migration: add public_chat_snapshots table, drop deprecated columns

surfsense_backend/alembic/versions/84_add_public_chat_snapshots_table.py

@@ -0,0 +1,157 @@
+"""Add public_chat_snapshots table and remove deprecated columns from new_chat_threads
+
+Revision ID: 84
+Revises: 83
+Create Date: 2026-01-29
+
+Changes:
+1. Create public_chat_snapshots table for immutable public chat sharing
+2. Drop deprecated columns from new_chat_threads:
+   - public_share_token (moved to snapshots)
+   - public_share_enabled (replaced by snapshot existence)
+   - clone_pending (single-phase clone)
+3. Drop related indexes
+"""
+
+from collections.abc import Sequence
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "84"
+down_revision: str | None = "83"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    """Create public_chat_snapshots table and remove deprecated columns."""
+
+    # 1. Create public_chat_snapshots table
+    op.execute(
+        """
+        CREATE TABLE IF NOT EXISTS public_chat_snapshots (
+            id SERIAL PRIMARY KEY,
+            created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT NOW(),
+            
+            -- Link to original thread (CASCADE DELETE)
+            thread_id INTEGER NOT NULL
+                REFERENCES new_chat_threads(id) ON DELETE CASCADE,
+            
+            -- Public access token (unique URL identifier)
+            share_token VARCHAR(64) NOT NULL UNIQUE,
+            
+            -- SHA-256 hash of message content for deduplication
+            content_hash VARCHAR(64) NOT NULL,
+            
+            -- Immutable snapshot data (JSONB)
+            snapshot_data JSONB NOT NULL,
+            
+            -- Array of message IDs for cascade delete on edit
+            message_ids INTEGER[] NOT NULL,
+            
+            -- Who created this snapshot
+            created_by_user_id UUID REFERENCES "user"(id) ON DELETE SET NULL,
+            
+            -- Prevent duplicate snapshots of same content for same thread
+            CONSTRAINT uq_snapshot_thread_content_hash UNIQUE (thread_id, content_hash)
+        );
+        """
+    )
+
+    # 2. Create indexes for public_chat_snapshots
+    op.execute(
+        """
+        CREATE INDEX IF NOT EXISTS ix_public_chat_snapshots_thread_id
+        ON public_chat_snapshots(thread_id);
+        """
+    )
+
+    op.execute(
+        """
+        CREATE INDEX IF NOT EXISTS ix_public_chat_snapshots_share_token
+        ON public_chat_snapshots(share_token);
+        """
+    )
+
+    op.execute(
+        """
+        CREATE INDEX IF NOT EXISTS ix_public_chat_snapshots_content_hash
+        ON public_chat_snapshots(content_hash);
+        """
+    )
+
+    op.execute(
+        """
+        CREATE INDEX IF NOT EXISTS ix_public_chat_snapshots_created_by_user_id
+        ON public_chat_snapshots(created_by_user_id);
+        """
+    )
+
+    # 3. Create GIN index for message_ids array (for fast overlap queries)
+    op.execute(
+        """
+        CREATE INDEX IF NOT EXISTS ix_public_chat_snapshots_message_ids
+        ON public_chat_snapshots USING GIN(message_ids);
+        """
+    )
+
+    # 4. Drop deprecated indexes from new_chat_threads
+    op.execute("DROP INDEX IF EXISTS ix_new_chat_threads_public_share_enabled")
+    op.execute("DROP INDEX IF EXISTS ix_new_chat_threads_public_share_token")
+
+    # 5. Drop deprecated columns from new_chat_threads
+    op.execute("ALTER TABLE new_chat_threads DROP COLUMN IF EXISTS clone_pending")
+    op.execute("ALTER TABLE new_chat_threads DROP COLUMN IF EXISTS public_share_enabled")
+    op.execute("ALTER TABLE new_chat_threads DROP COLUMN IF EXISTS public_share_token")
+
+
+def downgrade() -> None:
+    """Restore deprecated columns and drop public_chat_snapshots table."""
+
+    # 1. Restore deprecated columns on new_chat_threads
+    op.execute(
+        """
+        ALTER TABLE new_chat_threads
+        ADD COLUMN IF NOT EXISTS public_share_token VARCHAR(64);
+        """
+    )
+
+    op.execute(
+        """
+        ALTER TABLE new_chat_threads
+        ADD COLUMN IF NOT EXISTS public_share_enabled BOOLEAN NOT NULL DEFAULT FALSE;
+        """
+    )
+
+    op.execute(
+        """
+        ALTER TABLE new_chat_threads
+        ADD COLUMN IF NOT EXISTS clone_pending BOOLEAN NOT NULL DEFAULT FALSE;
+        """
+    )
+
+    # 2. Restore indexes
+    op.execute(
+        """
+        CREATE UNIQUE INDEX IF NOT EXISTS ix_new_chat_threads_public_share_token
+        ON new_chat_threads(public_share_token)
+        WHERE public_share_token IS NOT NULL;
+        """
+    )
+
+    op.execute(
+        """
+        CREATE INDEX IF NOT EXISTS ix_new_chat_threads_public_share_enabled
+        ON new_chat_threads(public_share_enabled)
+        WHERE public_share_enabled = TRUE;
+        """
+    )
+
+    # 3. Drop public_chat_snapshots table and its indexes
+    op.execute("DROP INDEX IF EXISTS ix_public_chat_snapshots_message_ids")
+    op.execute("DROP INDEX IF EXISTS ix_public_chat_snapshots_created_by_user_id")
+    op.execute("DROP INDEX IF EXISTS ix_public_chat_snapshots_content_hash")
+    op.execute("DROP INDEX IF EXISTS ix_public_chat_snapshots_share_token")
+    op.execute("DROP INDEX IF EXISTS ix_public_chat_snapshots_thread_id")
+    op.execute("DROP TABLE IF EXISTS public_chat_snapshots")