The smoke writer fed the endpoint to `model.provider: custom` through .env
OPENAI_BASE_URL, which runtime_provider's bare-`custom` trust path never reads
on v2026.8.31 -- that tree's own comment: "OPENAI_BASE_URL env var is no longer
consulted -- config.yaml is the single source of truth for endpoint URLs". So
the app's readiness check (setup.runtime_check) resolved `custom` to no endpoint
and booted behind its onboarding overlay ("No usable credentials found for
custom. setup.status reports configured credentials, but runtime resolution
still failed"), which is why every installer-script+desktop leg failed at its
OLD checkpoint and why the desktop smoke's trial click never landed.
Reproduced against the real ladder before changing anything: with the writer's
config, resolve_runtime_provider(requested='custom') raises
"provider 'custom' resolved without credentials (no endpoint or API key
configured)"; adding
model.base_url makes it resolve to the mock URL (api_key no-key-required, the
loopback bypass). A custom_providers entry alone is not enough, so the endpoint
now goes where both vintages read it. The named/custom:<name> entry and the .env
pair stay for the consumers that use them.
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