diff --git a/.github/workflows/release-js.yml b/.github/workflows/release-js.yml
index a365fb6..49aec90 100644
--- a/.github/workflows/release-js.yml
+++ b/.github/workflows/release-js.yml
@@ -133,6 +133,7 @@ jobs:
           dry_run: ${{ inputs.dry_run || github.event_name == 'pull_request' }}
           working_directory: test/release/js
           package_manager: pnpm
+          node_version_file: test/release/js/.tool-versions # exercises node-version-file sourcing
           package_name: '@braintrust/bt-publishing-test' # exercises the npm-availability fail-fast check
           channel: ${{ inputs.channel || 'latest' }}
           allowed_channels: 'latest,rc,next,beta'
@@ -231,6 +232,7 @@ jobs:
           checkout: 'false' # bt-publishing-test: skip internal checkout — version patching above must survive into the build
           working_directory: test/release/js
           package_manager: pnpm
+          node_version_file: test/release/js/.tool-versions
           dry_run: ${{ inputs.dry_run || github.event_name == 'pull_request' }}
           release_tag: ${{ needs.validate.outputs.release_tag }}
           github_release: 'false' # bt-publishing-test: omit GitHub release to avoid tag/release pollution from repeated test runs
diff --git a/actions/release/lang/js/publish/action.yml b/actions/release/lang/js/publish/action.yml
index a1887da..68e5582 100644
--- a/actions/release/lang/js/publish/action.yml
+++ b/actions/release/lang/js/publish/action.yml
@@ -25,7 +25,11 @@ inputs:
   node_version:
     description: "Node version to use"
     required: false
-    default: '22'
+    default: ''
+  node_version_file:
+    description: "Path to a node version file (.tool-versions, .nvmrc, .node-version), relative to the repo root"
+    required: false
+    default: ''
   pnpm_version:
     description: "pnpm version to install (when package_manager is pnpm)"
     required: false
@@ -145,7 +149,10 @@ runs:
     - name: Set up Node
       uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
       with:
+        # Explicit node_version wins (setup-node prefers node-version when set); node_version_file
+        # (.tool-versions / .nvmrc / .node-version) is the fallback. Provide one of the two.
         node-version: ${{ inputs.node_version }}
+        node-version-file: ${{ inputs.node_version_file }}
         registry-url: ${{ inputs.registry }}
         cache: ${{ inputs.package_manager }}
         cache-dependency-path: |
diff --git a/actions/release/lang/js/validate/action.yml b/actions/release/lang/js/validate/action.yml
index 3ef6764..77ca0d6 100644
--- a/actions/release/lang/js/validate/action.yml
+++ b/actions/release/lang/js/validate/action.yml
@@ -32,7 +32,11 @@ inputs:
   node_version:
     description: "Node version to use"
     required: false
-    default: '22'
+    default: ''
+  node_version_file:
+    description: "Path to a node version file (.tool-versions, .nvmrc, .node-version), relative to the repo root"
+    required: false
+    default: ''
   pnpm_version:
     description: "pnpm version to install (when package_manager is pnpm)"
     required: false
@@ -101,7 +105,10 @@ runs:
     - name: Set up Node
       uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
       with:
+        # Explicit node_version wins (setup-node prefers node-version when set); node_version_file
+        # (.tool-versions / .nvmrc / .node-version) is the fallback. Provide one of the two.
         node-version: ${{ inputs.node_version }}
+        node-version-file: ${{ inputs.node_version_file }}
         registry-url: ${{ inputs.registry }}
         cache: ${{ inputs.package_manager }}
         cache-dependency-path: |
diff --git a/actions/release/lang/ruby/publish/action.yml b/actions/release/lang/ruby/publish/action.yml
index 0e71f14..0d63cdc 100644
--- a/actions/release/lang/ruby/publish/action.yml
+++ b/actions/release/lang/ruby/publish/action.yml
@@ -18,7 +18,7 @@ inputs:
     required: false
     default: '.'
   ruby_version:
-    description: "Ruby version to use"
+    description: "Ruby version to use, or a version file path (.tool-versions, .ruby-version)"
     required: false
     default: '4.0'
   dry_run:
diff --git a/actions/release/lang/ruby/validate/action.yml b/actions/release/lang/ruby/validate/action.yml
index b141b2b..b2e77e1 100644
--- a/actions/release/lang/ruby/validate/action.yml
+++ b/actions/release/lang/ruby/validate/action.yml
@@ -33,7 +33,7 @@ inputs:
     required: false
     default: '.'
   ruby_version:
-    description: "Ruby version to use"
+    description: "Ruby version to use, or a version file path (.tool-versions, .ruby-version)"
     required: false
     default: '4.0'
 outputs:
diff --git a/templates/actions/release/lang/js/publish.yml.erb b/templates/actions/release/lang/js/publish.yml.erb
index 7ba93e6..0f707cb 100644
--- a/templates/actions/release/lang/js/publish.yml.erb
+++ b/templates/actions/release/lang/js/publish.yml.erb
@@ -24,7 +24,11 @@ inputs:
   node_version:
     description: "Node version to use"
     required: false
-    default: '22'
+    default: ''
+  node_version_file:
+    description: "Path to a node version file (.tool-versions, .nvmrc, .node-version), relative to the repo root"
+    required: false
+    default: ''
   pnpm_version:
     description: "pnpm version to install (when package_manager is pnpm)"
     required: false
diff --git a/templates/actions/release/lang/js/validate.yml.erb b/templates/actions/release/lang/js/validate.yml.erb
index e10d459..6288a0e 100644
--- a/templates/actions/release/lang/js/validate.yml.erb
+++ b/templates/actions/release/lang/js/validate.yml.erb
@@ -31,7 +31,11 @@ inputs:
   node_version:
     description: "Node version to use"
     required: false
-    default: '22'
+    default: ''
+  node_version_file:
+    description: "Path to a node version file (.tool-versions, .nvmrc, .node-version), relative to the repo root"
+    required: false
+    default: ''
   pnpm_version:
     description: "pnpm version to install (when package_manager is pnpm)"
     required: false
diff --git a/templates/actions/release/lang/ruby/publish.yml.erb b/templates/actions/release/lang/ruby/publish.yml.erb
index 6e1f8ca..184a15d 100644
--- a/templates/actions/release/lang/ruby/publish.yml.erb
+++ b/templates/actions/release/lang/ruby/publish.yml.erb
@@ -17,7 +17,7 @@ inputs:
     required: false
     default: '.'
   ruby_version:
-    description: "Ruby version to use"
+    description: "Ruby version to use, or a version file path (.tool-versions, .ruby-version)"
     required: false
     default: '4.0'
   dry_run:
diff --git a/templates/actions/release/lang/ruby/validate.yml.erb b/templates/actions/release/lang/ruby/validate.yml.erb
index 6402ac7..4b918d7 100644
--- a/templates/actions/release/lang/ruby/validate.yml.erb
+++ b/templates/actions/release/lang/ruby/validate.yml.erb
@@ -32,7 +32,7 @@ inputs:
     required: false
     default: '.'
   ruby_version:
-    description: "Ruby version to use"
+    description: "Ruby version to use, or a version file path (.tool-versions, .ruby-version)"
     required: false
     default: '4.0'
 outputs:
diff --git a/templates/steps/lang/js/setup.yml.erb b/templates/steps/lang/js/setup.yml.erb
index 9f5f68b..1e6b1ed 100644
--- a/templates/steps/lang/js/setup.yml.erb
+++ b/templates/steps/lang/js/setup.yml.erb
@@ -4,7 +4,9 @@
   install — genuine control flow that can't be a shell self-guard because the
   pnpm install is a `uses:` action, not a `run:` step.
 
-  @param node_version      [String] expr for the Node version.        Default: ${{ inputs.node_version }}
+  @param node_version      [String] expr for an explicit Node version. Wins when set.  Default: ${{ inputs.node_version }}
+  @param node_version_file [String] expr for a node version FILE (.tool-versions / .nvmrc /
+    .node-version), used when node_version is empty.                   Default: ${{ inputs.node_version_file }}
   @param package_manager   [String] expr for pnpm | npm | yarn.        Default: ${{ inputs.package_manager }}
   @param pnpm_version      [String] expr for the pnpm version (pnpm).  Default: ${{ inputs.pnpm_version }}
   @param registry          [String] expr for the npm registry URL.     Default: ${{ inputs.registry }}
@@ -19,7 +21,10 @@
 - name: Set up Node
   uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
   with:
+    # Explicit node_version wins (setup-node prefers node-version when set); node_version_file
+    # (.tool-versions / .nvmrc / .node-version) is the fallback. Provide one of the two.
     node-version: <%= locals.fetch(:node_version) { "${{ inputs.node_version }}" } %>
+    node-version-file: <%= locals.fetch(:node_version_file) { "${{ inputs.node_version_file }}" } %>
     registry-url: <%= locals.fetch(:registry) { "${{ inputs.registry }}" } %>
     cache: <%= locals.fetch(:package_manager) { "${{ inputs.package_manager }}" } %>
     cache-dependency-path: |
diff --git a/templates/steps/lang/ruby/setup.yml.erb b/templates/steps/lang/ruby/setup.yml.erb
index df24bcb..d4454ad 100644
--- a/templates/steps/lang/ruby/setup.yml.erb
+++ b/templates/steps/lang/ruby/setup.yml.erb
@@ -1,7 +1,8 @@
 <%#
   Installs Ruby and the bundle (with caching) for the gem.
 
-  @param ruby_version      [String] expr for the Ruby version.  Default: ${{ inputs.ruby_version }}
+  @param ruby_version      [String] expr for the Ruby version. Also accepts a version file
+    path (.tool-versions / .ruby-version) — ruby/setup-ruby reads it.   Default: ${{ inputs.ruby_version }}
   @param working_directory [String] expr for the gem root.      Default: ${{ inputs.working_directory }}
 -%>
 - name: Set up Ruby
diff --git a/test/release/js/.tool-versions b/test/release/js/.tool-versions
new file mode 100644
index 0000000..36e55c3
--- /dev/null
+++ b/test/release/js/.tool-versions
@@ -0,0 +1 @@
+nodejs 22.15.0