Backend: Add public_trips models and migration

app/backend/src/couchers/migrations/versions/981fb62b20ce_add_public_trips.py

@@ -0,0 +1,75 @@
+"""Add public trips
+
+Revision ID: 981fb62b20ce
+Revises: e9190b051324
+Create Date: 2026-01-22 12:00:00.000000
+
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = "981fb62b20ce"
+down_revision = "0138"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # Create public_trips table
+    op.create_table(
+        "public_trips",
+        sa.Column("id", sa.BigInteger(), nullable=False),
+        sa.Column("user_id", sa.BigInteger(), nullable=False),
+        sa.Column("node_id", sa.BigInteger(), nullable=False),
+        sa.Column("from_date", sa.Date(), nullable=False),
+        sa.Column("to_date", sa.Date(), nullable=False),
+        sa.Column("description", sa.String(), nullable=False),
+        sa.Column(
+            "status",
+            sa.Enum("searching_for_host", "closed", name="publictripstatus"),
+            nullable=False,
+        ),
+        sa.Column("created", sa.DateTime(timezone=True), server_default=sa.text("now()"), nullable=False),
+        sa.CheckConstraint("from_date <= to_date", name=op.f("ck_public_trips_valid_date_range")),
+        sa.ForeignKeyConstraint(["node_id"], ["nodes.id"], name=op.f("fk_public_trips_node_id_nodes")),
+        sa.ForeignKeyConstraint(["user_id"], ["users.id"], name=op.f("fk_public_trips_user_id_users")),
+        sa.PrimaryKeyConstraint("id", name=op.f("pk_public_trips")),
+    )
+    op.create_index(op.f("ix_public_trips_node_id"), "public_trips", ["node_id"], unique=False)
+    op.create_index(op.f("ix_public_trips_user_id"), "public_trips", ["user_id"], unique=False)
+    op.create_index(
+        "ix_public_trips_node_from_date_active",
+        "public_trips",
+        ["node_id", "from_date"],
+        unique=False,
+        postgresql_where=sa.text("status = 'searching_for_host'"),
+    )
+
+    # Add public_trip_id to host_requests
+    op.add_column("host_requests", sa.Column("public_trip_id", sa.BigInteger(), nullable=True))
+    op.create_index(op.f("ix_host_requests_public_trip_id"), "host_requests", ["public_trip_id"], unique=False)
+    op.create_foreign_key(
+        op.f("fk_host_requests_public_trip_id_public_trips"),
+        "host_requests",
+        "public_trips",
+        ["public_trip_id"],
+        ["id"],
+    )
+
+
+def downgrade() -> None:
+    # Remove public_trip_id from host_requests
+    op.drop_constraint(op.f("fk_host_requests_public_trip_id_public_trips"), "host_requests", type_="foreignkey")
+    op.drop_index(op.f("ix_host_requests_public_trip_id"), table_name="host_requests")
+    op.drop_column("host_requests", "public_trip_id")
+
+    # Drop public_trips table
+    op.drop_index("ix_public_trips_node_from_date_active", table_name="public_trips")
+    op.drop_index(op.f("ix_public_trips_user_id"), table_name="public_trips")
+    op.drop_index(op.f("ix_public_trips_node_id"), table_name="public_trips")
+    op.drop_table("public_trips")
+
+    # Drop enum
+    sa.Enum(name="publictripstatus").drop(op.get_bind(), checkfirst=True)

app/backend/src/couchers/models/__init__.py

@@ -14,6 +14,7 @@
 from .moderation import *  # noqa: F401,F403
 from .notifications import *  # noqa: F401,F403
 from .postal_verification import *  # noqa: F401,F403
+from .public_trips import *  # noqa: F401,F403
 from .rest import *  # noqa: F401,F403
 from .static import *  # noqa: F401,F403
 from .uploads import *  # noqa: F401,F403

app/backend/src/couchers/models/clusters.py

@@ -31,6 +31,7 @@
 
 if TYPE_CHECKING:
     from couchers.models import Discussion, Event, Thread, Upload, User
+    from couchers.models.public_trips import PublicTrip
 
 
 class NodeType(enum.Enum):
@@ -79,6 +80,7 @@ class Node(Base, kw_only=True):
         uselist=False,
         viewonly=True,
     )
+    public_trips: Mapped[list[PublicTrip]] = relationship(init=False, back_populates="node")
 
 
 class Cluster(Base, kw_only=True):

app/backend/src/couchers/models/host_requests.py

@@ -14,6 +14,7 @@
 if TYPE_CHECKING:
     from couchers.models.conversations import Conversation
     from couchers.models.moderation import ModerationState
+    from couchers.models.public_trips import PublicTrip
     from couchers.models.users import User
 
 
@@ -84,6 +85,9 @@ class HostRequest(Base, kw_only=True):
     host_reason_didnt_meetup: Mapped[str | None] = mapped_column(String, default=None)
     surfer_reason_didnt_meetup: Mapped[str | None] = mapped_column(String, default=None)
 
+    # Optional link to public trip if this request originated from one
+    public_trip_id: Mapped[int | None] = mapped_column(ForeignKey("public_trips.id"), index=True, default=None)
+
     surfer: Mapped[User] = relationship(
         init=False, backref="host_requests_sent", foreign_keys="HostRequest.surfer_user_id"
     )
@@ -92,6 +96,7 @@ class HostRequest(Base, kw_only=True):
     )
     conversation: Mapped[Conversation] = relationship(init=False)
     moderation_state: Mapped[ModerationState] = relationship(init=False)
+    public_trip: Mapped[PublicTrip | None] = relationship(init=False, back_populates="host_requests")
 
     __table_args__ = (
         # allows fast lookup as to whether they didn't meet up

app/backend/src/couchers/models/public_trips.py

@@ -0,0 +1,66 @@
+import enum
+from datetime import date, datetime
+from typing import TYPE_CHECKING
+
+from sqlalchemy import BigInteger, CheckConstraint, Date, DateTime, Enum, ForeignKey, Index, String, func
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from couchers.models.base import Base
+
+if TYPE_CHECKING:
+    from couchers.models import Node, User
+    from couchers.models.host_requests import HostRequest
+
+
+class PublicTripStatus(enum.Enum):
+    searching_for_host = enum.auto()
+    closed = enum.auto()
+
+
+class PublicTrip(Base, kw_only=True):
+    """
+    A public trip posted by a traveler looking for a host in a community.
+    """
+
+    __tablename__ = "public_trips"
+
+    id: Mapped[int] = mapped_column(BigInteger, primary_key=True, init=False)
+
+    # The traveler posting the trip
+    user_id: Mapped[int] = mapped_column(ForeignKey("users.id"), index=True)
+
+    # The community/location (city-level node)
+    node_id: Mapped[int] = mapped_column(ForeignKey("nodes.id"), index=True)
+
+    # Trip dates
+    from_date: Mapped[date] = mapped_column(Date)
+    to_date: Mapped[date] = mapped_column(Date)
+
+    # User's message about their trip
+    description: Mapped[str] = mapped_column(String)
+
+    # Current status
+    status: Mapped[PublicTripStatus] = mapped_column(
+        Enum(PublicTripStatus), default=PublicTripStatus.searching_for_host
+    )
+
+    # Timestamps
+    created: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), init=False)
+
+    # Relationships
+    user: Mapped[User] = relationship(init=False, back_populates="public_trips")
+    node: Mapped[Node] = relationship(init=False, back_populates="public_trips")
+    host_requests: Mapped[list[HostRequest]] = relationship(init=False, back_populates="public_trip")
+
+    __table_args__ = (
+        # Ensure from_date is not after to_date
+        CheckConstraint("from_date <= to_date", name="valid_date_range"),
+        # Index for querying active trips in a community
+        # Using partial index since we mostly query for active trips
+        Index(
+            "ix_public_trips_node_from_date_active",
+            node_id,
+            from_date,
+            postgresql_where=status == PublicTripStatus.searching_for_host,
+        ),
+    )

app/backend/src/couchers/models/users.py

@@ -46,6 +46,7 @@
 if TYPE_CHECKING:
     from couchers.models import UserBadge
     from couchers.models.admin import UserAdminTag
+    from couchers.models.public_trips import PublicTrip
     from couchers.models.rest import InviteCode, ModerationUserList
     from couchers.models.uploads import PhotoGallery
 
@@ -355,6 +356,8 @@ class User(Base, kw_only=True):
         back_populates="user",
     )
 
+    public_trips: Mapped[list[PublicTrip]] = relationship(init=False, back_populates="user")
+
     __table_args__ = (
         # Verified phone numbers should be unique
         Index(