test: drop pdf2htmlEX/wvWare cross-engine reference comparison

src/odr/internal/pdf/AGENTS.md

@@ -363,7 +363,10 @@ it.
 
 The **reference-output snapshot test** (`test/data/reference-output/`) is the
 graphics oracle: each change regenerates it and the diff is reviewed. (An
-automated perceptual-diff gate is deferred; see gaps.)
+automated perceptual-diff gate is deferred; see gaps.) The snapshot is now the
+**odr engine's own output only** — the `pdf2htmlEX`/poppler (`*.pdf-poppler`) and
+wvWare (`*.doc-wvware`) cross-engine reference snapshots were removed once the odr
+engine was ready to replace them, so the test no longer runs those engines.
 
 ## Module layout
 
@@ -701,8 +704,9 @@ Link annotations (`/URI` + internal `/GoTo`) already land — see *What works*.
     nested text/shadings/patterns inside a tile are skipped (rare).
   - **Text clipping**: the clip is not applied to text runs (paths and images are
     clipped); text clip render modes (`Tr` 4–7) add nothing to the clip.
-  - **Perceptual-diff oracle**: the reference-output snapshot test is the current
-    graphics gate; the automated poppler/pdf.js screenshot-diff is not built.
+  - **Perceptual-diff oracle**: the reference-output snapshot test (odr output
+    only) is the current graphics gate; an automated pdf.js screenshot-diff is
+    not built.
 - **Encryption edge cases** (deferred from stage 0 until a real file needs
   them): per-stream `/Crypt` filter `Name` overrides, the `EncryptMetadata
   false` metadata-stream `Identity` special case, and `Perms` (Algorithm 13)

test/src/html_output_test.cpp

@@ -249,18 +249,8 @@ TestParams create_test_params(const TestFile &test_file,
 std::vector<TestParams> list_test_params() {
   std::vector<TestParams> params;
   for (const TestFile &test_file : TestData::test_files()) {
-    std::vector engines = {DecoderEngine::odr};
-    if (test_file.type == FileType::portable_document_format) {
-      engines.push_back(DecoderEngine::poppler);
-    }
-    if (test_file.type == FileType::legacy_word_document) {
-      engines.push_back(DecoderEngine::wvware);
-    }
-
-    for (const DecoderEngine engine : engines) {
-      params.push_back(
-          create_test_params(test_file, engine, PdfTextMode::dual_layer));
-    }
+    params.push_back(create_test_params(test_file, DecoderEngine::odr,
+                                        PdfTextMode::dual_layer));
 
     // PDFs default to `PdfTextMode::dual_layer`. To keep the single-layer path
     // under reference-output coverage too, eject an extra `-single` test case