#26 Fix TinyGo net/http wasm build via pinned upstream patch (Go 1.26)

TinyGo 0.41.1 and earlier vendor tinygo-org/net@e54965e, whose net/http
js/wasm overlay (roundtrip_js.go) calls the private t.roundTrip fallback
removed from Go 1.25+/1.26 net/http, so `pnpm run build` fails to compile
on Go 1.26 (tinygo-org/tinygo#5467). No released TinyGo carries the fix
yet: it landed in tinygo-org/net@1026408a on 2026-04-27, after 0.41.1
shipped 2026-04-22, and is already on TinyGo's dev branch.

Keep Go 1.26 and apply the exact upstream fix in CI before the build:
- .ci/tinygo-net-roundtrip.patch: byte-exact tinygo-org/net@1026408a diff
  (its parent e54965e is the commit 0.41.1 ships), targeting
  src/net/http/roundtrip_js.go.
- ci.yml: new "Patch TinyGo net/http (temporary)" step applies it to
  $(tinygo env TINYGOROOT) via `git apply`, failing loudly on drift.
- .gitattributes: force LF on *.patch so `git apply` works on the Linux
  runner regardless of the committer's platform.
- README: document the temporary patch and its removal condition.

Temporary: remove the patch and the CI step once a TinyGo release later
than 0.41.1 ships the net fix. Tracking #26.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -38,9 +38,10 @@ jobs:
         with:
           go-version: '1.26'
 
-      # TinyGo is needed only for the Wasm Worker build (pnpm run build). The
-      # 0.41.x line is the first with Go 1.26 support; install-binaryen (default
-      # true) provides wasm-opt, which TinyGo invokes for the -target wasm build.
+      # TinyGo is needed only for the Wasm Worker build (pnpm run build).
+      # install-binaryen (default true) provides wasm-opt, which TinyGo invokes
+      # for the -target wasm build. 0.41.1's vendored net/http js overlay is
+      # patched just before the build (see "Patch TinyGo net/http" below).
       - name: Set up TinyGo
         uses: acifani/setup-tinygo@dd8a7075d951a7595b2ef2123ed0ab1af0c13e56 # v3.0.0
         with:
@@ -79,6 +80,25 @@ jobs:
             echo "infra/go.mod not present; skipping (no-op until ticket #2)"
           fi
 
+      # TEMPORARY (tracking #26; tinygo-org/tinygo#5467): TinyGo 0.41.1 and
+      # earlier vendor tinygo-org/net@e54965e, whose net/http js/wasm overlay
+      # (roundtrip_js.go) calls the private t.roundTrip fallback that no longer
+      # exists in Go 1.25+/1.26 net/http, so the wasm build fails to compile.
+      # Apply the exact upstream fix (tinygo-org/net@1026408a) to the installed
+      # TinyGo source. git apply exits non-zero (failing the job loudly) if the
+      # source has drifted, so we notice when TinyGo changes upstream.
+      # TODO: delete this step and .ci/tinygo-net-roundtrip.patch once a TinyGo
+      # release later than 0.41.1 ships the fix (already on TinyGo's dev branch).
+      - name: Patch TinyGo net/http (temporary)
+        run: |
+          patch_file="$PWD/.ci/tinygo-net-roundtrip.patch"
+          tinygoroot="$(tinygo env TINYGOROOT)"
+          echo "Applying $patch_file to $tinygoroot/src/net/http/roundtrip_js.go"
+          git -C "$tinygoroot" apply --verbose "$patch_file" || {
+            echo "::error::TinyGo net/http patch did not apply cleanly; TinyGo source may have changed. Update or remove .ci/tinygo-net-roundtrip.patch (see #26)."
+            exit 1
+          }
+
       # Confirms the Wasm Worker builds end to end: workers-assets-gen emits the
       # JS shim and TinyGo compiles ./worker into build/app.wasm.
       - name: Build Wasm Worker