Reduce batch size to 10 and tighten AI price check prompt

Still seeing stubs despite MaxTokens=8192 — smaller batches and explicit
word limits in the prompt eliminate any remaining truncation risk.

- BatchSize: 15 → 10 (~1200 output tokens per batch vs. potential 3000+)
- Prompt: added 20-word cap on assumptions, 25-word cap on reasoning
- Prompt: strengthened "nothing before or after the '['" instruction
- Error log: now includes item IDs and first 300 chars of raw response
  so the next failure tells us exactly what Claude returned
- JS timing: updated batch divisor from 25 → 10 to match actual batch size

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/PowderCoating.Infrastructure/Services/AiCatalogPriceCheckService.cs

@@ -20,7 +20,7 @@ public class AiCatalogPriceCheckService : IAiCatalogPriceCheckService
     private readonly ILogger<AiCatalogPriceCheckService> _logger;
 
     private const string Model = "claude-sonnet-4-6";
-    private const int BatchSize = 15; // 25 items at ~250 tokens each exceeds 4096 output tokens
+    private const int BatchSize = 10; // keep responses predictably short; 10 items × ~120 tokens ≈ 1200 output tokens
 
     private static readonly JsonSerializerOptions JsonOpts = new() { PropertyNameCaseInsensitive = true };
 
@@ -132,10 +132,11 @@ public class AiCatalogPriceCheckService : IAiCatalogPriceCheckService
             }
         };
 
+        var raw = string.Empty;
         try
         {
             var response = await SendAsync(client, parameters);
-            var raw = response.Content.OfType<TextContent>().FirstOrDefault()?.Text ?? "[]";
+            raw = response.Content.OfType<TextContent>().FirstOrDefault()?.Text ?? "[]";
             var json = ExtractJsonArray(raw);
 
             var claudeItems = JsonSerializer.Deserialize<List<ClaudePriceCheckItem>>(json, JsonOpts) ?? new();
@@ -164,8 +165,10 @@ public class AiCatalogPriceCheckService : IAiCatalogPriceCheckService
         }
         catch (Exception ex)
         {
-            _logger.LogError(ex, "AI catalog price check batch failed");
-            // Return stub verdicts so the rest of the report still renders
+            var preview = raw.Length > 300 ? raw[..300] + "…" : raw;
+            _logger.LogError(ex,
+                "AI price check batch failed for items [{ItemIds}]. Raw response preview: {RawPreview}",
+                string.Join(", ", batch.Select(b => b.Id)), preview);
             return batch.Select(item => new CatalogItemPriceVerdict
             {
                 CatalogItemId = item.Id,
@@ -220,10 +223,12 @@ public class AiCatalogPriceCheckService : IAiCatalogPriceCheckService
         sb.AppendLine();
         sb.AppendLine("If the item already has an ApproximateArea or EstimatedMinutes, use those instead of guessing.");
         sb.AppendLine();
-        sb.AppendLine("Return ONLY a JSON array, no prose, no markdown fences. Use this exact schema for each element:");
+        sb.AppendLine("IMPORTANT: Keep responses concise to avoid truncation. Limit assumptions to 20 words max. Limit reasoning to 25 words max.");
+        sb.AppendLine();
+        sb.AppendLine("Return ONLY a JSON array — no prose, no markdown fences, nothing before or after the '['. Use this exact schema for each element:");
         sb.AppendLine(@"{
   ""catalogItemId"": <int>,
-  ""assumptions"": ""<what you assumed about size/complexity>"",
+  ""assumptions"": ""<≤20 words>"",
   ""estimatedSqFtMin"": <decimal>,
   ""estimatedSqFtMax"": <decimal>,
   ""estimatedMinutesMin"": <int>,
@@ -233,7 +238,7 @@ public class AiCatalogPriceCheckService : IAiCatalogPriceCheckService
   ""suggestedPriceMin"": <decimal>,
   ""suggestedPriceMax"": <decimal>,
   ""confidence"": ""high|medium|low"",
-  ""reasoning"": ""<1-2 sentence explanation>""
+  ""reasoning"": ""<≤25 words>""
 }");
         return sb.ToString();
     }

src/PowderCoating.Web/wwwroot/js/catalog-price-check.js

@@ -12,14 +12,14 @@
 
     // Estimate total seconds based on item count (roughly 12s per batch of 25, min 15s).
     function estimateDuration(itemCount) {
-        var batches = Math.max(1, Math.ceil(itemCount / 25));
-        return Math.max(15, batches * 12);
+        var batches = Math.max(1, Math.ceil(itemCount / 10));
+        return Math.max(15, batches * 10);
     }
 
     // Messages keyed to approximate progress milestones (0–100).
     function messageAt(pct, batchCount) {
         if (pct < 10) return 'Loading catalog items…';
-        if (pct < 20) return 'Sending items to Claude…';
+        if (pct < 20) return 'Sending items for analysis…';
         if (batchCount <= 1) {
             if (pct < 75) return 'Analyzing your catalog with AI…';
             if (pct < 92) return 'Reviewing pricing data…';