feat: add branching columns to ai_sessions, ai_session_steps, file_uploads

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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,
+    )