto-reject, auto-diagnose, auto-send outside counsel — with no decision trace. Replace with fail-closed + human pack (handoff glossary).
The unofficial-as-official
Shipping jev.pro copy as if TypeSafe signed it. Replace with outbound https://docs.typesafe.ai and the site disclaimer.
Practical approach
In design review, ask: “If TypeSafe is down, what happens?” and “Can I replay this row in six months?” If either answer is a shrug, you are in an anti-pattern. See operating model.
Risks and trade-offs
Naming patterns can become slogans. Keep the test: does the design violate official snap-question guidance, documented jaggedness, or your own fail-closed rule?
What this page does not claim
- Not a complete catalog of bad AI systems.
- Not a smear of any competitor product — cover intents, do not clone them.
FAQ
Is using OpenRouter an anti-pattern?
No. Using a marketplace door is fine if you record that door’s model id and schema. Mixing first-party noul with another door’s boolean without a check is the anti-pattern.
Are replicas (open weights, unofficial UIs) endorsed? No. Open-cluster rule: replicas are not Jev and not endorsed.
Where do best practices live? Best practices is the constructive twin of this page.
Disclaimer
This is an independent unofficial site and is not affiliated with TypeSafe AI; official documentation is available at https://docs.typesafe.ai. Never treat jev.pro as TypeSafe official documentation. We do not sell, issue, or proxy API keys.
Open-cluster pages are independent field-guide notes. Replicas and third-party interfaces mentioned anywhere on jev.pro are not Jev and not endorsed. Hub: Open. Siblings: common mistakes, best practices, operating model. Canonical: https://docs.typesafe.ai.
Sources
Public TypeSafe or adjacent documentation only. No private claims.