diff --git a/decnet/web/db/models/__init__.py b/decnet/web/db/models/__init__.py
index d98d93e5..596ce8d9 100644
--- a/decnet/web/db/models/__init__.py
+++ b/decnet/web/db/models/__init__.py
@@ -39,6 +39,10 @@ from .attackers import (
 from .attacker_intel import (
     AttackerIntel,
 )
+from .campaigns import (
+    Campaign,
+    CampaignsResponse,
+)
 from .deploy import (
     DeployIniRequest,
     DeployResponse,
diff --git a/decnet/web/db/models/attackers.py b/decnet/web/db/models/attackers.py
index dc66efac..38f6124a 100644
--- a/decnet/web/db/models/attackers.py
+++ b/decnet/web/db/models/attackers.py
@@ -122,9 +122,12 @@ class AttackerIdentity(SQLModel, table=True):
     __tablename__ = "attacker_identities"
     uuid: str = Field(primary_key=True)
     schema_version: int = Field(default=1)
-    # Set by the campaign clusterer, downstream effort. The campaigns
-    # table doesn't exist yet — no FK constraint, just a soft pointer.
-    campaign_id: Optional[str] = Field(default=None, index=True)
+    # Set by the campaign clusterer. The ``campaigns`` table now
+    # exists; this is a real FK. Nullable until the campaign clusterer
+    # has run on this identity row.
+    campaign_id: Optional[str] = Field(
+        default=None, foreign_key="campaigns.uuid", index=True
+    )
     first_seen_at: Optional[datetime] = Field(default=None, index=True)
     last_seen_at: Optional[datetime] = Field(default=None, index=True)
     created_at: datetime = Field(
diff --git a/decnet/web/db/models/campaigns.py b/decnet/web/db/models/campaigns.py
new file mode 100644
index 00000000..478588e1
--- /dev/null
+++ b/decnet/web/db/models/campaigns.py
@@ -0,0 +1,80 @@
+"""Campaign — operation-level grouping of resolved attacker identities."""
+from datetime import datetime, timezone
+from typing import Any, List, Optional
+
+from pydantic import BaseModel
+from sqlalchemy import Column, Text
+from sqlmodel import Field, SQLModel
+
+
+class Campaign(SQLModel, table=True):
+    """
+    Campaign — one operation, one or more identities.
+
+    Sits one level above ``AttackerIdentity``: an actor (identity) may
+    appear in multiple campaigns over time, and a campaign may have
+    several distinct identities cooperating (e.g. a night-shift and
+    day-shift operator on the same job — fixture F5 multi_operator).
+
+    Populated by the campaign clusterer worker (downstream of identity
+    resolution). Empty rows are valid; the table ships empty until the
+    clusterer lands. ``schema_version`` is non-negotiable from day one
+    for the same federation-gossip reason ``AttackerIdentity`` carries
+    one — bumping campaign-level feature definitions without a version
+    field silently poisons cross-operator gossip in V2.
+
+    See ``development/CAMPAIGN_CLUSTERING.md`` for the signal taxonomy
+    (phase-handoff, shared-infra, temporal overlap, cohort).
+    """
+    __tablename__ = "campaigns"
+    uuid: str = Field(primary_key=True)
+    schema_version: int = Field(default=1)
+    first_seen_at: Optional[datetime] = Field(default=None, index=True)
+    last_seen_at: Optional[datetime] = Field(default=None, index=True)
+    created_at: datetime = Field(
+        default_factory=lambda: datetime.now(timezone.utc), index=True
+    )
+    updated_at: datetime = Field(
+        default_factory=lambda: datetime.now(timezone.utc), index=True
+    )
+    # Campaign-cohesion score from the clusterer. Range [0, 1]; null
+    # until the clusterer writes. Higher = more confident the linked
+    # identities are part of the same operation.
+    confidence: Optional[float] = Field(default=None)
+    # Denormalized count of FK'd ``AttackerIdentity`` rows.
+    identity_count: int = Field(default=0)
+    # Aggregated fingerprint summary across member identities. Same
+    # JSON-serialized list[str] in TEXT shape as
+    # ``AttackerIdentity.{ja3,hassh,payload_simhashes,c2_endpoints}`` —
+    # federation gossip wants the same wire shape at every layer.
+    ja3_hashes: Optional[str] = Field(
+        default=None, sa_column=Column("ja3_hashes", Text, nullable=True)
+    )
+    hassh_hashes: Optional[str] = Field(
+        default=None, sa_column=Column("hassh_hashes", Text, nullable=True)
+    )
+    payload_simhashes: Optional[str] = Field(
+        default=None, sa_column=Column("payload_simhashes", Text, nullable=True)
+    )
+    c2_endpoints: Optional[str] = Field(
+        default=None, sa_column=Column("c2_endpoints", Text, nullable=True)
+    )
+    # Soft-merge audit trail — same revocable-merge pattern as
+    # ``AttackerIdentity.merged_into_uuid``. When the clusterer
+    # collapses two campaigns, the loser's row stays in place with this
+    # set to the winner's UUID; resolvers follow the chain.
+    merged_into_uuid: Optional[str] = Field(
+        default=None, foreign_key="campaigns.uuid", index=True
+    )
+    # Operator-editable free-form notes — annotation surface for
+    # human analysts ("APT-XX Q2 campaign", "matches CTI report 5678").
+    notes: Optional[str] = Field(
+        default=None, sa_column=Column("notes", Text, nullable=True)
+    )
+
+
+class CampaignsResponse(BaseModel):
+    total: int
+    limit: int
+    offset: int
+    data: List[dict[str, Any]]
diff --git a/decnet/web/db/repository.py b/decnet/web/db/repository.py
index 79759c5d..a316f7f9 100644
--- a/decnet/web/db/repository.py
+++ b/decnet/web/db/repository.py
@@ -474,6 +474,113 @@ class BaseRepository(ABC):
         """
         pass
 
+    # ─── Campaign clustering reads ────────────────────────────────────────
+    # Layer above identity resolution: campaigns group identities into
+    # operations. Populated by ``decnet campaign-clusterer``. The
+    # read-only API below ships in the same wave; until the clusterer
+    # runs, every method returns empty/None against an empty table.
+    # See development/CAMPAIGN_CLUSTERING.md.
+
+    @abstractmethod
+    async def get_campaign_by_uuid(self, uuid: str) -> Optional[dict[str, Any]]:
+        """
+        Return one ``Campaign`` row by UUID, or ``None`` if absent.
+
+        If the row has ``merged_into_uuid`` set (i.e. the clusterer
+        soft-merged it into another campaign), implementations MUST
+        follow the chain and return the winner — same contract as
+        :meth:`get_identity_by_uuid`.
+        """
+        pass
+
+    @abstractmethod
+    async def list_campaigns(
+        self, limit: int = 50, offset: int = 0,
+    ) -> list[dict[str, Any]]:
+        """Paginated list of campaign rows, newest-updated first.
+
+        Excludes merged-out rows so the list view is the de-duped truth
+        (mirrors :meth:`list_identities`).
+        """
+        pass
+
+    @abstractmethod
+    async def count_campaigns(self) -> int:
+        """Total campaign rows. Excludes merged-out rows."""
+        pass
+
+    @abstractmethod
+    async def list_identities_for_campaign(
+        self, campaign_uuid: str, limit: int = 50, offset: int = 0,
+    ) -> list[dict[str, Any]]:
+        """``AttackerIdentity`` rows linked to the given campaign, newest first."""
+        pass
+
+    @abstractmethod
+    async def count_identities_for_campaign(self, campaign_uuid: str) -> int:
+        """Total ``AttackerIdentity`` rows FK'd to this campaign."""
+        pass
+
+    # ─── Campaign clustering writes (campaign-clusterer worker) ───────────
+
+    @abstractmethod
+    async def list_identities_for_clustering(
+        self, limit: Optional[int] = None,
+    ) -> list[dict[str, Any]]:
+        """Project every ``AttackerIdentity`` into the campaign
+        clusterer's input shape.
+
+        Returns dicts with at least ``uuid``, ``campaign_id``,
+        aggregated fingerprint summaries (``ja3_hashes``,
+        ``hassh_hashes``, ``payload_simhashes``, ``c2_endpoints``),
+        ``first_seen_at`` / ``last_seen_at``, ``merged_into_uuid``.
+        Empty list when no identities exist. ``limit`` bounds a
+        single tick's working set; leave ``None`` to fetch all.
+        """
+        pass
+
+    @abstractmethod
+    async def create_campaign(self, row: dict[str, Any]) -> str:
+        """Insert a new ``Campaign`` row and return its uuid.
+
+        ``row`` must include ``uuid``; other fields are optional and
+        default per the model. Caller generates the uuid so it can be
+        used in the same tick to back-link identities.
+        """
+        pass
+
+    @abstractmethod
+    async def set_identity_campaign_id(
+        self, identity_uuid: str, campaign_uuid: Optional[str],
+    ) -> None:
+        """Set or clear ``attacker_identities.campaign_id``.
+
+        Idempotent. Pass ``None`` to unlink (e.g. when revoking a
+        prior campaign assignment).
+        """
+        pass
+
+    @abstractmethod
+    async def list_all_campaigns(self) -> list[dict[str, Any]]:
+        """Every ``Campaign`` row, including merged-out ones.
+
+        Distinct from :meth:`list_campaigns`: the clusterer's
+        revocable-merge pass needs to re-evaluate merged-out
+        campaigns, so it pulls the unfiltered set.
+        """
+        pass
+
+    @abstractmethod
+    async def update_campaign_merged_into(
+        self, campaign_uuid: str, winner_uuid: Optional[str],
+    ) -> None:
+        """Set or clear ``campaigns.merged_into_uuid``.
+
+        Pass ``winner_uuid`` to soft-merge the row into another
+        campaign; pass ``None`` to revoke a prior merge.
+        """
+        pass
+
     @abstractmethod
     async def get_attacker_commands(
         self,
diff --git a/decnet/web/db/sqlmodel_repo.py b/decnet/web/db/sqlmodel_repo.py
index 0bc394be..817b51f1 100644
--- a/decnet/web/db/sqlmodel_repo.py
+++ b/decnet/web/db/sqlmodel_repo.py
@@ -38,6 +38,7 @@ from decnet.web.db.models import (
     AttackerBehavior,
     AttackerIdentity,
     AttackerIntel,
+    Campaign,
     SessionProfile,
     SmtpTarget,
     SwarmHost,
@@ -1535,6 +1536,164 @@ class SQLModelRepository(BaseRepository):
             await session.execute(statement)
             await session.commit()
 
+    # ─── Campaign clustering reads ────────────────────────────────────────
+
+    async def get_campaign_by_uuid(self, uuid: str) -> Optional[dict[str, Any]]:
+        # Same chain-walk as get_identity_by_uuid; bounded against
+        # corrupted rings.
+        _MAX_MERGE_HOPS = 8
+        async with self._session() as session:
+            current_uuid = uuid
+            for _ in range(_MAX_MERGE_HOPS):
+                result = await session.execute(
+                    select(Campaign).where(Campaign.uuid == current_uuid)
+                )
+                campaign = result.scalar_one_or_none()
+                if campaign is None:
+                    return None
+                if campaign.merged_into_uuid is None:
+                    return campaign.model_dump(mode="json")
+                current_uuid = campaign.merged_into_uuid
+            return campaign.model_dump(mode="json")
+
+    async def list_campaigns(
+        self, limit: int = 50, offset: int = 0,
+    ) -> list[dict[str, Any]]:
+        statement = (
+            select(Campaign)
+            .where(Campaign.merged_into_uuid.is_(None))
+            .order_by(desc(Campaign.updated_at))
+            .offset(offset)
+            .limit(limit)
+        )
+        async with self._session() as session:
+            result = await session.execute(statement)
+            return [c.model_dump(mode="json") for c in result.scalars().all()]
+
+    async def count_campaigns(self) -> int:
+        statement = (
+            select(func.count())
+            .select_from(Campaign)
+            .where(Campaign.merged_into_uuid.is_(None))
+        )
+        async with self._session() as session:
+            result = await session.execute(statement)
+            return result.scalar() or 0
+
+    async def list_identities_for_campaign(
+        self, campaign_uuid: str, limit: int = 50, offset: int = 0,
+    ) -> list[dict[str, Any]]:
+        statement = (
+            select(AttackerIdentity)
+            .where(AttackerIdentity.campaign_id == campaign_uuid)
+            .order_by(desc(AttackerIdentity.updated_at))
+            .offset(offset)
+            .limit(limit)
+        )
+        async with self._session() as session:
+            result = await session.execute(statement)
+            return [i.model_dump(mode="json") for i in result.scalars().all()]
+
+    async def count_identities_for_campaign(self, campaign_uuid: str) -> int:
+        statement = (
+            select(func.count())
+            .select_from(AttackerIdentity)
+            .where(AttackerIdentity.campaign_id == campaign_uuid)
+        )
+        async with self._session() as session:
+            result = await session.execute(statement)
+            return result.scalar() or 0
+
+    # ─── Campaign clustering writes (campaign-clusterer worker) ───────────
+
+    async def list_identities_for_clustering(
+        self, limit: Optional[int] = None,
+    ) -> list[dict[str, Any]]:
+        # Project the columns the campaign clusterer's similarity
+        # graph reads. Narrow on purpose — future denormalised
+        # projections (commands_by_phase from log mining, decky-set
+        # aggregates) can land here without churning callers.
+        statement = select(
+            AttackerIdentity.uuid,
+            AttackerIdentity.campaign_id,
+            AttackerIdentity.merged_into_uuid,
+            AttackerIdentity.first_seen_at,
+            AttackerIdentity.last_seen_at,
+            AttackerIdentity.ja3_hashes,
+            AttackerIdentity.hassh_hashes,
+            AttackerIdentity.payload_simhashes,
+            AttackerIdentity.c2_endpoints,
+        ).order_by(AttackerIdentity.created_at)
+        if limit is not None:
+            statement = statement.limit(limit)
+        async with self._session() as session:
+            result = await session.execute(statement)
+            return [
+                {
+                    "uuid": row.uuid,
+                    "campaign_id": row.campaign_id,
+                    "merged_into_uuid": row.merged_into_uuid,
+                    "first_seen_at": (
+                        row.first_seen_at.isoformat()
+                        if row.first_seen_at is not None
+                        else None
+                    ),
+                    "last_seen_at": (
+                        row.last_seen_at.isoformat()
+                        if row.last_seen_at is not None
+                        else None
+                    ),
+                    "ja3_hashes": row.ja3_hashes,
+                    "hassh_hashes": row.hassh_hashes,
+                    "payload_simhashes": row.payload_simhashes,
+                    "c2_endpoints": row.c2_endpoints,
+                }
+                for row in result.all()
+            ]
+
+    async def create_campaign(self, row: dict[str, Any]) -> str:
+        campaign = Campaign(**row)
+        async with self._session() as session:
+            session.add(campaign)
+            await session.commit()
+        return campaign.uuid
+
+    async def set_identity_campaign_id(
+        self, identity_uuid: str, campaign_uuid: Optional[str],
+    ) -> None:
+        statement = (
+            update(AttackerIdentity)
+            .where(AttackerIdentity.uuid == identity_uuid)
+            .values(
+                campaign_id=campaign_uuid,
+                updated_at=datetime.now(timezone.utc),
+            )
+        )
+        async with self._session() as session:
+            await session.execute(statement)
+            await session.commit()
+
+    async def list_all_campaigns(self) -> list[dict[str, Any]]:
+        statement = select(Campaign).order_by(Campaign.created_at)
+        async with self._session() as session:
+            result = await session.execute(statement)
+            return [c.model_dump(mode="json") for c in result.scalars().all()]
+
+    async def update_campaign_merged_into(
+        self, campaign_uuid: str, winner_uuid: Optional[str],
+    ) -> None:
+        statement = (
+            update(Campaign)
+            .where(Campaign.uuid == campaign_uuid)
+            .values(
+                merged_into_uuid=winner_uuid,
+                updated_at=datetime.now(timezone.utc),
+            )
+        )
+        async with self._session() as session:
+            await session.execute(statement)
+            await session.commit()
+
     async def get_attacker_commands(
         self,
         uuid: str,
diff --git a/tests/db/test_base_repo.py b/tests/db/test_base_repo.py
index 0d635d6e..271e6fc0 100644
--- a/tests/db/test_base_repo.py
+++ b/tests/db/test_base_repo.py
@@ -71,6 +71,17 @@ class DummyRepo(BaseRepository):
     async def set_attacker_identity_id(self, a, i): await super().set_attacker_identity_id(a, i)
     async def list_all_identities(self): await super().list_all_identities(); return []
     async def update_identity_merged_into(self, u, w): await super().update_identity_merged_into(u, w)
+    # Campaign clustering (this PR)
+    async def get_campaign_by_uuid(self, u): await super().get_campaign_by_uuid(u)
+    async def list_campaigns(self, limit=50, offset=0): await super().list_campaigns(limit, offset); return []
+    async def count_campaigns(self): await super().count_campaigns(); return 0
+    async def list_identities_for_campaign(self, u, limit=50, offset=0): await super().list_identities_for_campaign(u, limit, offset); return []
+    async def count_identities_for_campaign(self, u): await super().count_identities_for_campaign(u); return 0
+    async def list_identities_for_clustering(self, limit=None): await super().list_identities_for_clustering(limit); return []
+    async def create_campaign(self, row): await super().create_campaign(row); return ""
+    async def set_identity_campaign_id(self, i, c): await super().set_identity_campaign_id(i, c)
+    async def list_all_campaigns(self): await super().list_all_campaigns(); return []
+    async def update_campaign_merged_into(self, u, w): await super().update_campaign_merged_into(u, w)
 
 @pytest.mark.asyncio
 async def test_base_repo_coverage():
@@ -144,6 +155,18 @@ async def test_base_repo_coverage():
     await dr.list_all_identities()
     await dr.update_identity_merged_into("a", "b")
     await dr.update_identity_merged_into("a", None)
+    await dr.get_campaign_by_uuid("a")
+    await dr.list_campaigns()
+    await dr.count_campaigns()
+    await dr.list_identities_for_campaign("a")
+    await dr.count_identities_for_campaign("a")
+    await dr.list_identities_for_clustering()
+    await dr.create_campaign({"uuid": "c"})
+    await dr.set_identity_campaign_id("i", "c")
+    await dr.set_identity_campaign_id("i", None)
+    await dr.list_all_campaigns()
+    await dr.update_campaign_merged_into("c", "d")
+    await dr.update_campaign_merged_into("c", None)
 
     # Swarm methods: default NotImplementedError on BaseRepository.  Covering
     # them here keeps the coverage contract honest for the swarm CRUD surface.
diff --git a/tests/db/test_campaign_repo.py b/tests/db/test_campaign_repo.py
new file mode 100644
index 00000000..1e98a92d
--- /dev/null
+++ b/tests/db/test_campaign_repo.py
@@ -0,0 +1,145 @@
+"""Tests for the Campaign clustering repo methods on SQLModelRepository."""
+from __future__ import annotations
+
+from datetime import datetime, timezone
+
+import pytest
+
+from decnet.web.db.factory import get_repository
+
+
+@pytest.fixture
+async def repo(tmp_path):
+    r = get_repository(db_path=str(tmp_path / "campaigns.db"))
+    await r.initialize()
+    return r
+
+
+async def _create_identity(repo, uuid: str, **kwargs) -> str:
+    now = datetime.now(timezone.utc)
+    return await repo.create_attacker_identity({
+        "uuid": uuid,
+        "first_seen_at": kwargs.get("first_seen_at", now),
+        "last_seen_at": kwargs.get("last_seen_at", now),
+        "ja3_hashes": kwargs.get("ja3_hashes"),
+        "hassh_hashes": kwargs.get("hassh_hashes"),
+        "payload_simhashes": kwargs.get("payload_simhashes"),
+        "c2_endpoints": kwargs.get("c2_endpoints"),
+    })
+
+
+@pytest.mark.asyncio
+async def test_create_and_get_campaign(repo):
+    await repo.create_campaign({"uuid": "c1", "confidence": 0.8})
+    row = await repo.get_campaign_by_uuid("c1")
+    assert row is not None
+    assert row["uuid"] == "c1"
+    assert row["confidence"] == 0.8
+    assert row["merged_into_uuid"] is None
+
+
+@pytest.mark.asyncio
+async def test_get_campaign_follows_merge_chain(repo):
+    await repo.create_campaign({"uuid": "c1"})
+    await repo.create_campaign({"uuid": "c2"})
+    await repo.update_campaign_merged_into("c2", "c1")
+
+    # Querying the loser returns the winner.
+    row = await repo.get_campaign_by_uuid("c2")
+    assert row["uuid"] == "c1"
+
+
+@pytest.mark.asyncio
+async def test_list_and_count_excludes_merged_out(repo):
+    await repo.create_campaign({"uuid": "c1"})
+    await repo.create_campaign({"uuid": "c2"})
+    await repo.update_campaign_merged_into("c2", "c1")
+
+    listed = await repo.list_campaigns()
+    assert {c["uuid"] for c in listed} == {"c1"}
+    assert await repo.count_campaigns() == 1
+
+
+@pytest.mark.asyncio
+async def test_list_all_campaigns_includes_merged_out(repo):
+    await repo.create_campaign({"uuid": "c1"})
+    await repo.create_campaign({"uuid": "c2"})
+    await repo.update_campaign_merged_into("c2", "c1")
+
+    all_campaigns = await repo.list_all_campaigns()
+    assert {c["uuid"] for c in all_campaigns} == {"c1", "c2"}
+
+
+@pytest.mark.asyncio
+async def test_get_unknown_campaign_returns_none(repo):
+    assert await repo.get_campaign_by_uuid("nope") is None
+
+
+@pytest.mark.asyncio
+async def test_update_campaign_merged_into_can_revoke(repo):
+    await repo.create_campaign({"uuid": "c1"})
+    await repo.create_campaign({"uuid": "c2"})
+    await repo.update_campaign_merged_into("c2", "c1")
+    # Revoke
+    await repo.update_campaign_merged_into("c2", None)
+
+    row = await repo.get_campaign_by_uuid("c2")
+    assert row["uuid"] == "c2"
+    assert row["merged_into_uuid"] is None
+
+
+@pytest.mark.asyncio
+async def test_set_identity_campaign_id_links_and_unlinks(repo):
+    await repo.create_campaign({"uuid": "c1"})
+    await _create_identity(repo, "i1")
+
+    await repo.set_identity_campaign_id("i1", "c1")
+    linked = await repo.list_identities_for_campaign("c1")
+    assert {i["uuid"] for i in linked} == {"i1"}
+    assert await repo.count_identities_for_campaign("c1") == 1
+
+    await repo.set_identity_campaign_id("i1", None)
+    assert await repo.count_identities_for_campaign("c1") == 0
+
+
+@pytest.mark.asyncio
+async def test_list_identities_for_clustering_projects_expected_fields(repo):
+    await _create_identity(
+        repo, "i1",
+        ja3_hashes='["ja3-a"]',
+        hassh_hashes='["hassh-a"]',
+        payload_simhashes='["dead"]',
+        c2_endpoints='["1.2.3.4:443"]',
+    )
+    rows = await repo.list_identities_for_clustering()
+    assert len(rows) == 1
+    row = rows[0]
+    assert row["uuid"] == "i1"
+    assert row["ja3_hashes"] == '["ja3-a"]'
+    assert row["hassh_hashes"] == '["hassh-a"]'
+    assert row["payload_simhashes"] == '["dead"]'
+    assert row["c2_endpoints"] == '["1.2.3.4:443"]'
+    assert row["campaign_id"] is None
+    assert row["merged_into_uuid"] is None
+    assert row["first_seen_at"] is not None
+
+
+@pytest.mark.asyncio
+async def test_list_identities_for_clustering_respects_limit(repo):
+    for n in range(3):
+        await _create_identity(repo, f"i{n}")
+    assert len(await repo.list_identities_for_clustering(limit=2)) == 2
+    assert len(await repo.list_identities_for_clustering()) == 3
+
+
+@pytest.mark.asyncio
+async def test_list_identities_for_campaign_paginates(repo):
+    await repo.create_campaign({"uuid": "c1"})
+    for n in range(3):
+        await _create_identity(repo, f"i{n}")
+        await repo.set_identity_campaign_id(f"i{n}", "c1")
+
+    page = await repo.list_identities_for_campaign("c1", limit=2, offset=0)
+    assert len(page) == 2
+    page2 = await repo.list_identities_for_campaign("c1", limit=2, offset=2)
+    assert len(page2) == 1