tests: the fixtures that used the removed key, and the one assertion only macOS could fail

Three CI-only failures, all from this change and each in a fixture rather than
in the engine.

e2e 88 and 205 declared [xlings.envs], which is now refused. 205 drops it; 88
asserted the key was materialized and now asserts it is not, and gains two
criteria the merge introduced: the same statement in both tables collapses to
one entry, and the superseded key is reported with the line to write.

The manifest parser gained that collapse. deps and workspace agreeing about one
package is not an error and is not two entries — appending it twice would ask
xlings to install one package twice.

Manifest.XlingsWorkspaceAcceptsPerPlatformValues compared host_platform_key()
against "macos", and this change made that key xlings' own spelling, "macosx".
The assertion was written in terms of the function precisely so it would run on
every host, and it was the one line in the file that could only fail on a macOS
runner. It did.

Author: speak-agent

modules/manifest/src/toml.cppm

@@ -1552,7 +1552,14 @@ std::expected<Manifest, ManifestError> parse_string(std::string_view content,
             // Compared on the whole pin, not on the version: two namespaces at
             // one version are two packages sharing a name.
             if (auto pinned = m.xlings.workspace.find(entry.target);
-                pinned != m.xlings.workspace.end() && pinned->second != entry.pin()) {
+                pinned != m.xlings.workspace.end() && pinned->second == entry.pin()) {
+                // The same statement in both tables. Not an error and not two
+                // entries: appending it again would ask xlings to install one
+                // package twice, so only the advisory below is produced.
+                replacement += std::format("\n           {} = \"{}\"",
+                                           entry.target, entry.pin());
+                continue;
+            } else if (pinned != m.xlings.workspace.end()) {
                 auto say = [](const std::string& p) {
                     return p.empty() ? std::string("unconstrained") : p;
                 };

tests/e2e/205_root_local_subos.sh

@@ -79,9 +79,6 @@ members = ["app"]
 
 [xlings]
 subos = "root-el8"
-
-[xlings.envs]
-ROOT_ONLY = "1"
 EOF
 cat >"$ws/app/mcpp.toml" <<'EOF'
 [package]

tests/e2e/88_xlings_environment.sh

@@ -37,12 +37,10 @@ deps = ["ninja@1.12.1"]
 subos = "dev"
 
 [xlings.workspace]
-# Pin a tool version (the general form of [toolchain]).
+# The one table (2026.9.3.1+). The same statement as the `deps` line above,
+# which is deliberate: the two must collapse to one entry rather than ask
+# xlings to install one package twice.
 ninja = "1.12.1"
-
-[xlings.envs]
-# Env vars applied by xvm shims.
-APP_BUILD_ENV = "1"
 EOF
 echo 'int main() { return 0; }' > app/src/main.cpp
 
@@ -65,7 +63,12 @@ grep -q 'ninja@1.12.1'     "$J" || { echo "FAIL: deps entry missing"; exit 1; }
 grep -q '"subos": "dev"'   "$J" || { echo "FAIL: subos not materialized"; exit 1; }
 grep -q '"workspace"'      "$J" || { echo "FAIL: workspace not materialized"; exit 1; }
 grep -q '"ninja": "1.12.1"' "$J" || { echo "FAIL: workspace pin missing"; exit 1; }
-grep -q '"envs"'           "$J" || { echo "FAIL: envs not materialized"; exit 1; }
-grep -q '"APP_BUILD_ENV": "1"' "$J" || { echo "FAIL: env var missing"; exit 1; }
+grep -q '"envs"'           "$J" && { echo "FAIL: envs is materialized and nothing reads it"; exit 1; }
+# One statement, one entry: `deps` and `[xlings.workspace]` agree here, and the
+# materialized list must not name the package twice.
+[ "$(grep -o 'ninja@1.12.1' "$J" | wc -l)" -eq 1 ] \
+    || { echo "FAIL: the same statement was materialized twice"; exit 1; }
+# The superseded key is reported, with the line to write instead.
+grep -q '\[xlings.workspace\]' b.log || { echo "FAIL: no advisory for [xlings] deps"; cat b.log; exit 1; }
 
 echo "OK"

tests/unit/test_manifest.cpp

@@ -4503,7 +4503,10 @@ xmake = "3.0.7"
     const auto host = mcpp::manifest::host_platform_key();
     if (host == "linux") EXPECT_EQ(m->xlings.workspace.at("gcc"), "15.1.0");
     else                 EXPECT_EQ(m->xlings.workspace.count("gcc"), 0u);
-    EXPECT_EQ(m->xlings.workspace.at("llvm"), host == "macos" ? "20" : "22");
+    // `host_platform_key()` is xlings' spelling, `macosx`, since 2026.9.3.1.
+    // Comparing against "macos" here made this the one assertion in the file
+    // that could only fail on a macOS runner — and it did.
+    EXPECT_EQ(m->xlings.workspace.at("llvm"), host == "macosx" ? "20" : "22");
     EXPECT_EQ(m->xlings.workspace.at("xmake"), "3.0.7");
 }