From 399cd1845b39678a901516cf20ac243e2872f435 Mon Sep 17 00:00:00 2001
From: baku-ccron <baku-ccron@rainlang.xyz>
Date: Tue, 25 Aug 2026 16:03:02 +0000
Subject: [PATCH] fix: OpMeta Input computation requires bits

An Input carrying `computation` with no `bits` is a computed input that
never allocated the operand bits its computation reads, so schema-level
validation now rejects it.

`parameters` alongside `bits` stays valid: it is the spread shape every
dynamic-input op meta ships.

Closes #171

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
---
 crates/cli/src/meta/types/op/v1.rs | 39 ++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/crates/cli/src/meta/types/op/v1.rs b/crates/cli/src/meta/types/op/v1.rs
index c262efee..3edd21bc 100644
--- a/crates/cli/src/meta/types/op/v1.rs
+++ b/crates/cli/src/meta/types/op/v1.rs
@@ -147,11 +147,22 @@ impl TryFrom<RainMetaDocumentV1Item> for OpMeta {
     }
 }
 
+/// Computed inputs are discriminated by `bits`, so a computation over the
+/// extracted bits value cannot stand without them.
+fn validate_input_computation(input: &Input) -> Result<(), ValidationError> {
+    if input.computation.is_some() && input.bits.is_none() {
+        Err(ValidationError::new("Input computation requires bits.\n"))
+    } else {
+        Ok(())
+    }
+}
+
 /// # Input
 /// Data type of opcode's inputs that determines the number of inputs an opcode
 /// has and provide information about them.
 #[derive(Validate, Debug, Clone, Serialize, Deserialize)]
 #[cfg_attr(feature = "json-schema", derive(JsonSchema))]
+#[validate(schema(function = "validate_input_computation"))]
 pub struct Input {
     /// # Parameters
     /// List of InputParameters, may be empty.
@@ -368,17 +379,41 @@ mod tests {
     #[test]
     fn test_opmeta_input_computation_validated() {
         assert!(OpMeta::try_from(
-            br#"{"name":"add","inputs":[{"computation":"bits + 1"}]}"#.to_vec()
+            br#"{"name":"add","inputs":[{"bits":[0,7],"computation":"bits + 1"}]}"#.to_vec()
         )
         .is_ok());
         assert!(OpMeta::try_from(
-            "{\"name\":\"add\",\"inputs\":[{\"computation\":\"\u{2665}\"}]}"
+            "{\"name\":\"add\",\"inputs\":[{\"bits\":[0,7],\"computation\":\"\u{2665}\"}]}"
                 .as_bytes()
                 .to_vec()
         )
         .is_err());
     }
 
+    #[test]
+    fn test_opmeta_input_computation_requires_bits() {
+        assert!(OpMeta::try_from(
+            br#"{"name":"add","inputs":[{"computation":"bits + 1"}]}"#.to_vec()
+        )
+        .is_err());
+        assert!(OpMeta::try_from(
+            br#"{"name":"add","inputs":[{"parameters":[{"name":"lhs"}],"computation":"bits + 1"}]}"#
+                .to_vec()
+        )
+        .is_err());
+    }
+
+    #[test]
+    fn test_opmeta_input_parameters_alongside_bits_is_valid() {
+        // The spread shape every dynamic-input opcode ships, e.g.
+        // rainlanguage/rain-metadata examples/op-meta/Add.op.meta.json.
+        assert!(OpMeta::try_from(
+            br#"{"name":"add","inputs":[{"bits":[0,7],"parameters":[{"name":"input","spread":true}]}]}"#
+                .to_vec()
+        )
+        .is_ok());
+    }
+
     #[test]
     fn test_input_parameter_spread_defaults_false() {
         let meta = OpMeta::try_from(