feat: Per-plugin & per-skill cost attribution #201
Description
Break down token usage and cost by OpenClaw plugin, skill, and context source. With OpenClaw 2026.3.7 adding context-engine plugins and prependSystemContext/appendSystemContext, cost profiles are changing and users need visibility.
Why: Langfuse just shipped "spend-by-feature" dashboards. OpenClaw's plugin ecosystem is growing (Memori Labs plugin launched March 13). Users need to know which plugins are expensive.
Scope:
- Parse session data to attribute tokens to: base prompt, plugins, skills, user message, tool calls
- Dashboard breakdown: pie chart of cost by source
- Trend over time: which plugins are getting more expensive?
- Alert if a specific plugin's cost share exceeds threshold
Source: OpenClaw 2026.3.7 changelog, Langfuse spend-by-feature, Memori Labs plugin launch