Fix SSH trunk branch: use origin/ prefix for remote tracking branches

After git clone from bundle, branches exist as remote tracking branches
(origin/*), not as local branches. When creating a new branch from trunk,
we need to reference it as 'origin/trunkBranch' to properly resolve the ref.

Updated checkout command to try:
1. Checkout branch if it exists locally
2. Create from origin/trunkBranch (remote tracking branch)
3. Fallback to trunkBranch (local branch, shouldn't be needed)

This ensures the trunk branch ref is properly resolved after git clone.

Author: ammar-agent

src/runtime/SSHRuntime.ts

@@ -688,9 +688,11 @@ export class SSHRuntime implements Runtime {
       initLogger.logStep("Files synced successfully");
 
       // 2. Checkout branch remotely
-      // If branch exists, check it out; otherwise create it from the specified trunk branch
+      // If branch exists locally, check it out; otherwise create it from the specified trunk branch
+      // Note: After git clone from bundle, branches exist as origin/* refs, so we need to check both
+      // local branch and origin/branch when creating the new branch
       initLogger.logStep(`Checking out branch: ${branchName}`);
-      const checkoutCmd = `(git checkout ${shescape.quote(branchName)} 2>/dev/null || git checkout -b ${shescape.quote(branchName)} ${shescape.quote(trunkBranch)})`;
+      const checkoutCmd = `(git checkout ${shescape.quote(branchName)} 2>/dev/null || git checkout -b ${shescape.quote(branchName)} origin/${shescape.quote(trunkBranch)} 2>/dev/null || git checkout -b ${shescape.quote(branchName)} ${shescape.quote(trunkBranch)})`;
 
       const checkoutStream = await this.exec(checkoutCmd, {
         cwd: workspacePath, // Use the full workspace path for git operations