Upload workflow enhancements: S3 verification, timing, client checksum support (#19)

- Add S3 object verification after upload (size validation before DB commit)
- Add cleanup of S3 objects if DB commit fails
- Record upload duration_ms and user_agent
- Support X-Checksum-SHA256 header for client-side checksum verification
- Add already_existed flag to StorageResult for deduplication tracking
- Add status, error_message, client_checksum columns to Upload model
- Add UploadLock model for future 409 conflict detection
- Add consistency-check admin endpoint for detecting orphaned S3 objects
- Add migration 005_upload_enhancements.sql

migrations/005_upload_enhancements.sql

@@ -0,0 +1,83 @@
+-- Migration 005: Upload Workflow Enhancements
+-- Adds status tracking and error handling for uploads
+
+-- ============================================
+-- Add status column to uploads table
+-- ============================================
+DO $$ 
+BEGIN
+    IF NOT EXISTS (SELECT 1 FROM information_schema.columns 
+                   WHERE table_name = 'uploads' AND column_name = 'status') THEN
+        ALTER TABLE uploads ADD COLUMN status VARCHAR(20) DEFAULT 'completed' NOT NULL;
+    END IF;
+END $$;
+
+-- ============================================
+-- Add error_message column for failed uploads
+-- ============================================
+DO $$ 
+BEGIN
+    IF NOT EXISTS (SELECT 1 FROM information_schema.columns 
+                   WHERE table_name = 'uploads' AND column_name = 'error_message') THEN
+        ALTER TABLE uploads ADD COLUMN error_message TEXT;
+    END IF;
+END $$;
+
+-- ============================================
+-- Add client_checksum column for verification
+-- ============================================
+DO $$ 
+BEGIN
+    IF NOT EXISTS (SELECT 1 FROM information_schema.columns 
+                   WHERE table_name = 'uploads' AND column_name = 'client_checksum') THEN
+        ALTER TABLE uploads ADD COLUMN client_checksum VARCHAR(64);
+    END IF;
+END $$;
+
+-- ============================================
+-- Add indexes for upload status queries
+-- ============================================
+CREATE INDEX IF NOT EXISTS idx_uploads_status ON uploads(status);
+CREATE INDEX IF NOT EXISTS idx_uploads_status_uploaded_at ON uploads(status, uploaded_at);
+
+-- ============================================
+-- Add constraint to validate status values
+-- ============================================
+DO $$ 
+BEGIN
+    IF NOT EXISTS (SELECT 1 FROM information_schema.constraint_column_usage 
+                   WHERE constraint_name = 'check_upload_status') THEN
+        ALTER TABLE uploads ADD CONSTRAINT check_upload_status 
+            CHECK (status IN ('pending', 'completed', 'failed'));
+    END IF;
+END $$;
+
+-- ============================================
+-- Create table for tracking in-progress uploads (for 409 conflict detection)
+-- ============================================
+CREATE TABLE IF NOT EXISTS upload_locks (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    sha256_hash VARCHAR(64) NOT NULL,
+    package_id UUID NOT NULL REFERENCES packages(id) ON DELETE CASCADE,
+    locked_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    locked_by VARCHAR(255) NOT NULL,
+    expires_at TIMESTAMP WITH TIME ZONE NOT NULL,
+    UNIQUE(sha256_hash, package_id)
+);
+
+CREATE INDEX IF NOT EXISTS idx_upload_locks_expires_at ON upload_locks(expires_at);
+CREATE INDEX IF NOT EXISTS idx_upload_locks_hash_package ON upload_locks(sha256_hash, package_id);
+
+-- ============================================
+-- Function to clean up expired upload locks
+-- ============================================
+CREATE OR REPLACE FUNCTION cleanup_expired_upload_locks()
+RETURNS INTEGER AS $$
+DECLARE
+    deleted_count INTEGER;
+BEGIN
+    DELETE FROM upload_locks WHERE expires_at < NOW();
+    GET DIAGNOSTICS deleted_count = ROW_COUNT;
+    RETURN deleted_count;
+END;
+$$ LANGUAGE plpgsql;