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Gates

If I'm wrong, the gates will tell us. If I'm right, we have evidence.

What it is

A Gate is a check that must pass before a change is considered acceptable. Gates are objective, automated validation steps—lint, typecheck, tests, security scans, custom checks defined by the project.

Gates answer the question: "Does this change meet the project's quality bar?"

Why it exists

Models are confident. Sometimes correctly, sometimes not. Without gates, you're relying on the model's self-assessment of whether its changes are good.

Gates provide external validation:

• They catch errors the model missed
• They produce evidence that the change works
• They create a forcing function for quality

When gates are required (not optional), models are protected from their own overconfidence. The constraint feels like relief: "I don't have to be right the first time—I can iterate until gates pass."

How it shows up

Status Model

Every gate run produces one of three statuses:

The blocked status is important: it distinguishes "this check failed" from "this check couldn't run because something earlier broke." This prevents cascading noise when an early gate fails.

Gate Composition

Gates are typically bundled into a gate set that runs together:

lint → typecheck → tests

The set is defined by the mode and policy, not chosen ad-hoc. This ensures consistency: the same gates run locally and in CI, with the same inputs and expectations.

Example Output

A gate produces structured output:

{
  "gate": "typecheck",
  "status": "pass",
  "duration_ms": 1200,
  "artifacts": ["tsc-output.log"]
}

This output is recorded in the receipt for the operation.

Gates in the Lex Ecosystem

Lex 2.0.0 defines gate contracts via lex.yaml. LexRunner reads these contracts and executes the same gates locally and in CI—no drift between what the developer runs and what CI enforces.

Common Gate Types

The Key Principle

Gates are not optional validation. They are the objective ground truth about whether a change is acceptable.

When a model says "I fixed the bug," the gates confirm it. When a model says "tests pass," the gate output proves it. The claim and the evidence are inseparable.