Δρομολόγηση και πολιτική
Routing here means one thing: an OpenAI-compatible request goes in, and a pure function picks the endpoint that answers it. It filters the candidate endpoints down to the ones your policy allows, scores what survives, and takes the highest score. When the filter leaves nothing, the request fails with 409 no_endpoint_for_policy: residency is a filter, never a preference, and the failover path cannot step outside the set the filter produced.
The filter, in the order the router applies it
Each rejection below is a literal reason string from packages/router/src/engine.mjs, recorded per endpoint on the router's own decision. The order matters: the kind of an endpoint is decided before its status, residency before the provider and model lists, and price last — so the first reason an endpoint is rejected is the one that explains the route.
| Step | What it removes | Recorded reason |
|---|---|---|
| 1 | a row whose kind is catalogue_only: nothing on this deployment answers a request with it, so it is rejected before any other rule is considered | catalogue_only |
| 2 | an endpoint whose status is neither up nor degraded | endpoint_<status> |
| 3 | an endpoint whose sovereignty class is in neither the policy nor the residency the request asked for | residency:<class> |
| 4 | an endpoint whose region falls outside the scope of the residency the request named | residency_region:<region> |
| 5 | an endpoint in a region the residency values of the policy do not name | policy_region:<region> |
| 6 | a model that cannot generate text — a speech-recognition, embedding or reranker model | not_a_text_model |
| 7 | a model whose provider is listed in providers_deny | provider_denied |
| 8 | a model whose provider is missing from a non-empty providers_allow | provider_not_allowed |
| 9 | a model whose slug is listed in models_deny | model_denied |
| 10 | a model whose slug is missing from a non-empty models_allow | model_not_allowed |
| 11 | a partner endpoint while allow_partner_endpoints is off and the request does not set llmeu.allow_partners | partner_not_allowed |
| 12 | a model without the vision modality when the request carries an image | vision_required |
| 13 | a model whose documented context window is smaller than the input plus max_tokens the request needs | context_too_small:<window><<needed> |
| 14 | a model priced above the cap in the policy or in llmeu.max_usd_per_1m | price_above_cap:<micros> |
catalogue_unknown is not an addressable residency: a row that carries it does not know where it runs, so it can never win a route. Residency is applied as a filter before scoring, and the score never chooses between allowed and disallowed endpoints, because the disallowed ones are already gone.
The policy fields that decide a route
These are the fields packages/router/src/engine.mjs reads from the policy row while it filters. The console writes them; nothing else is consulted during filtering. The full column list with its types is on the policies page.
| Field | What it decides | Default |
|---|---|---|
| residency_allowed | which sovereignty classes and regions an endpoint may have; llmeu.residency in the request can only narrow it | ["eu_owned_eu_operated","eu_region_of_non_eu_parent"] |
| providers_allow | the only providers that may be used, once the list is not empty | [] — any |
| providers_deny | providers that may never be used, checked before the allow list | [] |
| models_allow | the only models that may be used, once the list is not empty | [] — any |
| models_deny | model slugs that may never be used | [] |
| allow_partner_endpoints | whether partner endpoints are eligible at all; the request can set this for a single call with llmeu.allow_partners | 0 |
| max_usd_per_1m | a price ceiling per million tokens; llmeu.max_usd_per_1m in the request can only lower it | null — no cap |
Three further policy columns never reach the engine, because they are checked one layer up in apps/api/src/inference.mjs around the same decision: retention (a request may ask for less, never more, and only zero is implemented), data_classes_allowed, and max_usd_per_day — a daily budget that is used up fails the request before any endpoint is scored, with budget_exceeded. A request that names no residency gets the set of the policy itself: eu-hosted while every class the policy admits is EU-hosted, and any once it admits anything else.
The score
Price and latency are normalised across the surviving set, so the score compares candidates with each other rather than against a fixed scale. A candidate with no recorded latency is scored at 500 ms.
score = task_fit * 5
+ language_fit * 3
+ docs_completeness * 1
+ sovereignty_bonus * 2
- price_norm * 2
- latency_ewma * 2
- error_rate * 3Ties break on lower price, then lower latency, then a stable id — so the same request always routes the same way.
Nothing satisfies the policy: 409 no_endpoint_for_policy
The filter is a filter, not a preference. When nothing survives it, the request fails with 409 no_endpoint_for_policy, and the router does not fall back to a wider residency, another region or a similar model to make the call succeed.
What to change is in the message. It is the engine's own sentence — that no endpoint satisfies the residency the request named, followed by "Residency is never relaxed silently." A model that was named by slug appears in the message too. The llmeu block of such an error carries the requested model, and the trace records the residency that was requested and the refusal. On a successful route the same sentence reports how many endpoints were excluded.
What helps: name a residency your policy does allow, widen the policy deliberately in the console (a decision, with a changelog entry), or accept that no route exists for that model under that rule. A 409 is the rule working, not a transient failure — the same request fails the same way again.
Failover
On a 5xx or an unreachable backend the next-best candidate is tried, up to three attempts (MAX_ATTEMPTS in apps/api/src/inference.mjs). Every attempt is recorded on the trace as failed_over. An error the backend marks as final is not retried at all.
Route reason
Every decision produces one sentence naming the region and the reason, shown verbatim in the console and returned as route_reason:
auto routing for task "coding" + residency eu-hosted + qwen3-coder-30b @ de-ber (EU-owned, EU-operated); 4 endpoint(s) excluded; partner endpoints not allowed.Συχνές ερωτήσεις
How does the router choose a model when I ask for llmeu-auto?
It does not pin one. Every endpoint that passes the filter stays in the pool, each candidate is scored, and the highest score wins; a tie breaks on the cheaper model, then the lower recorded latency, then the endpoint id, so the same request routes the same way twice. The answer reports the choice in its llmeu block: model_used, inference_region, sovereignty_class, policy_id and the route_reason sentence.
Which policy fields change the route?
residency_allowed decides which endpoints may be reached at all. providers_allow and providers_deny, then models_allow and models_deny, remove whole providers and models. The partner rule (allow_partner_endpoints), the vision requirement, the context window and max_usd_per_1m are the last four filters. retention, data_classes_allowed and max_usd_per_day are enforced in apps/api/src/inference.mjs around the same decision, not inside the engine.
What happens when no endpoint satisfies my residency?
The request fails with 409 no_endpoint_for_policy and the router does not widen the rule: the message is the engine's own sentence that no endpoint satisfies the residency that was requested, followed by "Residency is never relaxed silently." Nothing is retried somewhere else to make the call succeed. Change the residency, widen the policy deliberately, or accept that no route exists.
Can a failover attempt leave the region my policy allows?
No. failoverOrder() builds its list from the decision that was already filtered — the chosen endpoint first, then its scored alternatives, up to three attempts — so every retry is inside the set the policy and the residency produced. A 5xx or an unreachable backend is retried; an error the backend marks as final stops the request instead.
Why did asking for a specific model fail instead of routing somewhere else?
Because a named model is pinned. When no endpoint of that model survives the filter, the engine names the reason instead of substituting another model: model_not_found for a slug that does not exist, hosted_unavailable for a catalogue-only model, model_denied when a policy list excludes the model or its provider, not_a_text_model for a speech-recognition, embedding or reranker model. Only a model that exists, is allowed and can generate text falls through to no_endpoint_for_policy.
Is EU routing a preference for European endpoints, or a rule?
A rule. Residency is filtered before scoring, so a model outside the permitted set is never in the comparison — and catalogue_unknown is not an addressable residency at all, so a row that carries it never wins a route. What the score does prefer is documented sovereignty: a class you can check on the endpoint row earns points, and price, latency and recorded error rate cost points.