diff --git a/lib/clean/project.sh b/lib/clean/project.sh
index 209c02d..85a5c37 100644
--- a/lib/clean/project.sh
+++ b/lib/clean/project.sh
@@ -29,6 +29,7 @@ readonly PURGE_TARGETS=(
     ".nuxt"         # Nuxt.js
     ".output"       # Nuxt.js
     "vendor"        # PHP Composer
+    "bin"           # .NET build output (guarded; see is_protected_purge_artifact)
     "obj"           # C# / Unity
     ".turbo"        # Turborepo cache
     ".parcel-cache" # Parcel bundler
@@ -246,6 +247,22 @@ is_php_project_root() {
     [[ -f "$dir/composer.json" ]]
 }
 
+# Decide whether a "bin" directory is a .NET directory
+is_dotnet_bin_dir() {
+    local path="$1"
+    [[ "$(basename "$path")" == "bin" ]] || return 1
+
+    # Check if parent directory has a .csproj/.fsproj/.vbproj file
+    local parent_dir
+    parent_dir="$(dirname "$path")"
+    find "$parent_dir" -maxdepth 1 \( -name "*.csproj" -o -name "*.fsproj" -o -name "*.vbproj" \) 2> /dev/null | grep -q . || return 1
+
+    # Check if bin directory contains Debug/ or Release/ subdirectories
+    [[ -d "$path/Debug" || -d "$path/Release" ]] || return 1
+
+    return 0
+}
+
 # Check if a vendor directory should be protected from purge
 # Expects path to be a vendor directory (basename == vendor)
 # Strategy: Only clean PHP Composer vendor, protect all others
@@ -284,6 +301,13 @@ is_protected_purge_artifact() {
     base=$(basename "$path")
 
     case "$base" in
+        bin)
+            # Only allow purging bin/ when we can detect .NET context.
+            if is_dotnet_bin_dir "$path"; then
+                return 1
+            fi
+            return 0
+            ;;
         vendor)
             is_protected_vendor_dir "$path"
             return $?
diff --git a/tests/purge.bats b/tests/purge.bats
index a11a0c5..5ccab1f 100644
--- a/tests/purge.bats
+++ b/tests/purge.bats
@@ -547,3 +547,97 @@ EOF
 
     [ -d "$HOME/.cache/mole" ] || [ -d "${XDG_CACHE_HOME:-$HOME/.cache}/mole" ]
 }
+
+# .NET bin directory detection tests
+@test "is_dotnet_bin_dir: finds .NET context in parent directory with Debug dir" {
+    mkdir -p "$HOME/www/dotnet-app/bin/Debug"
+    touch "$HOME/www/dotnet-app/MyProject.csproj"
+
+    result=$(bash -c "
+        source '$PROJECT_ROOT/lib/clean/project.sh'
+        if is_dotnet_bin_dir '$HOME/www/dotnet-app/bin'; then
+            echo 'FOUND'
+        else
+            echo 'NOT_FOUND'
+        fi
+    ")
+
+    [[ "$result" == "FOUND" ]]
+}
+
+@test "is_dotnet_bin_dir: requires .csproj AND Debug/Release" {
+    mkdir -p "$HOME/www/dotnet-app/bin"
+    touch "$HOME/www/dotnet-app/MyProject.csproj"
+
+    result=$(bash -c "
+        source '$PROJECT_ROOT/lib/clean/project.sh'
+        if is_dotnet_bin_dir '$HOME/www/dotnet-app/bin'; then
+            echo 'FOUND'
+        else
+            echo 'NOT_FOUND'
+        fi
+    ")
+
+    # Should not find it because Debug/Release directories don't exist
+    [[ "$result" == "NOT_FOUND" ]]
+}
+
+@test "is_dotnet_bin_dir: rejects non-bin directories" {
+    mkdir -p "$HOME/www/dotnet-app/obj"
+    touch "$HOME/www/dotnet-app/MyProject.csproj"
+
+    result=$(bash -c "
+        source '$PROJECT_ROOT/lib/clean/project.sh'
+        if is_dotnet_bin_dir '$HOME/www/dotnet-app/obj'; then
+            echo 'FOUND'
+        else
+            echo 'NOT_FOUND'
+        fi
+    ")
+    [[ "$result" == "NOT_FOUND" ]]
+}
+
+
+# Integration test for bin scanning
+@test "scan_purge_targets: includes .NET bin directories with Debug/Release" {
+    mkdir -p "$HOME/www/dotnet-app/bin/Debug"
+    touch "$HOME/www/dotnet-app/MyProject.csproj"
+
+    local scan_output
+    scan_output="$(mktemp)"
+
+    result=$(bash -c "
+        source '$PROJECT_ROOT/lib/clean/project.sh'
+        scan_purge_targets '$HOME/www' '$scan_output'
+        if grep -q '$HOME/www/dotnet-app/bin' '$scan_output'; then
+            echo 'FOUND'
+        else
+            echo 'MISSING'
+        fi
+    ")
+
+    rm -f "$scan_output"
+
+    [[ "$result" == "FOUND" ]]
+}
+
+@test "scan_purge_targets: skips generic bin directories (non-.NET)" {
+    mkdir -p "$HOME/www/ruby-app/bin"
+    touch "$HOME/www/ruby-app/Gemfile"
+
+    local scan_output
+    scan_output="$(mktemp)"
+
+    result=$(bash -c "
+        source '$PROJECT_ROOT/lib/clean/project.sh'
+        scan_purge_targets '$HOME/www' '$scan_output'
+        if grep -q '$HOME/www/ruby-app/bin' '$scan_output'; then
+            echo 'FOUND'
+        else
+            echo 'SKIPPED'
+        fi
+    ")
+
+    rm -f "$scan_output"
+    [[ "$result" == "SKIPPED" ]]
+}