feat(kernel): wire CUJ-gap fixes — staging fail-loud, error context, sync cancel #2972

Job	Run time
check-types (3.14)	2m 2s
check-linting (3.12)	2m 18s
check-linting (3.13)	1m 34s
Unit Tests + PyArrow (Python 3.10, default deps)	3m 57s
check-types (3.9)	2m 7s
Unit Tests + PyArrow (Python 3.10, min deps)	4m 39s
check-types (3.12)	1m 50s
Unit Tests (Python 3.9, min deps)	4m 41s
Unit Tests + PyArrow (Python 3.11, default deps)	3m 57s
Unit Tests (Python 3.14, min deps)	3m 37s
Unit Tests + PyArrow (Python 3.13, default deps)	3m 59s
Unit Tests (Python 3.11, min deps)	4m 2s
Unit Tests (Python 3.9, default deps)	3m 23s
Unit Tests + PyArrow (Python 3.14, min deps)	4m 18s
Unit Tests (Python 3.14, default deps)	3m 8s
Unit Tests + PyArrow (Python 3.9, min deps)	4m 49s
Unit Tests + PyArrow (Python 3.12, default deps)	3m 55s
check-linting (3.11)	1m 33s
check-linting (3.10)	1m 35s
Unit Tests (Python 3.10, default deps)	3m 12s
check-linting (3.14)	1m 33s
Unit Tests (Python 3.12, default deps)	3m 8s
Unit Tests + PyArrow (Python 3.14, default deps)	3m 57s
Unit Tests (Python 3.10, min deps)	3m 56s
check-types (3.11)	1m 48s
check-linting (3.9)	1m 43s
Unit Tests + PyArrow (Python 3.9, default deps)	4m 15s
Unit Tests (Python 3.11, default deps)	3m 8s
Unit Tests + PyArrow (Python 3.11, min deps)	4m 44s
Unit Tests (Python 3.13, default deps)	3m 9s
check-types (3.10)	1m 50s
check-types (3.13)	1m 46s
	1h 39m 33s

Provide feedback