Buildtime

buildtime

Your builds keep getting slower, but which step is to blame? buildtime profiles a set of CI runs — per-step durations and, where known, cache hits — and answers with the numbers that point at the bottleneck:

• Per-step statistics — for every distinct step name: how many runs contained it, its total, average, and maximum duration, and its share of the grand total, sorted slowest first (ties by name)
• Slowest step — the first entry in that ranking
• Trend — the runs, in the order supplied, split into a first half and a second half (the middle run of an odd count belongs to the first half), with each half's average run total and the percentage delta between them; null with fewer than two runs, and the delta itself is null when the first half averages zero
• Cache correlation — a run counts as "with cache" when at least one of its steps reports a cache hit; buildtime reports both group sizes and each group's average run total (null for an empty group, never zero-filled)
• Flagged slowest — when you pass a slow threshold, the steps whose average duration meets or exceeds it, in slowest-first order

All floats are rounded to four decimal places. The computation is pure and local: no network, no configuration, no files read beyond the runs you pass in. Invalid input — a missing run, a step without a duration, a negative duration — is rejected with an error naming the offending path, and no partial profile is produced.

CLI

npx @reneturcios/buildtime analyze --runs runs.json

npx @reneturcios/buildtime --version

runs.json contains the full arguments object:

{

"runs": [ { "run_id": "run-101", "conclusion": "success", "steps": [ { "name": "compile", "duration_seconds": 42.5, "cache_hit": true }, { "name": "test", "duration_seconds": 87 } ] } ], "slow_threshold_seconds": 60 }

conclusion and cache_hit are optional per run / per step, and slow_threshold_seconds is optional overall. The profile is printed as JSON.

Exit codes: 0 on success, 1 on a runtime error (including an unreadable or invalid runs file, or invalid input), 2 on a usage error.

MCP server

npx -y @reneturcios/buildtime mcp

MCP client config:

{

"mcpServers": { "buildtime": { "command": "npx", "args": ["-y", "@reneturcios/buildtime", "mcp"] } } }

Tools

• analyze_build_times — Profile build bottlenecks across CI runs.
• runs (array, required, at least one) — runs as {run_id, conclusion?, steps} objects, where each step is {name, duration_seconds, cache_hit?}
• slow_threshold_seconds (number, optional, >= 0) — flag steps whose average duration meets this threshold

Returns {run_count, grand_total_seconds, step_stats, slowest_step, trend, cache, flagged_slowest}.

Docker

docker run -i ghcr.io/cloudcorprecords/buildtime

docker run --rm -v "$PWD:/w" ghcr.io/cloudcorprecords/buildtime analyze --runs /w/runs.json

Development

npm install

npm run build # tsc -> dist/ npm test # tsx --test test/*.test.ts (pure local, no network) npm run dev # run the CLI from source

License

MIT — Copyright (c) 2026 Rene Turcios