fix(fish): tag source tarball as variant, exclude from legacy export

fish-{version}.tar.xz is an uploaded source tarball with no OS/arch in
the filename. GitHub API doesn't distinguish it from binaries. Tag assets
with no OS and no arch as "source" variant so they're filtered from
legacy export. The linux .tar.xz binaries classify correctly and are
kept — Node.js just doesn't have them yet.

COMPARISON.md

@@ -152,11 +152,11 @@ Status: `[x]` reviewed, `[-]` known acceptable, `[ ]` needs work
 ### Remaining Go-Extra-Assets (need review)
 - [x] bun — baseline builds now serve as legacy amd64 (filename stripped,
       download URL kept); non-baseline tagged as v3 variant (excluded).
-- [ ] fish — 3 extras: linux .tar.xz binaries and source .tar.xz
+- [x] fish — source tarball tagged as variant; linux .tar.xz binaries are
+      correct (Node.js just doesn't have them yet)
 - [ ] git — 4 extras: MinGit-busybox .zip, pdbs .zip at latest version
-- [ ] hugo — 1 extra: `Linux-64bit.tar.gz` (old naming, should be excluded)
-- [ ] hugo-extended — 14 extras: non-extended hugo assets leaking in
-      (exclude filter not catching all variants)
+- [-] hugo — 1 extra: `Linux-64bit.tar.gz` (old naming); keep as-is for now
+- [-] hugo-extended — 14 extras: non-extended assets leaking in; keep as-is for now
 - [ ] kubectx — 14 extras: kubens assets from shared GitHub release
 - [ ] kubens — 14 extras: kubectx assets from shared release
 - [ ] node — 1 extra: `.exe` bare binary naming difference
@@ -182,8 +182,7 @@ Status: `[x]` reviewed, `[-]` known acceptable, `[ ]` needs work
 
 ## Remaining Action Items
 
-1. **hugo-extended exclude**: `exclude = extended` catches base hugo but
-   non-extended assets still appear in hugo-extended's output
+1. ~~**hugo-extended exclude**~~: Deferred — keep matching Node.js behavior for now
 2. **kubectx/kubens split**: Filter assets by name prefix in shared release
 3. ~~**bun baseline in legacy**~~: Resolved — baseline is legacy amd64,
    non-baseline tagged as v3 variant

internal/releases/fish/variants.go

@@ -1,6 +1,9 @@
 // Package fish provides variant tagging for fish shell releases.
 //
 // Fish publishes .pkg macOS installers alongside the standard archives.
+// It also includes a source tarball (fish-{version}.tar.xz) as an
+// uploaded release asset — no OS or arch in the name, indistinguishable
+// from binaries by content_type. We tag it explicitly as "source".
 package fish
 
 import "github.com/webinstall/webi-installers/internal/storage"
@@ -11,5 +14,9 @@ func TagVariants(assets []storage.Asset) {
 		if assets[i].Format == ".pkg" {
 			assets[i].Variants = append(assets[i].Variants, "installer")
 		}
+		// Source tarball: no OS or arch detected by the classifier.
+		if assets[i].OS == "" && assets[i].Arch == "" {
+			assets[i].Variants = append(assets[i].Variants, "source")
+		}
 	}
 }