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TIER-2 READ conductor/code_styleguides/error_handling.md end-to-end before Phase 2. Phase 2 covered: - t2.1 [5b139e6]: render_controller_error_modal — reads 8 controller attrs; opens per-attr popups (Pattern 2 drain point) - t2.2 [5b139e6]: _render_worker_error_indicator — status-bar widget - t2.3 [5b139e6]: _render_last_request_errors_modal — per-request modal - t2.4 [5b139e6]: 2 Phase 2 invariant tests (test_phase_2_invariant_drain_plane_render_functions_exist + test_phase_2_invariant_drain_plane_app_delegations_exist) - Phase 2 checkpoint: state.toml Phase 2 -> completed. Audit: no new violations. Tests: 4/4 pass. Phase 3 begins: INTERNAL_BROAD_CATCH Batch A migration (8 render-loop sites from the inventory: L731, L742, L1123, L1172, L1198, L1223, L1285, L4849).