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+"""PRG- pre-release audit gateway schema.
+
+Single-gate record asserting BRC (batch release checklist), PCC (pipeline
+completeness), and ECI (evidence completeness index) all pass before external
+sharing. Blocks release until all three gates are green.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+VALID_GATE_STATUSES: frozenset[str] = frozenset({"pass", "fail", "not_evaluated"})
+VALID_RELEASE_VERDICTS: frozenset[str] = frozenset({"approved", "blocked"})
+
+REQUIRED_GATES: tuple[str, ...] = ("BRC", "PCC", "ECI")
+
+
+@dataclass
+class GateResult:
+    gate_type: str
+    artifact_id: str
+    status: str
+    details: str
+
+
+@dataclass
+class PreReleaseAuditGateway:
+    prg_id: str
+    batch_id: str
+    pipeline_version: str
+    gate_results: list[GateResult]
+    n_gates_total: int
+    n_gates_passed: int
+    n_gates_failed: int
+    release_verdict: str
+    dry_lab_only: bool
+    limitations: list[str]
+    created_at: str
+
+
+def validate_pre_release_audit_gateway(prg: PreReleaseAuditGateway) -> None:
+    if not prg.prg_id.startswith("PRG-"):
+        raise ValueError(f"prg_id must start with 'PRG-': {prg.prg_id!r}")
+    if not prg.batch_id:
+        raise ValueError("batch_id must be non-empty")
+    if not prg.pipeline_version:
+        raise ValueError("pipeline_version must be non-empty")
+    for gr in prg.gate_results:
+        if gr.gate_type not in REQUIRED_GATES:
+            raise ValueError(
+                f"gate_type {gr.gate_type!r} must be one of {REQUIRED_GATES}"
+            )
+        if gr.status not in VALID_GATE_STATUSES:
+            raise ValueError(
+                f"gate status {gr.status!r} not in VALID_GATE_STATUSES"
+            )
+    gate_types = [gr.gate_type for gr in prg.gate_results]
+    for req in REQUIRED_GATES:
+        if gate_types.count(req) != 1:
+            raise ValueError(f"Exactly one gate result required for {req!r}")
+    if prg.release_verdict not in VALID_RELEASE_VERDICTS:
+        raise ValueError(
+            f"release_verdict {prg.release_verdict!r} not in VALID_RELEASE_VERDICTS"
+        )
+    if not prg.dry_lab_only:
+        raise ValueError("dry_lab_only must be True")
+    if not prg.limitations:
+        raise ValueError("limitations must be non-empty")
+    if not prg.created_at:
+        raise ValueError("created_at must be non-empty")
+    if prg.n_gates_total != len(prg.gate_results):
+        raise ValueError("n_gates_total must equal len(gate_results)")
+    n_passed = sum(1 for gr in prg.gate_results if gr.status == "pass")
+    if prg.n_gates_passed != n_passed:
+        raise ValueError("n_gates_passed mismatch")
+    if prg.n_gates_failed != sum(
+        1 for gr in prg.gate_results if gr.status == "fail"
+    ):
+        raise ValueError("n_gates_failed mismatch")
+
+
+def build_pre_release_audit_gateway(
+    *,
+    prg_id: str,
+    batch_id: str,
+    pipeline_version: str,
+    brc_artifact_id: str,
+    brc_verdict: str,
+    pcc_artifact_id: str,
+    pcc_grade: str,
+    eci_artifact_id: str,
+    eci_grade: str,
+    limitations: list[str],
+    created_at: str,
+) -> PreReleaseAuditGateway:
+    """Build a pre-release audit gateway.
+
+    brc_verdict: e.g. "approved", "blocked", "conditional"
+    pcc_grade: "A"/"B"/"C"/"D" — pass if A or B
+    eci_grade: "A"/"B"/"C"/"D" — pass if A or B
+    """
+    brc_pass = brc_verdict == "approved"
+    pcc_pass = pcc_grade in ("A", "B")
+    eci_pass = eci_grade in ("A", "B")
+
+    gate_results = [
+        GateResult(
+            gate_type="BRC",
+            artifact_id=brc_artifact_id,
+            status="pass" if brc_pass else "fail",
+            details=f"BRC verdict={brc_verdict!r} — {'pass' if brc_pass else 'fail'}",
+        ),
+        GateResult(
+            gate_type="PCC",
+            artifact_id=pcc_artifact_id,
+            status="pass" if pcc_pass else "fail",
+            details=f"PCC grade={pcc_grade!r} — {'pass' if pcc_pass else 'fail (need A or B)'}",
+        ),
+        GateResult(
+            gate_type="ECI",
+            artifact_id=eci_artifact_id,
+            status="pass" if eci_pass else "fail",
+            details=f"ECI grade={eci_grade!r} — {'pass' if eci_pass else 'fail (need A or B)'}",
+        ),
+    ]
+    n_total = len(gate_results)
+    n_passed = sum(1 for gr in gate_results if gr.status == "pass")
+    n_failed = sum(1 for gr in gate_results if gr.status == "fail")
+    verdict = "approved" if n_failed == 0 else "blocked"
+
+    prg = PreReleaseAuditGateway(
+        prg_id=prg_id,
+        batch_id=batch_id,
+        pipeline_version=pipeline_version,
+        gate_results=gate_results,
+        n_gates_total=n_total,
+        n_gates_passed=n_passed,
+        n_gates_failed=n_failed,
+        release_verdict=verdict,
+        dry_lab_only=True,
+        limitations=limitations,
+        created_at=created_at,
+    )
+    validate_pre_release_audit_gateway(prg)
+    return prg
+
+
+def format_pre_release_audit_gateway(prg: PreReleaseAuditGateway) -> str:
+    lines = [
+        f"Pre-Release Audit Gateway — {prg.prg_id}",
+        f"Batch: {prg.batch_id}  |  Pipeline: {prg.pipeline_version}",
+        f"Verdict: {prg.release_verdict}  |  Gates: {prg.n_gates_total}",
+        f"Passed: {prg.n_gates_passed}  |  Failed: {prg.n_gates_failed}",
+        "Gate results:",
+    ]
+    for gr in prg.gate_results:
+        status_label = "PASS" if gr.status == "pass" else "FAIL"
+        lines.append(f"  [{status_label}] {gr.gate_type} ({gr.artifact_id}): {gr.details}")
+    lines.append(f"Created: {prg.created_at}")
+    lines.append(f"Limitations: {'; '.join(prg.limitations)}")
+    lines.append(f"dry_lab_only: {prg.dry_lab_only}")
+    return "\n".join(lines)