diff --git a/src/commands/build.rs b/src/commands/build.rs
index 48032bf..74da099 100644
--- a/src/commands/build.rs
+++ b/src/commands/build.rs
@@ -111,7 +111,10 @@ pub fn run_build(
     // Upload
     let port = match port {
         Some(p) => p.to_string(),
-        None => board::auto_detect_port()?,
+        None => match &config.monitor.port {
+            Some(p) => p.clone(),
+            None => board::auto_detect_port()?,
+        },
     };
 
     upload_to_board(&cli, fqbn, &port, &cache_dir, verbose)?;
@@ -193,7 +196,10 @@ pub fn run_upload_only(
 
     let port = match port {
         Some(p) => p.to_string(),
-        None => board::auto_detect_port()?,
+        None => match &config.monitor.port {
+            Some(p) => p.clone(),
+            None => board::auto_detect_port()?,
+        },
     };
 
     upload_to_board(&cli, fqbn, &port, &cache_dir, verbose)?;
diff --git a/src/project/config.rs b/src/project/config.rs
index f1981eb..cb0614d 100644
--- a/src/project/config.rs
+++ b/src/project/config.rs
@@ -31,6 +31,8 @@ pub struct BuildConfig {
 #[derive(Debug, Serialize, Deserialize, Clone)]
 pub struct MonitorConfig {
     pub baud: u32,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub port: Option<String>,
 }
 
 impl ProjectConfig {
@@ -49,6 +51,7 @@ impl ProjectConfig {
             },
             monitor: MonitorConfig {
                 baud: 115200,
+                port: None,
             },
         }
     }
diff --git a/templates/basic/_dot_anvil.toml.tmpl b/templates/basic/_dot_anvil.toml.tmpl
index c8afc54..b098e40 100644
--- a/templates/basic/_dot_anvil.toml.tmpl
+++ b/templates/basic/_dot_anvil.toml.tmpl
@@ -10,3 +10,4 @@ extra_flags = ["-Werror"]
 
 [monitor]
 baud = 115200
+# port = "/dev/ttyUSB0"  # Uncomment to skip auto-detect
diff --git a/templates/basic/build.sh b/templates/basic/build.sh
index f0bbc0a..e796bd5 100644
--- a/templates/basic/build.sh
+++ b/templates/basic/build.sh
@@ -36,12 +36,12 @@ die()  { echo "${RED}FAIL${RST} $*" >&2; exit 1; }
 # Searches the whole file; for sectioned keys, grep is specific enough
 # given our small, flat schema.
 toml_get() {
-    grep "^$1 " "$CONFIG" | head -1 | sed 's/.*= *"\{0,1\}\([^"]*\)"\{0,1\}/\1/' | tr -d ' '
+    (grep "^$1 " "$CONFIG" 2>/dev/null || true) | head -1 | sed 's/.*= *"\{0,1\}\([^"]*\)"\{0,1\}/\1/' | tr -d ' '
 }
 
 # Extract a TOML array as space-separated values: toml_array "key"
 toml_array() {
-    grep "^$1 " "$CONFIG" | head -1 \
+    (grep "^$1 " "$CONFIG" 2>/dev/null || true) | head -1 \
         | sed 's/.*\[//; s/\].*//; s/"//g; s/,/ /g' | tr -s ' '
 }
 
diff --git a/templates/basic/monitor.sh b/templates/basic/monitor.sh
index 2e037ee..abf412e 100644
--- a/templates/basic/monitor.sh
+++ b/templates/basic/monitor.sh
@@ -32,11 +32,12 @@ die()  { echo "${RED}FAIL${RST} $*" >&2; exit 1; }
 [[ -f "$CONFIG" ]] || die "No .anvil.toml found in $SCRIPT_DIR"
 
 toml_get() {
-    grep "^$1 " "$CONFIG" | head -1 | sed 's/.*= *"\{0,1\}\([^"]*\)"\{0,1\}/\1/' | tr -d ' '
+    (grep "^$1 " "$CONFIG" 2>/dev/null || true) | head -1 | sed 's/.*= *"\{0,1\}\([^"]*\)"\{0,1\}/\1/' | tr -d ' '
 }
 
 BAUD="$(toml_get 'baud')"
 BAUD="${BAUD:-115200}"
+DEFAULT_PORT="$(toml_get 'port')"
 
 # -- Parse arguments -------------------------------------------------------
 PORT=""
@@ -62,16 +63,35 @@ command -v arduino-cli &>/dev/null \
 
 # -- Auto-detect port ------------------------------------------------------
 auto_detect() {
-    arduino-cli board list 2>/dev/null \
+    # Prefer ttyUSB/ttyACM (real USB devices) over ttyS (hardware UART)
+    local port
+    port=$(arduino-cli board list 2>/dev/null \
         | grep -i "serial" \
-        | head -1 \
-        | awk '{print $1}'
+        | awk '{print $1}' \
+        | grep -E 'ttyUSB|ttyACM|COM' \
+        | head -1)
+
+    # Fallback: any serial port
+    if [[ -z "$port" ]]; then
+        port=$(arduino-cli board list 2>/dev/null \
+            | grep -i "serial" \
+            | head -1 \
+            | awk '{print $1}')
+    fi
+
+    echo "$port"
 }
 
 if [[ -z "$PORT" ]]; then
-    PORT="$(auto_detect)"
+    # Check .anvil.toml for configured port
+    if [[ -n "$DEFAULT_PORT" ]]; then
+        PORT="$DEFAULT_PORT"
+    else
+        PORT="$(auto_detect)"
+    fi
+
     if [[ -z "$PORT" ]]; then
-        die "No serial port detected. Is the board plugged in?\n  Specify manually: ./monitor.sh -p /dev/ttyUSB0"
+        die "No serial port detected. Is the board plugged in?\n  Specify manually: ./monitor.sh -p /dev/ttyUSB0\n  Or set port in .anvil.toml"
     fi
     warn "Auto-detected port: $PORT (use -p to override)"
 fi
diff --git a/templates/basic/upload.sh b/templates/basic/upload.sh
index f0d8644..883f860 100644
--- a/templates/basic/upload.sh
+++ b/templates/basic/upload.sh
@@ -34,11 +34,11 @@ die()  { echo "${RED}FAIL${RST} $*" >&2; exit 1; }
 [[ -f "$CONFIG" ]] || die "No .anvil.toml found in $SCRIPT_DIR"
 
 toml_get() {
-    grep "^$1 " "$CONFIG" | head -1 | sed 's/.*= *"\{0,1\}\([^"]*\)"\{0,1\}/\1/' | tr -d ' '
+    (grep "^$1 " "$CONFIG" 2>/dev/null || true) | head -1 | sed 's/.*= *"\{0,1\}\([^"]*\)"\{0,1\}/\1/' | tr -d ' '
 }
 
 toml_array() {
-    grep "^$1 " "$CONFIG" | head -1 \
+    (grep "^$1 " "$CONFIG" 2>/dev/null || true) | head -1 \
         | sed 's/.*\[//; s/\].*//; s/"//g; s/,/ /g' | tr -s ' '
 }
 
@@ -53,6 +53,7 @@ BAUD="$(toml_get 'baud')"
 [[ -n "$FQBN" ]]        || die "Could not read fqbn from .anvil.toml"
 
 BAUD="${BAUD:-115200}"
+DEFAULT_PORT="$(toml_get 'port')"
 SKETCH_DIR="$SCRIPT_DIR/$SKETCH_NAME"
 BUILD_DIR="$SCRIPT_DIR/.build"
 
@@ -86,14 +87,28 @@ command -v arduino-cli &>/dev/null \
 
 # -- Auto-detect port ------------------------------------------------------
 if [[ -z "$PORT" ]]; then
-    # Look for the first serial port arduino-cli can see
-    PORT=$(arduino-cli board list 2>/dev/null \
-        | grep -i "serial" \
-        | head -1 \
-        | awk '{print $1}')
+    # Check .anvil.toml for configured port
+    if [[ -n "$DEFAULT_PORT" ]]; then
+        PORT="$DEFAULT_PORT"
+    else
+        # Prefer ttyUSB/ttyACM (real USB devices) over ttyS (hardware UART)
+        PORT=$(arduino-cli board list 2>/dev/null \
+            | grep -i "serial" \
+            | awk '{print $1}' \
+            | grep -E 'ttyUSB|ttyACM|COM' \
+            | head -1)
+
+        # Fallback: any serial port if no USB ports found
+        if [[ -z "$PORT" ]]; then
+            PORT=$(arduino-cli board list 2>/dev/null \
+                | grep -i "serial" \
+                | head -1 \
+                | awk '{print $1}')
+        fi
+    fi
 
     if [[ -z "$PORT" ]]; then
-        die "No serial port detected. Is the board plugged in?\n  Specify manually: ./upload.sh -p /dev/ttyUSB0"
+        die "No serial port detected. Is the board plugged in?\n  Specify manually: ./upload.sh -p /dev/ttyUSB0\n  Or set port in .anvil.toml"
     fi
 
     warn "Auto-detected port: $PORT (use -p to override)"
diff --git a/tests/integration_test.rs b/tests/integration_test.rs
index fbd07d1..96d5979 100644
--- a/tests/integration_test.rs
+++ b/tests/integration_test.rs
@@ -637,3 +637,35 @@ fn test_readme_documents_self_contained_workflow() {
         "README should mention self-contained"
     );
 }
+
+#[test]
+fn test_scripts_tolerate_missing_toml_keys() {
+    // Regression: toml_get must not kill the script when a key is absent.
+    // With set -euo pipefail, bare grep returns exit 1 on no match,
+    // pipefail propagates it, and set -e terminates silently.
+    // Every grep in toml_get/toml_array must have "|| true".
+    let tmp = TempDir::new().unwrap();
+    let ctx = TemplateContext {
+        project_name: "grep_safe".to_string(),
+        anvil_version: "1.0.0".to_string(),
+    };
+
+    TemplateManager::extract("basic", tmp.path(), &ctx).unwrap();
+
+    for script in &["build.sh", "upload.sh", "monitor.sh"] {
+        let content = fs::read_to_string(tmp.path().join(script)).unwrap();
+
+        // If the script uses set -e (or -euo pipefail), then every
+        // toml_get/toml_array function must guard grep with || true
+        if content.contains("set -e") || content.contains("set -euo") {
+            // Find the toml_get function body and check for || true
+            let has_safe_grep = content.contains("|| true");
+            assert!(
+                has_safe_grep,
+                "{} uses set -e but toml_get/toml_array lacks '|| true' guard. \
+                 Missing TOML keys will silently kill the script.",
+                script
+            );
+        }
+    }
+}