diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 9ee1c2e0..12cc0b3a 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -63,7 +63,11 @@ jobs:
 
   publish-crates:
     name: publish to crates.io
-    needs: [validate, quality-recheck]
+    # Gate the first irreversible publish on the CLI binaries building
+    # successfully (RFC-0110 / Codex #519 P1): if any platform build fails we
+    # must NOT publish to a registry, or the release is partial (crates live but
+    # binaries missing). npm/pypi are gated on publish-crates.
+    needs: [validate, quality-recheck, build-cli-binaries]
     runs-on: ubuntu-latest
     timeout-minutes: 60
     environment: crates-io
@@ -145,28 +149,62 @@ jobs:
 
   publish-npm:
     name: publish to npm
-    needs: [validate, quality-recheck, publish-crates]
+    # RFC-0110: assemble the per-platform + launcher packages from the prebuilt
+    # binaries and publish them. needs build-cli-binaries for the artifacts.
+    needs: [validate, quality-recheck, publish-crates, build-cli-binaries]
     runs-on: ubuntu-latest
     timeout-minutes: 30
     environment: npm
     permissions:
       id-token: write  # for provenance
+    env:
+      VERSION: ${{ needs.validate.outputs.version }}
     steps:
       - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
         with:
           node-version: '20'
           registry-url: 'https://registry.npmjs.org'
-      - run: |
-          if [ -d "bindings/node" ]; then
-            cd bindings/node
-            npm ci
-            npm publish --access public --provenance
-          else
-            echo "no bindings/node yet — skipping"
-          fi
+      - name: Download CLI binaries
+        uses: actions/download-artifact@v7
+        with:
+          pattern: cli-*
+          path: dl
+      - name: Reshape artifacts into a platform-keyed bin dir
+        run: |
+          mkdir -p dist-bin
+          for d in dl/cli-*; do
+            key="${d#dl/cli-}"
+            mkdir -p "dist-bin/$key"
+            cp "$d"/* "dist-bin/$key/"
+          done
+          ls -R dist-bin
+      - name: Assemble npm packages
+        run: node npm/scripts/build-npm.mjs --version "$VERSION" --bin-dir dist-bin --out dist-npm
+      - name: Publish packages (idempotent — platform packages first)
         env:
           NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
+        run: |
+          if [ -z "${NODE_AUTH_TOKEN:-}" ]; then
+            echo "::warning::NPM_TOKEN is not set — skipping npm publish. Configure it in repo Settings → Environments → npm."
+            exit 0
+          fi
+          publish_one() {
+            dir="$1"
+            name=$(node -p "require('./$dir/package.json').name")
+            ver=$(node -p "require('./$dir/package.json').version")
+            if npm view "$name@$ver" version >/dev/null 2>&1; then
+              echo "$name@$ver already on npm; skipping"
+              return 0
+            fi
+            ( cd "$dir" && npm publish --access public --provenance )
+          }
+          # Platform packages must exist before the main package (whose
+          # optionalDependencies reference them).
+          for dir in dist-npm/mycelium-*; do
+            [ -d "$dir" ] && publish_one "$dir"
+          done
+          publish_one "dist-npm/mycelium"
 
   publish-pypi:
     name: publish to PyPI
@@ -190,6 +228,56 @@ jobs:
             echo "no bindings/python yet — skipping"
           fi
 
+  build-cli-binaries:
+    # RFC-0110: cross-compile the `mycelium` CLI for each distributed platform,
+    # upload each as a workflow artifact (consumed by publish-npm in a follow-up
+    # and attached to the GitHub Release below). Native builds for 4 targets;
+    # `cross` handles the linux-arm64 C toolchain (tree-sitter grammars are C).
+    name: build CLI binary (${{ matrix.key }})
+    needs: [validate, quality-recheck]
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 30
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - { key: darwin-arm64, os: macos-14,        target: aarch64-apple-darwin,      exe: mycelium,     cross: false }
+          - { key: darwin-x64,   os: macos-13,        target: x86_64-apple-darwin,       exe: mycelium,     cross: false }
+          - { key: linux-x64,    os: ubuntu-latest,   target: x86_64-unknown-linux-gnu,  exe: mycelium,     cross: false }
+          - { key: linux-arm64,  os: ubuntu-latest,   target: aarch64-unknown-linux-gnu, exe: mycelium,     cross: true  }
+          - { key: win32-x64,    os: windows-latest,  target: x86_64-pc-windows-msvc,    exe: mycelium.exe, cross: false }
+    steps:
+      - uses: actions/checkout@v6
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: ${{ matrix.target }}
+      - uses: Swatinem/rust-cache@v2
+        with:
+          key: release-${{ matrix.target }}
+      - name: Install cross (linux-arm64)
+        if: ${{ matrix.cross }}
+        uses: taiki-e/install-action@v2
+        with:
+          tool: cross
+      - name: Build release binary
+        shell: bash
+        run: |
+          if [ "${{ matrix.cross }}" = "true" ]; then
+            cross build --release -p mycelium-rcig-cli --target ${{ matrix.target }}
+          else
+            cargo build --release -p mycelium-rcig-cli --target ${{ matrix.target }}
+          fi
+      - name: Stage binary under its platform key
+        shell: bash
+        run: |
+          mkdir -p "dist-bin/${{ matrix.key }}"
+          cp "target/${{ matrix.target }}/release/${{ matrix.exe }}" "dist-bin/${{ matrix.key }}/${{ matrix.exe }}"
+      - uses: actions/upload-artifact@v7
+        with:
+          name: cli-${{ matrix.key }}
+          path: dist-bin/${{ matrix.key }}/${{ matrix.exe }}
+          if-no-files-found: error
+
   finalize:
     name: merge to main, tag, GitHub Release
     # Charter §5.12: touching main requires founder authorization.
@@ -198,7 +286,7 @@ jobs:
     # (scripts/release-ceremony.sh) or a manual workflow_dispatch serves as
     # the explicit human authorization step.
     if: github.event_name == 'workflow_dispatch'
-    needs: [validate, publish-crates, publish-npm, publish-pypi]
+    needs: [validate, publish-crates, publish-npm, publish-pypi, build-cli-binaries]
     runs-on: ubuntu-latest
     timeout-minutes: 15
     permissions:
@@ -263,13 +351,38 @@ jobs:
           git tag -a "v$VERSION" -m "Release v$VERSION"
           git push origin "v$VERSION"
 
-      # Step D — Create the GitHub Release on the tag reachable from main.
+      # Step D — Download the per-platform CLI binaries and rename them with a
+      # platform suffix (the raw artifacts are all named `mycelium`/`.exe`, which
+      # would collide as release assets). RFC-0110.
+      - name: Download CLI binaries
+        uses: actions/download-artifact@v7
+        with:
+          pattern: cli-*
+          path: dist-release
+      - name: Collect release assets
+        shell: bash
+        run: |
+          mkdir -p release-assets
+          for d in dist-release/cli-*; do
+            key="${d#dist-release/cli-}"
+            if [ -f "$d/mycelium.exe" ]; then
+              cp "$d/mycelium.exe" "release-assets/mycelium-$key.exe"
+            elif [ -f "$d/mycelium" ]; then
+              cp "$d/mycelium" "release-assets/mycelium-$key"
+            fi
+          done
+          ls -la release-assets
+
+      # Step E — Create the GitHub Release on the tag reachable from main,
+      # attaching the per-platform binaries (a download path for users who do
+      # not use npm/bun/cargo).
       - name: Create GitHub Release
         uses: softprops/action-gh-release@v3
         with:
           tag_name: v${{ env.VERSION }}
           generate_release_notes: true
           target_commitish: main
+          files: release-assets/*
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}