feat(knowledge): 知识源维护与 TXT/Markdown/PDF 导入

支持文本、Markdown 与非扫描 PDF 上传解析，展示提取文本与切块结果。

frontend/src/utils/knowledgePages.ts

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+/*
+Copyright 2024-2026 ChatterMate
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import type { KnowledgeContentChunk, KnowledgeSubPage } from '@/types/knowledge'
+
+/** `<page>::<n>` — chunk ids written by app/knowledge/chunking.py. */
+const CHUNK_ID_SUFFIX = /::\d+$/
+/** `<page>_<n>` — chunk ids agno's PDF reader used to write. */
+const LEGACY_CHUNK_ID_SUFFIX = /_\d+$/
+
+/**
+ * Map a chunk id back to its page id by stripping the trailing chunk suffix:
+ * `<page>::<n>` (app/knowledge/chunking.py) or the legacy `<page>_<n>` that
+ * agno's PDF reader produced.
+ *
+ * Only a numeric suffix is stripped, so real underscores in a page name (e.g.
+ * `getting_started`) are preserved. Mirrors the backend `PAGE_ID_EXPR`
+ * (app/knowledge/page_editor.py) exactly, so the id derived here is the same
+ * `page_id` the backend expects for edit/delete and the `subpage` value it
+ * returns when listing sources — keep the two in sync.
+ */
+export function basePageId(id: string): string {
+  const chunked = id.replace(CHUNK_ID_SUFFIX, '')
+  if (chunked !== id) return chunked
+  return id.replace(LEGACY_CHUNK_ID_SUFFIX, '')
+}
+
+/**
+ * What goes between a chunk and the one before it when a page is rebuilt.
+ * `::n` chunks (app/knowledge/chunking.py) are verbatim slices of the page, so
+ * nothing: inserting a break would change the text that gets saved back.
+ * Legacy `_n` chunks were cut on whitespace that was dropped, so a paragraph
+ * break is the closest reconstruction.
+ */
+function chunkJoiner(chunkId: string): string {
+  return CHUNK_ID_SUFFIX.test(chunkId) ? '' : '\n\n'
+}
+
+function countWords(text: string): number {
+  const trimmed = text.trim()
+  return trimmed ? trimmed.split(/\s+/).length : 0
+}
+
+function laterIso(a: string | null, b: string | null): string | null {
+  if (!a) return b
+  if (!b) return a
+  return a > b ? a : b
+}
+
+/**
+ * Group a source's content chunks into sub-pages. Chunks are concatenated in
+ * their existing order (the backend returns them ordered by `created_at`), and
+ * page-level url/title/updated_at are taken from the chunk metadata.
+ */
+export function groupChunksIntoPages(chunks: KnowledgeContentChunk[]): KnowledgeSubPage[] {
+  const byPage = new Map<string, KnowledgeSubPage>()
+  const order: string[] = []
+
+  for (const chunk of chunks) {
+    const pageId = basePageId(chunk.id)
+    const meta = chunk.metadata || {}
+    const content = chunk.content || ''
+
+    let page = byPage.get(pageId)
+    if (!page) {
+      page = {
+        page_id: pageId,
+        url: typeof meta.url === 'string' && meta.url ? meta.url : pageId,
+        title: typeof meta.title === 'string' && meta.title ? meta.title : titleFromId(pageId),
+        content: '',
+        word_count: 0,
+        chunk_count: 0,
+        updated_at: chunk.created_at ?? null,
+        chunk_ids: [],
+      }
+      byPage.set(pageId, page)
+      order.push(pageId)
+    }
+
+    page.content = page.content ? `${page.content}${chunkJoiner(chunk.id)}${content}` : content
+    page.chunk_count += 1
+    page.chunk_ids.push(chunk.id)
+    page.updated_at = laterIso(page.updated_at, chunk.created_at ?? null)
+  }
+
+  for (const pageId of order) {
+    const page = byPage.get(pageId)!
+    page.word_count = countWords(page.content)
+  }
+
+  return order.map((pageId) => byPage.get(pageId)!)
+}
+
+/** Human-ish title fallback: last non-empty URL/path segment of the page id. */
+export function titleFromId(pageId: string): string {
+  const cleaned = pageId.replace(/[#?].*$/, '').replace(/\/+$/, '')
+  const segment = cleaned.split('/').filter(Boolean).pop()
+  return segment || pageId
+}