Ensure annotations.yml and tool.uv.extra-build-dependencies compose

Author: konsti-openai

e2e/cases/BUILD.bazel

@@ -116,20 +116,21 @@ write_source_files(
         # rule expands env keys correctly given an explicit fixture.
         "snapshots/sdist_build.uv_sdist_jdk_build.jpype1.BUILD.bazel": "@sdist_build__uv_sdist_jdk_build__jpype1__1_7_1//:BUILD.bazel",
 
-        # @sdist_build for cowsay with native annotation and monitor_memory
-        # ------------------------------------------------------------------
+        # @sdist_build for cowsay with composed annotations and monitor_memory
+        # ---------------------------------------------------------------------
         # cowsay is pure Python, so only `native = true` can select
         # pep517_native_whl. Its build and native annotations are split so the
         # snapshot also pins that a native-only annotation preserves explicit
-        # and configure-discovered build deps. This retains the monitor-only
-        # source-build coverage. The runtime //uv-sdist-fallback:test
+        # and configure-discovered build deps, while legacy build deps compose
+        # with distinctly marker-qualified uv-native deps. This retains the
+        # monitor-only source-build coverage. The runtime //uv-sdist-fallback:test
         # proves that the forced-native build produces a working wheel.
         "snapshots/sdist_build.uv_sdist_fallback.cowsay.BUILD.bazel": "@sdist_build__uv_sdist_fallback__cowsay__6_0//:BUILD.bazel",
 
         # @sdist_build for tqdm with tool.uv.extra-build-dependencies
         # -----------------------------------------------------------
-        # Pins the uv-native annotation path independently of cowsay's legacy
-        # annotations.toml entry.
+        # Pins the uv-native annotation and match-runtime paths independently
+        # of cowsay's composed legacy and uv-native annotations.
         "snapshots/sdist_build.uv_sdist_fallback.tqdm.BUILD.bazel": "@sdist_build__uv_sdist_fallback__tqdm__4_52_0//:BUILD.bazel",
 
         # @sdist_build for both conflicting versions of packaging

e2e/cases/uv-sdist-fallback/pyproject.toml

@@ -21,6 +21,13 @@ no-binary-package = ["cowsay", "tqdm"]
 [tool.uv.extra-build-dependencies]
 # `packaging` is intentionally absent from `default_build_dependencies`, so
 # the tqdm snapshot catches a broken uv-native annotation path.
+cowsay = [
+    # Keep two conditional dependencies under distinct markers so composing
+    # cowsay's legacy annotation does not accidentally discard a marker branch.
+    "colorama; sys_platform != 'win32'",
+    "colorama; sys_platform != 'imaginary'",
+    "pyproject-hooks; sys_platform != 'emscripten'",
+]
 tqdm = [
     # `ssl` is an empty setuptools extra that exercises extra-qualified
     # requirements without expanding this fixture's lockfile.

uv/private/extension/defs.bzl

@@ -300,8 +300,9 @@ def _parse_projects(module_ctx, hub_specs):
                                     break
                                 deps.append(resolved)
                             if not skip:
-                                lock_build_dep_anns[target] = deps
-                                lock_conditional_build_dep_anns.pop(target, None)
+                                # Legacy and uv-native annotations compose, including
+                                # any marker-qualified uv-native dependencies.
+                                lock_build_dep_anns[target] = lock_build_dep_anns.get(target, []) + deps
 
             package_overrides = {}
             package_console_scripts = {}