fix(natives): static-link win32 MSVC CRT so addon needs no VC++ redist

The shipped win32-x64 pi_natives addon linked the dynamic MSVC CRT (/MD)
and imported VCRUNTIME140.dll from the Visual C++ Redistributable, which
is absent on a clean Windows install. LoadLibrary of the extracted .node
then failed with error 126 ("The specified module could not be found"),
so omp could not start after a fresh `irm install.ps1 | iex`.

Static-link the CRT for the win32 addon: +crt-static for rustc (crate
BUILD select) plus the static_link_msvcrt cc feature enabled for win32 in
the native_addon transition, so its C deps (opus/cmake, tree-sitter,
blake3, ring) compile /MT in lock-step. The rebuilt .node imports only
core Windows system DLLs -- no VCRUNTIME140.dll, no api-ms-win-crt-*.

Fixes #8439

bazel/defs.bzl

@@ -16,19 +16,32 @@ _ADDON_RUSTC_FLAGS = [
 ]
 
 def _addon_transition_impl(settings, attr):
+    # Statically link the MSVC CRT for the shipped win32 addon: rustc gets
+    # +crt-static via the crate's rustc_flags select, and the C dependencies
+    # (opus/cmake, tree-sitter, blake3, ring) must move to /MT in lock-step so
+    # the final .node imports no VCRUNTIME140.dll from the Visual C++
+    # Redistributable (absent on a clean Windows install -> dlopen error 126).
+    # The static_link_msvcrt cc feature flips the toolchain compile flags that
+    # rules_rust forwards to cc-rs/cmake as CFLAGS/CXXFLAGS; it is inert for the
+    # zig/darwin toolchains, so scoping it to win32 is belt-and-suspenders.
+    features = list(settings["//command_line_option:features"])
+    if "win32" in str(attr.platform):
+        features = features + ["static_link_msvcrt"]
     return {
         "//command_line_option:platforms": str(attr.platform),
         "//command_line_option:compilation_mode": "opt",
+        "//command_line_option:features": features,
         "@rules_rust//rust/settings:lto": "thin",
         "@rules_rust//rust/settings:extra_rustc_flags": _ADDON_RUSTC_FLAGS,
     }
 
 _addon_transition = transition(
     implementation = _addon_transition_impl,
-    inputs = [],
+    inputs = ["//command_line_option:features"],
     outputs = [
         "//command_line_option:platforms",
         "//command_line_option:compilation_mode",
+        "//command_line_option:features",
         "@rules_rust//rust/settings:lto",
         "@rules_rust//rust/settings:extra_rustc_flags",
     ],

bazel/toolchains/msvc/NOTES.md

@@ -22,9 +22,16 @@ exec hosts. Replaces cargo-xwin.
   work from Bazel actions (cwd = execroot) *and* from build scripts, where
   rules_rust `${pwd}`-expands `CC`/`AR` to absolute paths and cc-rs/cmake spawn
   tools from other cwds.
-- **CRT: dynamic `/MD`** (rules_cc's msvc branch default outside `dbg` without
-  the `static_link_msvcrt` feature) — matches what napi/cc-rs produced under
-  cargo-xwin (rust msvc targets default to dynamic CRT without `+crt-static`).
+- **CRT: static `/MT` for the shipped addon.** The toolchain *default* is
+  dynamic `/MD` (rules_cc's msvc branch default outside `dbg` without the
+  `static_link_msvcrt` feature), matching what napi/cc-rs produced under
+  cargo-xwin. But `//:natives-win32-x64-baseline` overrides to static CRT:
+  `-Ctarget-feature=+crt-static` for rustc (crate BUILD select) plus the
+  `static_link_msvcrt` cc feature (enabled for win32 in the `native_addon`
+  transition, `bazel/defs.bzl`) so the C deps compile `/MT` in lock-step.
+  Without this the `.node` imports `VCRUNTIME140.dll` from the Visual C++
+  Redistributable, which is absent on a clean Windows install and makes the
+  loader's dlopen fail with error 126 (issue #8439).
 - **SSE floor in the wrapper, not annotations**: `-msse4.1 -msse4.2` live in the
   clang-cl wrapper, which only ever targets win32-x64 (baseline = x86-64-v2 ⊇
   SSE4.2). This is the old build-native.ts CFLAGS hack, windows-only by
@@ -103,8 +110,9 @@ exec hosts. Replaces cargo-xwin.
 ## What to verify on can.internal (linux-x64)
 
 1. `bazel build //:natives-win32-x64-baseline` end-to-end link; check the
-   produced `pi_natives.win32-x64-baseline.node` imports (dumpbin/llvm-readobj:
-   expect VCRUNTIME140/api-ms-win-crt-* → `/MD`, no static CRT).
+   produced `pi_natives.win32-x64-baseline.node` imports (dumpbin/llvm-readobj):
+   expect **no** `VCRUNTIME140.dll` and **no** `api-ms-win-crt-*` (static CRT);
+   only core Windows system DLLs (kernel32, ntdll, advapi32, …) should remain.
 2. LLVM 20.1.7 Linux-X64 binaries are built on a newish Ubuntu: confirm the
    kata runner image's glibc is ≥ 2.35-ish and has `libtinfo6`/`libstdc++6`
    (usual LLVM release-binary runtime deps).

crates/pi-natives/BUILD.bazel

@@ -40,6 +40,13 @@ rust_shared_library(
         # cdylib at all; napi musl addons have always linked the dynamic CRT.
         "//bazel/triples:x86_64-unknown-linux-musl": ["-Ctarget-feature=-crt-static"],
         "//bazel/triples:aarch64-unknown-linux-musl": ["-Ctarget-feature=-crt-static"],
+        # Statically link the MSVC CRT so the shipped .node does not import
+        # VCRUNTIME140.dll from the Visual C++ Redistributable, which is absent
+        # on a clean Windows install and makes the loader's dlopen fail with
+        # "The specified module could not be found" (error 126). The C deps are
+        # switched to /MT in lock-step via the static_link_msvcrt cc feature in
+        # the native_addon transition (bazel/defs.bzl).
+        "//bazel/triples:x86_64-pc-windows-msvc": ["-Ctarget-feature=+crt-static"],
         "//conditions:default": [],
     }),
     version = "17.1.5",

docs/natives-build-release-debugging.md

@@ -64,7 +64,7 @@ Notes:
 
 This mirrors the old cargo `ci` profile. Because the profile lives **in the transition**, a bare `bazel build //:natives-<t>` is always release-grade regardless of `-c`, and every addon shares one cache entry per (platform, source) pair. The rule then symlinks the produced shared library to the loader's canonical `pi_natives.<platform>-<arch>[-<variant>].node` name, scoped under the rule name (`bazel-bin/natives-<t>/…`) so gnu/musl outputs with identical basenames cannot collide at the package level.
 
-Per-target codegen that is not part of the transition lives in `crates/pi-natives/BUILD.bazel` `rustc_flags` selects: `-Ctarget-cpu=x86-64-v2` (baseline) / `x86-64-v3` (modern) via `//bazel/variants`, the napi link args (`-Wl,-undefined,dynamic_lookup` on macOS, `-Wl,-z,nodelete` on linux — `build.rs`/`napi_build::setup()` is deliberately not wired in), and `-Ctarget-feature=-crt-static` for musl.
+Per-target codegen that is not part of the transition lives in `crates/pi-natives/BUILD.bazel` `rustc_flags` selects: `-Ctarget-cpu=x86-64-v2` (baseline) / `x86-64-v3` (modern) via `//bazel/variants`, the napi link args (`-Wl,-undefined,dynamic_lookup` on macOS, `-Wl,-z,nodelete` on linux — `build.rs`/`napi_build::setup()` is deliberately not wired in), `-Ctarget-feature=-crt-static` for musl, and `-Ctarget-feature=+crt-static` for win32-x64 msvc (paired with the `static_link_msvcrt` cc feature enabled in the `native_addon` transition so the C deps compile `/MT` in lock-step — the shipped `.node` then imports no `VCRUNTIME140.dll` from the VC++ Redistributable).
 
 ### 3) Platforms and toolchains
 
@@ -73,7 +73,7 @@ Per-target codegen that is not part of the transition lives in `crates/pi-native
 | linux gnu (x64/arm64)  | `@zig_sdk//libc_aware/toolchain:linux_*_gnu.2.17` (hermetic zig cc)        | glibc **2.17** portability floor — same floor the previous cross builds used                          |
 | linux musl (x64/arm64) | `@zig_sdk//libc_aware/toolchain:linux_*_musl`                              | dynamic CRT (`-Ctarget-feature=-crt-static` in the crate BUILD)                                       |
 | darwin (x64/arm64)     | host Xcode toolchain                                                       | Apple frameworks aren't redistributable; darwin addons build on mac hosts only                        |
-| win32-x64 msvc         | `//bazel/toolchains/msvc` (`@msvc_cc`): clang-cl + lld-link + xwin CRT/SDK | hermetic cross-link from linux-x64 CI pods and darwin dev hosts; see `bazel/toolchains/msvc/NOTES.md` |
+| win32-x64 msvc         | `//bazel/toolchains/msvc` (`@msvc_cc`): clang-cl + lld-link + xwin CRT/SDK | hermetic cross-link from linux-x64 CI pods and darwin dev hosts; **static CRT** (`+crt-static` + `static_link_msvcrt`) so the addon needs no VC++ Redistributable; see `bazel/toolchains/msvc/NOTES.md` |
 
 Rust toolchains are nightly (pinned in `MODULE.bazel`), with repo-local musl re-registrations in `//bazel/toolchains` carrying an explicit `@zig_sdk//libc:musl` constraint (rules_rust's generated gnu and musl toolchains otherwise share (os, cpu) constraints).
 

packages/natives/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed `omp` failing to start on a clean Windows install with `Failed to load pi_natives native addon for win32-x64 ... The specified module could not be found` (LoadLibrary error 126). The shipped win32-x64 addon linked the dynamic MSVC CRT (`/MD`) and imported `VCRUNTIME140.dll` from the Visual C++ Redistributable, which is absent on a fresh Windows install. The addon now statically links the CRT (`+crt-static` for rustc plus the `static_link_msvcrt` cc feature for its C dependencies), so the `.node` imports only core Windows system DLLs ([#8439](https://github.com/can1357/oh-my-pi/issues/8439)).
+
 ## [17.3.0] - 2026-08-13
 
 ### Fixed