lex-llm-ledger

LLM observability persistence for LegionIO. Consumes metering and audit messages from AMQP queues, decrypts audit payloads, enforces retention policies, and writes records to a database for usage reporting and compliance.

• metering_records - One row per LLM inference (tokens, cost, latency, routing)
• prompt_records - Full prompt/response audit with retention TTL and PHI classification
• tool_records - Tool call audit linked to parent prompt via correlation_id

• Consumer only - never publishes to any exchange
• Passive exchange references - does not declare llm.metering or llm.audit (owned by legion-llm)
• DecryptionUnavailable causes NACK - messages requeue until the node has Vault credentials
• PHI TTL cap - records flagged contains_phi are capped at 30 days regardless of retention label
• Idempotent writes - duplicate message_id inserts are silently dropped

• legion-data >= 1.6 (Sequel DB connection)
• legion-json >= 1.2 (JSON serialization)
• legion-transport >= 1.4 (AMQP transport)
• legion-crypt >= 1.5 (for decrypting audit messages, optional at runtime)

# Metering write (called by MeteringWriter actor)
Legion::Extensions::LLM::Ledger::Runners::Metering.write_metering_record(payload, metadata)

# Usage summary
Legion::Extensions::LLM::Ledger::Runners::UsageReporter.summary(period: 'day', group_by: 'provider')

# Budget check
Legion::Extensions::LLM::Ledger::Runners::UsageReporter.budget_check(budget_id: 'budget_q1', budget_usd: 100.0)

# Provider health
Legion::Extensions::LLM::Ledger::Runners::ProviderStats.health_report

bundle install
bundle exec rspec
bundle exec rubocop

MIT