feat(models): 组织、用户、角色、客户、会话与消息模型

按组织边界定义数据关系，补齐仓储层与通用工具，迁移脚本可重复执行。

backend/app/models/ticket_db_connector.py

@@ -0,0 +1,148 @@
+"""
+Copyright 2024-2026 ReplyPier
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+import uuid
+
+from sqlalchemy import Boolean, Column, DateTime, ForeignKey, Index, Integer, String, Text
+from sqlalchemy.dialects.postgresql import JSON, UUID
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import expression, func
+
+from app.database import Base
+from app.models.ticket import _ValueStrEnum
+
+
+class DBConnectorEngine(_ValueStrEnum):
+    POSTGRESQL = "postgresql"
+    MYSQL = "mysql"
+
+
+# Which value of the ticket's customer is matched against the scope column.
+# Email is the default because it is the identifier a support database is most
+# likely to share with ReplyPier; phone suits channel-first businesses.
+ROW_SCOPE_KEYS = ("email", "phone")
+
+
+class TicketDBConnector(Base):
+    """A guardrailed, read-only database connection the ticket investigation
+    agent may query. Guardrails are structural, enforced outside the model:
+    SELECT-only AST validation against allowed_tables, forced row limits,
+    column masking, read-only transaction + statement timeout, full audit.
+    """
+    __tablename__ = "ticket_db_connectors"
+
+    id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    organization_id = Column(
+        UUID(as_uuid=True),
+        ForeignKey("organizations.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    name = Column(String(200), nullable=False)
+    engine = Column(String, nullable=False, default=DBConnectorEngine.POSTGRESQL)
+    host = Column(String(500), nullable=False)
+    port = Column(Integer, nullable=False, default=5432)
+    database = Column(String(200), nullable=False)
+    username = Column(String(200), nullable=False)
+    # Encrypted with app.core.security.encrypt_api_key — never stored plain.
+    encrypted_password = Column(Text, nullable=False)
+
+    enabled = Column(Boolean, nullable=False, default=True, server_default=expression.true())
+
+    # SSH tunnel (bastion / jump host). Production databases are rarely
+    # directly reachable — the connection is forwarded through an SSH host.
+    # host/port above are then resolved from the SSH host's perspective.
+    ssh_enabled = Column(Boolean, nullable=False, default=False, server_default=expression.false())
+    ssh_host = Column(String(500), nullable=True)
+    ssh_port = Column(Integer, nullable=False, default=22, server_default="22")
+    ssh_username = Column(String(200), nullable=True)
+    # Exactly one auth method is used: private key preferred, else password.
+    # All encrypted with app.core.security.encrypt_api_key.
+    encrypted_ssh_password = Column(Text, nullable=True)
+    encrypted_ssh_private_key = Column(Text, nullable=True)
+    encrypted_ssh_key_passphrase = Column(Text, nullable=True)
+
+    # ["schema.table", ...] — nothing is queryable unless listed here.
+    allowed_tables = Column(JSON, nullable=True)
+    # ["email", "phone", ...] — masked before the AI ever sees them; the AST
+    # validator also rejects any query referencing them.
+    masked_columns = Column(JSON, nullable=True)
+    # {"schema.table": "customer_email", ...} — row-level scoping. A listed
+    # table is rewritten into a subquery pre-filtered to the ticket customer's
+    # own rows, so the agent cannot read across customers even with a query
+    # that tries to. Tables left out are unscoped: reference data (products,
+    # error codes) that belongs to nobody in particular.
+    row_scope = Column(JSON, nullable=True)
+    # Which customer value fills the predicate — see ROW_SCOPE_KEYS.
+    row_scope_key = Column(
+        String(20), nullable=False, default="email", server_default="email"
+    )
+    max_rows = Column(Integer, nullable=False, default=100, server_default="100")
+    statement_timeout_ms = Column(Integer, nullable=False, default=5000, server_default="5000")
+
+    last_test_at = Column(DateTime(timezone=True), nullable=True)
+    last_test_ok = Column(Boolean, nullable=True)
+
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
+
+    organization = relationship("Organization")
+
+
+class DBConnectorAuditOutcome(_ValueStrEnum):
+    ALLOWED = "allowed"
+    BLOCKED = "blocked"
+    ERROR = "error"
+
+
+class DBConnectorAuditLog(Base):
+    """Append-only audit of every query the AI attempted against a
+    connector: the raw model SQL, what actually executed (canonical form),
+    and the outcome. Result rows are never stored."""
+    __tablename__ = "db_connector_audit_logs"
+
+    id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    connector_id = Column(
+        UUID(as_uuid=True),
+        ForeignKey("ticket_db_connectors.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    organization_id = Column(
+        UUID(as_uuid=True),
+        ForeignKey("organizations.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    ticket_id = Column(
+        UUID(as_uuid=True), ForeignKey("tickets.id", ondelete="SET NULL"), nullable=True
+    )
+    run_id = Column(
+        UUID(as_uuid=True),
+        ForeignKey("investigation_runs.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    raw_sql = Column(Text, nullable=False)
+    validated_sql = Column(Text, nullable=True)
+    outcome = Column(String, nullable=False)
+    block_reason = Column(Text, nullable=True)
+    row_count = Column(Integer, nullable=True)
+    duration_ms = Column(Integer, nullable=True)
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+
+    __table_args__ = (
+        Index("ix_db_connector_audit_logs_created", "organization_id", "created_at"),
+    )