feat: add session resume capability via 'codex resume' command

close #51

cli/src/codex/loop.ts

@@ -26,6 +26,7 @@ interface LoopOptions {
     codexArgs?: string[];
     codexCliOverrides?: CodexCliOverrides;
     permissionMode?: PermissionMode;
+    resumeSessionId?: string;
     onSessionReady?: (session: CodexSession) => void;
 }
 
@@ -37,7 +38,7 @@ export async function loop(opts: LoopOptions): Promise<void> {
         api: opts.api,
         client: opts.session,
         path: opts.path,
-        sessionId: null,
+        sessionId: opts.resumeSessionId ?? null,
         logPath,
         messageQueue: opts.messageQueue,
         onModeChange: opts.onModeChange,

cli/src/codex/runCodex.ts

@@ -17,6 +17,7 @@ export async function runCodex(opts: {
     startedBy?: 'daemon' | 'terminal';
     codexArgs?: string[];
     permissionMode?: PermissionMode;
+    resumeSessionId?: string;
 }): Promise<void> {
     const workingDirectory = process.cwd();
     const startedBy = opts.startedBy ?? 'terminal';
@@ -116,6 +117,7 @@ export async function runCodex(opts: {
             codexCliOverrides,
             startedBy,
             permissionMode: currentPermissionMode,
+            resumeSessionId: opts.resumeSessionId,
             onModeChange: createModeChangeHandler(session),
             onSessionReady: (instance) => {
                 sessionWrapperRef.current = instance;

cli/src/commands/codex.ts

@@ -16,11 +16,21 @@ export const codexCommand: CommandDefinition = {
                 startedBy?: 'daemon' | 'terminal'
                 codexArgs?: string[]
                 permissionMode?: CodexPermissionMode
+                resumeSessionId?: string
             } = {}
             const unknownArgs: string[] = []
 
             for (let i = 0; i < commandArgs.length; i++) {
                 const arg = commandArgs[i]
+                if (i === 0 && arg === 'resume') {
+                    const candidate = commandArgs[i + 1]
+                    if (!candidate || candidate.startsWith('-')) {
+                        throw new Error('resume requires a session id')
+                    }
+                    options.resumeSessionId = candidate
+                    i += 1
+                    continue
+                }
                 if (arg === '--started-by') {
                     options.startedBy = commandArgs[++i] as 'daemon' | 'terminal'
                 } else if (arg === '--yolo' || arg === '--dangerously-bypass-approvals-and-sandbox') {