Comprehensive E2E test scenarios

Objective

Create comprehensive end-to-end tests covering full workflows with mocked GitHub integration.

Tasks

Full Workflow Tests (tests/e2e/test_workflows.py)

• test_create_submit_edit_resubmit - Complete feature workflow
• test_create_stack_submit_all - Multi-branch stack workflow
• test_fetch_edit_submit - Collaboration workflow
• test_sync_with_main_resubmit - Rebase workflow
• test_complex_stack_5_branches - Large stack operations
• test_multiple_independent_stacks - Multiple stacks in same repo

Error Recovery Tests (tests/e2e/test_error_recovery.py)

• test_interrupted_submit - Handle Ctrl+C during submit
• test_network_failure_during_submit - Rollback on API failure
• test_merge_conflict_during_sync - Interactive conflict resolution
• test_force_push_rejected - Handle remote rejection
• test_pr_closed_unexpectedly - Handle stale metadata
• test_recover_from_failed_rebase - Clean up after rebase failure

Edge Case Tests (tests/e2e/test_edge_cases.py)

• test_empty_repository - Operations in new repo
• test_very_long_branch_names - Truncation handling
• test_stack_depth_10_plus - Deep stack operations
• test_branch_with_emojis - Unicode handling
• test_mixed_manual_shortcake_branches - Hybrid workflows
• test_detached_head_state - Recovery from detached HEAD
• test_multiple_children_per_parent - Branching detection

GitHub Integration Tests (tests/e2e/test_github_integration.py)

• test_pr_description_format - Stack context in description
• test_pr_base_branch_updates - Correct base for stacks
• test_pr_title_from_commit - Auto-generated titles
• test_rate_limiting_handling - Backoff and retry
• test_authentication_errors - Clear error messages
• test_concurrent_modifications - Handle remote changes

Test Utilities

• Create assert_stack_structure() helper
• Create assert_pr_metadata() helper
• Create simulate_github_error() helper
• Create create_complex_stack() factory

Acceptance Criteria

• 50+ e2e tests covering all workflows
• All tests pass with mocked GitHub API
• Test suite completes in <2 minutes
• Edge cases comprehensively covered
• Error scenarios tested
• Test helpers reduce boilerplate

Start with the requested files under tests/e2e/, beginning with tests/e2e/test_workflows.py, and review the listed workflow, error-recovery, edge-case, and GitHub-integration scenarios. Then define the four requested helpers and factory around the existing test structure. Done means 50+ mocked-GitHub E2E tests pass, edge and error scenarios are covered, helpers reduce boilerplate, and the suite finishes in under two minutes.