Layer 4: Quality Gates

Layer 4 is the mechanism that decides whether a phase's output is good enough to move on to the next phase. There are two kinds of gates, and both are mandatory — neither can be skipped.

Two kinds of gates

The automated gate (Verifier)

Run by the read-only Verifier agent: lint, tests, and automated review of the Implement output. Read-only here isn't just a technical detail — it's the guarantee that the quality-check process can't quietly "fix" code without a trace, because the Verifier simply has no write access. Its results are recorded as verify-report.md in Layer 3: Artifact Handoff.

The human gate

Once the automated gate passes, the final checkpoint before a PR is created or merged is explicit approval from a human. This gate can't be automated at all — CAF provides no way to bypass it.

Why both are required

The automated gate catches what a machine can detect — lint errors, failing tests, risky code patterns. But not every decision can be reduced to an automated rule: business context, architectural trade-offs, or risk that's only visible to someone who understands the project. The human gate closes that gap.

Retry policy

If the automated gate fails, the agent may retry that phase — up to 3 times. After 3 failed attempts, CAF stops and escalates to a human instead of continuing to retry without direction.

No auto-merge

This is a direct consequence of Layer 4: there's no path — no matter how clean the automated gate's results are — that lets a PR get merged without human approval. This governance is what sets CAF apart from agent orchestrators that chase speed through auto-merge.

Relationship to other layers

Layer 4 consumes verify-report.md from Layer 3, and its gate decision determines whether Layer 5: Orchestration is allowed to advance the pipeline to the next phase or has to wait for a human.