Fix migration 2.83.0 to be idempotent

Make ALTER TABLE check if columns exist before adding them

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: Fotios Tsakiridis

database/migrations/2.83.0_context_system.sql

@@ -2,10 +2,26 @@
 -- Adds global_context and project_context columns to projects table
 -- for per-project customizable AI context
 
--- Add context columns to projects table
-ALTER TABLE projects
-ADD COLUMN global_context TEXT COMMENT 'Customized global context for this project' AFTER context,
-ADD COLUMN project_context TEXT COMMENT 'Language-specific context for this project' AFTER global_context;
+-- Add context columns to projects table (if they don't exist)
+SET @dbname = DATABASE();
+
+SELECT COUNT(*) INTO @col_exists FROM information_schema.columns
+WHERE table_schema = @dbname AND table_name = 'projects' AND column_name = 'global_context';
+SET @sql = IF(@col_exists = 0,
+    'ALTER TABLE projects ADD COLUMN global_context TEXT COMMENT ''Customized global context for this project'' AFTER context',
+    'SELECT 1');
+PREPARE stmt FROM @sql;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
+SELECT COUNT(*) INTO @col_exists FROM information_schema.columns
+WHERE table_schema = @dbname AND table_name = 'projects' AND column_name = 'project_context';
+SET @sql = IF(@col_exists = 0,
+    'ALTER TABLE projects ADD COLUMN project_context TEXT COMMENT ''Language-specific context for this project'' AFTER global_context',
+    'SELECT 1');
+PREPARE stmt FROM @sql;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
 
 -- Update schema_migrations
 INSERT INTO schema_migrations (version) VALUES ('2.83.0')