fix: address Copilot review — input validation and flexible test assertion

- Bash: reject non-numeric --number with clear error before arithmetic
- PowerShell: reject negative -Number values (< 1) with clear error
- Test: use regex for elseif assertion to tolerate whitespace changes

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: fsilvaortiz

scripts/bash/create-new-feature.sh

@@ -263,6 +263,10 @@ else
     elif [ "$ALLOW_EXISTING" = false ]; then
         # Manual number provided -- validate it is not already in use
         # (skip when --allow-existing-branch, as the caller intentionally targets an existing branch)
+        if ! echo "$BRANCH_NUMBER" | grep -q '^[0-9]\+$'; then
+            >&2 echo "Error: --number requires a positive integer, got '$BRANCH_NUMBER'"
+            exit 1
+        fi
         MANUAL_NUM=$((10#$BRANCH_NUMBER))
         MANUAL_NUM_PADDED=$(printf "%03d" "$MANUAL_NUM")
         NUMBER_IN_USE=false

scripts/powershell/create-new-feature.ps1

@@ -214,6 +214,10 @@ if ($Timestamp) {
     } elseif (-not $AllowExistingBranch) {
         # Manual number provided -- validate it is not already in use
         # (skip when -AllowExistingBranch, as the caller intentionally targets an existing branch)
+        if ($Number -lt 1) {
+            Write-Error "-Number requires a positive integer, got $Number"
+            exit 1
+        }
         $manualNumPadded = '{0:000}' -f $Number
         $numberInUse = $false
 

tests/test_timestamp_branches.py

@@ -423,5 +423,7 @@ def test_powershell_has_number_collision_validation(self):
         assert "git fetch --all --prune" in contents
         # Must warn and auto-detect on conflict
         assert "conflicts with existing branch/spec" in contents
-        # Must skip validation when -AllowExistingBranch is set
-        assert "elseif (-not $AllowExistingBranch)" in contents
+        # Must skip validation when -AllowExistingBranch is set; allow flexible whitespace
+        assert re.search(r"elseif\s*\(\s*-not\s+\$AllowExistingBranch\s*\)", contents), (
+            "Expected an elseif guard that negates $AllowExistingBranch"
+        )