diff --git a/gravityweave/__init__.py b/gravityweave/__init__.py
index dfbab78..2d7ea82 100644
--- a/gravityweave/__init__.py
+++ b/gravityweave/__init__.py
@@ -16,6 +16,8 @@ from .witness import generate_feasibility_witness
 from .safety_stub import extract_safety_stub
 from .mission import MissionTask, ContactWindow, MissionNode, MissionSimulator
 from .pcp import create_entry, build_chain, inclusion_proof, head_hash, verify_inclusion
+from .mfr_v2 import MutualFeasibilityReceiptV2
+from .ticket import PassWindowTicket
 
 __all__ = [
     "Registry",
@@ -38,6 +40,8 @@ __all__ = [
     "inclusion_proof",
     "head_hash",
     "verify_inclusion",
+    "MutualFeasibilityReceiptV2",
+    "PassWindowTicket",
     "MissionTask",
     "ContactWindow",
     "MissionNode",
diff --git a/gravityweave/mfr_v2.py b/gravityweave/mfr_v2.py
new file mode 100644
index 0000000..d1098fa
--- /dev/null
+++ b/gravityweave/mfr_v2.py
@@ -0,0 +1,119 @@
+"""Mutual Feasibility Receipt v2 (MFR-v2)
+
+Compact, byte-stable receipt suitable for DTN-era custody handoffs. This
+implementation focuses on a small JSON representation with deterministic
+serialization and an HMAC-based signature for tests/POC. Fields are chosen to
+keep serialized size <= 512 bytes in typical use.
+
+Fields (compact):
+- receipt_id: short random id
+- proposal_hash: short hex digest of proposal
+- invariant_id_set: list[int] (small ints)
+- decision: "ok"/"partial"/"deny"
+- uncertainty_pct: coarse uncertainty percent (0..100)
+- pass_ticket_hash: optional hex pointer to pre-signed ticket
+- execution_hash_skim: optional short hex prefix (e.g., blake2b prefix)
+- round_nonce, ts, signer, sig
+"""
+from dataclasses import dataclass
+from typing import List, Optional
+import time
+import uuid
+import json
+import hmac
+import hashlib
+
+
+@dataclass
+class MutualFeasibilityReceiptV2:
+    receipt_id: str
+    proposal_hash: str
+    invariant_id_set: List[int]
+    decision: str
+    uncertainty_pct: int
+    round_nonce: int
+    ts: float
+    pass_ticket_hash: str = ""
+    execution_hash_skim: str = ""
+    signer: str = ""
+    sig: str = ""
+
+    @classmethod
+    def create(cls, proposal_hash: str, invariant_id_set: List[int], decision: str,
+               uncertainty_pct: int = 0, round_nonce: int = 0,
+               pass_ticket_hash: Optional[str] = None,
+               execution_hash_skim: Optional[str] = None,
+               signer: str = "", key: Optional[bytes] = None) -> "MutualFeasibilityReceiptV2":
+        rid = uuid.uuid4().hex[:12]
+        ts = time.time()
+        r = cls(receipt_id=rid, proposal_hash=proposal_hash,
+                invariant_id_set=list(invariant_id_set), decision=decision,
+                uncertainty_pct=int(uncertainty_pct), round_nonce=int(round_nonce), ts=ts,
+                pass_ticket_hash=pass_ticket_hash or "",
+                execution_hash_skim=execution_hash_skim or "",
+                signer=signer, sig="")
+        if key:
+            r.sig = r._sign(key)
+        return r
+
+    def _canonical_payload(self) -> str:
+        # deterministic and compact JSON over authoritative fields (exclude sig)
+        payload = {
+            "receipt_id": self.receipt_id,
+            "proposal_hash": self.proposal_hash,
+            "invariant_id_set": self.invariant_id_set,
+            "decision": self.decision,
+            "uncertainty_pct": int(self.uncertainty_pct),
+            "round_nonce": int(self.round_nonce),
+            "ts": int(self.ts),
+            "pass_ticket_hash": self.pass_ticket_hash,
+            "execution_hash_skim": self.execution_hash_skim,
+            "signer": self.signer,
+        }
+        return json.dumps(payload, sort_keys=True, separators=(",", ":"))
+
+    def _sign(self, key: bytes) -> str:
+        h = hmac.new(key, self._canonical_payload().encode("utf-8"), hashlib.blake2b)
+        # use hex digest truncated to 64 chars to keep sizes small
+        return h.hexdigest()[:64]
+
+    def verify(self, key: bytes) -> bool:
+        if not self.sig:
+            return False
+        expected = self._sign(key)
+        return hmac.compare_digest(expected, self.sig)
+
+    def serialize(self) -> bytes:
+        obj = {
+            "receipt_id": self.receipt_id,
+            "proposal_hash": self.proposal_hash,
+            "invariant_id_set": self.invariant_id_set,
+            "decision": self.decision,
+            "uncertainty_pct": self.uncertainty_pct,
+            "round_nonce": self.round_nonce,
+            "ts": self.ts,
+            "pass_ticket_hash": self.pass_ticket_hash,
+            "execution_hash_skim": self.execution_hash_skim,
+            "signer": self.signer,
+            "sig": self.sig,
+        }
+        return json.dumps(obj, sort_keys=True, separators=(",", ":")).encode("utf-8")
+
+    @classmethod
+    def deserialize(cls, b: bytes) -> "MutualFeasibilityReceiptV2":
+        obj = json.loads(b.decode("utf-8"))
+        return cls(receipt_id=obj.get("receipt_id", ""),
+                   proposal_hash=obj.get("proposal_hash", ""),
+                   invariant_id_set=[int(x) for x in obj.get("invariant_id_set", [])],
+                   decision=obj.get("decision", "deny"),
+                   uncertainty_pct=int(obj.get("uncertainty_pct", 0)),
+                   round_nonce=int(obj.get("round_nonce", 0)),
+                   ts=float(obj.get("ts", 0.0)),
+                   pass_ticket_hash=obj.get("pass_ticket_hash", ""),
+                   execution_hash_skim=obj.get("execution_hash_skim", ""),
+                   signer=obj.get("signer", ""),
+                   sig=obj.get("sig", ""))
+
+    @property
+    def size_bytes(self) -> int:
+        return len(self.serialize())
diff --git a/gravityweave/ticket.py b/gravityweave/ticket.py
new file mode 100644
index 0000000..045d35d
--- /dev/null
+++ b/gravityweave/ticket.py
@@ -0,0 +1,91 @@
+"""Pass-Window Ticket signer/verifier.
+
+Compact ticket structure intended for pre-signed pass-window triggers.
+Uses HMAC (blake2b) signatures for tests/POC. The ticket hash is the sha256
+of the canonical serialized payload (excluding signature), which can be used as
+an external pointer in MFR-v2.pass_ticket_hash.
+"""
+from dataclasses import dataclass
+from typing import Optional
+import json
+import time
+import uuid
+import hashlib
+import hmac
+
+
+@dataclass
+class PassWindowTicket:
+    window_start: int
+    window_end: int
+    comm_budget_bytes: int
+    resource_budget_digest: str
+    trigger_policy_id: str
+    nonce: str
+    signer: str = ""
+    sig: str = ""
+
+    @classmethod
+    def mint(cls, window_start: int, window_end: int, comm_budget_bytes: int,
+             resource_budget_digest: str, trigger_policy_id: str = "default",
+             signer: str = "", key: Optional[bytes] = None) -> "PassWindowTicket":
+        nonce = uuid.uuid4().hex[:12]
+        t = cls(window_start=window_start, window_end=window_end,
+                comm_budget_bytes=int(comm_budget_bytes),
+                resource_budget_digest=resource_budget_digest,
+                trigger_policy_id=trigger_policy_id, nonce=nonce,
+                signer=signer, sig="")
+        if key:
+            t.sig = t._sign(key)
+        return t
+
+    def _canonical(self) -> str:
+        payload = {
+            "window_start": int(self.window_start),
+            "window_end": int(self.window_end),
+            "comm_budget_bytes": int(self.comm_budget_bytes),
+            "resource_budget_digest": self.resource_budget_digest,
+            "trigger_policy_id": self.trigger_policy_id,
+            "nonce": self.nonce,
+            "signer": self.signer,
+        }
+        return json.dumps(payload, sort_keys=True, separators=(",", ":"))
+
+    def _sign(self, key: bytes) -> str:
+        h = hmac.new(key, self._canonical().encode("utf-8"), hashlib.blake2b)
+        return h.hexdigest()[:64]
+
+    def serialize(self) -> bytes:
+        obj = {
+            "window_start": self.window_start,
+            "window_end": self.window_end,
+            "comm_budget_bytes": self.comm_budget_bytes,
+            "resource_budget_digest": self.resource_budget_digest,
+            "trigger_policy_id": self.trigger_policy_id,
+            "nonce": self.nonce,
+            "signer": self.signer,
+            "sig": self.sig,
+        }
+        return json.dumps(obj, sort_keys=True, separators=(",", ":")).encode("utf-8")
+
+    def ticket_hash(self) -> str:
+        # external pointer: sha256 of canonical payload (no sig)
+        return hashlib.sha256(self._canonical().encode("utf-8")).hexdigest()
+
+    def verify(self, key: bytes) -> bool:
+        if not self.sig:
+            return False
+        expected = self._sign(key)
+        return hmac.compare_digest(expected, self.sig)
+
+    @classmethod
+    def deserialize(cls, b: bytes) -> "PassWindowTicket":
+        obj = json.loads(b.decode("utf-8"))
+        return cls(window_start=int(obj.get("window_start", 0)),
+                   window_end=int(obj.get("window_end", 0)),
+                   comm_budget_bytes=int(obj.get("comm_budget_bytes", 0)),
+                   resource_budget_digest=obj.get("resource_budget_digest", ""),
+                   trigger_policy_id=obj.get("trigger_policy_id", ""),
+                   nonce=obj.get("nonce", ""),
+                   signer=obj.get("signer", ""),
+                   sig=obj.get("sig", ""))
diff --git a/tests/test_mfr_v2.py b/tests/test_mfr_v2.py
new file mode 100644
index 0000000..4425fdc
--- /dev/null
+++ b/tests/test_mfr_v2.py
@@ -0,0 +1,29 @@
+import os
+from gravityweave.mfr_v2 import MutualFeasibilityReceiptV2
+
+
+def test_mfr_v2_sign_and_size():
+    key = b"test-key-12345"
+    proposal_hash = "abcd1234"
+    invariants = [1, 2, 7]
+    m = MutualFeasibilityReceiptV2.create(
+        proposal_hash=proposal_hash,
+        invariant_id_set=invariants,
+        decision="ok",
+        uncertainty_pct=5,
+        round_nonce=42,
+        pass_ticket_hash="",
+        execution_hash_skim="deadbeef",
+        signer="node-A",
+        key=key,
+    )
+
+    assert m.verify(key)
+    s = m.serialize()
+    # ensure size is small (<= 512 bytes as requested by spec)
+    assert len(s) <= 512
+
+    # roundtrip
+    m2 = MutualFeasibilityReceiptV2.deserialize(s)
+    assert m2.proposal_hash == proposal_hash
+    assert m2.invariant_id_set == invariants
diff --git a/tests/test_ticket.py b/tests/test_ticket.py
new file mode 100644
index 0000000..595ce1f
--- /dev/null
+++ b/tests/test_ticket.py
@@ -0,0 +1,28 @@
+from gravityweave.ticket import PassWindowTicket
+
+
+def test_ticket_mint_and_verify():
+    key = b"ticket-key-xyz"
+    start = 1700000000
+    end = start + 60
+    t = PassWindowTicket.mint(
+        window_start=start,
+        window_end=end,
+        comm_budget_bytes=2048,
+        resource_budget_digest="rbdig-0123",
+        trigger_policy_id="policy-1",
+        signer="authority-1",
+        key=key,
+    )
+
+    assert t.verify(key)
+    serialized = t.serialize()
+    assert len(serialized) < 1024
+    # ticket hash is stable and hex
+    th = t.ticket_hash()
+    assert isinstance(th, str) and len(th) == 64
+
+    # roundtrip
+    t2 = PassWindowTicket.deserialize(serialized)
+    assert t2.window_start == start
+    assert t2.window_end == end