diff --git a/backend/app/models/ai_session.py b/backend/app/models/ai_session.py
index 721924ad..85d5ef4e 100644
--- a/backend/app/models/ai_session.py
+++ b/backend/app/models/ai_session.py
@@ -20,6 +20,10 @@ if TYPE_CHECKING:
     from app.models.account import Account
     from app.models.tree import Tree
     from app.models.psa_connection import PsaConnection
+    from app.models.session_branch import SessionBranch
+    from app.models.fork_point import ForkPoint
+    from app.models.session_handoff import SessionHandoff
+    from app.models.session_resolution_output import SessionResolutionOutput
 
 
 class AISession(Base):
@@ -206,6 +210,28 @@ class AISession(Base):
         comment="Full LLM message history for context continuity",
     )
 
+    # ── Branching ──
+    is_branching: Mapped[bool] = mapped_column(
+        default=False,
+        comment="Whether conversational branching is active for this session",
+    )
+    active_branch_id: Mapped[Optional[uuid.UUID]] = mapped_column(
+        UUID(as_uuid=True), nullable=True,
+        comment="Currently viewed branch. No FK — soft pointer to avoid circular FK with session_branches",
+    )
+    handoff_count: Mapped[int] = mapped_column(
+        Integer, nullable=False, default=0,
+        comment="Number of times this session has been handed off",
+    )
+    total_active_seconds: Mapped[int] = mapped_column(
+        Integer, nullable=False, default=0,
+        comment="Cumulative active time in seconds",
+    )
+    total_parked_seconds: Mapped[int] = mapped_column(
+        Integer, nullable=False, default=0,
+        comment="Cumulative parked time in seconds",
+    )
+
     # ── Relationships ──
     user: Mapped["User"] = relationship("User", foreign_keys=[user_id])
     account: Mapped["Account"] = relationship("Account")
@@ -218,3 +244,18 @@ class AISession(Base):
         cascade="all, delete-orphan",
         order_by="AISessionStep.step_order",
     )
+    branches: Mapped[list["SessionBranch"]] = relationship(
+        "SessionBranch",
+        foreign_keys="SessionBranch.session_id",
+        cascade="all, delete-orphan",
+        order_by="SessionBranch.branch_order",
+    )
+    handoffs: Mapped[list["SessionHandoff"]] = relationship(
+        "SessionHandoff",
+        cascade="all, delete-orphan",
+        order_by="SessionHandoff.created_at",
+    )
+    resolution_outputs: Mapped[list["SessionResolutionOutput"]] = relationship(
+        "SessionResolutionOutput",
+        cascade="all, delete-orphan",
+    )
diff --git a/backend/app/models/ai_session_step.py b/backend/app/models/ai_session_step.py
index 413f142c..ac08da72 100644
--- a/backend/app/models/ai_session_step.py
+++ b/backend/app/models/ai_session_step.py
@@ -16,6 +16,8 @@ from app.core.database import Base
 if TYPE_CHECKING:
     from app.models.ai_session import AISession
     from app.models.script_template import ScriptGeneration
+    from app.models.session_branch import SessionBranch
+    from app.models.fork_point import ForkPoint
 
 
 class AISessionStep(Base):
@@ -34,7 +36,7 @@ class AISessionStep(Base):
     __table_args__ = (
         CheckConstraint(
             "step_type IN ('question', 'action', 'script_generation', 'verification', "
-            "'info_request', 'note', 'intake_analysis')",
+            "'info_request', 'note', 'intake_analysis', 'fork')",
             name="ck_ai_session_steps_step_type",
         ),
     )
@@ -119,6 +121,24 @@ class AISessionStep(Base):
         Integer, nullable=False, default=0,
     )
 
+    # ── Branching ──
+    branch_id: Mapped[Optional[uuid.UUID]] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("session_branches.id", ondelete="SET NULL"),
+        nullable=True,
+        index=True,
+        comment="NULL = pre-branching/root messages",
+    )
+    is_fork_point: Mapped[bool] = mapped_column(
+        default=False,
+        comment="Whether this step triggered a fork",
+    )
+    fork_point_id: Mapped[Optional[uuid.UUID]] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("fork_points.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+
     # ── Timestamps ──
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
diff --git a/backend/app/models/file_upload.py b/backend/app/models/file_upload.py
index 6846b1a3..208c35b5 100644
--- a/backend/app/models/file_upload.py
+++ b/backend/app/models/file_upload.py
@@ -3,7 +3,7 @@ import uuid
 from datetime import datetime, timezone
 from typing import Optional
 
-from sqlalchemy import String, Integer, DateTime, ForeignKey
+from sqlalchemy import String, Integer, DateTime, ForeignKey, Text
 from sqlalchemy.orm import Mapped, mapped_column
 from sqlalchemy.dialects.postgresql import UUID
 
@@ -30,3 +30,27 @@ class FileUpload(Base):
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
     )
+
+    # ── AI description + branching context ──
+    ai_description: Mapped[Optional[str]] = mapped_column(
+        Text, nullable=True,
+        comment="AI-generated one-sentence description of the file",
+    )
+    extracted_content: Mapped[Optional[str]] = mapped_column(
+        Text, nullable=True,
+        comment="Extracted text from logs/configs",
+    )
+    content_summary: Mapped[Optional[str]] = mapped_column(
+        Text, nullable=True,
+        comment="AI summary for long text files (>2000 tokens)",
+    )
+    uploaded_on_branch_id: Mapped[Optional[uuid.UUID]] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("session_branches.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    uploaded_at_step_id: Mapped[Optional[uuid.UUID]] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("ai_session_steps.id", ondelete="SET NULL"),
+        nullable=True,
+    )