---
title: "Session: prometheus-metrics — 2026-09-29"
type: source
tags: [claude-code, session-transcript, demo]
date: 2026-09-29
source_file: raw/sessions/edge-cache/2026-09-29-prometheus-metrics.md
sessionId: demo-264063653408
slug: prometheus-metrics
project: edge-cache
started: 2026-09-29T15:30:00+00:00
ended: 2026-09-29T16:54:00+00:00
cwd: /home/dev/code/edge-cache
gitBranch: feat/metrics
permissionMode: default
model: claude-sonnet-4-6
user_messages: 1
tool_calls: 4
tools_used: [Bash, Edit, Write]
tool_counts: {"Write": 2, "Edit": 1, "Bash": 1}
token_totals: {"input": 8400, "cache_creation": 16800, "cache_read": 50400, "output": 2800}
turn_count: 1
hour_buckets: {"2026-09-29T15": 4, "2026-09-29T16": 7}
duration_seconds: 5040
is_subagent: false
---

# Session: prometheus-metrics — 2026-09-29

**Project:** `edge-cache` · **Branch:** `feat/metrics` · **Mode:** `default` · **Model:** `claude-sonnet-4-6`

## Summary

Exposed Prometheus metrics: hit/miss/stale counters per route, an origin latency histogram with sensible buckets, and a gauge for in-flight refreshes. Added a Grafana dashboard JSON to the repo.

## Conversation

### Turn 1 — User

Add metrics so we can see the hit ratio per route.

### Turn 1 — Assistant

Counters labelled by route and result, latency histogram for origin fetches, in-flight gauge. Route labels come from the matched pattern, not the raw path, to keep cardinality low.

**Tools used in this turn:**

- `Write`: metrics/metrics.go
- `Edit`: cache/handler.go
- `Write`: deploy/grafana/edge-cache.json
- `Bash`: go test ./... — ok

## Connections

- [[edge-cache]]
- [[Prometheus]]
- [[Grafana]]
- [[Observability]]