diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d8b6e50..09dd732 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -134,6 +134,15 @@ jobs:
         shell: bash
         run: ./ci.sh test
 
+      # Linux-only inside the gate: soldr's compile daemon cannot spawn
+      # on GHA macOS/Windows runners (zackees/soldr#1300); the gate
+      # self-skips there.
+      - name: backend-smoke
+        id: backend_smoke
+        continue-on-error: true
+        shell: bash
+        run: ./ci.sh backend_smoke
+
       - name: action-yaml
         id: action_yaml
         continue-on-error: true
@@ -156,6 +165,7 @@ jobs:
           [ "${{ steps.clippy.outcome }}" = "failure" ] && fail+=("clippy") || true
           [ "${{ steps.ruff.outcome }}" = "failure" ] && fail+=("ruff") || true
           [ "${{ steps.test.outcome }}" = "failure" ] && fail+=("test") || true
+          [ "${{ steps.backend_smoke.outcome }}" = "failure" ] && fail+=("backend_smoke") || true
           [ "${{ steps.action_yaml.outcome }}" = "failure" ] && fail+=("action_yaml") || true
           [ "${{ steps.action_surface.outcome }}" = "failure" ] && fail+=("action_surface") || true
           if [ ${#fail[@]} -gt 0 ]; then
diff --git a/ci.py b/ci.py
index 046ffd7..ff052d0 100755
--- a/ci.py
+++ b/ci.py
@@ -41,6 +41,7 @@
     "ruff",
     "build",
     "test",
+    "backend_smoke",
     "action_yaml",
     "action_surface",
 ]
diff --git a/ci/build_wheel.py b/ci/build_wheel.py
index 8908976..08e73e4 100644
--- a/ci/build_wheel.py
+++ b/ci/build_wheel.py
@@ -36,13 +36,13 @@
   binary as a raw wheel script bypasses the Python launcher entirely.
   See fbuild#747 / zackees/template-python-rust-cmd#2 (items 1 + 10).
 """
+
 from __future__ import annotations
 
 import base64
 import hashlib
 import json
 import os
-import shutil
 import platform
 import subprocess
 import sys
@@ -289,9 +289,7 @@ def inject_cli_into_wheel(binary: Path) -> Path:
         entries: dict[str, bytes] = {name: wf.read(name) for name in wf.namelist()}
 
     if record_arcname not in entries:
-        raise SystemExit(
-            f"wheel has no {record_arcname}; cannot inject CLI script"
-        )
+        raise SystemExit(f"wheel has no {record_arcname}; cannot inject CLI script")
 
     # Append a RECORD row for the new script. RECORD's own row keeps
     # empty hash + size per spec — we preserve that.
@@ -311,7 +309,7 @@ def inject_cli_into_wheel(binary: Path) -> Path:
             # pip installs land it +x. create_system=3 = Unix.
             if name == script_arcname:
                 info.create_system = 3
-                info.external_attr = (0o755 << 16)
+                info.external_attr = 0o755 << 16
             wf.writestr(info, data)
     return wheel_path
 
diff --git a/ci/gates/backend_smoke.py b/ci/gates/backend_smoke.py
new file mode 100644
index 0000000..3690a1e
--- /dev/null
+++ b/ci/gates/backend_smoke.py
@@ -0,0 +1,52 @@
+"""PEP 517 backend smoke: `uv build --wheel` through the soldr backend.
+
+The `[build-system]` in pyproject.toml routes wheel builds through the
+soldr backend (which drives `maturin pep517` under a rustc-caching
+wrapper). The `test` gate deliberately avoids that path (see its
+docstring), so without this gate the backend swap would ship untested.
+
+This gate builds one wheel via the real backend — exactly what a
+downstream `pip install template-python-rust-cmd` (sdist) or
+`uv build` does.
+
+Linux-only: soldr's compile daemon cannot spawn on GHA macOS/Windows
+runners (zackees/soldr#1300) — macOS fails with "embedded compile
+dispatch failed after 30000ms budget: NotRunning" and Windows wedges
+the step for ~an hour. On those platforms the gate skips (returns 0)
+rather than burning an hour to report a known-upstream condition.
+Re-enable everywhere once soldr#1300 is fixed and the pin in
+pyproject.toml is bumped past the fixed release.
+"""
+
+from __future__ import annotations
+
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[2]
+
+
+def run() -> int:
+    if sys.platform != "linux":
+        print(
+            "backend_smoke: skipped on non-Linux (soldr compile daemon "
+            "cannot spawn on GHA macOS/Windows runners — "
+            "zackees/soldr#1300). The backend path is exercised on the "
+            "Linux lanes."
+        )
+        return 0
+    if shutil.which("uv") is None:
+        print("uv not on PATH; cannot run backend_smoke gate", file=sys.stderr)
+        return 1
+    proc = subprocess.run(
+        ["uv", "build", "--wheel", "--out-dir", "dist/backend-smoke"],
+        cwd=ROOT,
+        check=False,
+    )
+    return proc.returncode
+
+
+if __name__ == "__main__":
+    raise SystemExit(run())
diff --git a/ci/gates/ruff.py b/ci/gates/ruff.py
index f172f07..f83ee34 100644
--- a/ci/gates/ruff.py
+++ b/ci/gates/ruff.py
@@ -5,7 +5,8 @@
 points at a real issue (unused imports, shadowed names, etc.).
 
 Invoked via `uv run --no-project --with ruff` so we get a hermetic ruff
-without triggering the maturin build the surrounding pyproject.toml
+without triggering the wheel build (soldr PEP 517 backend driving
+maturin) the surrounding pyproject.toml
 otherwise demands. `--with ruff` provisions the dep at script-time even
 when the script itself has no PEP 723 deps declared for it.
 
diff --git a/ci/gates/test.py b/ci/gates/test.py
index 9510251..eb622b1 100644
--- a/ci/gates/test.py
+++ b/ci/gates/test.py
@@ -1,9 +1,12 @@
 """Test gate: `cargo test --workspace` + `pytest`.
 
 This is one of the named entry points that legitimately *needs* the
-maturin wheel built (pytest imports `template_python_rust_cmd._native`).
-We invoke it via plain `uv run` (project context kept on purpose) so
-maturin develop materializes the extension module before pytest runs.
+extension module built (pytest imports `template_python_rust_cmd._native`).
+We sync the dev deps with `--no-install-project` and let a direct
+`maturin develop` materialize the extension module before pytest runs —
+deliberately NOT via the PEP 517 backend (soldr), whose compile daemon
+cannot spawn on GHA macOS/Windows runners (zackees/soldr#1300). The
+backend path is covered by the `backend_smoke` gate on Linux.
 
 Reserve this opt-in to the build for named entry points — see [zccache#835
 rule 5](https://github.com/zackees/zccache/issues/835). Other gates use
@@ -38,13 +41,28 @@ def run() -> int:
     if rc != 0:
         return rc
 
-    # `maturin develop` needs the project context, so we do NOT pass
-    # --no-project here. This is the documented opt-in to the full
-    # build (see [zccache#835] rule 5).
+    # Materialize the dev dependency group (maturin, pytest) WITHOUT
+    # installing the project itself. A plain `uv run` here would sync
+    # the project editable through the PEP 517 backend (soldr), and
+    # soldr's compile daemon cannot spawn on GHA macOS/Windows runners
+    # (zackees/soldr#1300): macOS dies with "embedded compile dispatch
+    # failed after 30000ms budget: NotRunning", Windows wedges the step
+    # for an hour. The extension module is instead built by the direct
+    # `maturin develop` call below, which does not route through the
+    # backend. The backend itself is exercised by the `backend_smoke`
+    # gate on Linux, where the daemon spawns fine.
+    rc = _run(["uv", "sync", "--no-install-project"])
+    if rc != 0:
+        return rc
+
+    # `maturin develop` builds + installs the extension module into the
+    # synced venv directly (no PEP 517 backend involved). `--no-sync`
+    # keeps uv from re-syncing (and re-triggering the backend build).
     rc = _run(
         [
             "uv",
             "run",
+            "--no-sync",
             "maturin",
             "develop",
             "--uv",
@@ -55,7 +73,7 @@ def run() -> int:
     if rc != 0:
         return rc
 
-    rc = _run(["uv", "run", "pytest"])
+    rc = _run(["uv", "run", "--no-sync", "pytest"])
     return rc
 
 
diff --git a/ci/hooks/tool_guard.py b/ci/hooks/tool_guard.py
index 5a11782..f018317 100644
--- a/ci/hooks/tool_guard.py
+++ b/ci/hooks/tool_guard.py
@@ -298,7 +298,8 @@ def _check_segment(seg: str) -> tuple[str, str] | None:
                 "Use `./ci.sh <gate>` for lint/gate invocations, or run "
                 "your build through a named entry point (./test, ./build, "
                 "ci/build_wheel.py). Bare `uv run` walks up to pyproject.toml "
-                "and triggers the maturin wheel build before your script "
+                "and triggers the wheel build (soldr PEP 517 backend driving "
+                "maturin) before your script "
                 "starts. Add `--no-project --script` to skip discovery and "
                 "use the PEP 723 inline-deps path.",
             )
diff --git a/install b/install
index 417002d..2f4d668 100755
--- a/install
+++ b/install
@@ -10,8 +10,8 @@ Verifies the toolchain shape this repo expects:
   - The pinned Rust toolchain (rust-toolchain.toml) is resolvable.
   - The dev dependency group is materialized.
 
-Does NOT trigger a maturin build — that's reserved for `./test` /
-`./build`. Use `./install` after a fresh clone to confirm the
+Does NOT trigger a wheel build (soldr PEP 517 backend / maturin) —
+that's reserved for `./test` / `./build`. Use `./install` after a fresh clone to confirm the
 environment is sane.
 """
 
diff --git a/pyproject.toml b/pyproject.toml
index 5a4e90c..af2e20b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [build-system]
-requires = ["maturin>=1.7,<2"]
-build-backend = "maturin"
+requires = ["soldr>=0.7.98"]
+build-backend = "soldr"
 
 [project]
 name = "template-python-rust-cmd"
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 1125e3a..8b31f71 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -15,6 +15,7 @@
 script) is fundamentally not visible from the source tree anymore —
 there's no `_bin/` directory to look at. See #9.
 """
+
 from __future__ import annotations
 
 import os