v0.5.1

contextcost v0.5.1

Measure what a repository costs an AI coding agent to read — and prove how
much of it is waste by measuring again.

uvx contextcost .          # no install, no config, results in seconds

What it does

1. Measures the token cost of every file an agent could read (estimate
   with a published ±14% error bound; --accurate gives exact cl100k_base
   counts).
2. Proposes cuts — only where the filesystem itself proves a file isn't
   hand-written work: lockfiles, minified bundles, vendored deps, generated
   code, recorded fixtures.
3. Re-measures with the proposal applied, so the saving it reports is an
   observed difference between two walks of your repository — never a sum of
   guesses.

Real numbers from real repositories

Repository	Tokens to read	Measured saving	Waste
moby/buildkit	14.6M	13.1M	89.5%
jesseduffield/lazygit	5.8M	4.5M	77.8%
plotly.js	63.8M	26.8M	42.0%
sharkdp/bat	53.7M	30.0M	55.8%
astral-sh/ruff	20.7M	10.4M	50.2%
astropy	7.9M	212K	2.7%
mikefarah/yq	420K	3.0K	0.7%

The spread is the finding: there is no universal waste percentage — only
your repository's number. Full case studies with per-commit reproduction
commands:

• Seven repos measured
• Ten more repos
• Head-to-head vs repomix on the same checkout

Also in this release

• contextcost mcp — MCP server mode so Claude Code / Cursor / Codex can ask
  "what does this repo cost and what's wasting it" as a tool call
  (copy-paste configs)
• GitHub Action that posts the context delta of every pull request
• --delta main / --delta v4.0.0 — measure a change's context cost against
  any git revision without a second clone
• --fail-over BUDGET for CI gating (exit 4 when over budget)
• .contextcostignore — measurement-only exclusions that don't touch git

MIT, Python 3.9+, zero dependencies.
Questions and "this number looks wrong" reports:
Discussions — paste
--accurate --json output and it becomes a checkable claim.