Add tab-completion and persistent history to ac-cli shell

Use picocli-shell-jline3 to generate a completer from the command
tree, and explicitly save JLine history on exit so it persists
across sessions in ~/.agenticcode_history.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ac-cli/pom.xml

@@ -33,6 +33,10 @@
             <groupId>org.jline</groupId>
             <artifactId>jline</artifactId>
         </dependency>
+        <dependency>
+            <groupId>info.picocli</groupId>
+            <artifactId>picocli-shell-jline3</artifactId>
+        </dependency>
 
         <dependency>
             <groupId>org.junit.jupiter</groupId>

ac-cli/src/main/java/com/agenticcode/cli/InteractiveShell.java

@@ -1,6 +1,7 @@
 package com.agenticcode.cli;
 
 import org.jline.reader.EndOfFileException;
+import org.jline.reader.History;
 import org.jline.reader.LineReader;
 import org.jline.reader.LineReaderBuilder;
 import org.jline.reader.ParsedLine;
@@ -10,6 +11,7 @@ import org.jline.reader.impl.history.DefaultHistory;
 import org.jline.terminal.Terminal;
 import org.jline.terminal.TerminalBuilder;
 import picocli.CommandLine;
+import picocli.shell.jline3.PicocliCommands;
 
 import java.io.IOException;
 import java.nio.file.Path;
@@ -29,39 +31,45 @@ final class InteractiveShell {
 
     int run() throws IOException {
         try (Terminal terminal = TerminalBuilder.builder().build()) {
+            PicocliCommands picocliCommands = new PicocliCommands(commandLine);
             LineReader reader = LineReaderBuilder.builder()
                     .terminal(terminal)
                     .parser(new DefaultParser())
+                    .completer(picocliCommands.compileCompleters())
                     .appName("agenticcode")
                     .variable(LineReader.HISTORY_FILE, HISTORY_FILE)
                     .build();
-            new DefaultHistory(reader);
+            History history = new DefaultHistory(reader);
 
             terminal.writer().println("AgenticCode interactive shell. Type 'help' for commands, 'exit' to quit.");
 
-            while (true) {
-                String line;
-                try {
-                    line = reader.readLine("agenticcode> ").trim();
-                } catch (UserInterruptException e) {
-                    continue;
-                } catch (EndOfFileException e) {
-                    break;
-                }
+            try {
+                while (true) {
+                    String line;
+                    try {
+                        line = reader.readLine("agenticcode> ").trim();
+                    } catch (UserInterruptException e) {
+                        continue;
+                    } catch (EndOfFileException e) {
+                        break;
+                    }
 
-                if (line.isEmpty()) {
-                    continue;
-                }
-                if (line.equals("exit") || line.equals("quit")) {
-                    break;
-                }
-                if (line.equals("help") || line.equals("?")) {
-                    commandLine.usage(terminal.writer());
-                    continue;
-                }
+                    if (line.isEmpty()) {
+                        continue;
+                    }
+                    if (line.equals("exit") || line.equals("quit")) {
+                        break;
+                    }
+                    if (line.equals("help") || line.equals("?")) {
+                        commandLine.usage(terminal.writer());
+                        continue;
+                    }
 
-                ParsedLine parsed = reader.getParser().parse(line, line.length());
-                commandLine.execute(parsed.words().toArray(new String[0]));
+                    ParsedLine parsed = reader.getParser().parse(line, line.length());
+                    commandLine.execute(parsed.words().toArray(new String[0]));
+                }
+            } finally {
+                history.save();
             }
         }
         return 0;

pom.xml

@@ -111,6 +111,12 @@
                 <version>${picocli.version}</version>
             </dependency>
 
+            <dependency>
+                <groupId>info.picocli</groupId>
+                <artifactId>picocli-shell-jline3</artifactId>
+                <version>${picocli.version}</version>
+            </dependency>
+
             <dependency>
                 <groupId>org.jline</groupId>
                 <artifactId>jline</artifactId>