fixed transfer process

backend/src/db/schema.ts

@@ -216,6 +216,31 @@ export const ensureSchema = async (database: DatabaseClient = db) => {
     CREATE UNIQUE INDEX IF NOT EXISTS idx_birds_workspace_tag_id
       ON birds (workspace_id, tag_id);
 
+    CREATE TABLE IF NOT EXISTS pending_bird_transfers (
+      id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+      bird_id UUID NOT NULL REFERENCES birds(id) ON DELETE CASCADE,
+      source_workspace_id INTEGER NOT NULL REFERENCES workspaces(id) ON DELETE CASCADE,
+      destination_owner_email VARCHAR(255) NOT NULL,
+      requested_by_user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+      completed_at TIMESTAMPTZ,
+      completed_workspace_id INTEGER REFERENCES workspaces(id) ON DELETE SET NULL,
+      last_error TEXT,
+      created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP
+    );
+
+    ALTER TABLE pending_bird_transfers
+      ADD COLUMN IF NOT EXISTS completed_at TIMESTAMPTZ,
+      ADD COLUMN IF NOT EXISTS completed_workspace_id INTEGER REFERENCES workspaces(id) ON DELETE SET NULL,
+      ADD COLUMN IF NOT EXISTS last_error TEXT;
+
+    CREATE INDEX IF NOT EXISTS idx_pending_bird_transfers_destination_email
+      ON pending_bird_transfers (LOWER(destination_owner_email), created_at DESC)
+      WHERE completed_at IS NULL;
+
+    CREATE UNIQUE INDEX IF NOT EXISTS idx_pending_bird_transfers_open_bird
+      ON pending_bird_transfers (bird_id)
+      WHERE completed_at IS NULL;
+
     CREATE TABLE IF NOT EXISTS weight_records (
       id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
       bird_id UUID NOT NULL REFERENCES birds(id) ON DELETE CASCADE,