Improve input validation and error handling in admin console

Co-authored-by: Steake <530040+Steake@users.noreply.github.com>

Author: Copilot

crates/bitcell-admin/src/api/nodes.rs

@@ -34,7 +34,7 @@ pub struct StartNodeRequest {
 
 /// Validate node ID format (alphanumeric, hyphens, and underscores only)
 fn validate_node_id(id: &str) -> Result<(), (StatusCode, Json<ErrorResponse>)> {
-    if !id.chars().all(|c| c.is_alphanumeric() || c == '-' || c == '_') {
+    if id.is_empty() || !id.chars().all(|c| c.is_alphanumeric() || c == '-' || c == '_') {
         return Err((
             StatusCode::BAD_REQUEST,
             Json(ErrorResponse {
@@ -83,6 +83,7 @@ pub async fn start_node(
 
     // Config is not supported yet
     if req.config.is_some() {
+        tracing::warn!("Node '{}': Rejected start request with unsupported config", id);
         return Err((
             StatusCode::BAD_REQUEST,
             Json(ErrorResponse {

crates/bitcell-admin/src/web/dashboard.rs

@@ -1047,8 +1047,8 @@ pub async fn index() -> impl IntoResponse {
             const nodeType = document.getElementById('deploy-node-type').value;
             const count = parseInt(document.getElementById('deploy-count').value);
 
-            if (count < 1 || count > 10) {
-                alert('Please enter a number between 1 and 10');
+            if (isNaN(count) || count < 1 || count > 10) {
+                alert('Please enter a valid number between 1 and 10');
                 return;
             }
 
@@ -1063,8 +1063,18 @@ pub async fn index() -> impl IntoResponse {
                 });
 
                 if (!response.ok) {
-                    const error = await response.text();
-                    throw new Error(error);
+                    let errorMessage = 'Deployment failed';
+                    try {
+                        const error = await response.json();
+                        errorMessage = error.error || error.message || errorMessage;
+                    } catch (e) {
+                        const text = await response.text();
+                        // Avoid showing large HTML blobs; use a generic message if text looks like HTML
+                        if (text && !/^<!doctype|^<html/i.test(text.trim())) {
+                            errorMessage = text;
+                        }
+                    }
+                    throw new Error(errorMessage);
                 }
 
                 const data = await response.json();
@@ -1152,8 +1162,14 @@ pub async fn index() -> impl IntoResponse {
                 });
                 
                 if (!response.ok) {
-                    const error = await response.json();
-                    throw new Error(error.error || 'Failed to start node');
+                    let errorMessage = 'Failed to start node';
+                    try {
+                        const error = await response.json();
+                        errorMessage = error.error || errorMessage;
+                    } catch (e) {
+                        // If JSON parsing fails, use default message
+                    }
+                    throw new Error(errorMessage);
                 }
                 
                 updateNodes();
@@ -1168,8 +1184,14 @@ pub async fn index() -> impl IntoResponse {
                 const response = await fetch(`/api/nodes/${id}/stop`, { method: 'POST' });
                 
                 if (!response.ok) {
-                    const error = await response.json();
-                    throw new Error(error.error || 'Failed to stop node');
+                    let errorMessage = 'Failed to stop node';
+                    try {
+                        const error = await response.json();
+                        errorMessage = error.error || errorMessage;
+                    } catch (e) {
+                        // If JSON parsing fails, use default message
+                    }
+                    throw new Error(errorMessage);
                 }
                 
                 updateNodes();

crates/bitcell-ca/src/battle.rs

@@ -138,6 +138,11 @@ impl Battle {
     /// # Performance Note
     /// This implementation sorts steps internally for incremental evolution efficiency,
     /// but returns grids in the original order requested.
+    /// 
+    /// # Memory Overhead
+    /// Each grid clone can be expensive for large grids (e.g., 1024×1024 grids).
+    /// Requesting many sample steps will require storing multiple grid copies in memory.
+    /// For example, 100 sample steps could require several hundred MB of memory.
     pub fn grid_states(&self, sample_steps: &[usize]) -> Vec<Grid> {
         let initial = self.setup_grid();
 
@@ -158,7 +163,10 @@ impl Battle {
 
         for (original_idx, step) in &indexed_steps {
             let steps_to_evolve = step - prev_step;
-            current_grid = evolve_n_steps(&current_grid, steps_to_evolve);
+            // If steps_to_evolve is 0 (e.g., for step 0), the grid remains unchanged
+            if steps_to_evolve > 0 {
+                current_grid = evolve_n_steps(&current_grid, steps_to_evolve);
+            }
             evolved_grids.push((*original_idx, current_grid.clone()));
             prev_step = *step;
         }