feat(plugin): carry Http\Response across as a materialized value

A response is built for one request and the graph never retains it, so there
is no entity for a handle to point at. The child holds a real instance
instead, revived from the object record the wire carries, and collect() frees
the copy each world holds — which is what that method is for. The
value-object rule rejects the class only because collect() assigns to $this,
so the category comes from an overrides.list entry.

HttpDownloader::get() and copy() answer with one.

Two gaps stay: decodeJson() reaches Composer\Json\JsonFile, which a guard
shadows, and Composer answers a curl request with the CurlResponse subclass
where this port flattens the value into a Response.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/crates/shirabe/tests/plugin/e2e_http_downloader_test.rs b/crates/shirabe/tests/plugin/e2e_http_downloader_test.rs
index ecb0b34c..42471b61 100644
--- a/crates/shirabe/tests/plugin/e2e_http_downloader_test.rs
+++ b/crates/shirabe/tests/plugin/e2e_http_downloader_test.rs
@@ -61,7 +61,8 @@ fn test_plugin_owned_http_downloader_matches_upstream_composer() {
 
     // Pinned as well as compared, so a run where neither side wrote a trace cannot pass. The
     // second options line is the evidence that both worlds merge into one value rather than each
-    // holding its own copy of the map.
+    // holding its own copy of the map, and the response lines are the evidence that the value the
+    // request answers with is a real instance of the class rather than something shaped like one.
     assert_eq!(
         "\
 event=post-update-cmd
@@ -71,6 +72,11 @@ options merged=[\"X-Probe: 2\"]
 isCurlEnabled=true
 hints other=null transport=null
 outputWarnings=ok
+get=ok
+response class=\"Composer\\\\Util\\\\Http\\\\Response\" body=\"{\\\"probe\\\":true,\\\"n\\\":42}\" headers=[]
+getHeader=null
+copy=ok file=\"{\\\"probe\\\":true,\\\"n\\\":42}\"
+collect=ok
 ",
         upstream.trace
     );