# ADR: Introduce Tool Slim Mode, Real-Time Session Spend Meter, and Cost-Threshold Escalation

**Date**: 2026-04-10
**Status**: Accepted
**Affects**: src/llm_router/, tests/, .claude-plugin/, .factory-plugin/, CHANGELOG.md, README.md
**Risk**: high
**Reversibility**: low

## Decision

To save context tokens by registering only necessary tools (slim mode), provide real-time visibility into API costs (session spend meter), and prevent runaway costs (cost-threshold escalation). These features improve cost efficiency, user awareness, and system reliability, addressing a major version's focus on 'Token Efficiency, Real-Time Spend, Feedback Learning'.

## Consequences

_To be annotated as consequences become clear._
