From 40e7374bd72a4eae0da535807ecf21afc701af0c Mon Sep 17 00:00:00 2001
From: Ron Keizer <ron@insight-rx.com>
Date: Wed, 7 Jan 2026 22:03:49 -0800
Subject: [PATCH 1/2] fix sim when no CMT col in data

---
 R/run_sim.R | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/R/run_sim.R b/R/run_sim.R
index 934bbc6..7ab5e8c 100644
--- a/R/run_sim.R
+++ b/R/run_sim.R
@@ -101,6 +101,10 @@ run_sim <- function(
   } else {
     input_data <- data
   }
+  ## Set CMT to NA if not in dataset
+  if(is.null(input_data[[dictionary$CMT]])) {
+    input_data[[dictionary$CMT]] <- NA
+  }
   if(is.null(covariates)) { # use original dataset
     if(verbose) cli::cli_alert_info("Using input dataset for simulation")
     sim_data <- input_data
@@ -174,7 +178,8 @@ run_sim <- function(
       dplyr::arrange(.regimen, ID, TIME, EVID) |>
       dplyr::group_by(ID) |>
       tidyr::fill(
-        dplyr::everything(),
+        tidyselect::everything(),
+        -CMT,
         .direction = "downup"
       )
     if(is.null(t_obs)) {
@@ -191,7 +196,8 @@ run_sim <- function(
       sim_data,
       t_obs,
       n_subjects,
-      dictionary
+      dictionary,
+      model
     )
     ## remove old obs and add new
     sim_data <- sim_data |>
@@ -395,15 +401,19 @@ create_obs_records <- function(
     data,
     t_obs,
     n_subjects,
-    dictionary
+    dictionary,
+    model
 ) {
   unq_reg <- unique(data[[".regimen"]])
   ## create a template row
+  ## 1st try pull CMT from data. if not available in data, try based on ADVAN
   cmt <- data |>
     dplyr::filter(ID == 1 & EVID == 0) |>
     dplyr::slice(1) |>
     dplyr::pull(CMT)
-  if(is.null(cmt)) cmt <- 1
+  if(is.null(cmt) || is.na(cmt)) {
+    cmt <- get_obs_compartment(model)
+  }
   obs <- data.frame(
     ID = 1,
     TIME = t_obs,

From aa742ba20e1315e622278c92e16a62374100023b Mon Sep 17 00:00:00 2001
From: Ron Keizer <ron@insight-rx.com>
Date: Wed, 7 Jan 2026 22:10:58 -0800
Subject: [PATCH 2/2] add new test placeholder

---
 tests/testthat/test_run_sim.R | 9 +++++++++
 1 file changed, 9 insertions(+)
 create mode 100644 tests/testthat/test_run_sim.R

diff --git a/tests/testthat/test_run_sim.R b/tests/testthat/test_run_sim.R
new file mode 100644
index 0000000..51221f6
--- /dev/null
+++ b/tests/testthat/test_run_sim.R
@@ -0,0 +1,9 @@
+## TODO: add tests for simulations
+## 
+## - basic simulations
+## - test case for this fix: https://github.com/InsightRX/luna/pull/56
+
+test_that(
+  "dummy check",
+  expect_true(TRUE)
+)