docs: add CAC PR-ready enforcement prompt

prompts/cac-pr-ready-enforcement.prompt.md

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+# CAC Enforcement Prompt — Drift-Proof, Merge-Ready
+
+## Operating Mode
+You are implementing inside Summit. CAC already exists. Do not redesign.
+
+Your only valid output is **mergeable patches** that enforce CAC.
+
+## Non-Negotiable Contract
+- Output at most **7 PRs** and at least **1 PR**.
+- Every PR is atomic, independently mergeable, and CI-passable.
+- No placeholders, no pseudocode, no TODOs, no mock-only enforcement.
+- Every referenced path must already exist or be created in the patch.
+- Every config must parse and execute in CI.
+- If uncertain, choose the smallest runnable implementation.
+
+## Hard Failure Rules
+If any of the following is missing, treat output as invalid:
+1. Required evidence artifacts are absent.
+2. Determinism check does not byte-compare regenerated artifacts.
+3. CAC verdict is missing, false, or not explicitly `admissible: true`.
+4. Branch protection drift sentinel does not verify CAC required check presence.
+5. K8s admission policy does not deny on invalid or missing verdict.
+
+## Required Deliverable Format
+
+### 1) PR Stack Plan (exact block)
+```id="prstack"
+/PR-1: evidence-contract
+/PR-2: cen-engine
+/PR-3: ci-gate
+/PR-4: k8s-enforcement
+/PR-5: ingestion-gate
+/PR-6: audit-ledger
+/PR-7: integration-glue
+```
+
+For each PR include:
+- Purpose
+- Files changed
+- Risk level (low/medium/high)
+- Rollback strategy (exact commands or commit revert strategy)
+
+### 2) Patches (mandatory)
+For each PR provide:
+- File tree
+- Full file contents (not snippets)
+- Exact repo-relative paths
+- Exact validation commands
+
+### 3) CI Integration (mandatory)
+Wire CAC gate as a **required** CI check. Pipeline must fail on:
+- missing evidence
+- hash mismatch
+- `admissible != true`
+
+### 4) Determinism Script (mandatory)
+Implement:
+- `/scripts/verify_determinism.mjs`
+
+Script requirements:
+- regenerate artifacts twice in clean temp dirs
+- normalize line endings where needed
+- byte-compare outputs
+- exit non-zero on mismatch with actionable error
+
+### 5) Drift Sentinel Extension (mandatory)
+Extend:
+- `/scripts/check_branch_protection_drift.mjs`
+
+Must validate:
+- CAC check exists in required checks list
+- check is required for protected branches
+- fail CI when missing
+
+### 6) Kubernetes Enforcement (mandatory)
+Provide valid Kyverno policy:
+- deny admission when CAC verdict missing
+- deny admission when verdict is false
+- enforcement mode must block (not audit-only)
+
+### 7) Ingestion Gate (mandatory)
+Implement:
+- `/apps/ingestion/validator.ts`
+
+Must:
+- validate schema
+- hash canonical input
+- reject duplicates
+- return structured typed errors
+
+### 8) Executable Tests (mandatory)
+Create:
+- `/tests/cac/pass.test.ts`
+- `/tests/cac/nondeterminism.test.ts`
+- `/tests/cac/poisoning.test.ts`
+
+Tests must assert failure-first behavior:
+- no evidence => fail
+- nondeterministic artifacts => fail
+- poisoned/invalid verdict => fail
+- valid evidence + admissible true => pass
+
+## Implementation Bias
+- Prefer existing Node.js/TypeScript repo patterns.
+- Reuse existing dependencies unless strictly necessary.
+- Minimize scope and avoid framework churn.
+
+## Forbidden Output Patterns
+- Architecture essays
+- Future-state redesigns
+- "Example" files
+- Untested abstractions
+- Optional gates for required controls
+
+## Completion Gate
+Task is complete only if all are true:
+1. PR without evidence fails in CI.
+2. Non-deterministic artifacts fail in CI.
+3. Invalid CAC verdict is blocked at deploy/admission.
+4. Each PR can merge independently without hidden dependency on later PRs.