diff --git a/README.md b/README.md
index b0b66a0..d926bf3 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,47 @@
 
 Ollie is an AI agent runtime built around a 9P virtual filesystem. The runtime service, `olliesrv`, exposes sessions, agents, prompts, state, history, tools, and control operations as files. Frontends remain thin clients of that interface.
 
+```mermaid
+flowchart TB
+    B["olliesrv<br/>9P namespace · session lifecycle · agent runtime<br/>prompt + history · backend dispatch"]
+
+    S1["Session A (toolsrv)<br/>host + cwd"]
+    S2["Session B (toolsrv)<br/>host + cwd"]
+    S3["Session C (toolsrv)<br/>host + cwd"]
+    SX["(...)"]
+
+    B --- S1
+    B --- S2
+    B --- S3
+    B --- SX
+
+    A1["Agent 1"]
+    A2["Agent 2"]
+    A3["Agent 3"]
+    A4["Agent 4"]
+    A5["Agent 5"]
+    A6["Agent 6"]
+    AN["Agent N"]
+    AX["(...)"]
+
+    S1 --- A1
+    S1 --- A2
+    S2 --- A3
+    S2 --- A4
+    S3 --- A5
+    S3 --- A6
+    SX --- AN
+    SX --- AX
+
+    classDef brain fill:#d66b3d,stroke:#642b1c,color:#fff,stroke-width:4px;
+    classDef session fill:#e7c65c,stroke:#67551b,color:#211b08;
+    classDef agent fill:#c7d4eb,stroke:#354a70,color:#172033;
+
+    class B brain;
+    class S1,S2,S3,SX session;
+    class A1,A2,A3,A4,A5,A6,AN,AX agent;
+```
+
 ```text
 frontends (shell, Acme, KDE, scripts)
                          │ 9P
diff --git a/kde/gui/chatblockmodel.cpp b/kde/gui/chatblockmodel.cpp
index 7f78e12..927e713 100644
--- a/kde/gui/chatblockmodel.cpp
+++ b/kde/gui/chatblockmodel.cpp
@@ -238,7 +238,6 @@ void ChatBlockModel::reset()
     m_fenceContent.clear();
     m_pendingDiagrams.clear();
     m_inFlightRequests.clear();
-    m_diagramCache.clear();  // Clear cache on reset to pick up fixes
     endResetModel();
     emit countChanged();
 }
@@ -258,12 +257,6 @@ void ChatBlockModel::trimFront(int keepCount)
     emit countChanged();
 }
 
-void ChatBlockModel::clearDiagramCache()
-{
-    m_diagramCache.clear();
-    qDebug() << "Diagram cache cleared";
-}
-
 QString ChatBlockModel::getDefaultTextColor() const
 {
     const auto textColor = QApplication::palette().color(QPalette::Text);
@@ -375,56 +368,10 @@ void ChatBlockModel::rebuildBlockHtml(int blockIndex)
                 html += diagramPlaceholder(fenceLang);
                 seg.diagramLoading = true;
             } else {
-                // Complete fence — check cache or request diagram
-                const QString cacheKey = fenceLang + QStringLiteral(":") +
-                    QString::fromLatin1(QCryptographicHash::hash(
-                        code.toUtf8(), QCryptographicHash::Md5).toHex());
-
-                if (m_diagramCache.contains(cacheKey)) {
-                    const QByteArray cached = m_diagramCache.value(cacheKey);
-                    if (cached.startsWith("ERROR:")) {
-                        // Error: fall back to source code rendering (not a diagram segment)
-                        QString codeHtml = highlightCode(code, fenceLang);
-                        html += codeHtml;
-
-                        BlockSegment textSeg;
-                        textSeg.type = BlockSegment::Text;
-                        textSeg.html = codeHtml;
-                        segments.append(textSeg);
-
-                        fenceLines.clear();
-                        fenceLang.clear();
-                        return;  // Don't append diagram segment
-                    } else {
-                        // Check if JPEG, PNG, or SVG
-                        if (cached.startsWith("JPEG:")) {
-                            QByteArray jpegData = cached.mid(5);  // Skip "JPEG:" prefix
-                            html += diagramJpegHtml(jpegData);
-                            seg.diagramSvg = QStringLiteral("data:image/jpeg;base64,") +
-                                QString::fromLatin1(jpegData.toBase64());
-                        } else if (cached.startsWith("PNG:")) {
-                            QByteArray pngData = cached.mid(4);  // Skip "PNG:" prefix
-                            html += diagramPngHtml(pngData);
-                            seg.diagramSvg = QStringLiteral("data:image/png;base64,") +
-                                QString::fromLatin1(pngData.toBase64());
-                        } else if (cached.startsWith("SVG:")) {
-                            QByteArray svgData = cached.mid(4);  // Skip "SVG:" prefix
-                            html += diagramSvgHtml(svgData);
-                            seg.diagramSvg = QStringLiteral("data:image/svg+xml;base64,") +
-                                QString::fromLatin1(svgData.toBase64());
-                        } else {
-                            // Legacy: assume SVG if no prefix
-                            html += diagramSvgHtml(cached);
-                            seg.diagramSvg = QStringLiteral("data:image/svg+xml;base64,") +
-                                QString::fromLatin1(cached.toBase64());
-                        }
-                    }
-                } else {
-                    html += diagramPlaceholder(fenceLang);
-                    seg.diagramLoading = true;
-                    // Request diagram asynchronously
-                    requestDiagram(fenceLang, code, blockIndex);
-                }
+                // Complete fence — render through the local diagram server.
+                html += diagramPlaceholder(fenceLang);
+                seg.diagramLoading = true;
+                requestDiagram(fenceLang, code, blockIndex);
             }
             segments.append(seg);
         } else {
@@ -568,40 +515,15 @@ void ChatBlockModel::incrementalAppend(int blockIndex, const QString &line)
             rs.inFence = false;
             const QString code = rs.fenceLines.join('\n');
 
-            if (isDiagramLanguage(rs.fenceLang)) {
-                // Replace last segment with a diagram segment
-                BlockSegment seg;
-                seg.type = BlockSegment::Diagram;
-                seg.diagramLang = rs.fenceLang;
-                seg.diagramSource = code;
-                seg.html = highlightCode(code, rs.fenceLang);
-
-                const QString cacheKey = rs.fenceLang + QStringLiteral(":") +
-                    QString::fromLatin1(QCryptographicHash::hash(
-                        code.toUtf8(), QCryptographicHash::Md5).toHex());
-
-                if (m_diagramCache.contains(cacheKey)) {
-                    const QByteArray cached = m_diagramCache.value(cacheKey);
-                    if (cached.startsWith("ERROR:")) {
-                        // Error: keep as text segment with highlighted source
-                        seg.type = BlockSegment::Text;
-                    } else if (cached.startsWith("JPEG:")) {
-                        seg.diagramSvg = QStringLiteral("data:image/jpeg;base64,") +
-                            QString::fromLatin1(cached.mid(5).toBase64());
-                    } else if (cached.startsWith("PNG:")) {
-                        seg.diagramSvg = QStringLiteral("data:image/png;base64,") +
-                            QString::fromLatin1(cached.mid(4).toBase64());
-                    } else if (cached.startsWith("SVG:")) {
-                        seg.diagramSvg = QStringLiteral("data:image/svg+xml;base64,") +
-                            QString::fromLatin1(cached.mid(4).toBase64());
-                    } else {
-                        seg.diagramSvg = QStringLiteral("data:image/svg+xml;base64,") +
-                            QString::fromLatin1(cached.toBase64());
-                    }
-                } else {
+                if (isDiagramLanguage(rs.fenceLang)) {
+                    // Replace last segment with a diagram segment
+                    BlockSegment seg;
+                    seg.type = BlockSegment::Diagram;
+                    seg.diagramLang = rs.fenceLang;
+                    seg.diagramSource = code;
+                    seg.html = highlightCode(code, rs.fenceLang);
                     seg.diagramLoading = true;
                     requestDiagram(rs.fenceLang, code, blockIndex);
-                }
 
                 // Replace the in-progress fence segment
                 if (!block.segments.isEmpty())
@@ -826,31 +748,22 @@ QString ChatBlockModel::diagramJpegHtml(const QByteArray &jpeg) const
 
 void ChatBlockModel::requestDiagram(const QString &lang, const QString &code, int blockIndex)
 {
-    const QString cacheKey = lang + QStringLiteral(":") +
+    const QString requestKey = lang + QStringLiteral(":") +
         QString::fromLatin1(QCryptographicHash::hash(
             code.toUtf8(), QCryptographicHash::Md5).toHex());
 
-    // Already have it cached?
-    if (m_diagramCache.contains(cacheKey))
+    // Track duplicate requests only while this local render is in flight.
+    if (!m_pendingDiagrams.contains(requestKey))
+        m_pendingDiagrams[requestKey] = QList<int>();
+    if (!m_pendingDiagrams[requestKey].contains(blockIndex))
+        m_pendingDiagrams[requestKey].append(blockIndex);
+    if (m_inFlightRequests.contains(requestKey))
         return;
 
-    // Track which blocks need this diagram
-    if (!m_pendingDiagrams.contains(cacheKey)) {
-        m_pendingDiagrams[cacheKey] = QList<int>();
-    }
-    if (!m_pendingDiagrams[cacheKey].contains(blockIndex)) {
-        m_pendingDiagrams[cacheKey].append(blockIndex);
-    }
+    m_inFlightRequests.insert(requestKey);
 
-    // Already requesting?
-    if (m_inFlightRequests.contains(cacheKey))
-        return;
-
-    m_inFlightRequests.insert(cacheKey);
-
-    // Build request
     QNetworkRequest request;
-    request.setAttribute(QNetworkRequest::User, cacheKey);
+    request.setAttribute(QNetworkRequest::User, requestKey);
     request.setTransferTimeout(10000);
 
     const QString langLower = lang.toLower();
@@ -867,7 +780,7 @@ void ChatBlockModel::requestDiagram(const QString &lang, const QString &code, in
         request.setUrl(QUrl(QStringLiteral("http://localhost:8081/img/") + QString::fromLatin1(encoded)));
         m_netManager->get(request);
     } else {
-        m_inFlightRequests.remove(cacheKey);
+        m_inFlightRequests.remove(requestKey);
         return;
     }
 }
@@ -906,21 +819,75 @@ void ChatBlockModel::onDiagramReply(QNetworkReply *reply)
         errorMsg = reply->errorString();
     }
 
-    // Update cache
     if (success) {
-        m_diagramCache[cacheKey] = imageData;
+        // Keep the result only on the waiting segments; do not cache diagrams.
     } else {
-        // Cache error as empty data with special marker
-        m_diagramCache[cacheKey] = QByteArray("ERROR:") + errorMsg.toUtf8();
+        // The error is applied directly to waiting segments below.
     }
 
-    // Rebuild all blocks waiting for this diagram
+    // Apply the response directly to waiting segments. Nothing is retained after
+    // this request completes; a later occurrence renders through the local server.
     const QList<int> blocks = m_pendingDiagrams.take(cacheKey);
     for (int blockIndex : blocks) {
-        if (blockIndex < m_blocks.size()) {
-            rebuildBlockHtml(blockIndex);
-            QModelIndex idx = index(blockIndex);
-            emit dataChanged(idx, idx, {RenderedHtmlRole, SegmentsRole});
+        if (blockIndex < 0 || blockIndex >= m_blocks.size())
+            continue;
+
+        ChatBlock &block = m_blocks[blockIndex];
+        BlockSegment *matchingSegment = nullptr;
+        for (BlockSegment &segment : block.segments) {
+            if (segment.type != BlockSegment::Diagram || !segment.diagramLoading)
+                continue;
+            const QString segmentKey = segment.diagramLang + QStringLiteral(":") +
+                QString::fromLatin1(QCryptographicHash::hash(
+                    segment.diagramSource.toUtf8(), QCryptographicHash::Md5).toHex());
+            if (segmentKey == cacheKey) {
+                matchingSegment = &segment;
+                break;
+            }
         }
+
+        // A block can be rebuilt while a request is in flight. In that case
+        // the segment still represents this request, but its source may have
+        // been normalized by the parser. Use the sole pending diagram rather
+        // than leaving the UI loading forever.
+        if (!matchingSegment) {
+            for (BlockSegment &segment : block.segments) {
+                if (segment.type == BlockSegment::Diagram && segment.diagramLoading) {
+                    if (matchingSegment) {
+                        matchingSegment = nullptr;
+                        break;
+                    }
+                    matchingSegment = &segment;
+                }
+            }
+        }
+
+        if (!matchingSegment)
+            continue;
+
+        BlockSegment &segment = *matchingSegment;
+        segment.diagramLoading = false;
+        if (!success) {
+            segment.diagramError = errorMsg;
+            segment.html = diagramErrorHtml(errorMsg);
+        } else if (imageData.startsWith("JPEG:")) {
+            const QByteArray data = imageData.mid(5);
+            segment.diagramSvg = QStringLiteral("data:image/jpeg;base64,") +
+                QString::fromLatin1(data.toBase64());
+            segment.html = diagramJpegHtml(data);
+        } else if (imageData.startsWith("PNG:")) {
+            const QByteArray data = imageData.mid(4);
+            segment.diagramSvg = QStringLiteral("data:image/png;base64,") +
+                QString::fromLatin1(data.toBase64());
+            segment.html = diagramPngHtml(data);
+        } else {
+            const QByteArray data = imageData.startsWith("SVG:") ? imageData.mid(4) : imageData;
+            segment.diagramSvg = QStringLiteral("data:image/svg+xml;base64,") +
+                QString::fromLatin1(data.toBase64());
+            segment.html = diagramSvgHtml(data);
+        }
+        rebuildRenderedHtmlFromSegments(block);
+        QModelIndex idx = index(blockIndex);
+        emit dataChanged(idx, idx, {RenderedHtmlRole, SegmentsRole});
     }
 }
diff --git a/kde/gui/chatblockmodel.h b/kde/gui/chatblockmodel.h
index 6a795e4..da75296 100644
--- a/kde/gui/chatblockmodel.h
+++ b/kde/gui/chatblockmodel.h
@@ -95,7 +95,6 @@ public:
     Q_INVOKABLE void appendData(const QString &text);
     Q_INVOKABLE void reset();
     Q_INVOKABLE void trimFront(int keepCount);
-    Q_INVOKABLE void clearDiagramCache();
 
 signals:
     void countChanged();
@@ -140,8 +139,6 @@ private:
     QString m_fenceLanguage;
     QString m_fenceContent;
 
-    // Diagram cache: hash of (lang + code) -> SVG data
-    QHash<QString, QByteArray> m_diagramCache;
     // Pending requests: hash -> block indices waiting for this diagram
     QHash<QString, QList<int>> m_pendingDiagrams;
     // Track which requests are in flight