MODEL ROUTER SPEC TEMPLATE (v1)

Purpose
Define a stable contract between the product and any model provider. This document is the source of truth for routing, policy, telemetry, and change control.

1) Supported Providers + Models
- Provider list: (e.g., OpenAI, Anthropic, Google)
- Allowed model identifiers per provider
- Default model per capability (drafting, extraction, classification, code, summarization)
- Fallback order per capability

2) Request Contract (Inputs)
- Message format (roles allowed, max message count)
- System instruction ownership: which team can change it, where it lives
- Tool schema registry: name, input JSON schema, output schema
- Retrieval payload format: query, doc IDs, snippet text, metadata fields
- Redaction: what is removed or masked before sending to provider

3) Response Contract (Outputs)
- Required fields: final_text, structured_json (if applicable), citations[], tool_trace[], refusal_reason
- JSON schema rules (strict/loose), and what happens on violation
- Citation rules: when required, allowed sources, formatting

4) Policy Layer
- Tenant policies: tools allowed, data residency constraints, citation requirements
- Content policies: disallowed tasks, escalation rules, refusal taxonomy
- Prompt-injection defenses: tool allowlist, instruction hierarchy, sensitive string filters
- Human-in-the-loop gates: which tool calls require approval

5) Routing Rules
- Capability-based routing: which model for which task type
- Context-based routing: long context vs short; tool-heavy vs no-tools
- Degrade modes: no tools, no retrieval, smaller model, “summarize only”
- Timeouts, retries, and circuit breaker conditions (schema failures, tool loops, refusal spikes)

6) Telemetry + Audit
Log per request (minimum):
- request_id, tenant_id, user_id (or anonymized ID)
- provider, model, model_version if available
- policy bundle applied (policy ID/version)
- retrieval trace: doc IDs/snippet IDs used
- tool calls: names, inputs (redacted), outputs (redacted)
- outcome: latency, errors, schema_valid, user feedback event
Retention rules and access controls for logs.

7) Evaluation + Release Control
- Golden set definition: where examples come from, redaction rules
- Offline eval cadence and ownership
- Canary process: traffic percent, success criteria, rollback triggers
- Change log: every model/prompt/policy change requires an entry with date + owner

8) Security Checklist (Ship/No-Ship)
- Tools cannot access unscoped credentials
- All tool calls validated against schema
- PII redaction tested with real examples
- Request tracing enabled in production
- Fallback mode tested (provider outage simulation)

How to Use
- Put this file in your repo.
- Assign owners: Product (policy), Engineering (routing + telemetry), Security/Legal (data handling).
- Treat changes like API changes: review, canary, and document.