feat(worker): add ClaudeArgsBuilder for dynamic CLI argument construction

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/ClaudeDo.Worker.Tests/Runner/ClaudeArgsBuilderTests.cs

@@ -0,0 +1,71 @@
+using ClaudeDo.Worker.Runner;
+
+namespace ClaudeDo.Worker.Tests.Runner;
+
+public sealed class ClaudeArgsBuilderTests
+{
+    private readonly ClaudeArgsBuilder _builder = new();
+
+    [Fact]
+    public void Default_Config_Produces_Base_Args()
+    {
+        var args = _builder.Build(new ClaudeRunConfig(null, null, null, null));
+        Assert.Contains("-p", args);
+        Assert.Contains("--output-format stream-json", args);
+        Assert.Contains("--verbose", args);
+        Assert.Contains("--dangerously-skip-permissions", args);
+        Assert.Contains("--json-schema", args);
+        Assert.DoesNotContain("--model", args);
+        Assert.DoesNotContain("--append-system-prompt", args);
+        Assert.DoesNotContain("--agents", args);
+        Assert.DoesNotContain("--resume", args);
+    }
+
+    [Fact]
+    public void Model_Adds_Model_Flag()
+    {
+        var args = _builder.Build(new ClaudeRunConfig("sonnet-4-6", null, null, null));
+        Assert.Contains("--model sonnet-4-6", args);
+    }
+
+    [Fact]
+    public void SystemPrompt_Adds_Append_System_Prompt_Flag()
+    {
+        var args = _builder.Build(new ClaudeRunConfig(null, "Be concise.", null, null));
+        Assert.Contains("--append-system-prompt", args);
+        Assert.Contains("Be concise.", args);
+    }
+
+    [Fact]
+    public void AgentPath_Adds_Agents_Flag_As_Json()
+    {
+        var args = _builder.Build(new ClaudeRunConfig(null, null, "/path/to/agent.md", null));
+        Assert.Contains("--agents", args);
+        Assert.Contains("/path/to/agent.md", args);
+    }
+
+    [Fact]
+    public void ResumeSessionId_Adds_Resume_Flag()
+    {
+        var args = _builder.Build(new ClaudeRunConfig(null, null, null, "sess-abc-123"));
+        Assert.Contains("--resume sess-abc-123", args);
+    }
+
+    [Fact]
+    public void All_Options_Set_Includes_All_Flags()
+    {
+        var args = _builder.Build(new ClaudeRunConfig("opus-4-6", "Be thorough.", "/agents/dev.md", "sess-xyz"));
+        Assert.Contains("--model opus-4-6", args);
+        Assert.Contains("--append-system-prompt", args);
+        Assert.Contains("--agents", args);
+        Assert.Contains("--resume sess-xyz", args);
+        Assert.Contains("--json-schema", args);
+    }
+
+    [Fact]
+    public void SystemPrompt_With_Quotes_Is_Escaped()
+    {
+        var args = _builder.Build(new ClaudeRunConfig(null, """Don't say "hello".""", null, null));
+        Assert.Contains("--append-system-prompt", args);
+    }
+}