test assignment completion ui

frontend/website/cypress/e2e/today-assignments.cy.ts

@@ -113,6 +113,74 @@ describe("today's assignments", () => {
     )
   })
 
+  it('completes an assignment and keeps failures retryable', () => {
+    cy.intercept('GET', `**/api/assignments?date=${browserToday}`, {
+      statusCode: 200,
+      body: {
+        date: browserToday,
+        assignments: [
+          {
+            id: 12,
+            schedule: {
+              id: 73,
+              set: { name: 'Bible' },
+            },
+            element: {
+              name: 'Chapter 1',
+              kind: 'chapter',
+              path: ['Genesis', 'Chapter 1'],
+            },
+          },
+        ],
+      },
+    }).as('todayAssignments')
+    let requestCount = 0
+    cy.intercept('PATCH', '**/api/assignments/12', (request) => {
+      requestCount += 1
+      request.alias = `completion${requestCount}`
+      expect(request.body).to.deep.equal({ completed: true })
+
+      if (requestCount === 1) {
+        request.reply({ delay: 400, statusCode: 500 })
+        return
+      }
+
+      request.reply({
+        delay: 400,
+        statusCode: 200,
+        body: {
+          assignment: {
+            id: 12,
+            completedAt: '2026-08-15T12:30:00+00:00',
+          },
+        },
+      })
+    })
+
+    cy.visit('/dashboard')
+    cy.wait('@me')
+    cy.wait('@todayAssignments')
+
+    cy.get('[data-today-assignment="12"]').within(() => {
+      cy.contains('button', 'Mark complete').click()
+      cy.contains('button', 'Completing...').should('be.disabled')
+    })
+    cy.wait('@completion1')
+    cy.get('[data-today-assignment="12"]')
+      .should('contain.text', "We couldn't update this assignment.")
+      .within(() => {
+        cy.contains('button', 'Mark complete').click()
+        cy.contains('button', 'Completing...').should('be.disabled')
+      })
+    cy.wait('@completion2')
+
+    cy.get('[data-today-assignment="12"]').should('not.exist')
+    cy.get('.today-assignments [role="status"]').should(
+      'contain.text',
+      'Nothing is assigned for today.',
+    )
+  })
+
   it('retries independently after the request fails', () => {
     let requestCount = 0
     cy.intercept(