The linker is told once, not twice

novox/hq 04-ISSUES/161. A repeated flag is not a merged one. The Go
command takes the last -ldflags and drops the first, so passing the
toolchain's flags and then the system stamp as a second one produced a
binary that knew its system and had lost -s -w: 12.2MB against 8.5MB,
with its debug info intact.

My own comment said the linker "accepts and merges" them. It does not,
and I found out by reading the file the build produced rather than by
reading the comment again.

Linker flags are now the toolchain's own list, composed into one flag with
the stamp. A test refuses a compile line that carries -ldflags itself,
because that is what makes two.

internal/builder/toolchain.go

@@ -49,6 +49,14 @@ type Toolchain struct {
 	// is named as it will be FOUND, inside the unpacked bundle, so the source is the same path with
 	// the output directory taken off the front and this on the end.
 	SourceExt string
+	// LinkerFlags are passed to the linker as one flag, together with the system stamp below.
+	//
+	// **Separate from Compile because a repeated flag is not a merged one.** They were in the compile
+	// line, and appending the stamp as a second `-ldflags` meant the Go command took the last and
+	// dropped the first — so the binary gained its system and lost `-s -w`, growing by half and
+	// carrying its debug info. The mistake was believing a comment rather than reading the file it
+	// produced (novox/hq 04-ISSUES/161).
+	LinkerFlags []string
 	// SystemStamp is the variable this language's linker fills with the artifact's declared system,
 	// for a language whose binaries are pinned to one at link time (novox/hq ADR 0005).
 	//
@@ -126,9 +134,12 @@ var toolchains = []Toolchain{
 		// rather than from the linker: two builds of one commit produce the same bytes.
 		Compile: []string{
 			"env", "CGO_ENABLED=0", "GOFLAGS=-trimpath",
-			"go", "build", "-ldflags", "-s -w",
+			"go", "build",
 		},
-		OutputFlag: "-o",
+		// Stripped of symbols and debug info: what a machine holds is a file it runs, not one it
+		// debugs, and the difference measured 12.2MB against 8.5MB.
+		LinkerFlags: []string{"-s", "-w"},
+		OutputFlag:  "-o",
 		// Pointed at the package the artifact is built `from`, compiled whole. Go writes the binary
 		// into the output directory, named after the package — so the bundle a machine unpacks is a
 		// directory holding one executable, which is what the delivery mechanism expects