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/src/state/config.ts

@@ -1,35 +1,35 @@
-export type LoopMode = 'task' | 'phase';
-
-export interface SessionConfig {
-  agent: string;              // "claude-code" | "copilot-cli"
-  model: string;              // Selected model
-  maxIterations: number;      // 5-50
-  timeout: number;            // Base timeout in minutes per iteration attempt
-  maxRetries: number;         // Max retry attempts per iteration (timeout increments by 30s each retry)
-  verbose: boolean;
-  specPath: string;           // Path to the spec directory
-  startedAt: string;          // ISO timestamp
-  currentIteration: number;
-  jiraTicketId?: string;      // JIRA ticket ID for commit messages
-  loopMode: LoopMode;         // "task" = one task per loop, "phase" = one phase per loop
-}
-
-export interface IterationLogEntry {
-  iteration: number;
-  timestamp: string;          // ISO timestamp
-  duration: number;           // milliseconds
-  exitCode: number;
-  status: 'running' | 'completed' | 'error' | 'timeout' | 'interrupted' | 'blocked';
-  completionMarker?: string;
-}
-
-export type SessionState = 'new' | 'continue' | 'changed';
-
-export const DEFAULT_CONFIG: Partial<SessionConfig> = {
-  maxIterations: 100,
-  timeout: 3,
-  maxRetries: 5,
-  verbose: false,
-  currentIteration: 0,
-  loopMode: 'task',
-};
+export type LoopMode = 'task' | 'phase';
+
+export interface SessionConfig {
+  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
+  maxRetries: number;         // Max retry attempts per iteration (timeout increments by 30s each retry)
+  verbose: boolean;
+  specPath: string;           // Path to the spec directory
+  startedAt: string;          // ISO timestamp
+  currentIteration: number;
+  jiraTicketId?: string;      // JIRA ticket ID for commit messages
+  loopMode: LoopMode;         // "task" = one task per loop, "phase" = one phase per loop
+}
+
+export interface IterationLogEntry {
+  iteration: number;
+  timestamp: string;          // ISO timestamp
+  duration: number;           // milliseconds
+  exitCode: number;
+  status: 'running' | 'completed' | 'error' | 'timeout' | 'interrupted' | 'blocked';
+  completionMarker?: string;
+}
+
+export type SessionState = 'new' | 'continue' | 'changed';
+
+export const DEFAULT_CONFIG: Partial<SessionConfig> = {
+  maxIterations: 100,
+  timeout: 3,
+  maxRetries: 5,
+  verbose: false,
+  currentIteration: 0,
+  loopMode: 'task',
+};