feat: extend linux operations curriculum

index.html

@@ -94,6 +94,25 @@
     }
     .stat span { display: block; font-size: 12px; color: var(--muted); margin-bottom: 6px; }
     .stat strong { font-size: 22px; }
+    .mini-stats {
+      display: grid;
+      grid-template-columns: repeat(4, minmax(0, 1fr));
+      gap: 10px;
+      margin-top: 12px;
+    }
+    .mini-stat {
+      padding: 12px;
+      border: 1px solid var(--line);
+      border-radius: 16px;
+      background: rgba(255,255,255,0.2);
+    }
+    .mini-stat span {
+      display: block;
+      font-size: 12px;
+      color: var(--muted);
+      margin-bottom: 6px;
+    }
+    .mini-stat strong { font-size: 20px; }
     .search {
       display: flex;
       gap: 8px;
@@ -231,16 +250,90 @@
     .feedback.show { display: block; }
     .feedback.success { background: rgba(29,155,108,0.1); border: 1px solid rgba(29,155,108,0.22); color: #187653; }
     .feedback.warn { background: rgba(240,180,41,0.1); border: 1px solid rgba(240,180,41,0.24); color: #a26b04; }
+    .mastery-note {
+      margin-top: 12px;
+      padding: 12px 14px;
+      border-radius: 14px;
+      border: 1px solid var(--line);
+      background: rgba(255,255,255,0.18);
+      color: var(--muted);
+      line-height: 1.8;
+    }
+    .diagnostic {
+      padding: 12px 14px;
+      border: 1px solid var(--line);
+      border-radius: 16px;
+      background: rgba(255,255,255,0.18);
+      color: var(--muted);
+      line-height: 1.8;
+    }
+    .module-summary-grid {
+      display: grid;
+      grid-template-columns: repeat(2, minmax(0, 1fr));
+      gap: 12px;
+      margin-top: 14px;
+    }
+    .module-summary-card {
+      padding: 14px;
+      border: 1px solid var(--line);
+      border-radius: 18px;
+      background: rgba(255,255,255,0.18);
+    }
+    .module-summary-card h4 {
+      margin: 0 0 8px;
+      font-size: 16px;
+    }
+    .module-summary-card p {
+      margin: 0 0 8px;
+      color: var(--muted);
+      line-height: 1.7;
+    }
+    .stage-grid {
+      display: grid;
+      grid-template-columns: repeat(4, minmax(0, 1fr));
+      gap: 12px;
+      margin-top: 14px;
+    }
+    .stage-card {
+      padding: 14px;
+      border: 1px solid var(--line);
+      border-radius: 18px;
+      background: rgba(255,255,255,0.18);
+    }
+    .stage-card h4 {
+      margin: 0 0 8px;
+      font-size: 16px;
+    }
+    .stage-card p {
+      margin: 0 0 8px;
+      color: var(--muted);
+      line-height: 1.7;
+    }
+    .lesson-btn.done {
+      border-color: rgba(29, 155, 108, 0.4);
+      background: rgba(29, 155, 108, 0.1);
+    }
+    .ordered {
+      margin: 0;
+      padding-left: 18px;
+      color: var(--muted);
+      line-height: 1.9;
+    }
     .empty { padding: 12px; border: 1px dashed var(--line); border-radius: 14px; color: var(--muted); text-align: center; }
     @media (max-width: 1180px) {
       .layout { grid-template-columns: 1fr; }
       .sidebar { position: static; }
       .hero-grid, .detail-grid { grid-template-columns: 1fr; }
+      .mini-stats { grid-template-columns: repeat(2, minmax(0, 1fr)); }
+      .module-summary-grid { grid-template-columns: 1fr; }
+      .stage-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
     }
     @media (max-width: 720px) {
       .shell { padding: 14px; }
       .topbar, .hero-head, .search, .terminal-input { flex-direction: column; align-items: stretch; }
       .stats { grid-template-columns: 1fr; }
+      .mini-stats { grid-template-columns: 1fr; }
+      .stage-grid { grid-template-columns: 1fr; }
     }
   </style>
 </head>
@@ -270,6 +363,8 @@
             <div class="stat"><span>Lessons</span><strong id="lessonCount">0</strong></div>
             <div class="stat"><span>Exercises</span><strong id="exerciseCount">0</strong></div>
             <div class="stat"><span>Commands</span><strong id="commandCount">0</strong></div>
+            <div class="stat"><span>Mastered</span><strong id="masteredCount">0</strong></div>
+            <div class="stat"><span>Completion</span><strong id="completionRate">0%</strong></div>
           </div>
           <div class="chip-list" id="commandTags"></div>
           <p class="muted" id="metaLine" style="margin-top: 12px;">Version --</p>
@@ -290,6 +385,18 @@
           <h2>Course map</h2>
           <div class="modules" id="moduleList"><div class="empty">Loading modules...</div></div>
         </section>
+
+        <section class="section">
+          <div class="eyebrow">Diagnostics</div>
+          <h2>Course coverage check</h2>
+          <div class="mini-stats">
+            <div class="mini-stat"><span>Coverage</span><strong id="coverageRate">0%</strong></div>
+            <div class="mini-stat"><span>Operations</span><strong id="operationCount">0</strong></div>
+            <div class="mini-stat"><span>Reflection</span><strong id="reflectionCount">0</strong></div>
+            <div class="mini-stat"><span>Unsupported</span><strong id="unsupportedCount">0</strong></div>
+          </div>
+          <div class="diagnostic" id="diagnosticNote" style="margin-top: 12px;">Checking course and sandbox alignment...</div>
+        </section>
       </aside>
 
       <main class="main">
@@ -301,6 +408,7 @@
               <p class="muted" id="lessonGoal">Choose a lesson from the left to see goals, examples, common pitfalls, and runnable exercises.</p>
             </div>
             <div class="actions">
+              <button class="btn-soft" type="button" id="masteryBtn">Mark mastered</button>
               <button class="btn-ghost" type="button" id="prevBtn">Previous</button>
               <button class="btn" type="button" id="nextBtn">Next</button>
             </div>
@@ -320,6 +428,45 @@
               </ul>
             </div>
           </div>
+          <div class="mastery-note" id="masteryNote">Master a lesson after you can explain the command, predict the output, and connect it to a real operations step.</div>
+        </section>
+
+        <section class="detail card">
+          <div class="eyebrow">Learning stages</div>
+          <h2 style="margin: 8px 0 0;">System route from Linux basics to operations habits</h2>
+          <p class="muted">This view helps you study in phases instead of bouncing between unrelated commands.</p>
+          <div class="stage-grid" id="stageGrid"></div>
+        </section>
+
+        <section class="detail card">
+          <div class="eyebrow">Module heatmap</div>
+          <h2 style="margin: 8px 0 0;">See how the learning path is distributed</h2>
+          <p class="muted">This panel helps you check whether the project really teaches both command basics and operations workflows.</p>
+          <div class="module-summary-grid" id="moduleSummaryGrid"></div>
+        </section>
+
+        <section class="detail card">
+          <div class="eyebrow">Learning cockpit</div>
+          <h2 style="margin: 8px 0 0;">Visual study map for the current lesson</h2>
+          <p class="muted">These cards help you move from memorizing a command to understanding the workflow around it.</p>
+          <div class="detail-grid" style="margin-top: 16px;">
+            <article class="panel">
+              <h3>Lesson radar</h3>
+              <div class="mini-stats" id="lessonRadar"></div>
+            </article>
+            <article class="panel">
+              <h3>Experiment ladder</h3>
+              <ol class="ordered" id="experimentList"></ol>
+            </article>
+            <article class="panel">
+              <h3>Observation checklist</h3>
+              <ul id="observationList"></ul>
+            </article>
+            <article class="panel">
+              <h3>Related commands</h3>
+              <div class="chip-list" id="relatedCommandList"></div>
+            </article>
+          </div>
         </section>
 
         <section class="detail card">
@@ -371,7 +518,12 @@
   </div>
 
   <script>
-    const state = { overview: null, lesson: null, theme: localStorage.getItem('linux_lab_theme') || 'light' };
+    const state = {
+      overview: null,
+      lesson: null,
+      theme: localStorage.getItem('linux_lab_theme') || 'light',
+      progress: JSON.parse(localStorage.getItem('linux_lab_progress') || '{}')
+    };
 
     document.addEventListener('DOMContentLoaded', async () => {
       setTheme(state.theme);
@@ -385,9 +537,37 @@
       document.getElementById('nextBtn').addEventListener('click', () => {
         if (state.lesson?.next_lesson) openLesson(state.lesson.next_lesson.id);
       });
+      document.getElementById('masteryBtn').addEventListener('click', toggleMastery);
       await loadOverview();
     });
 
+    function saveProgress() {
+      localStorage.setItem('linux_lab_progress', JSON.stringify(state.progress));
+    }
+
+    function masteredCount() {
+      return Object.values(state.progress).filter(Boolean).length;
+    }
+
+    function isMastered(lessonId) {
+      return Boolean(state.progress[lessonId]);
+    }
+
+    function completionRate() {
+      const total = state.overview?.meta?.lesson_count || 0;
+      if (!total) return 0;
+      return Math.round((masteredCount() / total) * 100);
+    }
+
+    function toggleMastery() {
+      if (!state.lesson?.id) return;
+      state.progress[state.lesson.id] = !state.progress[state.lesson.id];
+      saveProgress();
+      renderOverview();
+      renderModules();
+      renderLesson();
+    }
+
     async function loadOverview() {
       const response = await fetch('/api/overview');
       state.overview = await response.json();
@@ -404,10 +584,21 @@
       document.getElementById('lessonCount').textContent = meta.lesson_count || 0;
       document.getElementById('exerciseCount').textContent = meta.exercise_count || 0;
       document.getElementById('commandCount').textContent = meta.command_count || 0;
+      document.getElementById('masteredCount').textContent = masteredCount();
+      document.getElementById('completionRate').textContent = completionRate() + '%';
+      document.getElementById('coverageRate').textContent = (state.overview.diagnostics?.coverage_rate ?? 0) + '%';
+      document.getElementById('operationCount').textContent = state.overview.diagnostics?.operation_exercises ?? 0;
+      document.getElementById('reflectionCount').textContent = state.overview.diagnostics?.reflection_exercises ?? 0;
+      document.getElementById('unsupportedCount').textContent = state.overview.diagnostics?.unsupported_count ?? 0;
+      document.getElementById('diagnosticNote').textContent = (state.overview.diagnostics?.unsupported_count ?? 0) === 0
+        ? 'All commands referenced by the course are covered by the sandbox command set.'
+        : 'Some course commands are not fully supported by the sandbox yet.';
       document.getElementById('metaLine').textContent = `Version ${meta.version || '4.0'} | Updated ${meta.updated || '--'}`;
       renderRuntime(state.overview.runtime || {});
       renderCommandTags(state.overview.commands || []);
       renderModules();
+      renderStageGrid();
+      renderModuleSummaryGrid();
     }
 
     function renderRuntime(runtime) {
@@ -437,8 +628,8 @@
           <p>${escapeHtml(module.display_summary)}</p>
           <div class="lesson-list">
             ${(module.lessons || []).map((lesson) => `
-              <button class="lesson-btn ${state.lesson?.id === lesson.id ? 'active' : ''}" type="button" onclick="openLesson('${lesson.id}')">
-                <strong>${escapeHtml(lesson.display_title)}</strong>
+              <button class="lesson-btn ${state.lesson?.id === lesson.id ? 'active' : ''} ${isMastered(lesson.id) ? 'done' : ''}" type="button" onclick="openLesson('${lesson.id}')">
+                <strong>${isMastered(lesson.id) ? 'Completed - ' : ''}${escapeHtml(lesson.display_title)}</strong>
                 <span class="muted">${escapeHtml((lesson.command_tokens || []).join(' | ') || lesson.command || 'mixed commands')} | ${lesson.exercise_count || 0} exercises</span>
               </button>
             `).join('')}
@@ -447,6 +638,55 @@
       `).join('');
     }
 
+    function renderModuleSummaryGrid() {
+      const modules = state.overview.modules || [];
+      const target = document.getElementById('moduleSummaryGrid');
+      if (!modules.length) {
+        target.innerHTML = '<div class="empty">No module diagnostics found.</div>';
+        return;
+      }
+      target.innerHTML = modules.map((module) => `
+        <article class="module-summary-card">
+          <h4>${escapeHtml(module.display_title)}</h4>
+          <p>${escapeHtml(module.display_summary)}</p>
+          <div class="mini-stats">
+            <div class="mini-stat"><span>Lessons</span><strong>${module.lesson_count || 0}</strong></div>
+            <div class="mini-stat"><span>Exercises</span><strong>${module.exercise_count || 0}</strong></div>
+            <div class="mini-stat"><span>Ops</span><strong>${module.operation_count || 0}</strong></div>
+            <div class="mini-stat"><span>Commands</span><strong>${module.command_count || 0}</strong></div>
+          </div>
+        </article>
+      `).join('');
+    }
+
+    function renderStageGrid() {
+      const groups = [
+        { title: 'Stage 1: Foundations', summary: 'Orientation, listing, file operations, and permissions.', range: [0, 1] },
+        { title: 'Stage 2: Search & Observation', summary: 'Text search, log preview, process, service, and network inspection.', range: [2, 3] },
+        { title: 'Stage 3: Incidents', summary: 'Disk, auth, and service-path drills that connect commands into playbooks.', range: [4, 4] },
+        { title: 'Stage 4: Automation & Platform', summary: 'Shell state, package tools, archives, monitoring, and scheduling.', range: [5, 7] }
+      ];
+      const modules = state.overview.modules || [];
+      const target = document.getElementById('stageGrid');
+      target.innerHTML = groups.map((group) => {
+        const selectedModules = modules.slice(group.range[0], group.range[1] + 1);
+        const lessonTotal = selectedModules.reduce((sum, item) => sum + (item.lesson_count || 0), 0);
+        const exerciseTotal = selectedModules.reduce((sum, item) => sum + (item.exercise_count || 0), 0);
+        return `
+          <article class="stage-card">
+            <h4>${escapeHtml(group.title)}</h4>
+            <p>${escapeHtml(group.summary)}</p>
+            <div class="mini-stats">
+              <div class="mini-stat"><span>Modules</span><strong>${selectedModules.length}</strong></div>
+              <div class="mini-stat"><span>Lessons</span><strong>${lessonTotal}</strong></div>
+              <div class="mini-stat"><span>Exercises</span><strong>${exerciseTotal}</strong></div>
+              <div class="mini-stat"><span>Mastered</span><strong>${selectedModules.reduce((sum, item) => sum + (item.lessons || []).filter((lesson) => isMastered(lesson.id)).length, 0)}</strong></div>
+            </div>
+          </article>
+        `;
+      }).join('');
+    }
+
     async function openLesson(lessonId, focusExerciseId = '') {
       const response = await fetch('/api/lesson?id=' + encodeURIComponent(lessonId));
       const payload = await response.json();
@@ -470,9 +710,14 @@
       document.getElementById('lessonWhy').textContent = lesson.display_why || '';
       document.getElementById('classicView').textContent = lesson.classic_view || '';
       document.getElementById('afterClass').textContent = lesson.after_class || '';
+      document.getElementById('masteryBtn').textContent = isMastered(lesson.id) ? 'Mark for review' : 'Mark mastered';
+      document.getElementById('masteryNote').textContent = isMastered(lesson.id)
+        ? 'This lesson is marked as mastered. Revisit it if you cannot explain the command chain from memory.'
+        : 'Mark a lesson as mastered after you can explain the command, predict the output, and choose the next troubleshooting step.';
       document.getElementById('prevBtn').disabled = !lesson.previous_lesson;
       document.getElementById('nextBtn').disabled = !lesson.next_lesson;
       document.getElementById('lessonCommands').innerHTML = (lesson.command_tokens || [lesson.command || 'mixed commands']).map((item) => `<span class="chip">${escapeHtml(item)}</span>`).join('');
+      renderLessonCockpit(lesson);
       renderList('conceptList', lesson.concepts, 'No concept notes yet.');
       renderList('scenarioList', lesson.scenarios, 'No scenario notes yet.');
       renderList('pitfallList', lesson.pitfalls, 'No pitfall notes yet.');
@@ -483,6 +728,40 @@
       renderExercises(lesson.exercises || []);
     }
 
+    function renderLessonCockpit(lesson) {
+      document.getElementById('lessonRadar').innerHTML = [
+        { label: 'Commands', value: lesson.command_tokens?.length || 1 },
+        { label: 'Exercises', value: lesson.exercise_count || 0 },
+        { label: 'Pitfalls', value: lesson.pitfalls?.length || 0 },
+        { label: 'Related', value: lesson.related_commands?.length || 0 }
+      ].map((item) => `
+        <div class="mini-stat">
+          <span>${escapeHtml(item.label)}</span>
+          <strong>${item.value}</strong>
+        </div>
+      `).join('');
+
+      const experimentSteps = [
+        `Confirm the goal: ${lesson.display_goal || 'Understand the command objective.'}`,
+        `Run ${lesson.command || 'the main command'} and inspect the immediate output.`,
+        `Compare the output with one example or scenario from this lesson.`,
+        `Choose the next troubleshooting step based on what the command revealed.`
+      ];
+      document.getElementById('experimentList').innerHTML = experimentSteps.map((item) => `<li>${escapeHtml(item)}</li>`).join('');
+
+      const observationItems = [
+        `Before running: confirm the current context and target path.`,
+        `During output review: look for the field or line that answers the lesson goal.`,
+        `After running: explain what should happen next in a real operations flow.`
+      ];
+      document.getElementById('observationList').innerHTML = observationItems.map((item) => `<li>${escapeHtml(item)}</li>`).join('');
+
+      const related = lesson.related_commands || [];
+      document.getElementById('relatedCommandList').innerHTML = related.length
+        ? related.map((item) => `<span class="chip">${escapeHtml(item)}</span>`).join('')
+        : '<span class="chip">No related commands yet</span>';
+    }
+
     function renderList(id, items, emptyText) {
       const target = document.getElementById(id);
       target.innerHTML = (items && items.length) ? items.map((item) => `<li>${escapeHtml(item)}</li>`).join('') : `<li>${escapeHtml(emptyText)}</li>`;

sandbox.py

@@ -75,6 +75,17 @@ COMMAND_INDEX = {
     "python3": "/usr/bin/python3",
 }
 
+SUPPORTED_COMMANDS = {
+    "alias", "apt", "awk", "bash", "bc", "cat", "cd", "chmod", "chgrp", "chown",
+    "clear", "cp", "crontab", "curl", "cut", "date", "df", "dig", "du", "echo",
+    "env", "export", "fdisk", "find", "free", "grep", "head", "history", "id",
+    "ifconfig", "ip", "journalctl", "kill", "last", "less", "ls", "lsof", "mkdir",
+    "more", "mount", "mv", "netstat", "nohup", "passwd", "ping", "pkill", "ps",
+    "pwd", "rm", "sed", "service", "sort", "ss", "stat", "su", "systemctl", "tail",
+    "tar", "top", "touch", "traceroute", "uniq", "uptime", "vi", "vim", "w",
+    "wc", "wget", "whereis", "which", "yum"
+}
+
 
 class LinuxSandbox:
     def __init__(self):
@@ -121,6 +132,9 @@ class LinuxSandbox:
         node = self.get_node(self.resolve_path(path))
         return bool(node and len(node.get("perm", "")) >= 3 and node["perm"][2] == "1" or node and "x" in node.get("perm_human", ""))
 
+    def supported_commands(self) -> set[str]:
+        return set(SUPPORTED_COMMANDS)
+
     def _perm_human(self, perm: str, is_dir: bool) -> str:
         mapping = {
             "0": "---", "1": "--x", "2": "-w-", "3": "-wx",

server.py

@@ -28,6 +28,7 @@ PUBLIC_GET_PATHS = {
     "/privacy.html",
     "/api/course",
     "/api/course/search",
+    "/api/diagnostics",
     "/api/health",
     "/api/lesson",
     "/api/overview",
@@ -243,16 +244,80 @@ def build_lesson_preview(module: dict[str, Any], lesson: dict[str, Any]) -> dict
 
 def build_module_preview(module: dict[str, Any]) -> dict[str, Any]:
     lessons = [build_lesson_preview(module, lesson) for lesson in module.get("lessons", [])]
+    exercises = [exercise for lesson in module.get("lessons", []) for exercise in lesson.get("exercises", [])]
+    operations = [exercise for exercise in exercises if exercise.get("type") == "operation"]
+    reflections = [exercise for exercise in exercises if exercise.get("type") != "operation"]
+    commands = sorted(
+        {
+            command
+            for lesson in module.get("lessons", [])
+            for command in split_commands(lesson.get("command"), lesson.get("id"))
+            if command
+        }
+    )
     return {
         "id": module.get("id"),
         "display_title": module_title(module),
         "display_summary": module_summary(module),
         "lesson_count": len(module.get("lessons", [])),
-        "exercise_count": sum(len(lesson.get("exercises", [])) for lesson in module.get("lessons", [])),
+        "exercise_count": len(exercises),
+        "operation_count": len(operations),
+        "reflection_count": len(reflections),
+        "command_count": len(commands),
+        "command_tokens": commands,
         "lessons": lessons,
     }
 
 
+def extract_solution_commands() -> list[str]:
+    commands: list[str] = []
+    for module in COURSE.get("modules", []):
+        for lesson in module.get("lessons", []):
+            for exercise in lesson.get("exercises", []):
+                for solution in exercise.get("solution", []):
+                    for segment in str(solution).split("|"):
+                        head = segment.strip().split(" ")[0].strip()
+                        if head:
+                            commands.append(head)
+    return commands
+
+
+def build_diagnostics() -> dict[str, Any]:
+    lessons = flatten_lessons()
+    course_commands = sorted(
+        {
+            command
+            for lesson in lessons
+            for command in split_commands(lesson.get("command"), lesson.get("id"))
+            if command
+        }
+    )
+    solution_commands = sorted(set(extract_solution_commands()))
+    required_commands = sorted(set(course_commands) | set(solution_commands))
+    supported_commands = sorted(SANDBOX.supported_commands())
+    unsupported_commands = [command for command in required_commands if command not in SANDBOX.supported_commands()]
+    total_exercises = sum(len(lesson.get("exercises", [])) for lesson in lessons)
+    operation_exercises = sum(
+        1
+        for lesson in lessons
+        for exercise in lesson.get("exercises", [])
+        if exercise.get("type") == "operation"
+    )
+    reflection_exercises = total_exercises - operation_exercises
+
+    return {
+        "supported_command_count": len(supported_commands),
+        "required_command_count": len(required_commands),
+        "covered_command_count": len(required_commands) - len(unsupported_commands),
+        "coverage_rate": 100 if not required_commands else round(((len(required_commands) - len(unsupported_commands)) / len(required_commands)) * 100)),
+        "unsupported_commands": unsupported_commands,
+        "course_commands": required_commands,
+        "operation_exercises": operation_exercises,
+        "reflection_exercises": reflection_exercises,
+        "module_checks": [build_module_preview(module) for module in COURSE.get("modules", [])],
+    }
+
+
 def build_exercise(exercise: dict[str, Any], lesson_stub: dict[str, Any]) -> dict[str, Any]:
     commands = split_commands(lesson_stub.get("command"), lesson_stub.get("id"))
     label = command_label(commands)
@@ -343,6 +408,7 @@ def build_overview() -> dict[str, Any]:
     )
     exercise_count = sum(len(lesson.get("exercises", [])) for lesson in lessons)
     meta = COURSE.get("meta", {})
+    diagnostics = build_diagnostics()
 
     return {
         "meta": {
@@ -362,6 +428,12 @@ def build_overview() -> dict[str, Any]:
             "cwd": SANDBOX.cwd,
             "user": SANDBOX.user,
         },
+        "diagnostics": {
+            "coverage_rate": diagnostics["coverage_rate"],
+            "unsupported_count": len(diagnostics["unsupported_commands"]),
+            "operation_exercises": diagnostics["operation_exercises"],
+            "reflection_exercises": diagnostics["reflection_exercises"],
+        },
         "modules": modules,
         "commands": commands[:24],
     }
@@ -531,6 +603,7 @@ class LinuxLearningHandler(http.server.BaseHTTPRequestHandler):
                     "module_count": overview["meta"]["module_count"],
                     "lesson_count": overview["meta"]["lesson_count"],
                     "exercise_count": overview["meta"]["exercise_count"],
+                    "coverage_rate": overview["diagnostics"]["coverage_rate"],
                 }
             )
             return
@@ -543,6 +616,10 @@ class LinuxLearningHandler(http.server.BaseHTTPRequestHandler):
             self.send_json(build_overview())
             return
 
+        if path == "/api/diagnostics":
+            self.send_json(build_diagnostics())
+            return
+
         if path == "/api/lesson":
             lesson_id = urllib.parse.parse_qs(parsed.query).get("id", [""])[0]
             if not lesson_id: