feat: add immutable level template lifecycle

src/App.tsx

@@ -117,11 +117,48 @@ export function App() {
   }
 
   const reset = async () => {
-    if (!window.confirm('Reset the entire investigation board?')) return
+    if (!caseState?.sourceTemplateVersionId || !window.confirm('Reset this investigation to its original template version?')) return
     const response = await fetch(`/api/levels/${encodeURIComponent(caseState!.id)}/reset`, { method: 'POST' })
     if (response.ok) { const data = await response.json(); setCaseState(normalizeCase(data)); localStorage.removeItem('gupi-osint-board:last'); setSelected(null); setStatus('CASE RESET') }
   }
 
+  const saveAsTemplate = async () => {
+    if (!caseState || !requestedEditMode || !caseState.editingAllowed) return
+    const name = window.prompt('Template name:', caseState.title)?.trim()
+    if (!name) return
+    window.clearTimeout(saveTimer.current)
+    setStatus('FREEZING TEMPLATE VERSION…')
+    const saved = await fetch(`/api/levels/${encodeURIComponent(caseState.id)}?edit=1`, {
+      method: 'PUT', headers: { 'content-type': 'application/json' }, body: JSON.stringify(caseState),
+    })
+    if (!saved.ok) { setStatus('LEVEL SAVE FAILED'); return }
+    const response = await fetch(`/api/levels/${encodeURIComponent(caseState.id)}/templates?edit=1`, {
+      method: 'POST', headers: { 'content-type': 'application/json' }, body: JSON.stringify({ name }),
+    })
+    if (!response.ok) { setStatus('TEMPLATE SAVE FAILED'); return }
+    const template: { slug: string; currentVersion: number } = await response.json()
+    setStatus(`TEMPLATE ${template.slug.toUpperCase()} · VERSION ${template.currentVersion}`)
+  }
+
+  const instantiateTemplate = async () => {
+    if (!requestedEditMode || !caseState?.editingAllowed) return
+    const templatesResponse = await fetch('/api/templates')
+    if (!templatesResponse.ok) { setStatus('TEMPLATE ARCHIVE UNAVAILABLE'); return }
+    const templates: { slug: string; name: string; currentVersion: number }[] = await templatesResponse.json()
+    if (!templates.length) { setStatus('NO TEMPLATES SAVED'); return }
+    const templateSlug = window.prompt(`Template slug:\n${templates.map(item => `${item.slug} (v${item.currentVersion})`).join('\n')}`, templates[0].slug)?.trim()
+    if (!templateSlug) return
+    const title = window.prompt('Name the new investigation:', templates.find(item => item.slug === templateSlug)?.name || 'New Investigation')?.trim()
+    if (!title) return
+    setStatus('CLONING TEMPLATE…')
+    const response = await fetch(`/api/templates/${encodeURIComponent(templateSlug)}/levels?edit=1`, {
+      method: 'POST', headers: { 'content-type': 'application/json' }, body: JSON.stringify({ title }),
+    })
+    if (!response.ok) { setStatus('TEMPLATE CLONE FAILED'); return }
+    const level: CaseState = await response.json()
+    window.location.assign(`?level=${encodeURIComponent(level.id)}&edit=1`)
+  }
+
   const uploadFiles = async (files: FileList | File[]) => {
     if (!caseState || !requestedEditMode || !caseState.editingAllowed) return
     const queue = Array.from(files)
@@ -161,7 +198,7 @@ export function App() {
     <header className="menubar">
       <div className="brand"><span className="brand-mark">GU</span><span>OSINT BOARD <em>/ {requestedEditMode && caseState.editingAllowed ? 'LEVEL EDITOR' : 'CASE TERMINAL'}</em></span></div>
       <nav>
-        <button onClick={() => setDocsOpen(v => !v)}>FILE</button><button onClick={addNote}>EVIDENCE</button><button onClick={() => update(s => ({ ...s, viewport: { x: 0, y: 28, zoom: .7 } }))}>VIEW</button><button onClick={() => { const firstWidget = temporalItems.find(item => item.evidenceId); if (firstWidget?.evidenceId) focusEvidence(firstWidget.evidenceId) }}>TIMELINE</button><button onClick={() => setHelpOpen(true)}>HELP</button>
+        <button onClick={() => setDocsOpen(v => !v)}>FILE</button><button onClick={addNote}>EVIDENCE</button><button onClick={() => update(s => ({ ...s, viewport: { x: 0, y: 28, zoom: .7 } }))}>VIEW</button><button onClick={() => { const firstWidget = temporalItems.find(item => item.evidenceId); if (firstWidget?.evidenceId) focusEvidence(firstWidget.evidenceId) }}>TIMELINE</button>{requestedEditMode && caseState.editingAllowed && <><button onClick={saveAsTemplate}>SAVE TEMPLATE</button><button onClick={instantiateTemplate}>NEW FROM TEMPLATE</button></>}<button onClick={() => setHelpOpen(true)}>HELP</button>
       </nav>
       <div className="terminal-status"><i /> {status}<span>{clock}</span></div>
     </header>
@@ -194,7 +231,7 @@ export function App() {
           <button aria-label="Zoom out" onClick={() => update(s => ({ ...s, viewport: { ...s.viewport, zoom: clampBoardZoom(s.viewport.zoom - .1) } }))}><ZoomOut size={18}/></button>
           <b>{Math.round(caseState.viewport.zoom * 100)}%</b>
           <button aria-label="Zoom in" onClick={() => update(s => ({ ...s, viewport: { ...s.viewport, zoom: clampBoardZoom(s.viewport.zoom + .1) } }))}><ZoomIn size={18}/></button>
-          <button aria-label="Reset" onClick={reset}><RotateCcw size={17}/></button>
+          <button aria-label="Reset" title={caseState.sourceTemplateVersionId ? 'Reset to source template' : 'This level has no source template'} disabled={!caseState.sourceTemplateVersionId} onClick={reset}><RotateCcw size={17}/></button>
         </div>
         {draggingFiles && <div className="file-drop-overlay"><div><Upload size={28}/><b>ADD SOURCE DOCUMENTS</b><span>DROP FILES INTO THIS LEVEL</span></div></div>}
       </div>