Files
OmniRoute/docs/adr/002-fallback-strategy.md
diegosouzapw f44ec7e1f2 feat: complete all 46 tasks — ADRs, eval framework, compliance, a11y, CLI, Playwright specs (Batch B)
T-30 — ADRs:
- 6 ADRs: SQLite, Fallback Strategy, OAuth, JS+JSDoc, Single-Tenant, Translator Registry

T-33 — JSDoc Coverage:
- Full JSDoc on all new modules (100% exported functions documented)

T-35 — Accessibility:
- a11yAudit.js: lightweight WCAG AA checker (aria-label, dialog role, alt text, labels)

T-38 — Password Reset CLI:
- bin/reset-password.mjs: interactive CLI tool for admin password reset

T-39 — Playwright Specs:
- tests/e2e/responsiveSpecs.mjs: viewports (375/768/1280), 4 pages, test matrix

T-42 — Eval Framework:
- evalRunner.js: 4 strategies (exact, contains, regex, custom) + golden set (10 cases)

T-43 — Compliance:
- audit_log table, noLog opt-out per API key, LOG_RETENTION_DAYS cleanup

TASKS.md: 46/46 Concluído 
Tests: 144/144 pass (119 existing + 25 new)
2026-02-14 19:18:02 -03:00

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1.4 KiB
Markdown

# ADR-002: Multi-Provider Fallback Strategy
**Date:** 2025-11-20
**Status:** Accepted
**Deciders:** @diegosouzapw
## Context
OmniRoute routes requests to multiple LLM providers (OpenAI, Anthropic, Google, etc.). Providers may become unavailable due to rate limiting, outages, or credential expiry. The system needs a strategy to handle these failures gracefully.
## Decision
Implement a **declarative fallback chain** with three layers:
1. **Credential Retry Loop** — Rotate through available credentials for the same provider before failing
2. **Model Fallback Policy** — Configurable fallback chain per model (e.g., `gpt-4o → azure-gpt-4o → anthropic-claude`)
3. **Circuit Breaker** — Trip open after consecutive failures to prevent cascading requests to broken providers
The fallback policy is defined in `src/domain/fallbackPolicy.js` and integrates with the circuit breaker in `src/shared/utils/circuitBreaker.js`.
## Consequences
### Positive
- Automatic failover with zero user intervention
- Per-model granularity — different models can have different fallback strategies
- Circuit breaker prevents wasting quota on broken providers
### Negative
- Fallback chain requires manual configuration per model
- Response latency increases when primary fails (retry + fallback time)
### Neutral
- Lockout policy (n consecutive failures → temporary block) complements but is separate from fallback