fix(model): Enforce the 512-character cap on a let binding identifier

crates/openjd-model/src/template/validate_v2023_09/format_strings.rs

@@ -23,6 +23,13 @@ use crate::error::{path_field, path_index, PathElement, ValidationErrors};
 use crate::template::*;
 use crate::types::{ModelExtension, ValidationContext};
 
+/// Maximum length of a `let` binding's `<UserIdentifier>` (§3.6.1).
+///
+/// Flat, so not `EffectiveLimits::max_identifier_len`: that is the §7.1 cap, 64
+/// without `FEATURE_BUNDLE_1`, and a 512-character name must be accepted with
+/// EXPR alone.
+const MAX_LET_IDENTIFIER_LEN: usize = 512;
+
 /// Build a symbol table containing Param/RawParam entries from job parameter definitions.
 /// RawParam.* is always STRING for PATH types and LIST_STRING for LIST_PATH types,
 /// matching Python behavior where RawParam holds the raw unprocessed value.
@@ -1385,6 +1392,13 @@ fn validate_let_bindings(
                 format!("name '{name}' contains invalid characters."),
             );
         }
+        // Name omitted from the message; at 513 characters it would dwarf it.
+        if name.len() > MAX_LET_IDENTIFIER_LEN {
+            errors.add(
+                &b_path,
+                format!("name exceeds {MAX_LET_IDENTIFIER_LEN} characters."),
+            );
+        }
         if !names.insert(name.to_string()) {
             errors.add(&b_path, format!("duplicate name '{name}'."));
         }

crates/openjd-model/tests/integration/test_let_bindings.rs

@@ -1122,3 +1122,62 @@ fn script_let_allows_apply_path_mapping() {
     }"#,
     );
 }
+
+// === Identifier length (§3.6.1: <UserIdentifier> max 512 characters) ===
+//
+// The cap is flat, so the `_expr_only` cases pin it without FEATURE_BUNDLE_1.
+// A regression to the §7.1 cap would pass without them.
+
+fn decode_ok_expr_only(s: &str) {
+    let v = yaml_val(s);
+    decode_job_template(v, Some(&["EXPR"]), &CallerLimits::default()).expect("Expected success");
+}
+
+#[test]
+fn test_let_name_512_chars_succeeds() {
+    let name = "a".repeat(512);
+    decode_ok(&job_with_step_let(&format!(r#""{name} = 1""#)));
+}
+
+#[test]
+fn test_let_name_512_chars_succeeds_expr_only() {
+    let name = "a".repeat(512);
+    decode_ok_expr_only(&job_with_step_let(&format!(r#""{name} = 1""#)));
+}
+
+#[test]
+fn test_let_name_513_chars_fails() {
+    let name = "a".repeat(513);
+    check_err(
+        &job_with_step_let(&format!(r#""{name} = 1""#)),
+        &["steps[0] -> let[0]:\n\tname exceeds 512 characters."],
+    );
+}
+
+#[test]
+fn test_let_name_513_chars_fails_expr_only() {
+    let name = "a".repeat(513);
+    let v = yaml_val(&job_with_step_let(&format!(r#""{name} = 1""#)));
+    let err = decode_job_template(v, Some(&["EXPR"]), &CallerLimits::default())
+        .expect_err("Expected error");
+    assert!(
+        err.to_string()
+            .contains("steps[0] -> let[0]:\n\tname exceeds 512 characters."),
+        "Got:\n{err}"
+    );
+}
+
+#[test]
+fn test_let_name_513_chars_fails_script() {
+    let name = "a".repeat(513);
+    check_err(
+        &job_with_script_let(&format!(r#""{name} = 1""#)),
+        &["steps[0] -> script -> let[0]:\n\tname exceeds 512 characters."],
+    );
+}
+
+#[test]
+fn test_let_name_512_chars_succeeds_script() {
+    let name = "a".repeat(512);
+    decode_ok(&job_with_script_let(&format!(r#""{name} = 1""#)));
+}