diff --git a/.github/workflows/nightly-publish.yml b/.github/workflows/nightly-publish.yml
index 2487a694f..ad80fd4d4 100644
--- a/.github/workflows/nightly-publish.yml
+++ b/.github/workflows/nightly-publish.yml
@@ -41,7 +41,33 @@ jobs:
             exit 1
           fi
 
+      - name: Skip if this push is a release merge
+        id: release-check
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          package_version=$(node -p "require('./src/package.json').version")
+          commit_subject=$(git log -1 --format=%s)
+          skip=false
+
+          if [[ "$commit_subject" =~ ^chore:\ prepare\ v[0-9]+\.[0-9]+\.[0-9]+\ release ]]; then
+            echo "Commit '${commit_subject}' looks like a release-prep merge; skipping nightly pre-release."
+            skip=true
+          else
+            release_error=$(gh release view "v${package_version}" 2>&1 >/dev/null) && release_found=true || release_found=false
+            if [ "$release_found" = "true" ]; then
+              echo "v${package_version} is already published as a stable release; skipping nightly pre-release."
+              skip=true
+            elif [ "$release_error" != "release not found" ]; then
+              echo "::error::gh release view failed unexpectedly: ${release_error}"
+              exit 1
+            fi
+          fi
+
+          echo "skip=${skip}" >> "$GITHUB_OUTPUT"
+
       - name: Set pre-release version
+        if: steps.release-check.outputs.skip != 'true'
         id: version
         env:
           RUN_NUMBER: ${{ github.run_number }}
@@ -61,6 +87,7 @@ jobs:
           EOF
 
       - name: Build workspace packages
+        if: steps.release-check.outputs.skip != 'true'
         env:
           PKG_RELEASE_CHANNEL: prerelease
         run: |
@@ -68,6 +95,7 @@ jobs:
           pnpm --filter @roo-code/vscode-webview build
 
       - name: Package pre-release VSIX
+        if: steps.release-check.outputs.skip != 'true'
         env:
           POSTHOG_API_KEY: ${{ secrets.POSTHOG_API_KEY }}
           PKG_RELEASE_CHANNEL: prerelease
@@ -76,6 +104,7 @@ jobs:
           pnpm --filter ./src exec vsce package --pre-release --no-dependencies --out ../bin
 
       - name: Verify VSIX contents
+        if: steps.release-check.outputs.skip != 'true'
         env:
           VERSION_NUMBER: ${{ steps.version.outputs.number }}
         run: |
@@ -87,6 +116,7 @@ jobs:
           grep -q "extension/webview-ui/audio/celebration.wav" /tmp/zoo-code-vsix-contents.txt
 
       - name: Validate packaged manifest identity
+        if: steps.release-check.outputs.skip != 'true'
         env:
           VERSION_NUMBER: ${{ steps.version.outputs.number }}
         run: |
@@ -98,12 +128,36 @@ jobs:
           test "$artifact_name" = "zoo-code"
           test "$artifact_publisher" = "ZooCodeOrganization"
 
-      # Open VSX is intentionally excluded: it has no pre-release channel concept,
-      # so pre-release builds would surface as the latest stable version for all users.
       - name: Publish pre-release to VS Code Marketplace
+        if: steps.release-check.outputs.skip != 'true'
         env:
           VSCE_PAT: ${{ secrets.VSCE_PAT }}
           VERSION_NUMBER: ${{ steps.version.outputs.number }}
         run: |
           npx @vscode/vsce publish --pre-release --packagePath "bin/zoo-code-${VERSION_NUMBER}.vsix"
           echo "Published ZooCodeOrganization.zoo-code ${VERSION_NUMBER} as a VS Code Marketplace pre-release"
+
+      # The VSIX built above with `vsce package --pre-release` already carries the
+      # Microsoft.VisualStudio.Code.PreRelease manifest property, which is what Open
+      # VSX reads to flag the version. `ovsx publish` ignores --pre-release for an
+      # already-packaged .vsix (it only applies when ovsx does the packaging itself),
+      # so it's intentionally omitted here.
+      #
+      # Open VSX's "latest" alias resolves to the highest semver across stable and
+      # pre-release alike (pre-release only breaks ties at equal major.minor.patch),
+      # so a nightly build can transiently become "latest" until the next stable
+      # release outranks it. This mirrors how Marketplace pre-release users already
+      # track the newest published version, so it's an accepted trade-off here too.
+      - name: Publish pre-release to Open VSX Registry
+        if: steps.release-check.outputs.skip != 'true'
+        env:
+          OVSX_PAT: ${{ secrets.OVSX_PAT }}
+          VERSION_NUMBER: ${{ steps.version.outputs.number }}
+        run: |
+          set -o pipefail
+          publish_output=$(pnpm exec ovsx publish "bin/zoo-code-${VERSION_NUMBER}.vsix" --skip-duplicate 2>&1 | tee /dev/stderr)
+          if echo "$publish_output" | grep -q "is already published"; then
+            echo "ZooCodeOrganization.zoo-code ${VERSION_NUMBER} was already published to Open VSX; skipped."
+          else
+            echo "Published ZooCodeOrganization.zoo-code ${VERSION_NUMBER} as an Open VSX pre-release"
+          fi