Follow-up to 54e61f933. The plugin enablement gate calls
``entry.is_connected(probe_cfg)`` BEFORE ``env_enablement_fn`` runs,
and the probe is built as ``existing_cfg or PlatformConfig()`` — empty
extras, ``enabled=False``.
For plugins whose ``is_connected`` reads ``config.extra`` instead
of env vars directly, that probe is a misrepresentation of what the
platform will look like after enablement. Google Chat's
``_is_connected`` short-circuits on ``config.enabled`` and inspects
``config.extra["project_id"]`` / ``config.extra["subscription_name"]``
— both False on the default probe even when the user has set
``GOOGLE_CHAT_PROJECT_ID`` and ``GOOGLE_CHAT_SUBSCRIPTION_NAME``. Result:
Google Chat silently fails the gate on every env-var-only setup.
Build a candidate probe that mirrors what the platform will look like
post-enablement:
- pre-call ``env_enablement_fn`` and layer its result into the probe's
``extra`` (without mutating any existing platform config)
- pass ``enabled=True`` on the probe — we're asking "would this BE
configured if we let it in?" not "is it currently enabled?"
- reuse the same seeded extras when we commit the platform to
``config.platforms`` (avoids calling ``env_enablement_fn`` twice)
Discord/IRC/Teams/LINE/ntfy/Simplex ``_is_connected`` hooks read env
vars directly, so they are unaffected. This change only restores
Google Chat on env-var-only setups while keeping the original #31116
Discord-no-token block intact.
All 6 shipped ``env_enablement_fn`` implementations were audited and
are pure reads (no ``os.environ`` writes), so running them earlier in
the loop has no observable side effects.
Tests: 2 new in tests/gateway/test_platform_registry.py covering
extras-seeded-before-is_connected and don't-leak-extras-on-gate-fail.
693 tests across 11 adjacent suites pass (platform_registry, config,
google_chat, matrix, discord_connect, ntfy_plugin, simplex_plugin,
line_plugin, irc_adapter, teams, gateway_platform_gating).
Refs #31116.
396ee69032