Per hermes-sweeper review on #56671: the fallback exclusion matched any
canonical string starting with "custom" (e.g. "customproxy"), not just
the durable named-custom-provider syntax ("custom" bucket or
"custom:<name>" slugs). Narrow it to an exact/prefix match on that
syntax so unrelated vendor names aren't accidentally exempted from the
openrouter fallback.
Also clarifies the test suite: a properly configured custom:<name>
provider now resolves via resolve_custom_provider before this fallback
is ever reached (added upstream in 9a15fad0d6), so the existing test
was mislabeled as exercising that primary path when it was actually
exercising the fallback-safety-net case (missing/unresolved config
entry). Split into explicit primary-path and fallback-safety-net tests,
plus a regression test for the "customproxy"-style false positive.
_normalize_main_model_assignment() (POST /api/model/set, the endpoint
Desktop's Settings -> Model page uses to persist the main model slot) has
a fallback for a specific analytics bug: an older session row with no
billing_provider sends the model's bare vendor prefix as "provider"
(e.g. "anthropic" from "anthropic/claude-opus-4.6"), so the code detects
an unrecognized provider paired with a slash-bearing model and treats it
as that stray-vendor-prefix case.
Named custom providers are represented as "custom:<name>" slugs
everywhere else in the codebase (runtime_provider.py, model_switch.py),
but _KNOWN_PROVIDER_NAMES only lists the bare "custom" bucket. So picking
a named custom provider (e.g. "custom:litellm", a LiteLLM proxy fronting
Ollama) together with a slash-bearing model ("ollama/glm-5.2") looked
identical to the stray-vendor-prefix case and got silently rewritten to
provider: openrouter in config.yaml on save -- reassigning the provider
entirely, not just mangling the model id.
Exclude anything starting with "custom" from the fallback, matching the
guard the same function already applies later for the actual
normalize_model_for_provider call.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
homelab-ha-agent