Serve the 2026-07-28 protocol over stdio: decide the era from the opening request #3596

Job	Run time
checks / pre-commit	51s
checks / docs	1m 3s
checks / readme-snippets	13s
checks / test (3.10, locked, windows-latest)	1m 50s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 13s
checks / test (3.12, locked, ubuntu-latest)	1m 41s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 22s
checks / test (3.10, locked, ubuntu-latest)	1m 31s
checks / test (3.12, lowest-direct, windows-latest)	1m 55s
checks / test (3.11, locked, windows-latest)	1m 53s
checks / test (3.10, lowest-direct, windows-latest)	1m 58s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 21s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 21s
checks / test (3.11, locked, ubuntu-latest)	1m 29s
checks / test (3.14, lowest-direct, windows-latest)	1m 57s
checks / test (3.14, locked, windows-latest)	1m 53s
checks / test (3.13, locked, windows-latest)	1m 53s
checks / test (3.14, locked, ubuntu-latest)	1m 18s
checks / test (3.13, locked, ubuntu-latest)	1m 20s
checks / test (3.13, lowest-direct, windows-latest)	1m 55s
checks / test (3.11, lowest-direct, windows-latest)	2m 21s
checks / test (3.12, locked, windows-latest)	2m 2s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 20s
all-green	4s
	35m 44s

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