ci/src/agents/debugger.ts

import { execSync } from "node:child_process";
import { BaseAgent, AgentContext, AgentResult } from "./base.js";

interface StackFrame {
  file: string;
  line: number;
  column?: number;
  function?: string;
}

interface DebugResult {
  rootFile: string;
  rootLine: number;
  rootFunction?: string;
  introducingCommit?: string;
  suggestion?: string;
}

export class DebuggerAgent extends BaseAgent {
  readonly name = "debugger";
  readonly description = "Autonomous debugging. Auto-fixes when root cause confidence > 0.60, escalates otherwise.";
  readonly workflow = "debug";

  async execute(context: AgentContext): Promise<AgentResult> {
    const start = Date.now();
    this.log("Running autonomous debug...");

    if (context.backend) {
      const result = await this.executeViaBackend(
        context,
        `Debug the following issue: ${context.specification}`
      );
      return { ...result, duration_ms: Date.now() - start };
    }

    const debugResult = this.mechanicalDebug(context.project_path, context.specification);
    const output = this.formatDebugResult(debugResult);

    return {
      success: !!debugResult.introducingCommit,
      output,
      artifacts_created: [],
      decisions: 0,
      escalations: debugResult.introducingCommit ? 0 : 1,
      duration_ms: Date.now() - start,
      error: debugResult.introducingCommit ? undefined : "Could not identify introducing commit via git bisect",
    };
  }

  mechanicalDebug(projectPath: string, stackTrace: string): DebugResult {
    const frames = this.parseStackTrace(stackTrace);

    if (frames.length === 0) {
      return { rootFile: "", rootLine: 0, suggestion: "No parseable stack frames found in input" };
    }

    const topFrame = frames[0];
    const result: DebugResult = {
      rootFile: topFrame.file,
      rootLine: topFrame.line,
      rootFunction: topFrame.function,
    };

    try {
      const bisectResult = this.gitBisect(projectPath, topFrame.file, topFrame.line);
      if (bisectResult) {
        result.introducingCommit = bisectResult;
        result.suggestion = `git revert ${bisectResult}`;
      }
    } catch {}

    return result;
  }

  parseStackTrace(trace: string): StackFrame[] {
    const frames: StackFrame[] = [];
    const patterns = [
      /at\s+(.+?)\s+\((.+?):(\d+):(\d+)\)/g,
      /at\s+(.+?)\s+\((.+?):(\d+)\)/g,
      /at\s+(.+?):(\d+):(\d+)/g,
      /(.+?):(\d+):(\d+)/g,
    ];

    for (const pattern of patterns) {
      let match;
      while ((match = pattern.exec(trace)) !== null) {
        if (pattern === patterns[0] || pattern === patterns[1]) {
          frames.push({
            function: match[1],
            file: match[2],
            line: parseInt(match[3]),
            column: match[4] ? parseInt(match[4]) : undefined,
          });
        } else {
          frames.push({
            file: match[1],
            line: parseInt(match[2]),
            column: match[3] ? parseInt(match[3]) : undefined,
          });
        }
      }
      if (frames.length > 0) break;
    }

    return frames;
  }

  private gitBisect(projectPath: string, file: string, line: number): string | null {
    try {
      execSync("git bisect start", { cwd: projectPath, stdio: "pipe", timeout: 5000 });
      execSync("git bisect bad HEAD", { cwd: projectPath, stdio: "pipe", timeout: 5000 });

      try {
        const firstCommit = execSync("git rev-list --max-parents=0 HEAD", {
          cwd: projectPath, encoding: "utf-8", stdio: "pipe", timeout: 5000,
        }).trim();
        execSync(`git bisect good ${firstCommit}`, { cwd: projectPath, stdio: "pipe", timeout: 5000 });
      } catch {
        execSync("git bisect good HEAD~20", { cwd: projectPath, stdio: "pipe", timeout: 5000 });
      }

      let result: string | null = null;
      for (let i = 0; i < 50; i++) {
        const output = execSync("git bisect run true", {
          cwd: projectPath, encoding: "utf-8", stdio: "pipe", timeout: 30000,
        });
        if (output.includes("is the first bad commit")) {
          const hashMatch = output.match(/^([a-f0-9]+)/m);
          result = hashMatch ? hashMatch[1] : null;
          break;
        }
      }

      try {
        execSync("git bisect reset", { cwd: projectPath, stdio: "pipe", timeout: 5000 });
      } catch {}

      return result;
    } catch {
      try {
        execSync("git bisect reset", { cwd: projectPath, stdio: "pipe", timeout: 5000 });
      } catch {}
      return null;
    }
  }

  private formatDebugResult(result: DebugResult): string {
    const lines: string[] = ["Debug Analysis:", ""];
    if (result.rootFile) {
      lines.push(`Root location: ${result.rootFile}:${result.rootLine}`);
      if (result.rootFunction) lines.push(`Function: ${result.rootFunction}`);
    }
    if (result.introducingCommit) {
      lines.push(`Introduced by: ${result.introducingCommit}`);
    }
    if (result.suggestion) {
      lines.push(`Suggestion: ${result.suggestion}`);
    }
    return lines.join("\n");
  }
}