Client notification support #3943

Job	Run time
checks / readme-snippets	11s
checks / pre-commit	33s
checks / test (3.10, lowest-direct, ubuntu-latest)	43s
checks / test (3.11, lowest-direct, windows-latest)	2m 48s
checks / test (3.10, lowest-direct, windows-latest)	2m 52s
checks / test (3.12, lowest-direct, windows-latest)	3m 25s
checks / test (3.11, lowest-direct, ubuntu-latest)	42s
checks / test (3.11, highest, ubuntu-latest)	46s
checks / test (3.10, highest, windows-latest)	2m 40s
checks / test (3.10, highest, ubuntu-latest)	48s
checks / test (3.12, lowest-direct, ubuntu-latest)	49s
checks / test (3.12, highest, ubuntu-latest)	50s
checks / test (3.11, highest, windows-latest)	2m 28s
checks / test (3.13, lowest-direct, ubuntu-latest)	43s
checks / test (3.13, lowest-direct, windows-latest)	2m 22s
checks / test (3.13, highest, ubuntu-latest)	47s
checks / test (3.13, highest, windows-latest)	2m 30s
checks / test (3.12, highest, windows-latest)	4m 6s
	30m 3s

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