Fall back to TDS sheet for cure specs when main lookup returns none

After the main AI lookup and catalog search, if CureTemperatureF or
CureTimeMinutes is still null but a TDS URL was found, fetch that page
and ask Claude to extract just the cure schedule.

- IInventoryAiLookupService.FetchTdsCureSpecsAsync: new interface method
- InventoryAiLookupService.FetchTdsCureSpecsAsync: fetches the TDS URL via
  the existing FetchPageAsync pipeline (JSON-LD + doc-link extraction, HTML
  stripping). If the page is a PDF or unreachable, returns Success=false
  silently so no error surfaces in the UI. Otherwise sends a small targeted
  prompt that asks only for cureTemperatureF and cureTimeMinutes and uses
  MaxTokens=256 so the call is fast and cheap.
- InventoryController.ScanLabel: after catalog lookup, computes the resolved
  cure values (catalog preferred over AI result). If either is null and a
  TDS URL exists, calls FetchTdsCureSpecsAsync and merges any newly found
  values back into aiResult before building the JSON response.

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

src/PowderCoating.Application/Interfaces/IInventoryAiLookupService.cs

@@ -54,4 +54,11 @@ public interface IInventoryAiLookupService
     /// using Claude vision. Used by the in-browser label scanner.
     /// </summary>
     Task<InventoryAiLookupResult> ScanLabelAsync(string base64Image, string mediaType);
+
+    /// <summary>
+    /// Fetches a Technical Data Sheet URL and extracts cure temperature and cure time.
+    /// Called when the main lookup found a TDS URL but cure specs are still missing.
+    /// Returns Success=false silently (no UI error) when the TDS is a PDF or unreachable.
+    /// </summary>
+    Task<InventoryAiLookupResult> FetchTdsCureSpecsAsync(string tdsUrl, string? colorName);
 }

src/PowderCoating.Infrastructure/Services/InventoryAiLookupService.cs

@@ -478,6 +478,108 @@ Rules:
         }
     }
 
+    /// <summary>
+    /// Fetches a TDS URL (if it is an HTML page — PDFs are silently skipped) and asks Claude
+    /// to extract cure temperature and cure time only. Uses the same <see cref="FetchPageAsync"/>
+    /// pipeline so JSON-LD and document links are still extracted before stripping HTML.
+    /// Returns <see cref="InventoryAiLookupResult.Success"/> = <c>false</c> without an error
+    /// message when the page could not be fetched (PDF, redirect loop, etc.) so the caller
+    /// can merge results without surfacing a user-visible error.
+    /// </summary>
+    public async Task<InventoryAiLookupResult> FetchTdsCureSpecsAsync(string tdsUrl, string? colorName)
+    {
+        var apiKey = _config["AI:Anthropic:ApiKey"];
+        if (string.IsNullOrWhiteSpace(apiKey) || apiKey.StartsWith("your-"))
+            return new InventoryAiLookupResult { Success = false };
+
+        try
+        {
+            var (pageContent, _) = await FetchPageAsync(tdsUrl);
+            if (string.IsNullOrWhiteSpace(pageContent))
+            {
+                // PDF or unreachable — nothing to send to Claude
+                _logger.LogInformation("TDS cure lookup skipped (PDF or unreachable): {Url}", tdsUrl);
+                return new InventoryAiLookupResult { Success = false };
+            }
+
+            // Targeted prompt: we only need cure specs from this document
+            const string curePrompt = @"You are reading a Technical Data Sheet (TDS) for a powder coating product.
+Extract ONLY the cure schedule. Respond with a valid JSON object — no markdown, no explanation:
+
+{
+  ""cureTemperatureF"": number or null,
+  ""cureTimeMinutes"": number or null,
+  ""reasoning"": ""one sentence: what cure schedule you found""
+}
+
+Rules:
+- cureTemperatureF: the recommended cure temperature in °F. Convert from °C if needed (multiply by 1.8 + 32). If a range is given use the midpoint. Most powders cure 325–400 °F.
+- cureTimeMinutes: the hold time at cure temperature in minutes (NOT total oven time). Typically 10–20 min.
+- If neither value can be found in the document, return null for both.";
+
+            var sb = new StringBuilder();
+            sb.AppendLine("Technical Data Sheet content:");
+            if (!string.IsNullOrWhiteSpace(colorName)) sb.AppendLine($"Product: {colorName}");
+            sb.AppendLine($"Source: {tdsUrl}");
+            sb.AppendLine();
+            sb.AppendLine(pageContent);
+
+            var client = new AnthropicClient(apiKey);
+            var messageRequest = new MessageParameters
+            {
+                Model = "claude-sonnet-4-6",
+                MaxTokens = 256,
+                SystemMessage = curePrompt,
+                Messages = new List<Message>
+                {
+                    new Message
+                    {
+                        Role = RoleType.User,
+                        Content = new List<ContentBase> { new TextContent { Text = sb.ToString() } }
+                    }
+                }
+            };
+
+            var response = await client.Messages.GetClaudeMessageAsync(messageRequest);
+            var rawText = (response.FirstMessage?.Text
+                ?? response.Content.OfType<TextContent>().FirstOrDefault()?.Text
+                ?? string.Empty).Trim();
+
+            if (rawText.StartsWith("```"))
+            {
+                var start = rawText.IndexOf('\n') + 1;
+                var end   = rawText.LastIndexOf("```");
+                rawText   = rawText[start..end].Trim();
+            }
+
+            if (!rawText.StartsWith("{"))
+            {
+                var j = rawText.IndexOf('{');
+                var k = rawText.LastIndexOf('}');
+                if (j >= 0 && k > j) rawText = rawText[j..(k + 1)];
+                else return new InventoryAiLookupResult { Success = false };
+            }
+
+            var parsed = JsonSerializer.Deserialize<JsonElement>(rawText);
+            var result = new InventoryAiLookupResult
+            {
+                Success          = true,
+                CureTemperatureF = GetDecimal(parsed, "cureTemperatureF"),
+                CureTimeMinutes  = GetInt(parsed,     "cureTimeMinutes"),
+                Reasoning        = GetString(parsed,  "reasoning"),
+            };
+
+            _logger.LogInformation("TDS cure lookup for {Url}: temp={Temp}°F, time={Time}min ({Reasoning})",
+                tdsUrl, result.CureTemperatureF, result.CureTimeMinutes, result.Reasoning);
+            return result;
+        }
+        catch (Exception ex)
+        {
+            _logger.LogWarning(ex, "TDS cure spec fetch failed for {Url}", tdsUrl);
+            return new InventoryAiLookupResult { Success = false };
+        }
+    }
+
     // ── Manufacturer URL pattern: build direct product page URL ───────────────
 
     /// <summary>

src/PowderCoating.Web/Controllers/InventoryController.cs

@@ -834,6 +834,23 @@ public class InventoryController : Controller
             }
         }
 
+        // If cure specs are still missing but we have a TDS URL, fetch it and try to extract
+        // cure temperature and cure time. Most TDS pages are HTML; PDFs fail silently.
+        var resolvedCureTemp = catalogMatch?.CureTemperatureF ?? aiResult.CureTemperatureF;
+        var resolvedCureTime = catalogMatch?.CureTimeMinutes  ?? aiResult.CureTimeMinutes;
+        var resolvedTdsUrl   = catalogMatch?.TdsUrl ?? aiResult.TdsUrl;
+
+        if ((resolvedCureTemp == null || resolvedCureTime == null) && !string.IsNullOrEmpty(resolvedTdsUrl))
+        {
+            _logger.LogInformation("Cure specs missing after main lookup; trying TDS at {Url}", resolvedTdsUrl);
+            var tdsResult = await _aiLookupService.FetchTdsCureSpecsAsync(resolvedTdsUrl, colorName);
+            if (tdsResult.Success)
+            {
+                if (resolvedCureTemp == null) aiResult.CureTemperatureF = tdsResult.CureTemperatureF;
+                if (resolvedCureTime == null) aiResult.CureTimeMinutes  = tdsResult.CureTimeMinutes;
+            }
+        }
+
         // Check if this product already exists in the tenant's inventory.
         // Match by ManufacturerPartNumber first (most precise); fall back to color name + manufacturer.
         // Returns the first active match so the UI can prompt to add stock inline.