fix: Model flag parsing and model args (#42)

src/headless.ts

@@ -8,6 +8,7 @@ import type { StopReasonType } from "@letta-ai/letta-client/resources/runs/runs"
 import { getClient } from "./agent/client";
 import { createAgent } from "./agent/create";
 import { sendMessageStream } from "./agent/message";
+import { getModelUpdateArgs } from "./agent/model";
 import { SessionStats } from "./agent/stats";
 import { createBuffers, toLines } from "./cli/helpers/accumulator";
 import { safeJsonParseOr } from "./cli/helpers/safeJsonParse";
@@ -25,6 +26,8 @@ export async function handleHeadlessCommand(argv: string[], model?: string) {
       continue: { type: "boolean", short: "c" },
       new: { type: "boolean" },
       agent: { type: "string", short: "a" },
+      model: { type: "string", short: "m" },
+      prompt: { type: "boolean", short: "p" },
       "output-format": { type: "string" },
     },
     strict: false,
@@ -70,7 +73,8 @@ export async function handleHeadlessCommand(argv: string[], model?: string) {
 
   // Priority 2: Check if --new flag was passed (skip all resume logic)
   if (!agent && forceNew) {
-    agent = await createAgent(undefined, model);
+    const updateArgs = getModelUpdateArgs(model);
+    agent = await createAgent(undefined, model, undefined, updateArgs);
   }
 
   // Priority 3: Try to resume from project settings (.letta/settings.local.json)
@@ -101,7 +105,8 @@ export async function handleHeadlessCommand(argv: string[], model?: string) {
 
   // Priority 5: Create a new agent
   if (!agent) {
-    agent = await createAgent(undefined, model);
+    const updateArgs = getModelUpdateArgs(model);
+    agent = await createAgent(undefined, model, undefined, updateArgs);
   }
 
   // Save agent ID to both project and global settings