diff --git a/decnet/web/db/sqlmodel_repo/__init__.py b/decnet/web/db/sqlmodel_repo/__init__.py
index df49a194..37568d26 100644
--- a/decnet/web/db/sqlmodel_repo/__init__.py
+++ b/decnet/web/db/sqlmodel_repo/__init__.py
@@ -49,6 +49,7 @@ from decnet.web.db.sqlmodel_repo.realism import RealismMixin
 from decnet.web.db.sqlmodel_repo.swarm import SwarmMixin
 from decnet.web.db.sqlmodel_repo.topology import TopologyMixin
 from decnet.web.db.sqlmodel_repo.tarpit import TarpitMixin
+from decnet.web.db.sqlmodel_repo.ttp import TTPMixin
 from decnet.web.db.sqlmodel_repo.webhooks import WebhooksMixin
 
 
@@ -69,6 +70,7 @@ class SQLModelRepository(
     SwarmMixin,
     TarpitMixin,
     TopologyMixin,
+    TTPMixin,
     WebhooksMixin,
     BaseRepository,
 ):
diff --git a/decnet/web/db/sqlmodel_repo/ttp.py b/decnet/web/db/sqlmodel_repo/ttp.py
new file mode 100644
index 00000000..8cac32a8
--- /dev/null
+++ b/decnet/web/db/sqlmodel_repo/ttp.py
@@ -0,0 +1,106 @@
+"""TTP-tagging repository — `ttp_tag` reads + idempotent inserts.
+
+Contract step E.1.10 of `development/TTP_TAGGING.md`. Method bodies
+raise ``NotImplementedError``; the SQL lands at E.3 implementation
+phase. The shape — argument types, return types, idempotency
+semantics on ``insert_tags`` — is the public contract from this
+commit forward.
+
+Per the dual-DB-backend project convention, dialect-specific behavior
+(``INSERT OR IGNORE`` on SQLite vs ``INSERT IGNORE`` on MySQL) is
+overridden in the per-dialect subclasses (``decnet.web.db.sqlite``,
+``decnet.web.db.mysql``); the shared base lives here.
+"""
+from __future__ import annotations
+
+from decnet.web.db.models import (
+    CampaignTechniqueRow,
+    IdentityTechniqueRow,
+    TechniqueRollupRow,
+    TTPTag,
+)
+from decnet.web.db.sqlmodel_repo._helpers import _MixinBase
+
+
+class TTPMixin(_MixinBase):
+    """Mixin: TTP-tag query + insert methods composed onto
+    :class:`SQLModelRepository`.
+
+    Expects ``self._session()`` from the base mixin. Adding a new
+    ``ttp_tag`` query method here requires adding a contract test in
+    ``tests/web/db/test_ttp_repo.py`` (E.2.13) AND a parametrized run
+    against both SQLite and MySQL via the existing ``db_backends``
+    fixture.
+    """
+
+    async def insert_tags(self, rows: list[TTPTag]) -> int:
+        """Bulk-upsert tags with ``INSERT OR IGNORE`` semantics.
+
+        Returns the number of rows actually inserted (i.e. that were
+        not already present at their deterministic
+        :func:`compute_tag_uuid` PK). The idempotency property is the
+        load-bearing contract: replaying the same source events must
+        converge to the same tag set without writing duplicates and
+        without raising. See TTP_TAGGING.md §"Idempotency" + §"Bus
+        topics — Loop-prevention invariant".
+        """
+        raise NotImplementedError(
+            "insert_tags lands at E.3 implementation phase",
+        )
+
+    async def list_techniques_by_identity(
+        self,
+        uuid: str,
+    ) -> list[IdentityTechniqueRow]:
+        """Per-Identity TTP rollup. Joins ``ttp_tag`` on
+        ``identity_uuid`` and groups by ``(technique_id,
+        sub_technique_id)``. Includes identity-rollup tags (with NULL
+        ``attacker_uuid``) and per-event tags whose denormalised
+        ``identity_uuid`` matches.
+        """
+        raise NotImplementedError(
+            "list_techniques_by_identity lands at E.3",
+        )
+
+    async def list_techniques_by_attacker(
+        self,
+        uuid: str,
+    ) -> list[IdentityTechniqueRow]:
+        """Per-Attacker (per-IP) TTP rollup. Reads ``ttp_tag`` filtered
+        on ``attacker_uuid``. Identity-rollup tags (NULL attacker
+        anchor) are deliberately excluded — those belong to the
+        Identity, not any one IP underneath it.
+        """
+        raise NotImplementedError(
+            "list_techniques_by_attacker lands at E.3",
+        )
+
+    async def list_techniques_by_campaign(
+        self,
+        uuid: str,
+    ) -> list[CampaignTechniqueRow]:
+        """Campaign-wide TTP rollup. Joins ``ttp_tag`` -> Identity ->
+        ``campaign_uuid`` and groups across all member Identities.
+        """
+        raise NotImplementedError(
+            "list_techniques_by_campaign lands at E.3",
+        )
+
+    async def list_techniques_by_session(
+        self,
+        sid: str,
+    ) -> list[IdentityTechniqueRow]:
+        """Session-scoped TTP timeline. Filtered on ``ttp_tag.session_id``.
+        Used by the SessionDetail page (post-v0).
+        """
+        raise NotImplementedError(
+            "list_techniques_by_session lands at E.3",
+        )
+
+    async def list_distinct_techniques(self) -> list[TechniqueRollupRow]:
+        """Fleet-wide distinct-technique rollup with counts +
+        most-recent-seen timestamps. Backs ``GET /api/v1/ttp/techniques``.
+        """
+        raise NotImplementedError(
+            "list_distinct_techniques lands at E.3",
+        )
diff --git a/development/TTP_TAGGING.md b/development/TTP_TAGGING.md
index 867ba297..2570f460 100644
--- a/development/TTP_TAGGING.md
+++ b/development/TTP_TAGGING.md
@@ -2360,6 +2360,8 @@ unrelated events.
 
 **E.1.10 — Repository contract** (`decnet/web/db/sqlmodel_repo/ttp.py`)
 
+**Status:** ✅ done.
+
 - `async def insert_tags(rows: list[TTPTag]) -> int` — bulk upsert
   with `INSERT OR IGNORE` semantics for idempotency.
 - `async def list_techniques_by_identity(uuid: str) -> list[...]`.