Model Router | Zyeon UI

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status='ready' — five ordered rules over one shared fallback chain. The prompt in the test box hits rule 3 on the keyword 'stack trace': rules 1 and 2 mark the condition that failed, rule 4 says it was never evaluated (first match wins) and rule 5 says it is switched off. Clear the box and type 'thanks!' — nothing claims it, so the default route lights up; now flip 'Cheap chatter' on and rule 5 takes it. Flipping 'EU data residency' off is rejected 600 ms later: the switch snaps back and the row prints why.

4 of 5 rules on · evaluated top to bottom, first match wins

Test a prompt against this policy

signals

+ attached contexttokens

≈ 66 tokens — a rough estimate (characters ÷ 4 plus attached context), not your provider's tokenizer.

Rule 3 “Code, tests & stack traces” claims it → Halcyon 1 Reasoning

Rule 1: EU data residencyNot a match
Contractual: nothing from an EU workspace may leave eu-central-1.
eu tenant (not met)
route toBeacon 8B InstructSelf-hostedstays in eu-central-1
Rule 2: Images & screenshotsNot a match
Screenshots, PDFs and whiteboard photos need the vision model.
image attached (not met)
route toNorthwind 4 LargeNorthwind AIdetail: high
Rule 3: Code, tests & stack tracesClaims this prompt
Debugging and refactoring go to the reasoning model, sampled cold.
any ofmentions stack trace · exception · segfault · refactor +2 more (met)starts a line with code (not met)
route toHalcyon 1 ReasoningHalcyon Labstemperature 0.2 · 8k max output
Rule 4: Long documentsNot evaluated · rule 3 matched first
Anything above the summariser threshold is chunked and map-reduced.
≥ 32,000 tokens
route toNorthwind 4 LargeNorthwind AImap-reduce · 1M context
Rule 5: Cheap chatterOff · the router skips it
One-liners and follow-ups don't need a frontier model. Off until the eval lands.
all of< 600 tokensno image attached
route toBeacon 8B InstructSelf-hosted512 max output · no tools

no rule matches →Northwind 3.5 TurboNorthwind AIthe house default

Fallback chain

Halcyon 1 ReasoningHalcyon Labschosen by rule 3temperature 0.2 · 8k max output
on 429 · overloaded
Halcyon 1 ReasoningHalcyon LabsDown
on 5xx or timeout over 20 s
Northwind 3.5 TurboNorthwind AIDegradedretries land herep95 latency 3× normal
when every hosted provider fails
Beacon 8B InstructSelf-hostedanswers get shorter, nothing goes offline

If the chosen model fails, the request retries on Northwind 3.5 Turbo. 1 hop above it is down and skipped.

no test callback yet

The same policy with matchRule delegated to a stand-in embedding classifier. It claims the prompt for the code rule although no keyword in the policy appears in that sentence — and the per-condition ✓/✗ marks disappear, because the panel did not compute this verdict and will not invent an explanation for it.

4 of 5 rules on · evaluated top to bottom, first match wins

Test a prompt against this policy

signals

+ attached contexttokens

≈ 16 tokens — a rough estimate (characters ÷ 4 plus attached context), not your provider's tokenizer.

Rule 3 “Code, tests & stack traces” claims it → Halcyon 1 Reasoning

Rule 1: EU data residency
Contractual: nothing from an EU workspace may leave eu-central-1.
eu tenant
route toBeacon 8B InstructSelf-hostedstays in eu-central-1
Rule 2: Images & screenshots
Screenshots, PDFs and whiteboard photos need the vision model.
image attached
route toNorthwind 4 LargeNorthwind AIdetail: high
Rule 3: Code, tests & stack tracesClaims this prompt
Debugging and refactoring go to the reasoning model, sampled cold.
any ofmentions stack trace · exception · segfault · refactor +2 morestarts a line with code
route toHalcyon 1 ReasoningHalcyon Labstemperature 0.2 · 8k max output
Rule 4: Long documents
Anything above the summariser threshold is chunked and map-reduced.
≥ 32,000 tokens
route toNorthwind 4 LargeNorthwind AImap-reduce · 1M context
Rule 5: Cheap chatterOff · the router skips it
One-liners and follow-ups don't need a frontier model. Off until the eval lands.
all of< 600 tokensno image attached
route toBeacon 8B InstructSelf-hosted512 max output · no tools

no rule matches →Northwind 3.5 TurboNorthwind AIthe house default

Fallback chain

Halcyon 1 ReasoningHalcyon Labschosen by rule 3temperature 0.2 · 8k max output
on 429 · overloaded
Halcyon 1 ReasoningHalcyon LabsDown
on 5xx or timeout over 20 s
Northwind 3.5 TurboNorthwind AIDegradedretries land herep95 latency 3× normal
when every hosted provider fails
Beacon 8B InstructSelf-hostedanswers get shorter, nothing goes offline

If the chosen model fails, the request retries on Northwind 3.5 Turbo. 1 hop above it is down and skipped.

A policy that grew in the dark: a regex that no longer compiles (flagged, never matches), a rule carrying 14 trigger words (4 chips + '+10 more', never silently cut), a 68-character model name that wraps instead of widening the card, and a 'temporary' catch-all at position 4 that has quietly killed rules 5 and 6 — the header says so, and the chain below is down at every hop. Switch the catch-all off and the warning clears.

6 of 6 rules on · evaluated top to bottom, first match wins

Rule 4 claims every request — nothing below it can ever match.

Test a prompt against this policy

signals

+ attached contexttokens

≈ 13 tokens — a rough estimate (characters ÷ 4 plus attached context), not your provider's tokenizer.

Rule 4 “Catch everything (temporary)” claims it → Northwind 3.5 Turbo

Rule 1: Triage by patternNot a match
Migrated from the old YAML config and never compiled since.
invalid pattern: (?<unclosed[a-z (not met)
route toHalcyon 1 ReasoningHalcyon Labs
Rule 2: Platform vocabularyNot a match
Grown one word at a time over eleven months.
mentions parse matrix · generate protocol · connect monitor · override circuit +10 more (not met)
route toNorthwind 4 LargeNorthwind AItemperature 0.7
Rule 3: Offline evaluation harness · nightly regression sweep over the golden setNot a match
eval harness (not met)
route toInternal Platform Evaluation Checkpoint 2026-03-11 · RC4 (quantized)Platform Researchpinned by the applied evaluation group
Rule 4: Catch everything (temporary)Claims this prompt
Added during the 4 March incident. Nobody removed it.
no conditions · catch-all
route toNorthwind 3.5 TurboNorthwind AIadded 2026-03-04
Rule 5: Long documentsNot evaluated · rule 4 matched first
≥ 128,000 tokens
route toNorthwind 4 LargeNorthwind AI
Rule 6: Weekend savingsNot evaluated · rule 4 matched first
mentions weekend · batch
route toBeacon 8B InstructSelf-hosted

Fallback chain

Northwind 3.5 TurboNorthwind AIchosen by rule 4added 2026-03-04
on 429 · overloaded
Northwind 4 LargeNorthwind AIDown
on 5xx
Halcyon 1 ReasoningHalcyon LabsDown
last resort
Beacon 8B InstructSelf-hostedDown

Every hop in this chain is down — a failed request has nowhere left to go.

status='empty' — no rules at all, so every request goes to the default model. The CTA seeds the first rule for real: the panel becomes ready, with a working policy inside it.

No routing rules yet

Every request goes to the default model until a rule claims it. Add one to send code, long context or cheap chatter somewhere else.

status='loading' — the policy document itself hasn't arrived; the skeleton keeps the shape of a rule row so nothing jumps when it does.

status='error' — reading the policy failed. That is a different failure from a model failing, which is what the fallback chain is for, so it reads differently and offers a retry.

Couldn't load the routing policy

The policy service answered 503. request-id: 7f2c-9ad1

onRetry not called yet

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