--- title: "Introducing sling: an agent-first CLI for your CI" description: "sling is the agent-first CLI for StarSling Runners. Diagnose a failed job, rank your slowest workflows, see CI costs, and read only the log lines that matter." date: 2026-08-27 url: https://starsling.dev/blog/introducing-sling-an-agent-first-cli-for-your-ci canonicalUrl: https://starsling.dev/blog/introducing-sling-an-agent-first-cli-for-your-ci --- # Introducing sling: an agent-first CLI for your CI
[Image: The sling command typed at a terminal prompt, answering with its block-letter SLING banner]
Today we're releasing [**sling**](/cli), the official StarSling CLI. It's an agent-first CLI for your CI. StarSling Runners are fast, AI-native GitHub Actions runners: a one-line swap for `ubuntu-latest` that our agents keep tuning. sling is how you and your agent see what those runners are doing. Why a job failed, where the time went, what it cost, and which workflow to fix first, without leaving the terminal. ```console curl -fsSL https://runners.starsling.dev/cli/install.sh | sh ``` *Apple Silicon macOS and glibc x64 Linux.* Then [`sling login`](https://docs.starsling.dev/sling-cli/commands/auth#sling-login) shows a short device code you approve in the browser with the GitHub account you're already signed into. Or hand the whole setup to your coding agent. This prompt installs sling and the `/sling` agent skill, which teaches your agent when to reach for it, and it works in Claude Code, Codex, Cursor, OpenCode and more: ```text Set up the StarSling `sling` CLI and its agent skill on this machine (Apple Silicon macOS or glibc x64 Linux). 1. Install the CLI: run `curl -fsSL https://runners.starsling.dev/cli/install.sh | sh`, then confirm it with `sling --version`. 2. Install the agent skill: run `npx skills add starslingdev/skills --skill sling -y`, then read the installed SKILL.md end to end and follow it for every CI question I ask from now on. 3. Signing in is mine to do: `sling login` prints a short device code I approve in a browser. Print that command for me and wait until I tell you I am signed in. 4. Once I confirm, run `sling doctor` and tell me what it reports about the CLI, the login, and the StarSling GitHub App on my organization. ``` ## CLI for agents Agents pick sling up seamlessly: it acquires the session you are already logged into. Three things make it usable from inside an agent loop: - **Machine mode, one flag.** `--agent` returns JSON on stdout, refuses prompts rather than waiting on them, and turns colour off, so an agent gets a shape it can parse and an exit code it can branch on. - **Discoverable by design.** `sling --help` maps every command to the question it answers, so an agent can find the right one without spending context hunting for it. - **One command for what's broken.** [`sling doctor`](https://docs.starsling.dev/sling-cli/commands/auth#sling-doctor) checks your token, org, git remote, control-plane reachability and clock skew, and fails when something is genuinely broken. ```console $ sling top --agent { "by": "workflow", "metric": "runner-minutes", "window": { "from": "2026-07-25T22:47:14.312Z", "to": "2026-08-24T22:47:14.312Z" }, "rows": [ { "key": "integration-tests", "repo": "web-platform", "runner_minutes": 69559, "cost_usd": 556.472, "runs": 12480, "jobs": 28715, "p50_ms": 69000, "p95_ms": 180000, "p99_ms": 358540, "queue_wait_ms": 14000, "trend_pct": 170.7 } ], "local": { "org": "acme-corp" } } ``` ## CLI for humans When someone hits a failed job, they have three bad options: click through the GitHub UI, dump the whole log into an agent and pray, or pull raw data out of an API and diagnose by hand. sling lets you investigate a failed run, find the bottleneck in your pipeline, and share usage and cost with your team: - **Deterministic diagnostics.** `sling why` classifies a failure on the server with no LLM in the loop, so your agent spends its reasoning on the fix instead of the triage. ```console $ sling --help USAGE sling [flags] AUTH & SETUP COMMANDS login: Sign in via the GitHub device authorization flow logout: Sign out and clear the stored credential and preferences whoami: View your identity, organizations and credential doctor: Check your environment and know what's broken org switch: Set your organization that other commands use by default INSPECT CI COMMANDS runs list: Find workflow runs by branch, status, conclusion, or trigger runs show: See which job in a run failed, or wait for it to finish jobs list: List jobs in a run, or across a repo jobs show: See which step in a job failed, and how long each took logs: Read just the log lines you need, not the whole transcript resolve: Resolve an id or GitHub Actions URL to its target DIAGNOSE COMMANDS why: Diagnose why a job failed, with evidence and next steps time: Decompose CI wall-clock into runner-lifecycle phases COST & CAPACITY COMMANDS usage: Attribute runner minutes and usage cost over a window top: Rank the biggest time and cost hotspots, with a trend bill: See what you owe so far and the month-end projection bill history: List prior finalized billed invoices labels list: Compare runner sizes and per-minute cost for runs-on ``` ## Alongside `gh` [`gh`](https://cli.github.com), GitHub's own command-line tool, lists and acts: it lists runs, streams logs, triggers workflows, re-runs jobs. sling reads and explains. It gives you a verdict instead of a transcript, a ranking instead of a list, and what CI costs, which `gh` does not report at all. `gh` is already a prerequisite for every StarSling agent skill, so it is on every machine sling runs on. The two are built to sit beside each other, and the `/sling` skill decides which one answers each question. [The full breakdown is on the sling CLI page](/cli#beside-gh). ## The agent skill Calling sling agent-first means more than machine-readable output. The other half is a skill that teaches your coding agent when to reach for it, and when not to: ```console npx skills add starslingdev/skills --skill sling -y ``` The skill's whole job is picking the right tool per request. A live question about a run, a job or your spend goes to sling. sling reads and analyzes, so anything that *changes* CI state goes to `gh`: - re-running a job - cancelling a run - triggering a workflow - enabling or disabling one - downloading an artifact A repo-wide audit of your workflow files is neither, so it hands off to [ci-score](/ci-score), [ci-speedup](/ci-speedup) or [ci-secure](/ci-secure) and stops. ## Analyze your CI Find the bottlenecks across your workflows ([`sling top`](https://docs.starsling.dev/sling-cli/commands/analyze#sling-top)): ```bash sling top ``` Diagnose a failed job and get a suggested path to a clean run ([`sling why`](https://docs.starsling.dev/sling-cli/commands/analyze#sling-why)): ```bash sling why ``` ```console $ sling why https://github.com/acme-corp/api/actions/runs/1827/job/5274 JobName: Unit and E2E Tests / Affected UNIT Test Failure Reason: A process ran out of memory. The runtime aborted, so the step's exit code is a consequence, not the cause. Evidence Classification: oom Logs: node::OOMErrorHandler(char const*, v8::OOMDetails const&) Error: [vitest-pool]: Worker forks emitted error. Caused by: Error: Worker exited unexpectedly Suggestions: 1. Verify the logs sling logs 5274 --grep '##\[error\]|failures?:|FAIL|panicked' ``` Decompose CI **wall-clock into phases** with [`sling time`](https://docs.starsling.dev/sling-cli/commands/analyze#sling-time), so you know whether the time went to a slow checkout, your own steps, or the managed infrastructure: ```bash sling time ``` ```console $ sling time https://github.com/acme-corp/api/actions/runs/1831/job/5291 Job Name: Lint docs (att_5291.1) - Wall-Clock: 2m 55s - Queue-Wait: 1s PHASES TIME %-SHARE TIMELINE provision 3.0s 1.71% checkout+patch 50.0s 28.57% steps 117.0s 66.86% teardown 5.0s 2.86% Top Steps STEP TIME Setup pnpm and Node.js 97.0s Check formatting 7.0s Lint with remark 6.0s ``` Attribute runner minutes and cost across your repos with [`sling usage`](https://docs.starsling.dev/sling-cli/commands/analyze#sling-usage): ```bash sling usage ``` ```console $ sling usage StarSling usage - by repo 2026-08-08 -> 2026-09-08 (current cycle) KEY - REPO RUNNER MIN JOBS COST $ % TOTAL acme-corp/web-platform 975.0 1284 $7.80 52.0% acme-corp/api-gateway 630.0 856 $5.04 33.6% acme-corp/mobile-app 270.0 342 $2.16 14.4% ``` ## Inspect your CI See every run and its status across the board with [`sling runs list`](https://docs.starsling.dev/sling-cli/commands/inspect#sling-runs): ```bash sling runs list ``` ```console $ sling runs list --limit 5 RUN WORKFLOW BRANCH EVENT STATUS DUR JOBS CREATED 18274531902 .github/workflows/integration-tests.yml main push in_progress - 0/22 2026-08-24 09:14 18274418860 .github/workflows/integration-tests.yml main push success 5m 42s 25/25 2026-08-24 08:51 18274102724 .github/workflows/changed-test-gate.yml main pull_request success 32s 1/1 2026-08-24 08:33 18273960124 .github/workflows/flag-spam-comments.yml main issue_comment success 13s 1/1 2026-08-24 08:19 18273943287 .github/workflows/codeql.yml main schedule in_progress - 0/2 2026-08-24 08:12 ``` ## Billing See what you owe so far and where the month is projected to land with [`sling bill`](https://docs.starsling.dev/sling-cli/commands/billing#sling-bill): ```bash sling bill ``` ```console $ sling bill Current cycle: 2026-08-08 -> 2026-09-08 Invoice: pending (issued when the period closes) Runner minutes 12500.0 Amount $97.20 Projected month-end $167.40 RUNNER LABEL TIME COST starsling-ubuntu-24.04 11800.0 min $94.40 starsling-ubuntu-24.04-2 700.0 min $2.80 ``` Every command, with the install line and the skill that teaches your agent to use it, is on [the sling CLI page](/cli). The full reference for every flag and exit code is at [docs.starsling.dev/sling-cli](https://docs.starsling.dev/sling-cli). sling is a client for StarSling's HTTP API, and that API is documented at [docs.starsling.dev/api](https://docs.starsling.dev/api): the same runs, jobs, logs, labels, usage and billing endpoints the commands above call, generated from the OpenAPI spec. Reach for it when you want the data somewhere the terminal is not, like a dashboard or a bot of your own. If your team runs CI on GitHub Actions, [install the StarSling GitHub App](https://github.com/apps/starslingdev) to keep it in shape automatically.