diff --git a/.github/workflows/publish_nuget.yml b/.github/workflows/publish_nuget.yml
index 8d5d129..9a72bc0 100644
--- a/.github/workflows/publish_nuget.yml
+++ b/.github/workflows/publish_nuget.yml
@@ -8,11 +8,13 @@ on:
 
 permissions:
   contents: write
+  id-token: write   # Required for NuGet trusted publishing (OIDC token exchange).
 
 jobs:
   publish-nuget:
     name: publish-nuget
     runs-on: ubuntu-latest
+    environment: nuget   # Must match the environment named in the nuget.org Trusted Publisher policy.
 
     steps:
       - name: "Checkout"
@@ -41,8 +43,29 @@ jobs:
       - name: "dotnet pack"
         run: dotnet pack /p:PackageVersion=${{ env.PACKAGE_VERSION }} -c Release -o ./output
 
+      - name: "NuGet login (OIDC)"
+        # Exchanges the workflow's OIDC token for a short-lived NuGet API key
+        # under the Trusted Publisher policy configured on nuget.org.
+        # Requires:
+        #   - permissions.id-token: write at the workflow level (above)
+        #   - environment: nuget on this job (matches the policy)
+        #   - NUGET_USER repo secret = the package owner's nuget.org username
+        # See https://learn.microsoft.com/en-us/nuget/nuget-org/trusted-publishing
+        uses: NuGet/login@v1
+        id: nuget-login
+        with:
+          user: ${{ secrets.NUGET_USER }}
+
       - name: "dotnet nuget push"
-        run: dotnet nuget push "output/*.nupkg" -k ${{ secrets.NUGET_KEY }} -s https://api.nuget.org/v3/index.json --skip-duplicate
+        run: |
+          dotnet nuget push "output/*.nupkg" \
+            --api-key ${{ steps.nuget-login.outputs.NUGET_API_KEY }} \
+            --source https://api.nuget.org/v3/index.json \
+            --skip-duplicate
+          dotnet nuget push "output/*.snupkg" \
+            --api-key ${{ steps.nuget-login.outputs.NUGET_API_KEY }} \
+            --source https://api.nuget.org/v3/index.json \
+            --skip-duplicate
 
       - name: "Extract latest release notes"
         shell: pwsh
@@ -64,7 +87,9 @@ jobs:
           name: "ShellSyntaxTree ${{ github.ref_name }}"
           tag_name: ${{ github.ref_name }}
           body_path: RELEASE_NOTES_LATEST.md
-          files: output/*.nupkg
+          files: |
+            output/*.nupkg
+            output/*.snupkg
           draft: false
           prerelease: ${{ contains(github.ref_name, '-') }}
         env:
diff --git a/TOOLING.md b/TOOLING.md
index 14207e8..8f17fff 100644
--- a/TOOLING.md
+++ b/TOOLING.md
@@ -41,9 +41,38 @@ parses to its declared `expected` AST.
 |---|---|---|
 | `NuGet.Config` | repo root | feed configuration (currently `nuget.org`) |
 | `dotnet pack` | shell | produces `.nupkg` and `.snupkg` (symbol package) |
-| `dotnet nuget push` | CI only (`NUGET_KEY` secret) | publishes to `nuget.org` on tag |
+| `dotnet nuget push` | CI only (`NuGet/login@v1` OIDC) | publishes to `nuget.org` on tag |
 | Central Package Management | `Directory.Packages.props` | single source of truth for package versions |
 
+### NuGet trusted publishing
+
+`publish_nuget.yml` uses
+[trusted publishing](https://learn.microsoft.com/en-us/nuget/nuget-org/trusted-publishing)
+— no long-lived API key in repo secrets. The workflow exchanges its
+OIDC token for a short-lived API key via the `NuGet/login@v1` action.
+
+Required configuration (one-time, on `nuget.org`):
+
+1. Sign in to nuget.org → **Account → Trusted Publisher Policies** →
+   **Add new policy**.
+2. Publisher: GitHub Actions. Repository owner: `Aaronontheweb`.
+   Repository: `ShellSyntaxTree`. Workflow file: `publish_nuget.yml`.
+   Environment: `nuget`. Optional package-name pattern:
+   `ShellSyntaxTree*`.
+
+Required configuration (one-time, in repo settings):
+
+1. **Settings → Environments → New environment** → name `nuget`.
+   Optional protection: restrict deployment to tags matching
+   `v*.*.*`.
+2. **Settings → Secrets and variables → Actions → New repository
+   secret** — `NUGET_USER` set to the nuget.org account username
+   that owns the package. The legacy `NUGET_KEY` secret can be
+   deleted once trusted publishing is verified.
+
+The workflow's `permissions: id-token: write` and `environment: nuget`
+declarations are required for the OIDC exchange to succeed.
+
 ## Source-Level Conventions
 
 - `Directory.Build.props` enforces: `Nullable=enable`, `LangVersion=latest`,