fix(sessions): disable session conversion

- Mark derived sessions in session-detail responses for UI gating\n- Disable conversion for derived sessions across sources\n- Disable the conversion button in the sessions UI

Author: ymkiux

cli.js

@@ -6346,10 +6346,14 @@ function isDerivedSessionFile(filePath) {
     const metaPath = getDerivedSessionMetaPath(filePath);
     if (!metaPath) return false;
     try {
-        return fs.existsSync(metaPath);
+        if (fs.existsSync(metaPath)) {
+            return true;
+        }
     } catch (_) {
         return false;
     }
+    const base = path.basename(filePath || '', path.extname(filePath || ''));
+    return /-\d{8}-\d{6}-[0-9a-f]{6}$/i.test(base);
 }
 
 function resolveStateMaxMessages(state) {
@@ -6697,6 +6701,20 @@ async function readSessionDetail(params = {}) {
         sessionId,
         cwd: extracted.cwd || '',
         updatedAt: extracted.updatedAt || '',
+        derived: (() => {
+            try {
+                const metaPath = filePath.toLowerCase().endsWith('.jsonl')
+                    ? `${filePath.slice(0, -5)}.meta.json`
+                    : `${filePath}.meta.json`;
+                if (fs.existsSync(metaPath)) {
+                    return true;
+                }
+            } catch (_) {
+                return false;
+            }
+            const base = path.basename(filePath || '', path.extname(filePath || ''));
+            return /-\d{8}-\d{6}-[0-9a-f]{6}$/i.test(base);
+        })(),
         totalMessages: hasExactTotalMessages ? extracted.totalMessages : null,
         clipped: typeof extracted.clipped === 'boolean'
             ? extracted.clipped

tests/unit/web-ui-behavior-parity.test.mjs

@@ -487,6 +487,8 @@ test('captured bundled app skeleton only exposes expected data key drift versus
         'openClaudeMdEditor'
     ];
     allowedExtraCurrentMethodKeys.push(
+        'isDerivedSession',
+        'isDerivedSessionId',
         'resetConfigTemplateDiffState',
         'onConfigTemplateContentInput',
         'buildConfigTemplateDiffFingerprint',

web-ui/modules/app.methods.session-actions.mjs

@@ -10,6 +10,24 @@ export function createSessionActionMethods(options = {}) {
     } = options;
 
     return {
+        isDerivedSessionId(value) {
+            const sessionId = typeof value === 'string' ? value.trim() : String(value || '');
+            if (!sessionId) return false;
+            return /-\d{8}-\d{6}-[0-9a-f]{6}$/i.test(sessionId);
+        },
+
+        isDerivedSession(session) {
+            if (!session || typeof session !== 'object') return false;
+            if (session.derived === true) return true;
+            if (this.isDerivedSessionId(session.sessionId)) return true;
+            const rawFilePath = typeof session.filePath === 'string' ? session.filePath.trim() : '';
+            if (!rawFilePath) return false;
+            const normalized = rawFilePath.replace(/\\/g, '/');
+            if (normalized.includes('/.codexmate/sessions/derived/')) return true;
+            if (normalized.includes('/codexmate-derived/')) return true;
+            return false;
+        },
+
         getSessionStandaloneContext() {
             try {
                 const url = new URL(window.location.href);

web-ui/partials/index/panel-sessions.html

@@ -208,7 +208,7 @@
                                         <button
                                             class="btn-session-export"
                                             @click="convertSession(activeSession)"
-                                            :disabled="!activeSession || activeSession.derived || sessionConverting[getSessionExportKey(activeSession)] || (activeSession.source !== 'codex' && activeSession.source !== 'claude')">
+                                            :disabled="true">
                                             {{ (activeSession && sessionConverting[getSessionExportKey(activeSession)]) ? t('sessions.preview.converting') : t('sessions.preview.convert') }}
                                         </button>
                                         <button

web-ui/session-helpers.mjs

@@ -422,6 +422,9 @@ export async function loadActiveSessionDetail(api, options = {}) {
         if (res.sourceLabel) {
             this.activeSession.sourceLabel = res.sourceLabel;
         }
+        if (typeof res.derived === 'boolean') {
+            this.activeSession.derived = res.derived;
+        }
         if (res.sessionId) {
             this.activeSession.sessionId = res.sessionId;
             if (!this.activeSession.title) {