Refactored out OSC protocol query logic into the Connection interface…

terminal-api/src/main/java/org/aesh/terminal/Connection.java

@@ -376,4 +376,72 @@ default TerminalColorCapability getColorCapability() {
         return new TerminalColorCapability(depth, TerminalColorCapability.detectThemeFromEnvironment());
     }
 
+    /**
+     * Send an OSC (Operating System Command) query to the terminal.
+     * <p>
+     * This method sends an OSC query sequence and waits for the terminal's response.
+     * The terminal must be actively reading input (via {@link #openBlocking()} or
+     * {@link #openNonBlocking()}) for this to work.
+     * <p>
+     * Common OSC codes:
+     * <ul>
+     * <li>10 - Query/set foreground color</li>
+     * <li>11 - Query/set background color</li>
+     * <li>12 - Query/set cursor color</li>
+     * <li>4;N - Query/set palette color N</li>
+     * </ul>
+     *
+     * @param oscCode the OSC code (e.g., 10 for foreground, 11 for background)
+     * @param param the query parameter (typically "?" for queries)
+     * @param timeoutMs timeout in milliseconds to wait for response
+     * @param responseParser function to parse the response; should return non-null
+     *        when a complete response is received, null to continue waiting
+     * @param <T> the type of the parsed response
+     * @return the parsed response, or null if timeout or not supported
+     */
+    default <T> T queryOsc(int oscCode, String param, long timeoutMs,
+            java.util.function.Function<int[], T> responseParser) {
+        String query = ANSI.buildOscQuery(oscCode, param);
+        return queryTerminal(query, timeoutMs, responseParser);
+    }
+
+    /**
+     * Query the terminal for its foreground color using OSC 10.
+     * <p>
+     * The terminal must be actively reading input for this to work.
+     *
+     * @param timeoutMs timeout in milliseconds to wait for response
+     * @return RGB array [r, g, b] (0-255 each), or null if not supported or timeout
+     */
+    default int[] queryForegroundColor(long timeoutMs) {
+        return queryOsc(ANSI.OSC_FOREGROUND, "?", timeoutMs,
+                input -> ANSI.parseOscColorResponse(input, ANSI.OSC_FOREGROUND));
+    }
+
+    /**
+     * Query the terminal for its background color using OSC 11.
+     * <p>
+     * The terminal must be actively reading input for this to work.
+     *
+     * @param timeoutMs timeout in milliseconds to wait for response
+     * @return RGB array [r, g, b] (0-255 each), or null if not supported or timeout
+     */
+    default int[] queryBackgroundColor(long timeoutMs) {
+        return queryOsc(ANSI.OSC_BACKGROUND, "?", timeoutMs,
+                input -> ANSI.parseOscColorResponse(input, ANSI.OSC_BACKGROUND));
+    }
+
+    /**
+     * Query the terminal for its cursor color using OSC 12.
+     * <p>
+     * The terminal must be actively reading input for this to work.
+     *
+     * @param timeoutMs timeout in milliseconds to wait for response
+     * @return RGB array [r, g, b] (0-255 each), or null if not supported or timeout
+     */
+    default int[] queryCursorColor(long timeoutMs) {
+        return queryOsc(ANSI.OSC_CURSOR_COLOR, "?", timeoutMs,
+                input -> ANSI.parseOscColorResponse(input, ANSI.OSC_CURSOR_COLOR));
+    }
+
 }

terminal-api/src/main/java/org/aesh/terminal/utils/ANSI.java

@@ -122,6 +122,20 @@ public class ANSI {
     /** ANSI escape code to enable dark (normal) background mode. */
     public static final String DARK_BG = "\u001B[?5l";
 
+    /** OSC (Operating System Command) escape sequence start. */
+    public static final String OSC_START = "\u001B]";
+    /** BEL character, used as OSC terminator. */
+    public static final String BEL = "\u0007";
+    /** ST (String Terminator), alternate OSC terminator. */
+    public static final String ST = "\u001B\\";
+
+    /** OSC code for foreground color query/set. */
+    public static final int OSC_FOREGROUND = 10;
+    /** OSC code for background color query/set. */
+    public static final int OSC_BACKGROUND = 11;
+    /** OSC code for cursor color query/set. */
+    public static final int OSC_CURSOR_COLOR = 12;
+
     private ANSI() {
     }
 
@@ -295,4 +309,105 @@ else if (value > 999 && value < 9999)
             return 5;
     }
 
+    /**
+     * Build an OSC (Operating System Command) query string.
+     * <p>
+     * OSC format: ESC ] Ps ; Pt BEL
+     * Where Ps is the OSC code and Pt is the parameter.
+     *
+     * @param oscCode the OSC code (e.g., 10 for foreground, 11 for background)
+     * @param param the parameter (e.g., "?" for query)
+     * @return the OSC query string
+     */
+    public static String buildOscQuery(int oscCode, String param) {
+        return OSC_START + oscCode + ";" + param + BEL;
+    }
+
+    /**
+     * Parse an OSC color response.
+     * <p>
+     * Expected format: ESC ] {oscCode} ; rgb:RRRR/GGGG/BBBB {ST}
+     * Where:
+     * <ul>
+     * <li>ESC is 0x1B (27)</li>
+     * <li>oscCode is the OSC code (e.g., 10 for foreground, 11 for background)</li>
+     * <li>RRRR, GGGG, BBBB are 4-digit or 2-digit hex values</li>
+     * <li>ST is either BEL (0x07) or ESC \ (0x1B 0x5C)</li>
+     * </ul>
+     *
+     * @param input the input sequence as code points
+     * @param oscCode the expected OSC code in response
+     * @return RGB array [r, g, b] (0-255 each), or null if parsing failed
+     */
+    public static int[] parseOscColorResponse(int[] input, int oscCode) {
+        if (input == null || input.length < 10) {
+            return null;
+        }
+
+        // Convert to string for easier parsing
+        StringBuilder sb = new StringBuilder();
+        for (int c : input) {
+            sb.appendCodePoint(c);
+        }
+        String response = sb.toString();
+
+        // Look for the OSC response pattern
+        // Format: ESC ] {code} ; rgb:RRRR/GGGG/BBBB {terminator}
+        int start = response.indexOf("\u001B]" + oscCode + ";rgb:");
+        if (start < 0) {
+            // Try alternate format with just ']'
+            start = response.indexOf("]" + oscCode + ";rgb:");
+            if (start >= 0 && start > 0 && response.charAt(start - 1) == '\u001B') {
+                start--;
+            } else if (start < 0) {
+                return null;
+            }
+        }
+
+        // Extract the rgb: part
+        int rgbStart = response.indexOf("rgb:", start);
+        if (rgbStart < 0) {
+            return null;
+        }
+        rgbStart += 4; // skip "rgb:"
+
+        // Find the terminator (BEL or ESC \)
+        int end = response.indexOf('\u0007', rgbStart);
+        if (end < 0) {
+            end = response.indexOf("\u001B\\", rgbStart);
+        }
+        if (end < 0) {
+            end = response.length();
+        }
+
+        String rgbPart = response.substring(rgbStart, end);
+
+        // Parse RRRR/GGGG/BBBB
+        String[] parts = rgbPart.split("/");
+        if (parts.length != 3) {
+            return null;
+        }
+
+        try {
+            int[] rgb = new int[3];
+            for (int i = 0; i < 3; i++) {
+                String hex = parts[i].trim();
+                int value;
+                if (hex.length() == 4) {
+                    // 4-digit hex (e.g., FFFF), take high byte
+                    value = Integer.parseInt(hex, 16) >> 8;
+                } else if (hex.length() == 2) {
+                    // 2-digit hex
+                    value = Integer.parseInt(hex, 16);
+                } else {
+                    return null;
+                }
+                rgb[i] = Math.min(255, Math.max(0, value));
+            }
+            return rgb;
+        } catch (NumberFormatException e) {
+            return null;
+        }
+    }
+
 }