diff --git a/contract-bridge/README.contract.md b/contract-bridge/README.contract.md
new file mode 100644
index 0000000..ab48b95
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+++ b/contract-bridge/README.contract.md
@@ -0,0 +1,36 @@
+# Biscuit × semantic_byte ZK security (contract-native)
+
+[Eclipse Biscuit](https://github.com/eclipse-biscuit/biscuit) provides **attenuated
+authorization** (Datalog policies on signed tokens). `/contract` provides:
+
+| Layer | Module | Role |
+|-------|--------|------|
+| State | `semantic_byte.zig` | 8-bit emergence per cell; seal bit (b5) |
+| Hiding | `commit.zig` | commit-reveal over byte streams (honest wall: NOT SNARK) |
+| RBAC | `capability.zig` | signed capability ladder + zk-sealed params |
+| Identity | `zkproof.zig` | Schnorr PoK of discrete log |
+| Deploy | `scripts/deploy.sh` | sign-before-swap wallet gate |
+
+**Security composition:** semantic bytes define *what* is sealed; commitments hide the
+stream until open; Biscuit policies define *who* may deploy/attenuate; `contract-deploy`
+enforces the live binary swap under witness.
+
+## Gates
+
+```bash
+bash scripts/gate.sh
+bash ../../../witness/biscuit_semantic_byte_gate.sh
+```
+
+## Build deploy policy artifact
+
+```bash
+python3 scripts/build_deploy_policy.py --cells 1,42,6,7
+bash ../../../scripts/deploy-biscuit-policy.sh --policy references/upstream/biscuit/out/contract_deploy_policy.json
+```
+
+## Wallet deploy witness
+
+```bash
+bash ../../../scripts/deploy.sh --witness 'bash witness/biscuit_semantic_byte_gate.sh'
+```
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diff --git a/contract-bridge/scripts/build_deploy_policy.py b/contract-bridge/scripts/build_deploy_policy.py
new file mode 100755
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+++ b/contract-bridge/scripts/build_deploy_policy.py
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+#!/usr/bin/env python3
+"""Build contract-deploy authorization policy artifact."""
+from __future__ import annotations
+
+import argparse
+import os
+import sys
+
+ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+sys.path.insert(0, ROOT)
+
+from semantic_byte_biscuit import policy_bundle, write_policy_artifact  # noqa: E402
+
+
+def main() -> int:
+    ap = argparse.ArgumentParser()
+    ap.add_argument("--cells", default="1,42,6,7", help="comma-separated semantic byte values")
+    ap.add_argument("--out-dir", default=os.path.join(ROOT, "out"))
+    ap.add_argument("--name", default="contract_deploy_policy")
+    args = ap.parse_args()
+
+    cells = [int(x.strip()) for x in args.cells.split(",") if x.strip()]
+    bundle = policy_bundle(cells, scope="contract-deploy")
+    os.makedirs(args.out_dir, exist_ok=True)
+    path = os.path.join(args.out_dir, f"{args.name}.json")
+    write_policy_artifact(path, bundle)
+    print(path)
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
\ No newline at end of file
diff --git a/contract-bridge/scripts/gate.sh b/contract-bridge/scripts/gate.sh
new file mode 100755
index 0000000..0018154
--- /dev/null
+++ b/contract-bridge/scripts/gate.sh
@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+# Runnable gate: biscuit semantic-byte ZK bridge (Python + native zig ground truth).
+set -euo pipefail
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+cd "$ROOT"
+PY="${PYTHON:-python3}"
+CONTRACT_ROOT="$(cd "$ROOT/../../.." && pwd)"
+
+"$PY" -m unittest test_portability -v
+PYTHONPATH="$ROOT" "$PY" scripts/list_security_primitives.py | grep -q semantic_commitment
+
+echo "== libcontract semantic_byte.zig =="
+(cd "$CONTRACT_ROOT/libcontract" && zig test src/semantic_byte.zig --test-filter 'SemanticByte' >/dev/null)
+
+echo "== libcontract commit.zig (zk commitment) =="
+(cd "$CONTRACT_ROOT/libcontract" && zig test src/commit.zig >/dev/null)
+
+echo "== libcontract capability.zig (RBAC ladder) =="
+(cd "$CONTRACT_ROOT/libcontract" && zig test src/capability.zig >/dev/null)
+
+if "$PY" -c "import biscuit_auth" 2>/dev/null; then
+  echo "== optional: biscuit-auth python present =="
+  "$PY" -c "import biscuit_auth; print('biscuit_auth', biscuit_auth.__name__)"
+else
+  echo "skip: biscuit-auth wheel (policy DSL + zig gates are sufficient)"
+fi
+
+echo "GATE GREEN: biscuit semantic-byte zk security"
\ No newline at end of file
diff --git a/contract-bridge/scripts/list_security_primitives.py b/contract-bridge/scripts/list_security_primitives.py
new file mode 100755
index 0000000..88b1ae8
--- /dev/null
+++ b/contract-bridge/scripts/list_security_primitives.py
@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+"""Map Biscuit + /contract ZK security primitives."""
+from __future__ import annotations
+
+PRIMITIVES = [
+    ("semantic_byte", "8-bit emergence state — libcontract/src/semantic_byte.zig"),
+    ("semantic_commitment", "commit-reveal over byte stream — libcontract/src/commit.zig"),
+    ("capability", "signed RBAC ladder + zk-sealed params — capability.zig"),
+    ("biscuit_policy", "Datalog attenuation over committed facts — eclipse-biscuit/biscuit"),
+    ("zkproof", "Schnorr PoK discrete log — libcontract/src/zkproof.zig (identity)"),
+    ("contract-deploy", "sign-before-swap deploy gate — scripts/deploy.sh"),
+]
+
+def main() -> None:
+    print("Biscuit × semantic_byte ZK security (contract-native)")
+    for name, desc in PRIMITIVES:
+        print(f"{name}\t{desc}")
+
+
+if __name__ == "__main__":
+    main()
\ No newline at end of file
diff --git a/contract-bridge/semantic_byte_biscuit.py b/contract-bridge/semantic_byte_biscuit.py
new file mode 100644
index 0000000..baa1e58
--- /dev/null
+++ b/contract-bridge/semantic_byte_biscuit.py
@@ -0,0 +1,148 @@
+"""Biscuit × contract semantic_byte ZK security bridge.
+
+Layers (native to /contract):
+  1. semantic_byte.zig — 8-bit emergence state per cell (seal bit b5)
+  2. commit.zig — hiding+binding commitment over byte streams (NOT SNARK; honest wall)
+  3. capability.zig — signed RBAC ladder with zk-sealed params
+  4. biscuit Datalog — attenuated authorization policies over committed facts
+
+Biscuit proves *who may act*; semantic bytes prove *what state is sealed*;
+commit proves *the stream is fixed* without revealing it until open.
+"""
+from __future__ import annotations
+
+import hashlib
+import json
+import os
+import secrets
+from dataclasses import dataclass
+
+HEBREW = "אבגדהוזחטיכלמנסעפצקרשת"
+COMMIT_DOMAIN = b"aiko-commit-v1"
+BLIND_LEN = 32
+
+
+@dataclass(frozen=True)
+class SemanticByte:
+    value: int
+
+    def __post_init__(self) -> None:
+        if not 0 <= self.value <= 255:
+            raise ValueError(f"out of range: {self.value}")
+
+    @property
+    def seal_bit(self) -> bool:
+        return bool(self.value & 32)
+
+    def hebrew(self) -> str:
+        return HEBREW[self.value % 22]
+
+    def biscuit_fact(self, index: int) -> str:
+        return f"semantic_byte({index}, {self.value});"
+
+    def biscuit_seal_fact(self, index: int) -> str:
+        return f"semantic_seal({index});" if self.seal_bit else ""
+
+
+def witness_pair(a: int, b: int) -> int:
+    return 2 if a == 1 and b == 1 else (a * b) & 0xFF
+
+
+def operator_collapse_at_42(a: int, b: int) -> int:
+    if (a, b) in ((6, 7), (7, 6)):
+        return 42
+    mul = (a * b) & 0xFF
+    add = (a + b) & 0xFF
+    xor = a ^ b
+    if mul in (add, xor) or add == xor:
+        return 42
+    return mul
+
+
+def commit(value: bytes, blinding: bytes) -> bytes:
+    if len(blinding) != BLIND_LEN:
+        raise ValueError("blinding must be 32 bytes")
+    h = hashlib.sha256()
+    h.update(COMMIT_DOMAIN)
+    h.update(blinding)
+    h.update(value)
+    return h.digest()
+
+
+def verify_commitment(commitment: bytes, value: bytes, blinding: bytes) -> bool:
+    return commit(value, blinding) == commitment
+
+
+def commit_semantic_stream(cells: list[int]) -> dict:
+    """ZK-seal a semantic-byte stream (commit-reveal; mirrors commit.zig)."""
+    payload = bytes(c & 0xFF for c in cells)
+    blinding = secrets.token_bytes(BLIND_LEN)
+    c = commit(payload, blinding)
+    return {
+        "commitment": c.hex(),
+        "blinding": blinding.hex(),
+        "length": len(cells),
+        "domain": COMMIT_DOMAIN.decode(),
+    }
+
+
+def semantic_facts(cells: list[int]) -> list[str]:
+    facts: list[str] = []
+    for i, v in enumerate(cells):
+        sb = SemanticByte(v)
+        facts.append(sb.biscuit_fact(i))
+        sf = sb.biscuit_seal_fact(i)
+        if sf:
+            facts.append(sf)
+    return facts
+
+
+def deploy_authorization_policy(
+    *,
+    commitment_hex: str,
+    max_byte: int = 42,
+    scope: str = "contract-deploy",
+    role: str = "operator",
+) -> str:
+    """Datalog-shaped policy for /contract-deploy attenuation."""
+    lines = [
+        f'right("{scope}", "{role}");',
+        f'semantic_commitment("{commitment_hex}");',
+        "check if semantic_byte($i, $b), $b <= " + str(max_byte) + ";",
+        "check if semantic_seal($i);",
+        f'allow if right("{scope}", "{role}"), semantic_commitment("{commitment_hex}");',
+    ]
+    return "\n".join(lines)
+
+
+def attenuation_block(parent_max: int, child_max: int) -> str:
+    """Biscuit attenuation: child token cannot exceed parent byte ceiling."""
+    if child_max > parent_max:
+        raise ValueError("attenuation violation: child exceeds parent")
+    return "\n".join(
+        [
+            f"check if semantic_byte($i, $b), $b <= {child_max};",
+            f"// attenuated from parent max {parent_max}",
+        ]
+    )
+
+
+def policy_bundle(cells: list[int], scope: str = "contract-deploy") -> dict:
+    sealed = commit_semantic_stream(cells)
+    policy = deploy_authorization_policy(
+        commitment_hex=sealed["commitment"],
+        max_byte=max(cells) if cells else 255,
+        scope=scope,
+    )
+    return {
+        "sealed": sealed,
+        "facts": semantic_facts(cells),
+        "policy": policy,
+        "attenuation": attenuation_block(max(cells) if cells else 255, 42),
+    }
+
+
+def write_policy_artifact(path: str, bundle: dict) -> None:
+    os.makedirs(os.path.dirname(path) or ".", exist_ok=True)
+    with open(path, "w", encoding="utf-8") as f:
+        json.dump(bundle, f, indent=2)
\ No newline at end of file
diff --git a/contract-bridge/test_portability.py b/contract-bridge/test_portability.py
new file mode 100644
index 0000000..0c700e9
--- /dev/null
+++ b/contract-bridge/test_portability.py
@@ -0,0 +1,75 @@
+"""Portability tests — biscuit semantic-byte ZK bridge (no biscuit-auth wheel required)."""
+import json
+import os
+import tempfile
+import unittest
+
+from semantic_byte_biscuit import (
+    BLIND_LEN,
+    SemanticByte,
+    attenuation_block,
+    commit,
+    commit_semantic_stream,
+    deploy_authorization_policy,
+    operator_collapse_at_42,
+    policy_bundle,
+    semantic_facts,
+    verify_commitment,
+    witness_pair,
+    write_policy_artifact,
+)
+
+
+class TestSemanticByteBiscuit(unittest.TestCase):
+    def test_seal_bit_on_42(self):
+        sb = SemanticByte(42)
+        self.assertTrue(sb.seal_bit)
+        self.assertEqual(sb.hebrew(), "ש")
+
+    def test_witness_and_collapse(self):
+        self.assertEqual(witness_pair(1, 1), 2)
+        self.assertEqual(operator_collapse_at_42(6, 7), 42)
+
+    def test_commit_round_trip(self):
+        val = b"semantic-byte-stream"
+        blind = bytes(range(BLIND_LEN))
+        c = commit(val, blind)
+        self.assertTrue(verify_commitment(c, val, blind))
+        self.assertFalse(verify_commitment(c, b"tampered", blind))
+
+    def test_stream_commitment(self):
+        cells = [1, 2, 42, 255]
+        sealed = commit_semantic_stream(cells)
+        self.assertEqual(sealed["length"], 4)
+        payload = bytes(cells)
+        blind = bytes.fromhex(sealed["blinding"])
+        c = bytes.fromhex(sealed["commitment"])
+        self.assertTrue(verify_commitment(c, payload, blind))
+
+    def test_facts_include_seal(self):
+        facts = semantic_facts([42, 10])
+        self.assertTrue(any("semantic_byte(0, 42)" in f for f in facts))
+        self.assertTrue(any("semantic_seal(0)" in f for f in facts))
+
+    def test_deploy_policy_mentions_commitment(self):
+        sealed = commit_semantic_stream([6, 7, 42])
+        pol = deploy_authorization_policy(commitment_hex=sealed["commitment"])
+        self.assertIn("semantic_commitment", pol)
+        self.assertIn("contract-deploy", pol)
+
+    def test_attenuation_rejects_escalation(self):
+        with self.assertRaises(ValueError):
+            attenuation_block(42, 100)
+
+    def test_policy_bundle_writes(self):
+        bundle = policy_bundle([1, 42, 6, 7])
+        with tempfile.TemporaryDirectory() as td:
+            path = os.path.join(td, "deploy-policy.json")
+            write_policy_artifact(path, bundle)
+            loaded = json.load(open(path, encoding="utf-8"))
+            self.assertIn("policy", loaded)
+            self.assertIn("sealed", loaded)
+
+
+if __name__ == "__main__":
+    unittest.main()
\ No newline at end of file