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

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

src/ClaudeDo.Worker/Runner/ClaudeArgsBuilder.cs

@@ -0,0 +1,65 @@
+using System.Text.Json;
+
+namespace ClaudeDo.Worker.Runner;
+
+public sealed record ClaudeRunConfig(
+    string? Model,
+    string? SystemPrompt,
+    string? AgentPath,
+    string? ResumeSessionId
+);
+
+public sealed class ClaudeArgsBuilder
+{
+    private static readonly string ResultSchema = JsonSerializer.Serialize(new
+    {
+        type = "object",
+        properties = new
+        {
+            summary = new { type = "string" },
+            files_changed = new { type = "array", items = new { type = "string" } },
+            commit_type = new { type = "string" },
+        },
+        required = new[] { "summary" },
+    });
+
+    public string Build(ClaudeRunConfig config)
+    {
+        var args = new List<string>
+        {
+            "-p",
+            "--output-format stream-json",
+            "--verbose",
+            "--dangerously-skip-permissions",
+        };
+
+        if (config.Model is not null)
+            args.Add($"--model {config.Model}");
+
+        if (config.SystemPrompt is not null)
+            args.Add($"--append-system-prompt {Escape(config.SystemPrompt)}");
+
+        if (config.AgentPath is not null)
+        {
+            var agentJson = JsonSerializer.Serialize(new[] { new { file = config.AgentPath } });
+            args.Add($"--agents {Escape(agentJson)}");
+        }
+
+        args.Add($"--json-schema {Escape(ResultSchema)}");
+
+        if (config.ResumeSessionId is not null)
+            args.Add($"--resume {config.ResumeSessionId}");
+
+        return string.Join(" ", args);
+    }
+
+    private static string Escape(string value)
+    {
+        if (value.Contains(' ') || value.Contains('"') || value.Contains('\''))
+        {
+            var escaped = value.Replace("\\", "\\\\").Replace("\"", "\\\"");
+            return $"\"{escaped}\"";
+        }
+        return value;
+    }
+}

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);
+    }
+}