feat: runner install resolves the latest release when --version is omitted

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -61,14 +61,14 @@ Control-plane box only. Installs Coolify at exactly the pinned version with
 the platform must never move underneath it on its own. Upgrading is an
 explicit re-run with a new pin. The pin is required; there is no default.
 
-### `rig runner install --repo <owner/repo> --version <pin>`
+### `rig runner install --repo <owner/repo>`
 
 Runner box only, run after `rig bootstrap runner` (the same two-step rhythm
 as `bootstrap control-plane` → `coolify install`):
 
 ```sh
 rig bootstrap runner --hostname my-ci-box
-rig runner install --repo acme/widgets --version 2.335.1
+rig runner install --repo acme/widgets
 ```
 
 Installs GitHub's official `actions/runner` as a systemd service under an
@@ -84,6 +84,10 @@ membership is root-equivalent, which is a gratuitous path to root on a box
 whose whole point is a narrow blast radius. Add Docker only once a job
 genuinely needs it, and rethink the isolation model then.
 
+- `--version <pin>` — actions/runner release to install (default: the
+  latest release, resolved at install time; e.g. `--version 2.335.1` —
+  the latest as of this writing). Pin it when you need a deterministic,
+  auditable install.
 - `--name <name>` — runner name (default: this host's hostname)
 - `--labels <csv>` — runner labels, replacing the `ci-runner` default — keep
   any label your workflows' `runs-on` needs (GitHub adds `self-hosted` itself)
@@ -93,11 +97,13 @@ genuinely needs it, and rethink the isolation model then.
 it at the interactive prompt. It's short-lived, consumed at registration, and
 never written to disk by rig.
 
-The version pin is required, same as `coolify install` — but unlike Coolify,
-the installed runner **self-updates**: GitHub refuses jobs from stale
-runners, so freezing the version would just make it silently stop taking
-work. The pin states what you install today; GitHub owns the treadmill after
-that.
+Why latest-by-default here when `coolify install` demands a pin: the two
+tools age differently. Coolify never self-updates (`AUTOUPDATE=false`), so
+its version is a contract your deploy tooling is verified against — stating
+it is the point. The runner **self-updates regardless**: GitHub refuses jobs
+from stale runners, so freezing it would just make it silently stop taking
+work. The install-time version is a starting point either way; `--version`
+exists for when you want that starting point deterministic and auditable.
 
 Convergent — safe to re-run; an already-registered runner is left alone.
 

commands/runner-install.sh

@@ -10,11 +10,14 @@ die()  { printf 'rig-runner: ERROR: %s\n' "$1" >&2; exit "${2:-1}"; }
 
 usage() {
   cat <<'EOF'
-usage: rig runner install --repo <owner/repo> --version <pin> [options]
+usage: rig runner install --repo <owner/repo> [options]
 
   --repo <owner/repo>   GitHub repository the runner registers to (required)
   --version <pin>       actions/runner release to install, e.g. 2.335.1
-                        (required; no default — you state what you install)
+                        (default: the latest release, resolved at install
+                        time — safe here because the runner self-updates
+                        regardless; pin it when you need a deterministic,
+                        auditable install)
   --name <name>         runner name (default: this host's hostname)
   --labels <csv>        runner labels; replaces the default (default: ci-runner)
   --user <name>         unprivileged service user (default: github-runner;
@@ -66,7 +69,6 @@ done
 if ! printf '%s' "$REPO" | grep -qE '^[A-Za-z0-9_.-]+/[A-Za-z0-9_.-]+$'; then
   die "--repo must be owner/repo" 2
 fi
-[ -n "$VERSION" ] || die "--version <pin> is required" 2
 VERSION="${VERSION#v}"
 [ "$RUNNER_USER" != "root" ] || die "runner user must not be root" 2
 
@@ -123,6 +125,20 @@ else
     aarch64) ARCH="arm64" ;;
     *) die "unsupported arch: $(uname -m)" ;;
   esac
+  if [ -z "$VERSION" ]; then
+    # No pin given: resolve the latest release by following the redirect on
+    # the /releases/latest page — no API call, no rate limit, no JSON to
+    # parse on a dependency-free box.
+    LATEST_URL="$(curl -fsSLI -o /dev/null -w '%{url_effective}' \
+      https://github.com/actions/runner/releases/latest)" \
+      || die "could not resolve the latest actions/runner release"
+    VERSION="${LATEST_URL##*/}"
+    VERSION="${VERSION#v}"
+    case "$VERSION" in
+      ""|*[!0-9.]*) die "could not parse a version from ${LATEST_URL}" ;;
+    esac
+    log "resolved latest actions/runner: ${VERSION}"
+  fi
   URL="https://github.com/actions/runner/releases/download/v${VERSION}/actions-runner-linux-${ARCH}-${VERSION}.tar.gz"
   WORKDIR="$(mktemp -d)"
   cleanup() { rm -rf "$WORKDIR"; }

docs/plans/2026-07-11-runner-install.md

@@ -286,6 +286,15 @@ Everything else about bootstrap is unchanged; `runner install`'s contract is
 untouched. Tests: +2 (`runner refuses tag:server`, `runner role parses /
 refuses non-root`) → 27 non-root.
 
+Second amendment (same day): `runner install --version` becomes **optional**
+— omitted, rig resolves the latest release at install time by following the
+`releases/latest` redirect (no API, no rate limit, no JSON parsing; validated
+against a digits-and-dots pattern before use). Safe here, and only here,
+because the runner self-updates regardless of what you install; `coolify
+install` keeps its mandatory pin — Coolify never self-updates, so its version
+is a verified contract, not a starting point. The `version required` test is
+replaced by a `--version needs a value` test → still 27 non-root.
+
 ## Integration (orchestrator, after final review — not an SDD task)
 
 1. Push the branch to the fork and open the PR **against upstream**:

test/cli.sh

@@ -57,7 +57,7 @@ fi
 check "bare runner shows usage, exit 2"  2 "usage:"          "$ROOT/bin/rig" runner
 check "runner: --help exits 0"           0 "usage:"          "$ROOT/commands/runner-install.sh" --help
 check "runner: repo required, exit 2"    2 "--repo"          "$ROOT/commands/runner-install.sh" --version 2.335.1
-check "runner: version required, exit 2" 2 "--version"       "$ROOT/commands/runner-install.sh" --repo acme/widgets
+check "runner: version needs value"      2 "needs a value"   "$ROOT/commands/runner-install.sh" --repo acme/widgets --version
 check "runner: repo needs value"         2 "needs a value"   "$ROOT/commands/runner-install.sh" --repo
 check "runner: rejects bad repo slug"    2 "owner/repo"      "$ROOT/commands/runner-install.sh" --repo not-a-slug --version 2.335.1
 check "runner: refuses --user root"      2 "must not be root" "$ROOT/commands/runner-install.sh" --repo acme/widgets --version 2.335.1 --user root