Fix Read Modified Query from Moshix bug report

lib3270j/src/main/java/haus/nightmare/lib3270j/datastream/DataStreamProcessor.java

@@ -257,6 +257,9 @@ public class DataStreamProcessor {
                 case SNA_CMD_EAU:
                     qreplyPending = false;
                     programSymbolManager.commitStagedSymbols();
+                    if (inputProcessor != null) {
+                        inputProcessor.setLastAid(AID_NO);
+                    }
                     log.info(">>> EAU: erasing all unprotected fields");
                     screen.eraseAllUnprotected();
                     currentFg = 0;
@@ -290,6 +293,7 @@ public class DataStreamProcessor {
                               cmd == CMD_EWA || cmd == SNA_CMD_EWA);
         if (!isWriteCmd && keyboardRestore && inputProcessor != null && !contentionResolution) {
             inputProcessor.setKeyboardLocked(false);
+            inputProcessor.setLastAid(AID_NO);
         }
 
         // Debug: dump non-empty screen lines
@@ -389,10 +393,14 @@ public class DataStreamProcessor {
         if (kbdRestore) {
             unlockPending = true;
             unlockSysPending = true;
+            if (inputProcessor != null) {
+                inputProcessor.setLastAid(AID_NO);
+            }
         }
 
         if (!contentionResolution && kbdRestore && inputProcessor != null) {
             inputProcessor.setKeyboardLocked(false);
+            inputProcessor.setLastAid(AID_NO);
         }
 
         if (resetMdt) {
@@ -1053,7 +1061,7 @@ public class DataStreamProcessor {
     // ========== Read Modified ==========
 
     public void processReadModified(boolean all) {
-        int aid = (inputProcessor != null && inputProcessor.getLastAid() != 0)
+        int aid = (inputProcessor != null && inputProcessor.isKeyboardLocked() && inputProcessor.getLastAid() != 0 && inputProcessor.getLastAid() != AID_NO)
                 ? inputProcessor.getLastAid()
                 : AID_NO;
         processReadModified(aid, all);

lib3270j/src/main/java/haus/nightmare/lib3270j/input/InputProcessor.java

@@ -129,6 +129,9 @@ public class InputProcessor {
                 lockStateListener.onLockStateChanged(locked);
             }
         }
+        if (!locked) {
+            this.lastAid = AID_NO;
+        }
     }
     public boolean isInsertMode() { return insertMode; }
     public void setInsertMode(boolean insert) {
@@ -756,7 +759,7 @@ public class InputProcessor {
      * Build inbound 3270 Read Modified data stream (AID + Cursor + SBA + Modified fields).
      */
     public byte[] buildReadModifiedInboundData() {
-        return buildReadModifiedInboundData(lastAid != 0 ? lastAid : AID_ENTER, false);
+        return buildReadModifiedInboundData(lastAid != 0 ? lastAid : AID_NO, false);
     }
 
     /**
@@ -1659,6 +1662,7 @@ public class InputProcessor {
     /** Reset (unlock keyboard, cancel insert mode, clear OIA error states). */
     public void reset() {
         setKeyboardLocked(false);
+        lastAid = AID_NO;
         insertMode = false;
         if (oia != null) {
             oia.setInputInhibited(ECLConstants.INHIBIT_NOT_INHIBITED);

lib3270j/src/test/java/haus/nightmare/lib3270j/datastream/DataStreamProcessorTest.java

@@ -358,4 +358,69 @@ public class DataStreamProcessorTest {
         assertEquals((byte) AID_SF, sent[0], "Query reply header AID must be AID_SF (0x88)");
         assertFalse(processor.isQreplyPending(), "qreplyPending should be cleared after reply is sent");
     }
+
+    @Test
+    public void testStandaloneReadModifiedReturnsAidNo() {
+        haus.nightmare.lib3270j.input.InputProcessor input = new haus.nightmare.lib3270j.input.InputProcessor(screen, translator, null);
+        processor.setInputProcessor(input);
+
+        // Simulate operator previously pressing Enter
+        input.setLastAid(AID_ENTER);
+        input.setKeyboardLocked(true);
+
+        java.io.ByteArrayOutputStream out = new java.io.ByteArrayOutputStream();
+        processor.setOutputSender(out::writeBytes);
+
+        // Host responds with Erase/Write Alternate (0x7E) with WCC 0xC3 (kbdRestore=true)
+        byte[] ewa = new byte[] { (byte) SNA_CMD_EWA, (byte) 0xC3 };
+        processor.processRecord(ewa, 0, ewa.length, true);
+
+        assertFalse(input.isKeyboardLocked(), "Keyboard should be restored by WCC");
+        assertEquals(AID_NO, input.getLastAid(), "lastAid should be reset to AID_NO on keyboard restore");
+
+        // Host subsequently polls terminal with standalone Read Modified (0xF6)
+        byte[] rm = new byte[] { (byte) SNA_CMD_RM };
+        out.reset();
+        processor.processRecord(rm, 0, rm.length, true);
+
+        byte[] sent = out.toByteArray();
+        assertTrue(sent.length >= 3, "Read Modified response must contain at least AID and 2-byte cursor address");
+        assertEquals((byte) AID_NO, sent[0], "Standalone Read Modified from host must respond with AID_NO (0x60)");
+        assertFalse(input.isKeyboardLocked(), "Keyboard must remain unlocked after host Read Modified poll");
+    }
+
+    @Test
+    public void testStandaloneReadModifiedWithModifiedFieldSendsDataAndAidNo() {
+        haus.nightmare.lib3270j.input.InputProcessor input = new haus.nightmare.lib3270j.input.InputProcessor(screen, translator, null);
+        processor.setInputProcessor(input);
+
+        java.io.ByteArrayOutputStream out = new java.io.ByteArrayOutputStream();
+        processor.setOutputSender(out::writeBytes);
+
+        // Write a screen with an unprotected field at pos 10, WCC kbdRestore
+        byte[] initStream = new byte[] {
+            (byte) CMD_EW, (byte) 0xC3,
+            (byte) ORDER_SBA, 0x00, 0x0A, // SBA 10
+            (byte) ORDER_SF, (byte) FA_PRINTABLE, // unprotected
+            (byte) 0xC1, (byte) 0xC2 // EBCDIC 'A', 'B'
+        };
+        processor.processRecord(initStream, 0, initStream.length, true);
+
+        // Modify the field by setting MDT (e.g. user typed into it)
+        screen.getCell(10).fa = (byte) (screen.getCell(10).fa | FA_MODIFY);
+
+        // Host polls with 0xF6 (SNA_CMD_RM)
+        out.reset();
+        byte[] rm = new byte[] { (byte) SNA_CMD_RM };
+        processor.processRecord(rm, 0, rm.length, true);
+
+        byte[] sent = out.toByteArray();
+        assertTrue(sent.length > 3, "Should include SBA and field contents for modified field");
+        assertEquals((byte) AID_NO, sent[0], "AID must be AID_NO (0x60)");
+        assertEquals((byte) ORDER_SBA, sent[3], "Order must be SBA");
+        assertEquals((byte) 0xC1, sent[6], "First char should be 'A'");
+        assertEquals((byte) 0xC2, sent[7], "Second char should be 'B'");
+        assertTrue((screen.getCell(10).fa & FA_MODIFY) != 0, "MDT must not be cleared by Read Modified command");
+    }
 }
+