fix: improve LLM diagram context awareness and image preview (#202)

- Add replaceHistoricalToolInputs to replace XML in tool calls with placeholders
- Send both previousXml and current xml so LLM can understand user's manual edits
- Update system message to mark current XML as authoritative source of truth
- Fix React StrictMode issue with blob URL cleanup in FilePreviewList
- Add unoptimized prop to Image components for blob URLs

components/chat-panel.tsx

@@ -764,6 +764,15 @@ Please retry with an adjusted search pattern or use display_diagram if retries a
                     }
                 }
 
+                // Get previous XML from the last snapshot (before this message)
+                const snapshotKeys = Array.from(
+                    xmlSnapshotsRef.current.keys(),
+                ).sort((a, b) => b - a)
+                const previousXml =
+                    snapshotKeys.length > 0
+                        ? xmlSnapshotsRef.current.get(snapshotKeys[0]) || ""
+                        : ""
+
                 // Save XML snapshot for this message (will be at index = current messages.length)
                 const messageIndex = messages.length
                 xmlSnapshotsRef.current.set(messageIndex, chartXml)
@@ -805,6 +814,7 @@ Please retry with an adjusted search pattern or use display_diagram if retries a
                     {
                         body: {
                             xml: chartXml,
+                            previousXml,
                             sessionId,
                         },
                         headers: {
@@ -869,6 +879,15 @@ Please retry with an adjusted search pattern or use display_diagram if retries a
             return
         }
 
+        // Get previous XML (snapshot before the one being regenerated)
+        const snapshotKeys = Array.from(xmlSnapshotsRef.current.keys())
+            .filter((k) => k < userMessageIndex)
+            .sort((a, b) => b - a)
+        const previousXml =
+            snapshotKeys.length > 0
+                ? xmlSnapshotsRef.current.get(snapshotKeys[0]) || ""
+                : ""
+
         // Restore the diagram to the saved state (skip validation for trusted snapshots)
         onDisplayChart(savedXml, true)
 
@@ -923,6 +942,7 @@ Please retry with an adjusted search pattern or use display_diagram if retries a
             {
                 body: {
                     xml: savedXml,
+                    previousXml,
                     sessionId,
                 },
                 headers: {
@@ -956,6 +976,15 @@ Please retry with an adjusted search pattern or use display_diagram if retries a
             return
         }
 
+        // Get previous XML (snapshot before the one being edited)
+        const snapshotKeys = Array.from(xmlSnapshotsRef.current.keys())
+            .filter((k) => k < messageIndex)
+            .sort((a, b) => b - a)
+        const previousXml =
+            snapshotKeys.length > 0
+                ? xmlSnapshotsRef.current.get(snapshotKeys[0]) || ""
+                : ""
+
         // Restore the diagram to the saved state (skip validation for trusted snapshots)
         onDisplayChart(savedXml, true)
 
@@ -1018,6 +1047,7 @@ Please retry with an adjusted search pattern or use display_diagram if retries a
             {
                 body: {
                     xml: savedXml,
+                    previousXml,
                     sessionId,
                 },
                 headers: {

components/file-preview-list.tsx

@@ -48,6 +48,8 @@ export function FilePreviewList({ files, onRemoveFile }: FilePreviewListProps) {
             imageUrlsRef.current.forEach((url) => {
                 URL.revokeObjectURL(url)
             })
+            // Clear the ref so StrictMode remount creates fresh URLs
+            imageUrlsRef.current = new Map()
         }
     }, [])
 
@@ -83,6 +85,7 @@ export function FilePreviewList({ files, onRemoveFile }: FilePreviewListProps) {
                                         width={80}
                                         height={80}
                                         className="object-cover w-full h-full"
+                                        unoptimized
                                     />
                                 ) : (
                                     <div className="flex items-center justify-center h-full text-xs text-center p-1">
@@ -124,6 +127,7 @@ export function FilePreviewList({ files, onRemoveFile }: FilePreviewListProps) {
                             height={900}
                             className="object-contain max-w-full max-h-[90vh] w-auto h-auto"
                             onClick={(e) => e.stopPropagation()}
+                            unoptimized
                         />
                     </div>
                 </div>