diff --git a/.github/workflows/rust-multiplatform.yml b/.github/workflows/rust-multiplatform.yml
index f98e75bdf..4857d3980 100644
--- a/.github/workflows/rust-multiplatform.yml
+++ b/.github/workflows/rust-multiplatform.yml
@@ -114,16 +114,9 @@ jobs:
       - name: Test (host, macOS / Windows)
         if: matrix.cross == false && matrix.check_only != true && runner.os != 'Linux'
         run: cargo test --workspace --target ${{ matrix.target }}
-      - name: Upload openpencil-app binary
-        if: matrix.cross == false && matrix.check_only != true
-        uses: actions/upload-artifact@v4
-        with:
-          name: openpencil-app-${{ matrix.label }}
-          path: |
-            target/${{ matrix.target }}/release/openpencil-app
-            target/${{ matrix.target }}/release/openpencil-app.exe
-          if-no-files-found: ignore
-          retention-days: 14
+      # Desktop binary artifact upload removed with the `openpencil-app`
+      # placeholder crate (Phase 1 Task 1.2). Step 1f reintroduces a
+      # real desktop binary (new `op-*` crate) and its upload step here.
 
   wasm-web:
     name: wasm32-unknown-unknown / openpencil-shell-web (compile guard)
diff --git a/.github/workflows/rust-release.yml b/.github/workflows/rust-release.yml
index 5780c0e36..c55766afb 100644
--- a/.github/workflows/rust-release.yml
+++ b/.github/workflows/rust-release.yml
@@ -1,13 +1,12 @@
 name: Rust release artifacts
 
-# Triggered on tag push (v*) — builds release binaries across desktop targets
-# and uploads them to a GitHub Release draft. The wasm web bundle is currently
-# DEFERRED (see comment block above the removed `wasm` job below); when the
-# CI-side C-hard pipeline (emscripten install + EMSDK + symlink hack +
-# wasm-bindgen + wasm-opt) lands it will re-enter the matrix. Step 1a
-# kill-spike only ships `openpencil-app` (a placeholder binary entry); real
-# desktop apps (DMG / AppImage / EXE installer) come in Step 1f and replace
-# this scaffolding.
+# Triggered on tag push (v*) — assembles a GitHub Release draft. The desktop
+# binary build job has been removed: the `openpencil-app` placeholder crate
+# was deleted in Phase 1 Task 1.2, and real desktop apps (DMG / AppImage / EXE
+# installer) arrive in Step 1f as new `op-*` crates that will reintroduce a
+# build matrix here. The wasm web bundle is currently DEFERRED (see comment
+# block below); when the CI-side C-hard pipeline (emscripten install + EMSDK +
+# symlink hack + wasm-bindgen + wasm-opt) lands it will re-enter the matrix.
 
 on:
   push:
@@ -15,95 +14,6 @@ on:
   workflow_dispatch:
 
 jobs:
-  build:
-    name: ${{ matrix.label }}
-    runs-on: ${{ matrix.runner }}
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-          - label: macos-aarch64
-            runner: macos-latest
-            target: aarch64-apple-darwin
-            archive: tar.gz
-          # macos-13 (Intel) deprecated; cross-compile x86_64-apple-darwin
-          # from Apple Silicon (cargo supports cross-compile to host's other
-          # arch out of the box, no `cross` needed).
-          - label: macos-x86_64
-            runner: macos-latest
-            target: x86_64-apple-darwin
-            archive: tar.gz
-          - label: linux-x86_64
-            runner: ubuntu-latest
-            target: x86_64-unknown-linux-gnu
-            archive: tar.gz
-          - label: linux-aarch64
-            runner: ubuntu-latest
-            target: aarch64-unknown-linux-gnu
-            archive: tar.gz
-            cross: true
-          - label: windows-x86_64
-            runner: windows-latest
-            target: x86_64-pc-windows-msvc
-            archive: zip
-          # Windows ARM64 — cargo cross-compile from x86_64 windows runner.
-          - label: windows-aarch64
-            runner: windows-latest
-            target: aarch64-pc-windows-msvc
-            archive: zip
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          submodules: recursive
-      - uses: dtolnay/rust-toolchain@stable
-        with:
-          toolchain: '1.85'
-          targets: ${{ matrix.target }}
-      - uses: Swatinem/rust-cache@v2
-        with:
-          key: release-${{ matrix.target }}
-      - name: Install Linux GL/EGL prereqs
-        if: runner.os == 'Linux' && matrix.cross != true
-        run: |
-          sudo apt-get update
-          sudo apt-get install -y \
-            libxkbcommon-dev libxkbcommon-x11-dev \
-            libwayland-dev libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev \
-            libegl1-mesa-dev libgles2-mesa-dev libgbm-dev \
-            libfreetype-dev libfontconfig1-dev
-      - name: Install cross
-        if: matrix.cross == true
-        run: cargo install cross --locked --version 0.2.5
-      - name: Build (host)
-        if: matrix.cross != true
-        run: cargo build -p openpencil-app --target ${{ matrix.target }} --release
-      - name: Build (cross)
-        if: matrix.cross == true
-        run: cross build -p openpencil-app --target ${{ matrix.target }} --release
-      - name: Package archive (unix)
-        if: matrix.archive == 'tar.gz'
-        shell: bash
-        run: |
-          cd target/${{ matrix.target }}/release
-          tar czf ../../../openpencil-app-${{ matrix.label }}.tar.gz openpencil-app 2>/dev/null || \
-            tar czf ../../../openpencil-app-${{ matrix.label }}.tar.gz openpencil-app.placeholder
-      - name: Package archive (windows)
-        if: matrix.archive == 'zip'
-        shell: pwsh
-        run: |
-          Compress-Archive `
-            -Path target\${{ matrix.target }}\release\openpencil-app.exe `
-            -DestinationPath openpencil-app-${{ matrix.label }}.zip `
-            -ErrorAction SilentlyContinue
-      - name: Upload artifact
-        uses: actions/upload-artifact@v4
-        with:
-          name: openpencil-app-${{ matrix.label }}
-          path: |
-            openpencil-app-${{ matrix.label }}.tar.gz
-            openpencil-app-${{ matrix.label }}.zip
-          if-no-files-found: ignore
-
   # Phase 1b release wasm artifact: explicitly DEFERRED (not silently
   # dropped). The local C-hard pipeline (vendor/skia-safe-op fork +
   # crates/wasm-libc-shim) does produce a runtime-loadable
@@ -125,10 +35,11 @@ jobs:
 
   release-draft:
     name: Create / update GitHub Release draft
-    # `wasm` job deferred (see comment block above); when the
-    # CI-side C-hard pipeline lands, re-add the job and append its
-    # name to this `needs:` list.
-    needs: [build]
+    # Desktop `build` job removed with the `openpencil-app` placeholder
+    # crate (Phase 1 Task 1.2); the `wasm` job is deferred (see comment
+    # block above). When the Step 1f `op-*` desktop crates and the
+    # CI-side C-hard pipeline land, re-add those jobs and list their
+    # names in this `needs:` field.
     runs-on: ubuntu-latest
     if: startsWith(github.ref, 'refs/tags/v')
     steps:
diff --git a/.github/workflows/wasm-bundle-check.yml b/.github/workflows/wasm-bundle-check.yml
index 9bf926fdb..d4d768695 100644
--- a/.github/workflows/wasm-bundle-check.yml
+++ b/.github/workflows/wasm-bundle-check.yml
@@ -30,8 +30,6 @@ jobs:
         run: |
           cargo check --target wasm32-unknown-unknown \
             -p openpencil-shell-web --no-default-features --features web
-          cargo check --target wasm32-unknown-unknown \
-            -p pen-types -p pen-core -p pen-engine -p pen-codegen -p pen-figma
 
   wasm32-deny:
     name: cargo-deny --target wasm32-unknown-unknown check bans
diff --git a/Cargo.lock b/Cargo.lock
index 4c05840b8..2243235c7 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2380,10 +2380,6 @@ version = "1.21.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9f7c3e4beb33f85d45ae3e3a1792185706c8e16d043238c593331cc7cd313b50"
 
-[[package]]
-name = "openpencil-app"
-version = "0.1.0"
-
 [[package]]
 name = "openpencil-desktop"
 version = "0.1.0"
@@ -2530,48 +2526,6 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c5a797f0e07bdf071d15742978fc3128ec6c22891c31a3a931513263904c982a"
 
-[[package]]
-name = "pen-codegen"
-version = "0.1.0"
-dependencies = [
- "pen-types",
-]
-
-[[package]]
-name = "pen-core"
-version = "0.1.0"
-dependencies = [
- "pen-types",
- "serde",
- "thiserror 1.0.69",
-]
-
-[[package]]
-name = "pen-engine"
-version = "0.1.0"
-dependencies = [
- "pen-core",
- "pen-types",
-]
-
-[[package]]
-name = "pen-figma"
-version = "0.1.0"
-dependencies = [
- "pen-types",
- "serde",
- "serde_json",
-]
-
-[[package]]
-name = "pen-types"
-version = "0.1.0"
-dependencies = [
- "serde",
- "serde_json",
- "thiserror 1.0.69",
-]
-
 [[package]]
 name = "percent-encoding"
 version = "2.3.2"
diff --git a/crates/openpencil-app/Cargo.toml b/crates/openpencil-app/Cargo.toml
deleted file mode 100644
index 970eeec26..000000000
--- a/crates/openpencil-app/Cargo.toml
+++ /dev/null
@@ -1,15 +0,0 @@
-[package]
-name = "openpencil-app"
-version.workspace = true
-edition.workspace = true
-rust-version.workspace = true
-license.workspace = true
-description = "OpenPencil entry point (Step 5 Stage F shell entry placeholder)"
-
-[[bin]]
-name = "openpencil-app"
-path = "src/main.rs"
-
-[features]
-default = []
-shell-native = []
diff --git a/crates/openpencil-app/src/main.rs b/crates/openpencil-app/src/main.rs
deleted file mode 100644
index cfa9efdcd..000000000
--- a/crates/openpencil-app/src/main.rs
+++ /dev/null
@@ -1,6 +0,0 @@
-// OpenPencil application entry point.
-// Stage F cutover replaces this skeleton with the real shell host.
-
-fn main() {
-    println!("openpencil-app placeholder (Step 0 skeleton — see kickoff spec §2 Step 5)");
-}
diff --git a/crates/pen-codegen/Cargo.toml b/crates/pen-codegen/Cargo.toml
deleted file mode 100644
index ecbe5d182..000000000
--- a/crates/pen-codegen/Cargo.toml
+++ /dev/null
@@ -1,14 +0,0 @@
-[package]
-name = "pen-codegen"
-version.workspace = true
-edition.workspace = true
-rust-version.workspace = true
-license.workspace = true
-description = "OpenPencil codegen (.op → React/Vue/Svelte/...) — bucket A in-WASM"
-
-[lib]
-name = "pen_codegen"
-path = "src/lib.rs"
-
-[dependencies]
-pen-types = { path = "../pen-types", version = "0.1.0" }
diff --git a/crates/pen-codegen/src/lib.rs b/crates/pen-codegen/src/lib.rs
deleted file mode 100644
index 4b134ca9e..000000000
--- a/crates/pen-codegen/src/lib.rs
+++ /dev/null
@@ -1,5 +0,0 @@
-//! OpenPencil codegen.
-
-pub fn placeholder() -> String {
-    format!("pen-codegen ({})", pen_types::placeholder())
-}
diff --git a/crates/pen-core/Cargo.toml b/crates/pen-core/Cargo.toml
deleted file mode 100644
index f76f5cace..000000000
--- a/crates/pen-core/Cargo.toml
+++ /dev/null
@@ -1,16 +0,0 @@
-[package]
-name = "pen-core"
-version.workspace = true
-edition.workspace = true
-rust-version.workspace = true
-license.workspace = true
-description = "OpenPencil core engine (Action DSL / Signal graph) — bucket A in-WASM"
-
-[lib]
-name = "pen_core"
-path = "src/lib.rs"
-
-[dependencies]
-pen-types = { path = "../pen-types", version = "0.1.0" }
-serde = { workspace = true }
-thiserror = { workspace = true }
diff --git a/crates/pen-core/src/lib.rs b/crates/pen-core/src/lib.rs
deleted file mode 100644
index 517d2cd83..000000000
--- a/crates/pen-core/src/lib.rs
+++ /dev/null
@@ -1,15 +0,0 @@
-//! OpenPencil core engine.
-
-pub fn placeholder() -> String {
-    format!("pen-core ({})", pen_types::placeholder())
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn skeleton_links_types() {
-        assert!(placeholder().contains("pen-types"));
-    }
-}
diff --git a/crates/pen-engine/Cargo.toml b/crates/pen-engine/Cargo.toml
deleted file mode 100644
index d8614b081..000000000
--- a/crates/pen-engine/Cargo.toml
+++ /dev/null
@@ -1,15 +0,0 @@
-[package]
-name = "pen-engine"
-version.workspace = true
-edition.workspace = true
-rust-version.workspace = true
-license.workspace = true
-description = "OpenPencil rendering engine (canvas viewport, signal-driven render) — bucket A in-WASM"
-
-[lib]
-name = "pen_engine"
-path = "src/lib.rs"
-
-[dependencies]
-pen-types = { path = "../pen-types", version = "0.1.0" }
-pen-core = { path = "../pen-core", version = "0.1.0" }
diff --git a/crates/pen-engine/src/lib.rs b/crates/pen-engine/src/lib.rs
deleted file mode 100644
index 43b945756..000000000
--- a/crates/pen-engine/src/lib.rs
+++ /dev/null
@@ -1,5 +0,0 @@
-//! OpenPencil rendering engine (canvas pipeline).
-
-pub fn placeholder() -> String {
-    format!("pen-engine ({})", pen_core::placeholder())
-}
diff --git a/crates/pen-figma/Cargo.toml b/crates/pen-figma/Cargo.toml
deleted file mode 100644
index 55f115e4d..000000000
--- a/crates/pen-figma/Cargo.toml
+++ /dev/null
@@ -1,16 +0,0 @@
-[package]
-name = "pen-figma"
-version.workspace = true
-edition.workspace = true
-rust-version.workspace = true
-license.workspace = true
-description = "OpenPencil Figma import/export — bucket A in-WASM"
-
-[lib]
-name = "pen_figma"
-path = "src/lib.rs"
-
-[dependencies]
-pen-types = { path = "../pen-types", version = "0.1.0" }
-serde = { workspace = true }
-serde_json = { workspace = true }
diff --git a/crates/pen-figma/src/lib.rs b/crates/pen-figma/src/lib.rs
deleted file mode 100644
index 472cb2d29..000000000
--- a/crates/pen-figma/src/lib.rs
+++ /dev/null
@@ -1,5 +0,0 @@
-//! OpenPencil Figma adapter.
-
-pub fn placeholder() -> String {
-    format!("pen-figma ({})", pen_types::placeholder())
-}
diff --git a/crates/pen-types/Cargo.toml b/crates/pen-types/Cargo.toml
deleted file mode 100644
index 208969f4e..000000000
--- a/crates/pen-types/Cargo.toml
+++ /dev/null
@@ -1,16 +0,0 @@
-[package]
-name = "pen-types"
-version.workspace = true
-edition.workspace = true
-rust-version.workspace = true
-license.workspace = true
-description = "OpenPencil core types (PenNode / Layer / Style / .op format) — bucket A in-WASM"
-
-[lib]
-name = "pen_types"
-path = "src/lib.rs"
-
-[dependencies]
-serde = { workspace = true }
-serde_json = { workspace = true }
-thiserror = { workspace = true }
diff --git a/crates/pen-types/src/lib.rs b/crates/pen-types/src/lib.rs
deleted file mode 100644
index bf1117a6c..000000000
--- a/crates/pen-types/src/lib.rs
+++ /dev/null
@@ -1,23 +0,0 @@
-//! OpenPencil core types.
-//!
-//! Per kickoff spec §1.2 bucket A: must compile on wasm32-unknown-unknown.
-
-#[derive(Debug, thiserror::Error)]
-pub enum PenError {
-    #[error("placeholder error")]
-    Placeholder,
-}
-
-pub fn placeholder() -> &'static str {
-    "pen-types skeleton"
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn skeleton_works() {
-        assert_eq!(placeholder(), "pen-types skeleton");
-    }
-}
diff --git a/tools/check-jian-boundaries.sh b/tools/check-jian-boundaries.sh
index 315d5cffc..1cbf58ac4 100755
--- a/tools/check-jian-boundaries.sh
+++ b/tools/check-jian-boundaries.sh
@@ -4,9 +4,10 @@
 # Verifies the following Jian crate boundary invariants from outside the
 # Rust build system. Run from the repo root.
 #
-# Invariant 1 (§12.3): openpencil-app must NOT depend directly on any
-#   `jian-*` crate — Jian is a shell-native implementation detail; the
-#   app only sees OP's `RenderBackend` / `ShellEvent` facade.
+# (The former Invariant 1 — "openpencil-app must not depend directly on
+#  any jian-* crate" — was dropped in Phase 1 Task 1.2 along with the
+#  `openpencil-app` placeholder crate. Step 1f reintroduces a real app
+#  crate; reinstate an equivalent facade check against it then.)
 #
 # Invariant 2 (§11.1, §12.3 — REVISED 2026-05-10): mobile targets
 #   (`aarch64-linux-android`, `aarch64-apple-ios`) must NOT pull
@@ -43,24 +44,6 @@ if ! command -v jq >/dev/null 2>&1; then
     exit 2
 fi
 
-# ── Invariant 1: openpencil-app has no direct jian-* dependency. ──────
-# `cargo metadata` returns a workspace-wide resolve graph; we filter
-# the `resolve.nodes[]` entry whose name matches `openpencil-app` and
-# inspect its direct `deps[]`. A direct dep on any `jian-*` crate
-# fails the invariant.
-metadata_full="$(cargo metadata --format-version 1)"
-forbidden_app="$(echo "$metadata_full" | jq -r '
-    [.packages[] | select(.name == "openpencil-app") | .id] as $app_ids
-    | .resolve.nodes[]
-    | select(.id as $id | $app_ids | index($id))
-    | .deps[].name
-' | grep -E '^jian-' || true)"
-if [ -n "$forbidden_app" ]; then
-    echo "INVARIANT 1 FAILED: openpencil-app directly depends on jian-* crate(s):" >&2
-    echo "$forbidden_app" >&2
-    exit 1
-fi
-
 # ── Invariant 2: mobile targets don't pull jian-host-desktop. ─────────
 # `cargo tree` honours `--target` cfg-gates so only the deps that
 # actually compile under the mobile target are listed. `jian-skia` IS