diff --git a/agent/knowledge/service.py b/agent/knowledge/service.py
index a4fc3d6b..a9425385 100644
--- a/agent/knowledge/service.py
+++ b/agent/knowledge/service.py
@@ -34,7 +34,8 @@ class KnowledgeService:
     # ------------------------------------------------------------------
     def list_tree(self) -> dict:
         """
-        Return the knowledge directory tree grouped by category.
+        Return the knowledge directory tree grouped by category,
+        supporting arbitrarily nested sub-directories.
 
         Returns::
 
@@ -44,10 +45,20 @@ class KnowledgeService:
                         "dir": "concepts",
                         "files": [
                             {"name": "moe.md", "title": "MoE", "size": 1234},
-                            ...
+                        ],
+                        "children": []
+                    },
+                    {
+                        "dir": "platform",
+                        "files": [],
+                        "children": [
+                            {
+                                "dir": "analysis",
+                                "files": [{"name": "perf.md", ...}],
+                                "children": []
+                            }
                         ]
                     },
-                    ...
                 ],
                 "stats": {"pages": 15, "size": 32768},
                 "enabled": true
@@ -56,37 +67,43 @@ class KnowledgeService:
         if not os.path.isdir(self.knowledge_dir):
             return {"tree": [], "stats": {"pages": 0, "size": 0}, "enabled": conf().get("knowledge", True)}
 
-        tree = []
-        total_files = 0
-        total_bytes = 0
-        for name in sorted(os.listdir(self.knowledge_dir)):
-            full = os.path.join(self.knowledge_dir, name)
-            if not os.path.isdir(full) or name.startswith("."):
-                continue
-            files = []
-            for fname in sorted(os.listdir(full)):
-                if fname.endswith(".md") and not fname.startswith("."):
-                    fpath = os.path.join(full, fname)
-                    size = os.path.getsize(fpath)
-                    total_files += 1
-                    total_bytes += size
-                    title = fname.replace(".md", "")
-                    try:
-                        with open(fpath, "r", encoding="utf-8") as f:
-                            first_line = f.readline().strip()
-                        if first_line.startswith("# "):
-                            title = first_line[2:].strip()
-                    except Exception:
-                        pass
-                    files.append({"name": fname, "title": title, "size": size})
-            tree.append({"dir": name, "files": files})
+        stats = {"pages": 0, "size": 0}
+        tree = self._scan_dir(self.knowledge_dir, stats)
 
         return {
             "tree": tree,
-            "stats": {"pages": total_files, "size": total_bytes},
+            "stats": stats,
             "enabled": conf().get("knowledge", True),
         }
 
+    def _scan_dir(self, dir_path: str, stats: dict) -> list:
+        """Recursively scan a directory and return list of group nodes."""
+        result = []
+        for name in sorted(os.listdir(dir_path)):
+            if name.startswith("."):
+                continue
+            full = os.path.join(dir_path, name)
+            if os.path.isdir(full):
+                files = []
+                for fname in sorted(os.listdir(full)):
+                    fpath = os.path.join(full, fname)
+                    if os.path.isfile(fpath) and fname.endswith(".md") and not fname.startswith("."):
+                        size = os.path.getsize(fpath)
+                        stats["pages"] += 1
+                        stats["size"] += size
+                        title = fname.replace(".md", "")
+                        try:
+                            with open(fpath, "r", encoding="utf-8") as f:
+                                first_line = f.readline().strip()
+                            if first_line.startswith("# "):
+                                title = first_line[2:].strip()
+                        except Exception:
+                            pass
+                        files.append({"name": fname, "title": title, "size": size})
+                children = self._scan_dir(full, stats)
+                result.append({"dir": name, "files": files, "children": children})
+        return result
+
     # ------------------------------------------------------------------
     # read — single file content
     # ------------------------------------------------------------------
diff --git a/channel/web/static/css/console.css b/channel/web/static/css/console.css
index 2cf47449..7f8b594c 100644
--- a/channel/web/static/css/console.css
+++ b/channel/web/static/css/console.css
@@ -952,13 +952,13 @@
     font-size: 8px;
     transition: transform 0.15s;
 }
-.knowledge-tree-group.open .chevron {
+.knowledge-tree-group.open > .knowledge-tree-group-btn .chevron {
     transform: rotate(90deg);
 }
 .knowledge-tree-group-items {
     display: none;
 }
-.knowledge-tree-group.open .knowledge-tree-group-items {
+.knowledge-tree-group.open > .knowledge-tree-group-items {
     display: block;
 }
 
diff --git a/channel/web/static/js/console.js b/channel/web/static/js/console.js
index 8ec9e469..61cf9bda 100644
--- a/channel/web/static/js/console.js
+++ b/channel/web/static/js/console.js
@@ -3620,19 +3620,28 @@ function renderKnowledgeTree(tree, filter) {
     const container = document.getElementById('knowledge-tree');
     container.innerHTML = '';
     const lowerFilter = (filter || '').toLowerCase();
+    _renderKnowledgeGroups(container, tree, '', lowerFilter, 0);
+}
 
-    tree.forEach(group => {
-        const files = group.files.filter(f =>
+function _renderKnowledgeGroups(container, groups, parentPath, lowerFilter, depth) {
+    const indent = depth * 12;
+    groups.forEach(group => {
+        const groupPath = parentPath ? parentPath + '/' + group.dir : group.dir;
+        const files = (group.files || []).filter(f =>
             !lowerFilter || f.title.toLowerCase().includes(lowerFilter) || f.name.toLowerCase().includes(lowerFilter)
         );
-        if (files.length === 0 && lowerFilter) return;
+        const children = group.children || [];
+        const hasMatchingChildren = lowerFilter ? _hasFilterMatch(children, lowerFilter) : children.length > 0;
+        if (files.length === 0 && !hasMatchingChildren && lowerFilter) return;
 
         const div = document.createElement('div');
         div.className = 'knowledge-tree-group open';
 
+        const fileCount = _countFiles(group);
         const btn = document.createElement('button');
         btn.className = 'knowledge-tree-group-btn';
-        btn.innerHTML = `<i class="fas fa-chevron-right chevron"></i><i class="fas fa-folder text-amber-400 text-[11px]"></i><span>${escapeHtml(group.dir)}</span><span class="ml-auto text-[10px] text-slate-400">${files.length}</span>`;
+        btn.style.paddingLeft = (8 + indent) + 'px';
+        btn.innerHTML = `<i class="fas fa-chevron-right chevron"></i><i class="fas fa-folder text-amber-400 text-[11px]"></i><span>${escapeHtml(group.dir)}</span><span class="ml-auto text-[10px] text-slate-400">${fileCount}</span>`;
         btn.onclick = () => div.classList.toggle('open');
         div.appendChild(btn);
 
@@ -3640,18 +3649,40 @@ function renderKnowledgeTree(tree, filter) {
         items.className = 'knowledge-tree-group-items';
         files.forEach(f => {
             const fbtn = document.createElement('button');
-            const fpath = group.dir + '/' + f.name;
+            const fpath = groupPath + '/' + f.name;
             fbtn.className = 'knowledge-tree-file' + (_knowledgeCurrentFile === fpath ? ' active' : '');
             fbtn.dataset.path = fpath;
+            fbtn.style.paddingLeft = (24 + indent) + 'px';
             fbtn.innerHTML = `<i class="fas fa-file-lines text-[10px] text-slate-400"></i><span class="truncate">${escapeHtml(f.title)}</span>`;
             fbtn.onclick = () => openKnowledgeFile(fpath, f.title);
             items.appendChild(fbtn);
         });
+        if (children.length > 0) {
+            _renderKnowledgeGroups(items, children, groupPath, lowerFilter, depth + 1);
+        }
         div.appendChild(items);
         container.appendChild(div);
     });
 }
 
+function _hasFilterMatch(groups, lowerFilter) {
+    for (const g of groups) {
+        for (const f of (g.files || [])) {
+            if (f.title.toLowerCase().includes(lowerFilter) || f.name.toLowerCase().includes(lowerFilter)) return true;
+        }
+        if (_hasFilterMatch(g.children || [], lowerFilter)) return true;
+    }
+    return false;
+}
+
+function _countFiles(group) {
+    let count = (group.files || []).length;
+    for (const child of (group.children || [])) {
+        count += _countFiles(child);
+    }
+    return count;
+}
+
 function filterKnowledgeTree(query) {
     renderKnowledgeTree(_knowledgeTreeData, query);
 }
@@ -3732,12 +3763,19 @@ function bindChatKnowledgeLinks(container) {
 }
 
 function _findKnowledgeFileByName(filename) {
-    for (const group of _knowledgeTreeData) {
-        for (const f of group.files) {
+    return _searchFileInGroups(_knowledgeTreeData, '', filename);
+}
+
+function _searchFileInGroups(groups, parentPath, filename) {
+    for (const group of groups) {
+        const groupPath = parentPath ? parentPath + '/' + group.dir : group.dir;
+        for (const f of (group.files || [])) {
             if (f.name === filename) {
-                return { path: group.dir + '/' + f.name, title: f.title };
+                return { path: groupPath + '/' + f.name, title: f.title };
             }
         }
+        const found = _searchFileInGroups(group.children || [], groupPath, filename);
+        if (found) return found;
     }
     return null;
 }
diff --git a/skills/knowledge-wiki/SKILL.md b/skills/knowledge-wiki/SKILL.md
index 1b0123da..9fdf5f5b 100644
--- a/skills/knowledge-wiki/SKILL.md
+++ b/skills/knowledge-wiki/SKILL.md
@@ -40,6 +40,8 @@ Maintain a persistent, structured knowledge base in the `knowledge/` directory.
 ```markdown
 # Page Title
 
+> Source: <URL or description of the original material>
+
 Content here. Cross-reference related pages with markdown links:
 [Related Page](../category/related-page.md)
 
@@ -53,6 +55,8 @@ Content here. Cross-reference related pages with markdown links:
 - [Page B](../category/page-b.md) — how it relates
 ```
 
+The `> Source:` line records where the knowledge came from (URL, document name, conversation, etc.). Always include it when the material originates from a specific source.
+
 Cross-references build a knowledge graph. When creating or updating a page, link to related pages and update those pages to link back. **Only link to pages that already exist** — if a concept deserves its own page, create it first, then add the link.
 
 ## Index Format (`knowledge/index.md`)