fix(sdk): stop isTDF rejecting archives by entry count

isTDF required the archive to hold exactly two entries. An archive
carrying both manifest names holds three, and TDFReader now reads it by
preferring the spec name -- so the sniffer rejected what the reader it
screens for accepts. The count also made isTDF stricter than the reader
generally: the spec fixes where the manifest lives, not what else the
archive may hold.

Entry presence is what isTDF was checking for; the count was never part
of the structure it describes.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Signed-off-by: Paul Flynn <pflynn-virtru@users.noreply.github.com>

Author: pflynn-virtru

sdk/src/main/java/io/opentdf/platform/sdk/SDK.java

@@ -159,7 +159,9 @@ public Optional<SrtSigner> getSrtSigner() {
      * a `manifest.json` and a `0.payload`
      * <p>
      * The off-spec `0.manifest.json` that this SDK writes is also accepted, matching
-     * {@link TDFReader}.
+     * {@link TDFReader}. Entries beyond the manifest and payload are ignored rather than
+     * disqualifying: an archive carrying both manifest names holds three, and the reader
+     * accepts it, so a count check here would reject what the reader it screens for reads.
      *
      * @param channel A channel containing the bytes of the potential Z-TDF
      * @return `true` if
@@ -172,9 +174,6 @@ public static boolean isTDF(SeekableByteChannel channel) {
             return false;
         }
         var entries = zipReader.getEntries();
-        if (entries.size() != 2) {
-            return false;
-        }
         return entries.stream().anyMatch(e -> TDFWriter.TDF_MANIFEST_FILE_NAME_SPEC.equals(e.getName())
                 || TDFWriter.TDF_MANIFEST_FILE_NAME.equals(e.getName()))
                 && entries.stream().anyMatch(e -> TDFWriter.TDF_PAYLOAD_FILE_NAME.equals(e.getName()));

sdk/src/test/java/io/opentdf/platform/sdk/SDKTest.java

@@ -43,6 +43,24 @@ void testExaminingTDFWithSpecManifestName() throws IOException {
         }
     }
 
+    /**
+     * The reader accepts an archive carrying both manifest names, so the sniffer that
+     * screens for it must not turn that third entry into a rejection.
+     */
+    @Test
+    void testExaminingTDFWithBothManifestNames() throws IOException {
+        try (var chan = zipOf("0.payload", "manifest.json", "0.manifest.json")) {
+            assertThat(SDK.isTDF(chan)).isTrue();
+        }
+    }
+
+    @Test
+    void testExaminingTDFWithAnExtraEntry() throws IOException {
+        try (var chan = zipOf("0.payload", "manifest.json", "something-else")) {
+            assertThat(SDK.isTDF(chan)).isTrue();
+        }
+    }
+
     @Test
     void testExaminingZipWithNoManifest() throws IOException {
         try (var chan = zipOf("0.payload", "something-else")) {