feat: support release tag names in JBANG_DOWNLOAD_VERSION (early-access)

docs/modules/ROOT/pages/installation.adoc

@@ -444,6 +444,23 @@ By default JBang downloads itself from GitHub. You can override the download URL
 export JBANG_DOWNLOAD_URL=https://internal-mirror.example.com/jbang/jbang.tar
 ----
 
+=== Downloading a specific version or the early-access build
+
+Set `JBANG_DOWNLOAD_VERSION` to pick a specific release. Numeric values are resolved to the matching `vX.Y.Z` GitHub release; any other value is used as a release tag name as-is. This means you can opt-in to the perpetual early-access build with a simple:
+
+[source,bash]
+----
+export JBANG_DOWNLOAD_VERSION=early-access
+----
+
+which resolves to https://github.com/jbangdev/jbang/releases/download/early-access/ . Equivalent forms:
+
+[source,bash]
+----
+export JBANG_DOWNLOAD_VERSION=0.120.0     # -> .../download/v0.120.0/jbang.tar
+export JBANG_DOWNLOAD_VERSION=early-access # -> .../download/early-access/jbang.tar
+----
+
 == Version Check
 
 `jbang` will check once a day if a new version is available. If a new version is available a message will be printed with information on how to install.
@@ -504,7 +521,7 @@ These are read by the scripts themselves before Java or JBang's Java code is inv
 
 | `JBANG_DOWNLOAD_VERSION`
 | _(latest)_
-| Specific JBang version to download (e.g., `0.120.0`). When unset, the latest release is used.
+| Specific JBang version to download. Numeric values (e.g., `0.120.0`) are resolved to the matching `vX.Y.Z` GitHub release; any non-numeric value (e.g., `early-access`) is used as a release tag name as-is. When unset, the latest release is used.
 
 | `JBANG_JAVA_OPTIONS`
 | _(empty)_

jreleaser.yml

@@ -39,6 +39,7 @@ project:
   snapshot:
     pattern: '^\d+\.\d+\.\d+\.\d+(?:-SNAPSHOT)?$'
     label: early-access
+    fullChangelog: true
 
 release:
   github:
@@ -53,6 +54,29 @@ release:
       formatted: always
       preset: "conventional-commits"
       format: '- {{commitShortHash}} {{commitTitle}}'
+      content: |
+        {{#Model.project.snapshot.enabled}}
+        WARNING: This is an early-access release directly from `main` branch, not intended for production use. 
+
+        If you want to try the latest and greatest, please give it a spin and report any issues you find.
+
+        Here is how to install it:
+
+        Linux / macOS / WSL (bash):
+        ```
+        curl -Ls https://sh.jbang.dev | JBANG_DOWNLOAD_VERSION=early-access bash -s - app setup
+        ```
+
+        Windows PowerShell:
+        ```
+        $env:JBANG_DOWNLOAD_VERSION='early-access'; iex "& { $(iwr -useb https://ps.jbang.dev) } app setup"
+        ```
+        {{/Model.project.snapshot.enabled}}
+
+        ## Changelog
+
+        {{changelogChanges}}
+        {{changelogContributors}}
 
 checksum:
   individual: true

src/main/scripts/jbang

@@ -287,7 +287,13 @@ if [[ -z "$binaryPath" && -z "$jarPath" ]]; then
     elif [ -z "$JBANG_DOWNLOAD_VERSION" ]; then
       jburl="${jbangDownloadBaseUrl}/latest/download/jbang.tar";
     else
-      jburl="${jbangDownloadBaseUrl}/download/v$JBANG_DOWNLOAD_VERSION/jbang.tar";
+      # Numeric versions get a 'v' prefix (e.g. 0.120.0 -> v0.120.0); named
+      # release tags (e.g. 'early-access', '1.0.0-rc1') are used as-is.
+      case "$JBANG_DOWNLOAD_VERSION" in
+        *[!0-9.]*) jbtag="$JBANG_DOWNLOAD_VERSION" ;;
+        *)         jbtag="v$JBANG_DOWNLOAD_VERSION" ;;
+      esac
+      jburl="${jbangDownloadBaseUrl}/download/$jbtag/jbang.tar";
     fi
     echo "Downloading JBang ${JBANG_DOWNLOAD_VERSION:-latest} from $jburl..." 1>&2
     download "$jburl" "$TDIR/urls/jbang.tar"

src/main/scripts/jbang.ps1

@@ -157,7 +157,14 @@ if (-not $binaryPath -and -not $jarPath) {
     } elseif (-not (Test-Path env:JBANG_DOWNLOAD_VERSION)) {
         $jburl="$jbangDownloadBaseUrl/latest/download/jbang.zip"
     } else {
-        $jburl="$jbangDownloadBaseUrl/download/v$env:JBANG_DOWNLOAD_VERSION/jbang.zip";
+        # Numeric versions get a 'v' prefix (e.g. 0.120.0 -> v0.120.0); named
+        # release tags (e.g. 'early-access', '1.0.0-rc1') are used as-is.
+        if ($env:JBANG_DOWNLOAD_VERSION -match '^[0-9]+(\.[0-9]+)*$') {
+            $jbtag = "v$env:JBANG_DOWNLOAD_VERSION"
+        } else {
+            $jbtag = $env:JBANG_DOWNLOAD_VERSION
+        }
+        $jburl="$jbangDownloadBaseUrl/download/$jbtag/jbang.zip";
     }
     $dlVersion = if ($env:JBANG_DOWNLOAD_VERSION) { $env:JBANG_DOWNLOAD_VERSION } else { 'latest' }
     [Console]::Error.WriteLine("Downloading JBang $dlVersion from $jburl...")