Improve commit message prompts and use Opus model

src/commands/helpers.ts

@@ -173,10 +173,10 @@ async function squashCommit(branch: string, cwd: string): Promise<void> {
   if (diff.trim()) {
     const gen = await vm.claudePipe(
       diff,
-      "write a single-line commit message for these changes, max 50 characters. no body, no blank line, just the subject. output only the message, no quotes or extra text.",
+      "Write a commit message summarizing all changes in this squash merge. Subject line: imperative mood, max 72 characters, no period. Add a blank line then a concise body with the key changes as bullet points. Output only the raw commit message, no quotes or markdown.",
     )
     if (gen.exitCode === 0 && gen.stdout.trim()) {
-      await git.commit(gen.stdout.trim().split("\n")[0], cwd)
+      await git.commit(gen.stdout.trim(), cwd)
       return
     }
   }
@@ -209,7 +209,7 @@ export async function saveChanges(worktree: string, branch: string, message?: st
 
     const gen = await vm.claudePipe(
       diff,
-      "write a single-line commit message for these changes, max 50 characters. no body, no blank line, just the subject. output only the message, no quotes or extra text.",
+      "Write a commit message for this diff. Subject line: imperative mood, max 72 characters, no period. If the changes warrant it, add a blank line then a brief body explaining why, not what. Output only the raw commit message, no quotes or markdown.",
     )
 
     if (gen.exitCode !== 0) {

src/vm.ts

@@ -386,7 +386,7 @@ export async function claudePipe(input: string, prompt: string): Promise<{ exitC
     await Bun.write(tmpPath, input)
     return await exec(
       join(homedir(), '.sandlot'),
-      `cat /sandlot/${tmpName} | claude -p "${prompt.replace(/"/g, '\\"')}"`,
+      `cat /sandlot/${tmpName} | claude --model claude-opus-4-6 -p "${prompt.replace(/"/g, '\\"')}"`,
     )
   } finally {
     await Bun.file(tmpPath).unlink().catch(() => {})