fix: add missing wikilink enrichment step to ingest pipeline

[SunRicardo]

Summary / 概述

The enrichWithWikilinks function was implemented but never called in the ingest pipeline, causing generated wiki pages to lack [[wikilinks]] in their body text. This made pages invisible in the knowledge graph.

enrichWithWikilinks 函数已在代码中实现，但从未在 ingest pipeline 中被调用，导致生成的 wiki 页面正文缺少 [[wikilinks]]。

Problem / 问题

• Generated wiki pages had related: frontmatter with wikilinks, but body text used plain text

• The graph builder (wiki-graph.ts) only uses body [[wikilinks]] to create edges

• This made ~14% of pages invisible in the knowledge graph

• 生成的 wiki 页面在 related: frontmatter 中有 wikilinks，但正文使用纯文本

• 图谱构建器 (wiki-graph.ts) 仅使用正文中的 [[wikilinks]] 创建边

• 这导致约 14% 的页面在知识图谱中不可见

Root Cause / 根因

The ingest LLM prompt correctly instructs the model to use [[wikilink]] syntax in the body. However, mid-size models often ignore this instruction and output plain text entity/concept names instead.

The enrichWithWikilinks function was designed as a post-save enrichment step to fix this: it asks the LLM to return a JSON list of {term, target} substitutions, then applies them safely. But this function was never imported or called in the ingest pipeline.

Ingest LLM prompt 正确指示模型在正文中使用 [[wikilink]] 语法。但中等规模模型常忽略此指令，输出纯文本实体/概念名。

enrichWithWikilinks 函数设计为保存后的增强步骤来修复此问题：它要求 LLM 返回 {term, target} 替换列表，然后安全应用。但此函数从未在 ingest pipeline 中被导入或调用。

Solution / 修复方案

Added Step 6 (wikilink enrichment) before Step 7 (embeddings) in autoIngestImpl:

在 autoIngestImpl 函数的 Step 7（embeddings）之前添加 Step 6（wikilink enrichment）：

Key Changes / 关键变更

1. Reordered execution steps / 调整执行顺序 — Enrichment before embeddings ensures embeddings reflect final content with wikilinks.

2. AbortSignal support / 取消信号支持 — enrichWithWikilinks accepts optional AbortSignal. Checks after readFile and before writeFile.

3. Wikilink boundary detection / wikilink 边界检测 — findUnlinkedOccurrence pre-scans all [[...]] intervals to prevent nested/corrupted wikilinks.

4. Target validation / 目标验证 — extractPageNamesFromIndex validates that LLM-returned targets exist in the wiki index before writing.

5. Cache-hit enrichment / 缓存命中增强 — Cache-hit branch also runs wikilink enrichment for cached pages, so older pages generated before this pipeline step can be repaired when the same source is re-ingested.

6. Helper extraction / 辅助函数提取 — shouldSkipWikilinkEnrichment extracted and exported for DRY and testability.

7. Improved logging / 改善日志 — activity.updateItem shows progress; console.warn for individual failures.

Verification / 验证

Local verification:

npm run typecheck
npm run test:mocks

Result:

• ✅ TypeScript type check passed locally
• ✅ Mock test suite passed locally: 1533 tests
• ⚠️ npm run test:llm was not run because it requires real LLM credentials
• ⚠️ GitHub Actions currently shows action_required with no jobs, likely because this PR is from an external contributor/fork and requires maintainer approval to run workflows

Tests / 测试

Language directive prompt tests / 语言指令测试

• Verifies language directive is built at call time
• Verifies successive calls pick up changed output language
• Uses the real buildLanguageDirective implementation and checks the actual system prompt passed to streamChat

Core enrichment tests / 核心增强测试

• Frontmatter preservation — exact frontmatter match, not just toContain
• Existing wikilink boundary protection — terms inside [[...]] target/alias parts are skipped
• Invalid target filtering — targets not in wiki index are rejected
• No valid links no-op — file not written when LLM returns empty/invalid links

AbortSignal tests / 取消信号测试

• Early abort before readFile — streamChat not called, file not written
• Abort after streamChat returns — file not written

Skip helper tests / 跳过辅助函数测试

• shouldSkipWikilinkEnrichment covers: wiki/index.md, wiki/log.md, wiki/overview.md, wiki/sources/*, nested paths, normal concept/entity pages

Files Modified / 修改文件

• src/lib/ingest.ts — Step 6/7 reorder, cache-hit enrichment, exported helper
• src/lib/enrich-wikilinks.ts — Signal checks, target validation, boundary detection
• src/lib/enrich-wikilinks.test.ts — 17 test cases covering all scenarios