[v2] Dispatcher/ServerRunner receive-path swap — replaces BaseSession #2512

Job	Run time
checks / pre-commit	32s
checks / readme-snippets	11s
checks / test (3.11, locked, ubuntu-latest)	45s
checks / test (3.12, lowest-direct, windows-latest)	1m 44s
checks / test (3.10, locked, windows-latest)	1m 22s
checks / test (3.10, locked, ubuntu-latest)	48s
checks / test (3.11, lowest-direct, ubuntu-latest)	55s
checks / test (3.10, lowest-direct, windows-latest)	1m 21s
checks / test (3.11, lowest-direct, windows-latest)	1m 15s
checks / test (3.12, locked, ubuntu-latest)	57s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 0s
checks / test (3.11, locked, windows-latest)	1m 17s
checks / test (3.14, lowest-direct, windows-latest)	1m 46s
checks / test (3.14, locked, windows-latest)	2m 5s
checks / test (3.14, lowest-direct, ubuntu-latest)	50s
checks / test (3.13, locked, ubuntu-latest)	49s
checks / test (3.10, lowest-direct, ubuntu-latest)	51s
checks / test (3.13, locked, windows-latest)	1m 26s
checks / test (3.13, lowest-direct, ubuntu-latest)	56s
checks / test (3.13, lowest-direct, windows-latest)	1m 35s
checks / test (3.12, locked, windows-latest)	1m 22s
checks / test (3.14, locked, ubuntu-latest)	2m 0s
all-green	6s
	25m 53s

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