fix(contacts): strip "2nd tier" tag when interactions are inserted

Telegram group member sync tags new contacts "2nd Tier" and only
clears it on subsequent group syncs. If the user DMs a contact
before the next group sync (or they leave the group), the tag
persists despite active conversations — 167 such contacts existed
on prod.

Enforces the invariant with an AFTER INSERT trigger on interactions
so every code path that creates an Interaction (Telegram, Gmail,
Twitter, LinkedIn, manual, etc.) gets the tag stripped automatically.

Trigger SQL is shared between the alembic migration and test setup
via app/models/_triggers.py so create_all-based tests mirror prod.

Author: Nick Sawinyh

backend/alembic/versions/b1c2d3e4f5a6_clear_2nd_tier_on_interaction_insert.py

@@ -0,0 +1,30 @@
+"""clear 2nd tier tag when an interaction is inserted
+
+Revision ID: b1c2d3e4f5a6
+Revises: 5fcb77520fec
+Create Date: 2026-04-14
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+
+from app.models._triggers import (
+    CLEAR_2ND_TIER_FUNCTION,
+    CLEAR_2ND_TIER_TRIGGER,
+    DROP_CLEAR_2ND_TIER,
+)
+
+revision: str = "b1c2d3e4f5a6"
+down_revision: Union[str, None] = "5fcb77520fec"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.execute(CLEAR_2ND_TIER_FUNCTION)
+    op.execute(CLEAR_2ND_TIER_TRIGGER)
+
+
+def downgrade() -> None:
+    op.execute(DROP_CLEAR_2ND_TIER)

backend/app/models/_triggers.py

@@ -0,0 +1,26 @@
+"""Shared DDL for Postgres triggers used by both alembic migrations and tests."""
+from __future__ import annotations
+
+CLEAR_2ND_TIER_FUNCTION = """
+CREATE OR REPLACE FUNCTION clear_2nd_tier_on_interaction() RETURNS trigger AS $$
+BEGIN
+    UPDATE contacts
+    SET tags = array_remove(array_remove(tags, '2nd tier'), '2nd Tier')
+    WHERE id = NEW.contact_id
+      AND (tags @> ARRAY['2nd tier']::varchar[]
+           OR tags @> ARRAY['2nd Tier']::varchar[]);
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+"""
+
+CLEAR_2ND_TIER_TRIGGER = """
+CREATE TRIGGER trg_clear_2nd_tier_on_interaction
+AFTER INSERT ON interactions
+FOR EACH ROW EXECUTE FUNCTION clear_2nd_tier_on_interaction();
+"""
+
+DROP_CLEAR_2ND_TIER = """
+DROP TRIGGER IF EXISTS trg_clear_2nd_tier_on_interaction ON interactions;
+DROP FUNCTION IF EXISTS clear_2nd_tier_on_interaction();
+"""

backend/tests/conftest.py

@@ -16,9 +16,12 @@
     "postgresql+asyncpg://localhost:5432/pingcrm_test",
 )
 
+from sqlalchemy import text
+
 from app.core.auth import create_access_token, hash_password
 from app.core.database import Base, get_db
 from app.main import fastapi_app as app
+from app.models._triggers import CLEAR_2ND_TIER_FUNCTION, CLEAR_2ND_TIER_TRIGGER
 from app.models.contact import Contact
 from app.models.detected_event import DetectedEvent
 from app.models.follow_up import FollowUpSuggestion
@@ -36,6 +39,8 @@ async def setup_database():
     engine = create_async_engine(os.environ["DATABASE_URL"], echo=False)
     async with engine.begin() as conn:
         await conn.run_sync(Base.metadata.create_all)
+        await conn.execute(text(CLEAR_2ND_TIER_FUNCTION))
+        await conn.execute(text(CLEAR_2ND_TIER_TRIGGER))
     yield engine
     async with engine.begin() as conn:
         await conn.run_sync(Base.metadata.drop_all)

backend/tests/test_clear_2nd_tier_trigger.py

@@ -0,0 +1,88 @@
+"""Verify the Postgres trigger that strips the '2nd tier' tag when an interaction is inserted."""
+from __future__ import annotations
+
+import uuid
+from datetime import UTC, datetime
+
+import pytest
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.contact import Contact
+from app.models.interaction import Interaction
+from app.models.user import User
+
+
+async def _make_contact(db: AsyncSession, user: User, tags: list[str]) -> Contact:
+    contact = Contact(
+        id=uuid.uuid4(),
+        user_id=user.id,
+        full_name="Group Friend",
+        given_name="Group",
+        family_name="Friend",
+        tags=tags,
+        source="telegram",
+    )
+    db.add(contact)
+    await db.commit()
+    await db.refresh(contact)
+    return contact
+
+
+@pytest.mark.asyncio
+async def test_inserting_interaction_strips_lowercase_tag(db: AsyncSession, test_user: User):
+    contact = await _make_contact(db, test_user, tags=["2nd tier", "friend"])
+
+    db.add(Interaction(
+        id=uuid.uuid4(),
+        contact_id=contact.id,
+        user_id=test_user.id,
+        platform="telegram",
+        direction="inbound",
+        content_preview="hi",
+        occurred_at=datetime.now(UTC),
+    ))
+    await db.commit()
+    await db.refresh(contact)
+
+    assert contact.tags == ["friend"]
+
+
+@pytest.mark.asyncio
+async def test_inserting_interaction_strips_titlecase_tag(db: AsyncSession, test_user: User):
+    contact = await _make_contact(db, test_user, tags=["2nd Tier"])
+
+    db.add(Interaction(
+        id=uuid.uuid4(),
+        contact_id=contact.id,
+        user_id=test_user.id,
+        platform="telegram",
+        direction="outbound",
+        content_preview="hi",
+        occurred_at=datetime.now(UTC),
+    ))
+    await db.commit()
+    await db.refresh(contact)
+
+    assert contact.tags == []
+
+
+@pytest.mark.asyncio
+async def test_trigger_leaves_other_contacts_alone(db: AsyncSession, test_user: User):
+    other = await _make_contact(db, test_user, tags=["2nd tier"])
+    target = await _make_contact(db, test_user, tags=["2nd tier"])
+
+    db.add(Interaction(
+        id=uuid.uuid4(),
+        contact_id=target.id,
+        user_id=test_user.id,
+        platform="telegram",
+        direction="inbound",
+        content_preview="hi",
+        occurred_at=datetime.now(UTC),
+    ))
+    await db.commit()
+    await db.refresh(target)
+    await db.refresh(other)
+
+    assert target.tags == []
+    assert other.tags == ["2nd tier"]