diff --git a/mlf-cli/src/generate/mlf.rs b/mlf-cli/src/generate/mlf.rs
index 5ce9845..39e75bf 100644
--- a/mlf-cli/src/generate/mlf.rs
+++ b/mlf-cli/src/generate/mlf.rs
@@ -827,12 +827,24 @@ fn generate_type(
 ) -> Result<Rendered, MlfGenerateError> {
     let type_name = type_def.get("type").and_then(|v| v.as_str());
 
+    // Primitive types that the ATProto spec defines with constraint fields
+    // are routed through `with_constraints`; it returns an atom when no
+    // constraint keys are present, so it's equally valid for inputs
+    // written without any. The spec permits:
+    //   boolean — default, const
+    //   integer — minimum, maximum, enum, default, const
+    //   string  — format, min/maxLength, min/maxGraphemes, knownValues,
+    //             enum, default, const  (via `render_string`)
+    //   bytes   — minLength, maxLength
+    //   blob    — accept, maxSize
+    // `null` and `unknown` have no defined constraint fields and stay
+    // atomic.
     match type_name {
         Some("null") => Ok(Rendered::atom("null")),
-        Some("boolean") => Ok(Rendered::atom("boolean")),
+        Some("boolean") => Ok(Rendered::with_constraints("boolean", type_def, indent_level)),
         Some("integer") => Ok(Rendered::with_constraints("integer", type_def, indent_level)),
         Some("string") => Ok(render_string(type_def, indent_level)),
-        Some("bytes") => Ok(Rendered::atom("bytes")),
+        Some("bytes") => Ok(Rendered::with_constraints("bytes", type_def, indent_level)),
         Some("blob") => Ok(Rendered::with_constraints("blob", type_def, indent_level)),
         Some("unknown") => Ok(Rendered::atom("unknown")),
         Some("array") => render_array(type_def, ctx, indent_level),
diff --git a/tests/lexicon_to_mlf/all_constraint_keys/expected.mlf b/tests/lexicon_to_mlf/all_constraint_keys/expected.mlf
index 9701f11..1860573 100644
--- a/tests/lexicon_to_mlf/all_constraint_keys/expected.mlf
+++ b/tests/lexicon_to_mlf/all_constraint_keys/expected.mlf
@@ -23,3 +23,16 @@ def type status = string constrained {
     default: "active",
 };
 
+def type blocked = boolean constrained {
+    const: true,
+};
+
+def type flag = boolean constrained {
+    default: false,
+};
+
+def type digest = bytes constrained {
+    minLength: 32,
+    maxLength: 64,
+};
+
diff --git a/tests/lexicon_to_mlf/all_constraint_keys/input.json b/tests/lexicon_to_mlf/all_constraint_keys/input.json
index 1e00ffc..6c85f4f 100644
--- a/tests/lexicon_to_mlf/all_constraint_keys/input.json
+++ b/tests/lexicon_to_mlf/all_constraint_keys/input.json
@@ -26,6 +26,19 @@
       "type": "string",
       "enum": ["active", "inactive"],
       "default": "active"
+    },
+    "blocked": {
+      "type": "boolean",
+      "const": true
+    },
+    "flag": {
+      "type": "boolean",
+      "default": false
+    },
+    "digest": {
+      "type": "bytes",
+      "minLength": 32,
+      "maxLength": 64
     }
   }
 }