# Regression Watch

Detect quality and efficiency regressions over time using Agent Monitor data, rising...

- Repository: https://github.com/hoangsonww/Claude-Code-Agent-Monitor (1136 stars)
- Category: AI and agents
- License: MIT
- Last updated: 2026-10-31
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add hoangsonww/Claude-Code-Agent-Monitor --skill regression-watch -g -a claude-code -y`
Codex: `npx skills add hoangsonww/Claude-Code-Agent-Monitor --skill regression-watch -g -a codex -y`
Cursor: `npx skills add hoangsonww/Claude-Code-Agent-Monitor --skill regression-watch -g -a cursor -y`
Gemini CLI: `npx skills add hoangsonww/Claude-Code-Agent-Monitor --skill regression-watch -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add hoangsonww/Claude-Code-Agent-Monitor`

## Description

Detect quality and efficiency regressions over time using Agent Monitor data, rising error rate (APIError events), falling cache hit rate, growing compaction frequency, and climbing cost-per-session. Splits history into an earlier baseline window and a recent window and reports which metrics are getting worse, by how much, and where. Use when checking whether things are degrading or trending in the wrong direction.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Regression Watch

Detect whether Claude Code sessions are getting worse over time across quality and
efficiency metrics, using Agent Monitor data.

## Input

The user provides: **$ARGUMENTS**

This may be:
- empty or "all", check every regression metric (default)
- "errors", error-rate regression only
- "cache", cache hit-rate regression only
- "compaction", compaction-frequency regression only
- "cost", cost-per-session regression only
- A window like "last 30d" or "30 vs 90", set the recent vs baseline window sizes

## Data Sources

| Endpoint | Returns |
|----------|---------|
| `GET /api/analytics` | `daily_events` (365d), `daily_sessions` (365d), `event_types`, `tokens` (total_input, total_output, total_cache_read, total_cache_write, baselines pre-summed), `avg_events_per_session` |
| `GET /api/events?session_id=X` | Event stream incl. `APIError`, `Compaction`, `PreToolUse`/`PostToolUse`, used to localize regressions to specific sessions |
| `GET /api/pricing/cost` | `{ total_cost, breakdown[...] }`, total cost to derive cost-per-session |
| `GET /api/pricing/cost/{sessionId}` | Per-session cost, used to compare recent vs baseline session cost |
| `GET /api/workflows/{sessionId}` | `compaction` (impact), `errorPropagation` (by depth), `effectiveness`, per-session quality signals |
| `GET /api/sessions?limit=N` | Sessions with `started_at`, `cost`, `metadata`, to bucket sessions into time windows |

## Report Sections

### 1. Windowing
Split history into a **baseline window** (older) and a **recent window** (newer).
Default: recent = last 30 days, baseline = the 30, 90 day range before it. Use
`daily_events`/`daily_sessions` for series metrics and `GET /api/sessions?limit=N`
to assign sessions to each window by `started_at`.

The rest: https://github.com/hoangsonww/Claude-Code-Agent-Monitor/blob/HEAD/plugins/ccam-insights/skills/regression-watch/SKILL.md