B5 and B6 make different promises about an adopted scoreboard, and only the
second is obvious. The table:
| bundled copy present | bundled copy removed
pinned old core | loads (the fallback) | ERROR, naming the module
current core | loads, using core code | loads, using core code
The top-left cell is the one worth having. Nothing in the suite proved that an
adopted plugin still runs on a core predating src.common.sports_scroll, and
that claim is the entire basis for having shipped B5 ahead of B6's gate.
The bottom-left cell is asserted through PluginManager.load_plugin rather than
a bare import, deliberately. The manager catches the ModuleNotFoundError, so a
test written around pytest.raises would pass against a core where the module is
merely broken rather than absent, and would say nothing about what the user
meets: a plugin parked in ERROR and one log line. The assertion is the ERROR
state plus an error naming the module, which is what makes the log actionable.
Modelling notes, both of which were wrong first time and matter:
- The copy-removed shape is an UNGUARDED import, not the guarded one with the
legacy file deleted. Keeping the guard while removing its fallback only
mislabels the failure -- the plugin reports a missing scroll_display_legacy
and never mentions the core module that is actually absent.
- Only the leaf module is hidden. A pre-3.2.0 core still ships src/common/;
hiding the package would be a harsher core than any that shipped, and would
make the failure name the package instead of the module.
Ablation: disabling the old-core simulation fails three cells, and dropping the
error object from load_plugin's set_state fails the fourth, so none of it
passes vacuously. The install gate -- the other half of the guarantee -- stays
in test_plugin_compatibility_gate.py rather than being duplicated here.
Refs docs/SPORTS_UNIFICATION.md, "B6 -- why the sunset needs more than a
version floor".
Claude-Session: https://claude.ai/code/session_01STMbQE4YctTacQXfbYqKuW
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
