Add Devin CLI as a selectable agent backend in plan2code-loop

Upstream replaced GitHub Copilot CLI with Devin; Plan2Code keeps both, so
Claude Code, Copilot CLI and Devin are all selectable and existing Copilot
selections keep working.

AI Assisted

plan2code-loop/README.md

@@ -109,6 +109,7 @@ The scratchpad is managed by the LLM itself - after each task, the AI appends no
 |-------|--------|
 | Claude Code | Supported |
 | GitHub Copilot CLI | Supported |
+| Devin CLI | Supported |
 
 The loop uses your configured default model for each agent.
 
@@ -119,7 +120,7 @@ $ plan2code-loop
 
     ╭──────────────────────────────────────╮
     │                                      │
-    │   🔮  Plany's Loop               │
+    │   🔮  Planny's Loop                  │
     │       Autonomous Implementation      │
     │                                      │
     ╰──────────────────────────────────────╯
@@ -196,7 +197,8 @@ src/
 ├── cli.ts                    # Interactive prompts
 ├── agents/                   # Agent implementations
 │   ├── claude-code.ts
-│   └── copilot-cli.ts
+│   ├── copilot-cli.ts
+│   └── devin-cli.ts
 ├── prompt/                   # Prompt building
 │   ├── templates.ts
 │   └── builder.ts

plan2code-loop/package.json

@@ -20,6 +20,7 @@
     "automation",
     "claude",
     "copilot",
+    "devin",
     "spec-driven"
   ],
   "license": "MIT",

plan2code-loop/src/agents/devin-cli.ts

@@ -0,0 +1,81 @@
+import type { Agent, AgentConfig, AgentExecutionOptions, AgentExecutionResult } from './types.js';
+import { executeCommand } from '../utils/process.js';
+import { writeFileSync, unlinkSync } from 'fs';
+import { join } from 'path';
+import { tmpdir } from 'os';
+
+const devinCliConfig: AgentConfig = {
+  name: 'devin-cli',
+  displayName: 'Devin CLI',
+  command: 'devin',
+  models: [
+    { value: 'default', label: 'Default (use Devin config)' },
+  ],
+  defaultModel: 'default',
+  flags: {
+    prompt: '--print',
+    promptFile: '--prompt-file',
+    model: '--model',
+    skipPermissions: '--permission-mode',
+  },
+};
+
+class DevinCliAgent implements Agent {
+  readonly config = devinCliConfig;
+
+  async execute(options: AgentExecutionOptions): Promise<AgentExecutionResult> {
+    // Devin CLI takes the prompt via --prompt-file rather than stdin
+    const tempFile = join(tmpdir(), `plan2code-prompt-${Date.now()}.txt`);
+    writeFileSync(tempFile, options.prompt, 'utf-8');
+
+    try {
+      const args: string[] = [
+        this.config.flags.prompt,                 // --print for non-interactive mode
+        this.config.flags.promptFile!, tempFile,   // --prompt-file <path>
+        this.config.flags.skipPermissions, 'dangerous', // --permission-mode dangerous (auto-approve all tools)
+      ];
+
+      // Only add --model if not using default
+      if (options.model && options.model !== 'default') {
+        args.push(this.config.flags.model, options.model);
+      }
+
+      const result = await executeCommand({
+        command: this.config.command,
+        args,
+        cwd: options.cwd,
+        timeout: options.timeout,
+        signal: options.signal,
+      });
+
+      return {
+        stdout: result.stdout,
+        stderr: result.stderr,
+        exitCode: result.exitCode,
+        timedOut: result.timedOut,
+        cancelled: result.cancelled,
+        duration: result.duration,
+      };
+    } finally {
+      // Clean up temp file
+      try {
+        unlinkSync(tempFile);
+      } catch {
+        // Ignore cleanup errors
+      }
+    }
+  }
+
+  async isAvailable(): Promise<boolean> {
+    // Run devin --version to verify it's actually installed and working
+    const result = await executeCommand({
+      command: this.config.command,
+      args: ['--version'],
+      cwd: process.cwd(),
+      timeout: 5000,
+    });
+    return result.exitCode === 0;
+  }
+}
+
+export const devinCliAgent = new DevinCliAgent();

plan2code-loop/src/agents/index.ts

@@ -9,11 +9,14 @@ export type {
 export { agentRegistry } from './registry.js';
 export { claudeCodeAgent } from './claude-code.js';
 export { copilotCliAgent } from './copilot-cli.js';
+export { devinCliAgent } from './devin-cli.js';
 
 // Register all agents
 import { agentRegistry } from './registry.js';
 import { claudeCodeAgent } from './claude-code.js';
 import { copilotCliAgent } from './copilot-cli.js';
+import { devinCliAgent } from './devin-cli.js';
 
 agentRegistry.register(claudeCodeAgent);
 agentRegistry.register(copilotCliAgent);
+agentRegistry.register(devinCliAgent);

plan2code-loop/src/agents/types.ts

@@ -14,6 +14,7 @@ export interface AgentConfig {
     model: string;
     skipPermissions: string;
     silent?: string;
+    promptFile?: string;
   };
 }
 

plan2code-loop/src/state/config.ts

@@ -1,7 +1,7 @@
 export type LoopMode = 'task' | 'phase';
 
 export interface SessionConfig {
-  agent: string;              // "claude-code" | "copilot-cli"
+  agent: string;              // "claude-code" | "copilot-cli" | "devin-cli"
   model: string;              // Selected model
   maxIterations: number;      // 5-50
   timeout: number;            // Base timeout in minutes per iteration attempt