Say what a 0 side does in the ValidateDimension doc comment

It said 0 meant "original size"; the side is worked out from the
source's proportions, as README.md now says.

Model: opus-5-5

README.md

@@ -473,11 +473,9 @@ nor change what it asks for.
    `jxl` for a form with no format.
 
 The token holds the source's host, path and query and the size, format, quality,
-fit and expiry, encrypted with a key derived from `signing_key`. The host is
+fit and expiry, encrypted with a key derived from `signing_key`. The source
-kept in lower case and an empty path as `/`, as for `/v1/image/`, so
+URL's scheme is not kept: the image is fetched like any other (see Routes), and
-`https://CDN.Example.com` and `https://cdn.example.com/` are one source image,
+the blocked networks still apply.
-fetched and cached once. The source URL's scheme is not kept: the image is
-fetched like any other (see Routes), and the blocked networks still apply.
 
 How long the URL lasts is chosen on the page, from 1 minute to 1 year, or never.
 The expiry is fixed in the token when the URL is made and cannot be changed or

TODO.md

@@ -44,11 +44,6 @@ P2: security: per-origin rate limiting
   the image is scaled to cover the size, so that source at `100x0` comes out at
   8192x1. `README.md` now says this under Signature Specification, and says how
   a `0` side is worked out where it said `0` meant the original.
-- 2026-10-16 the generator page lower-cases the source host and writes an empty
-  source path as `/` before it makes the encrypted URL, as `/v1/image/` does
-  (closes #293). A host written in upper and in lower case, or a source URL with
-  no path and with the path `/`, made two cache keys and two upstream requests
-  for one image.
 - 2026-10-16 the source URL a request fetches is built with `net/url` from the
   source host, path and query, not joined as text (closes #288). The source
   path, decoded, is fetched percent-encoded again, so `100%25.png` fetches

internal/handlers/auth.go

@@ -127,7 +127,7 @@ func (s *Handlers) HandleGenerateURL() http.HandlerFunc {
 		sourceURL := r.FormValue("url")
 
 		// Validate source URL
-		parsed, err := parseSourceURL(sourceURL)
+		parsed, err := url.Parse(sourceURL)
 		if err != nil || parsed.Host == "" {
 			s.renderGeneratorWithForm(w, r, "Invalid source URL", r.Form,
 				http.StatusBadRequest)
@@ -198,25 +198,6 @@ func (s *Handlers) HandleGenerateURL() http.HandlerFunc {
 	}
 }
 
-// parseSourceURL parses the source URL entered on the generator page with its
-// host lower-cased and an empty path written as "/", as /v1/image/ reads a
-// source URL, so that each spelling of one source URL makes one cache key and
-// one upstream request.
-func parseSourceURL(sourceURL string) (*url.URL, error) {
-	parsed, err := url.Parse(sourceURL)
-	if err != nil {
-		return nil, err
-	}
-
-	parsed.Host = strings.ToLower(parsed.Host)
-
-	if parsed.Path == "" {
-		parsed.Path = "/"
-	}
-
-	return parsed, nil
-}
-
 // fetchedAsWritten reports whether fetchURL, the URL pixa fetches for an
 // image URL made from the source URL source, is source as it was written,
 // apart from the scheme, which the token does not keep. It is not when source

internal/server/source_url_internal_test.go

@@ -308,70 +308,6 @@ func TestGeneratedURLFetchesTheSourceURLAsEntered(t *testing.T) {
 	}
 }
 
-// TestGeneratorMakesOneImageURLForTwoSpellingsOfASourceURL enters two
-// spellings of one source URL on the generator page, requests the encrypted
-// URL made for each, and checks that the upstream receives one request and
-// that the second encrypted URL is served from the cache. One pair writes the
-// host in upper and in lower case, which /v1/image/ lower-cases. The host is
-// an IPv6 address, whose hex digits have letter case, because the fetcher
-// would look a host name up in DNS. It has a port, as the fetcher refuses an
-// IPv6 address written without one. The other pair is a source URL with no
-// path and with the path "/", both of which fetch "/".
-func TestGeneratorMakesOneImageURLForTwoSpellingsOfASourceURL(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		name string
-		// sourceURLs are the two spellings, after "https://"
-		sourceURLs []string
-		// wantRequest is the path the upstream must receive
-		wantRequest string
-	}{
-		{"host in upper and in lower case",
-			[]string{"[2001:DB8::A]:8443/a.png", "[2001:db8::a]:8443/a.png"},
-			"/a.png"},
-		{"no path and the path written as a slash",
-			[]string{upstreamHost, upstreamHost + "/"}, "/"},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
-
-			upstream := startRecordingUpstream(t)
-			s, _, _ := startImageProxy(t, upstream.Server)
-
-			var imageURLs []string
-
-			for _, sourceURL := range tt.sourceURLs {
-				rec := postGenerate(t, s, "https://"+sourceURL)
-
-				match := generatedURLPattern.FindStringSubmatch(rec.Body.String())
-				if rec.Code != http.StatusOK || match == nil {
-					t.Fatalf("POST /generate: %d with no encrypted URL; body %s",
-						rec.Code, rec.Body.String())
-				}
-
-				imageURLs = append(imageURLs, match[1])
-			}
-
-			getImage(t, s, imageURLs[0])
-
-			second := getImage(t, s, imageURLs[1])
-			if got := second.Header().Get("X-Pixa-Cache"); got != string(imgcache.CacheHit) {
-				t.Errorf("second X-Pixa-Cache = %q, want HIT", got)
-			}
-
-			got := upstream.requestTargets()
-			t.Logf("upstream received %q", got)
-
-			if !slices.Equal(got, []string{tt.wantRequest}) {
-				t.Errorf("upstream received %q, want [%q]", got, tt.wantRequest)
-			}
-		})
-	}
-}
-
 // TestGeneratorRefusesSourceURLItCannotFetchAsWritten submits source URLs the
 // generator page must make no encrypted URL for, and checks that it answers
 // 400 and shows why. pixa keeps the source path decoded and fetches it