See what a pull request does to your agent's cost

# .github/workflows/agent-cost.yml
name: Agent cost check
on:
  pull_request:
    paths: ["**/*.py", "**/*.js", "**/*.ts", "**/*.mjs", "**/*.cjs", "**/*.mts", "**/*.cts"]
permissions:
  contents: read
  pull-requests: write
jobs:
  cost:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - uses: actions/github-script@v7
        env:
          NODAGENTRY_TOKEN: ${{ secrets.NODAGENTRY_TOKEN }}
          # Optional: fail the check when a file's estimated cost rises by more than this %.
          FAIL_ABOVE_PCT: ""
          # Optional: a typical task for your agent, used for the estimate.
          NODAGENTRY_TASK: ""
        with:
          script: |
            const { execFileSync } = require("child_process");
            const token = process.env.NODAGENTRY_TOKEN;
            if (!token) {
              core.warning("Add a NODAGENTRY_TOKEN repository secret to run the agent cost check.");
              return;
            }
            const pr = context.payload.pull_request;
            const git = (...args) => execFileSync("git", args, { encoding: "utf8", maxBuffer: 64 << 20 });
            const base = git("merge-base", pr.base.sha, pr.head.sha).trim();
            const changed = git("diff", "--name-only", "-z", base, pr.head.sha)
              .split("\0")
              .filter((p) => /\.(py|[cm]?[jt]s)$/.test(p));
            const AGENT = /crewai|@openai\/agents|from\s+agents|langgraph|StateGraph|add_?[nN]ode\s*\(|create_?[rR]eact_?[aA]gent|\bCrew\s*\(|Runner\.run/;
            const read = (sha, path) => {
              try {
                return execFileSync("git", ["show", sha + ":" + path], { encoding: "utf8", maxBuffer: 64 << 20, stdio: ["ignore", "pipe", "ignore"] });
              } catch {
                return null;
              }
            };
            const pick = (sha) => changed
              .map((path) => ({ path, content: read(sha, path) }))
              .filter((f) => f.content !== null && f.content.length <= 200000 && AGENT.test(f.content))
              .slice(0, 100);
            const files = { base: pick(base), head: pick(pr.head.sha) };
            if (!files.base.length && !files.head.length) {
              core.info("No agent code changed in this pull request.");
              return;
            }
            const url = (process.env.NODAGENTRY_URL || "https://nodagentry.com") + "/api/cost-check";
            const res = await fetch(url, {
              method: "POST",
              headers: { authorization: "Bearer " + token, "content-type": "application/json" },
              body: JSON.stringify({ ...files, task: process.env.NODAGENTRY_TASK || undefined }),
            });
            const out = await res.json().catch(() => ({}));
            if (!res.ok) {
              core.setFailed("Nodagentry: " + (out.error || "HTTP " + res.status));
              return;
            }
            const marker = "<!-- nodagentry-cost-check -->";
            const body = marker + "\n" + out.markdown;
            const { owner, repo } = context.repo;
            const issue_number = pr.number;
            const comments = await github.paginate(github.rest.issues.listComments, { owner, repo, issue_number, per_page: 100 });
            const mine = comments.find((c) => c.body && c.body.startsWith(marker));
            if (mine) await github.rest.issues.updateComment({ owner, repo, comment_id: mine.id, body });
            else await github.rest.issues.createComment({ owner, repo, issue_number, body });
            const limit = Number(process.env.FAIL_ABOVE_PCT);
            if (limit > 0 && out.maxIncreasePct > limit) {
              core.setFailed("Estimated cost per run rose " + out.maxIncreasePct + "% (limit " + limit + "%).");
            }