feat: debug-only type verification for materialized values

crates/plotnik-cli/src/commands/exec.rs

@@ -7,7 +7,9 @@ use plotnik_lib::emit::emit_linked;
 use plotnik_lib::Colors;
 use plotnik_lib::QueryBuilder;
 
-use plotnik_lib::engine::{FuelLimits, Materializer, RuntimeError, ValueMaterializer, VM};
+use plotnik_lib::engine::{
+    debug_verify_type, FuelLimits, Materializer, RuntimeError, ValueMaterializer, VM,
+};
 
 use super::query_loader::load_query_source;
 use super::run_common;
@@ -34,14 +36,14 @@ pub fn run(args: ExecArgs) {
         std::process::exit(1);
     }
 
-    let source_map =
-        match load_query_source(args.query_path.as_deref(), args.query_text.as_deref()) {
-            Ok(map) => map,
-            Err(msg) => {
-                eprintln!("error: {}", msg);
-                std::process::exit(1);
-            }
-        };
+    let source_map = match load_query_source(args.query_path.as_deref(), args.query_text.as_deref())
+    {
+        Ok(map) => map,
+        Err(msg) => {
+            eprintln!("error: {}", msg);
+            std::process::exit(1);
+        }
+    };
 
     if source_map.is_empty() {
         eprintln!("error: query cannot be empty");
@@ -96,6 +98,10 @@ pub fn run(args: ExecArgs) {
     let value = materializer.materialize(effects.as_slice(), entrypoint.result_type);
 
     let colors = Colors::new(args.color);
+
+    // Debug-only: verify output matches declared type
+    debug_verify_type(&value, &module, colors);
+
     let output = value.format(args.pretty, colors);
     println!("{}", output);
 }

crates/plotnik-cli/src/commands/trace.rs

@@ -8,7 +8,8 @@ use plotnik_lib::Colors;
 use plotnik_lib::QueryBuilder;
 
 use plotnik_lib::engine::{
-    FuelLimits, Materializer, PrintTracer, RuntimeError, ValueMaterializer, Verbosity, VM,
+    debug_verify_type, FuelLimits, Materializer, PrintTracer, RuntimeError, ValueMaterializer,
+    Verbosity, VM,
 };
 
 use super::query_loader::load_query_source;
@@ -38,14 +39,14 @@ pub fn run(args: TraceArgs) {
         std::process::exit(1);
     }
 
-    let source_map =
-        match load_query_source(args.query_path.as_deref(), args.query_text.as_deref()) {
-            Ok(map) => map,
-            Err(msg) => {
-                eprintln!("error: {}", msg);
-                std::process::exit(1);
-            }
-        };
+    let source_map = match load_query_source(args.query_path.as_deref(), args.query_text.as_deref())
+    {
+        Ok(map) => map,
+        Err(msg) => {
+            eprintln!("error: {}", msg);
+            std::process::exit(1);
+        }
+    };
 
     if source_map.is_empty() {
         eprintln!("error: query cannot be empty");
@@ -116,6 +117,9 @@ pub fn run(args: TraceArgs) {
     let materializer = ValueMaterializer::new(&source_code, module.types(), module.strings());
     let value = materializer.materialize(effects.as_slice(), entrypoint.result_type);
 
+    // Debug-only: verify output matches declared type
+    debug_verify_type(&value, &module, colors);
+
     let output = value.format(true, colors);
     println!("{}", output);
 }

crates/plotnik-lib/src/engine/mod.rs

@@ -11,6 +11,7 @@ mod frame;
 mod materializer;
 mod trace;
 mod value;
+mod verify;
 mod vm;
 
 #[cfg(test)]
@@ -21,4 +22,5 @@ pub use error::RuntimeError;
 pub use materializer::{Materializer, ValueMaterializer};
 pub use trace::{PrintTracer, Tracer, Verbosity};
 pub use value::{NodeHandle, Value};
+pub use verify::debug_verify_type;
 pub use vm::{FuelLimits, VM};