feat: session resume — detect leftover staging dirs and offer to resume analysis

- GET /api/v1/sessions scans tmp/ for session dirs with staged files
- Index page shows resumable sessions with filenames and sizes
- Resume button skips download and starts analysis with stored session_id
- session_id carried through analysis → confirm → job for correct file paths

backend/app.py

@@ -139,6 +139,44 @@ def storage_pools():
     return {"pools": result}
 
 
+@app.get(f"{API_PREFIX}/sessions")
+def list_sessions():
+    """Return existing session directories with staged files that can be resumed."""
+    tmp = Path("/mnt/converter/tmp") if Path("/mnt/converter/tmp").exists() else Path(__file__).resolve().parent.parent / "tmp"
+    sessions = []
+    try:
+        for entry in sorted(tmp.iterdir(), reverse=True):
+            if not entry.is_dir():
+                continue
+            in_dir = entry / "in"
+            if not in_dir.is_dir():
+                continue
+            session_files = []
+            total_bytes = 0
+            has_disks = False
+            for f in sorted(in_dir.iterdir()):
+                if f.is_file():
+                    sz = f.stat().st_size
+                    session_files.append({"name": f.name, "size_bytes": sz, "size_gb": round(sz / (1024**3), 1)})
+                    total_bytes += sz
+                elif f.is_dir():
+                    for df in f.rglob("*"):
+                        if df.is_file() and df.suffix.lower() in {".vmdk", ".qcow2", ".img", ".raw", ".vhd", ".vhdx"}:
+                            has_disks = True
+                            break
+            if not session_files:
+                continue
+            sessions.append({
+                "session_id": entry.name,
+                "files": session_files,
+                "total_size_gb": round(total_bytes / (1024**3), 1),
+                "has_disks": has_disks,
+            })
+    except Exception:
+        pass
+    return {"sessions": sessions}
+
+
 @app.post(f"{API_PREFIX}/analyze", response_model=AnalyzeStatusResponse, status_code=202)
 def analyze(req: AnalyzeRequest) -> AnalyzeStatusResponse:
     """Analyze a source file asynchronously: extraction + disk probing + OS detection."""

frontend/api_client.py

@@ -58,6 +58,10 @@ class ApiClient:
         """GET /api/v1/storage/pools — list available Proxmox storage pools."""
         return self._get("/api/v1/storage/pools")
 
+    def get_sessions(self) -> dict:
+        """GET /api/v1/sessions — list resumable staging sessions."""
+        return self._get("/api/v1/sessions")
+
     def create_job(self, payload: dict) -> dict:
         """POST /api/v1/jobs — submit conversion job."""
         return self._post("/api/v1/jobs", payload)

frontend/app.py

@@ -337,6 +337,15 @@ async def session_analyze_status(analysis_id: str):
         return JSONResponse({"error": exc.detail}, status_code=502)
 
 
+@app.get("/session/sessions")
+async def session_list():
+    """Proxy to backend to list resumable sessions."""
+    try:
+        return api.get_sessions()
+    except ApiError as exc:
+        return JSONResponse({"sessions": []})
+
+
 @app.get("/session/analyze/result/{analysis_id}", response_class=HTMLResponse)
 async def session_analyze_result(
     request: Request,
@@ -344,6 +353,7 @@ async def session_analyze_result(
     vmid: str = "",
     source_filename: str = "",
     vm_name: str = "",
+    session_id: str = "",
 ):
     """Render the analysis result after polling completes."""
     try:
@@ -370,7 +380,8 @@ async def session_analyze_result(
 
     return render("_analysis.html", request=request,
                   vmid=vmid, source_filename=source_filename,
-                  vm_name=name, analysis=analysis, storage_pools=pools)
+                  vm_name=name, analysis=analysis, storage_pools=pools,
+                  session_id=session_id)
 
 
 @app.post("/session/confirm", response_class=HTMLResponse)

frontend/templates/_analysis.html

@@ -31,6 +31,7 @@
     <input type="hidden" name="vmid" value="{{ vmid }}">
     <input type="hidden" name="source_filename" value="{{ source_filename }}">
     <input type="hidden" name="disk_format" value="{{ analysis.disk_format }}">
+    <input type="hidden" name="session_id" value="{{ session_id or '' }}">
 
     <div class="pve-row">
       <div class="pve-form-group">

frontend/templates/index.html

@@ -1,6 +1,14 @@
 {% extends "base.html" %}
 {% block content %}
 
+<div id="resume-sessions" class="pve-panel pve-hidden">
+  <div class="pve-panel-header">
+    <span class="pve-panel-title">Resume Previous Session</span>
+  </div>
+  <div class="pve-panel-body" id="resume-sessions-list">
+  </div>
+</div>
+
 <div class="pve-panel" id="step1">
   <div class="pve-panel-header">
     <span class="pve-panel-title">New Conversion Session</span>
@@ -53,6 +61,46 @@
 <div id="polling-section"></div>
 
 <script>
+loadSessions();
+
+async function loadSessions() {
+  try {
+    var resp = await fetch('/session/sessions');
+    var data = await resp.json();
+    var sessions = data.sessions || [];
+    if (!sessions.length) return;
+    var panel = document.getElementById('resume-sessions');
+    var list = document.getElementById('resume-sessions-list');
+    panel.classList.remove('pve-hidden');
+    var html = '';
+    for (var i = 0; i < sessions.length; i++) {
+      var s = sessions[i];
+      var fileNames = s.files.map(function(f) { return f.name; }).join(', ');
+      html += '<div style="display:flex;align-items:center;justify-content:space-between;padding:0.4rem 0;border-bottom:1px solid var(--pve-border);">';
+      html += '<div><span class="pve-code">' + s.session_id.substring(0, 8) + '</span> &mdash; ' + fileNames + ' <span class="pve-dim">(' + s.total_size_gb + ' GiB)</span>';
+      if (s.has_disks) html += ' <span class="pve-badge pve-badge-completed" style="font-size:0.65rem;">extracted</span>';
+      html += '</div>';
+      html += '<button class="pve-btn pve-btn-primary pve-btn-small" onclick="resumeSession(\'' + s.session_id + '\', \'' + fileNames.replace(/'/g, "\\'") + '\')">Resume</button>';
+      html += '</div>';
+    }
+    list.innerHTML = html;
+  } catch (_) {}
+}
+
+function resumeSession(sessionId, firstFile) {
+  var vmid = document.getElementById('vmid').value;
+  var vmName = document.getElementById('vm-name').value.trim();
+  if (!vmid) { alert('Please enter a VM ID first.'); return; }
+  window.RESUMED_SID = sessionId;
+  var ses = document.getElementById('resume-sessions');
+  ses.classList.add('pve-hidden');
+  document.getElementById('step1').style.display = 'none';
+  var status = document.getElementById('session-status');
+  status.classList.remove('pve-hidden');
+  setPhase('Analysing source image...', 0, true);
+  runAnalysis(vmid, firstFile, vmName, sessionId);
+}
+
 function setPhase(label, pct, isSpinner) {
   const el = document.getElementById('phase-label');
   const fill = document.getElementById('pve-progress-bar');
@@ -141,11 +189,11 @@ async function handleDownload(formData) {
   }
 }
 
-async function runAnalysis(vmid, filename, vmName) {
+async function runAnalysis(vmid, filename, vmName, sessionOverride) {
   setPhase('Step 2/2: Analysing source image...', 0, true);
   const fd = new FormData();
   fd.append('vmid', vmid); fd.append('filename', filename); fd.append('vm_name', vmName);
-  fd.append('session_id', window.VM_BENCH_SID || '');
+  fd.append('session_id', sessionOverride || window.VM_BENCH_SID || '');
   const resp = await fetch('/session/analyze', { method: 'POST', body: fd });
   const data = await resp.json();
 
@@ -175,7 +223,8 @@ async function runAnalysis(vmid, filename, vmName) {
 
       if (sdata.status === 'completed') {
         await sleep(500);
-        var rr = await fetch('/session/analyze/result/' + analysisId + '?source_filename=' + encodeURIComponent(filename) + '&vm_name=' + encodeURIComponent(vmName) + '&vmid=' + vmid);
+        var sid = window.RESUMED_SID || window.VM_BENCH_SID || '';
+        var rr = await fetch('/session/analyze/result/' + analysisId + '?source_filename=' + encodeURIComponent(filename) + '&vm_name=' + encodeURIComponent(vmName) + '&vmid=' + vmid + '&session_id=' + encodeURIComponent(sid));
         var html = await rr.text();
         document.getElementById('analysis-section').innerHTML = html;
         document.getElementById('session-status').classList.add('pve-hidden');
@@ -223,7 +272,8 @@ async function submitJob(e) {
   status.classList.remove('pve-hidden');
   status.innerHTML = '<div class="pve-spinner"></div> Submitting job...';
   const formData = new FormData(form);
-  formData.append('session_id', window.VM_BENCH_SID || '');
+  var sid = formData.get('session_id') || window.VM_BENCH_SID || '';
+  formData.set('session_id', sid);
   try {
     const resp = await fetch('/session/confirm', { method: 'POST', body: formData });
     const html = await resp.text();