Serve the 2026-07-28 protocol over stdio: decide the era from the opening request #3595

Job	Run time
checks / readme-snippets	12s
checks / pre-commit	54s
checks / test (3.12, locked, windows-latest)	1m 58s
checks / test (3.10, locked, windows-latest)	2m 50s
checks / docs	1m 5s
checks / test (3.11, lowest-direct, windows-latest)	1m 55s
checks / test (3.12, locked, ubuntu-latest)	1m 32s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 23s
checks / test (3.10, locked, ubuntu-latest)	1m 34s
checks / test (3.14, lowest-direct, windows-latest)	1m 53s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 16s
checks / test (3.12, lowest-direct, windows-latest)	2m 11s
checks / test (3.11, locked, ubuntu-latest)	1m 27s
checks / test (3.13, locked, windows-latest)	1m 58s
checks / test (3.14, locked, ubuntu-latest)	1m 23s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 22s
checks / test (3.11, locked, windows-latest)	1m 50s
checks / test (3.10, lowest-direct, windows-latest)	1m 50s
checks / test (3.13, lowest-direct, windows-latest)	1m 55s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 24s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 20s
checks / test (3.13, locked, ubuntu-latest)	1m 7s
checks / test (3.14, locked, windows-latest)	2m 2s
all-green	4s
	36m 25s

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