chore: establish YCode replication baseline and TODO

scripts/fixtures/typography.mjs

@@ -0,0 +1,26 @@
+// Verification fixture only. Does not create real sessions or contact a model.
+const now = Date.now()
+const content = [
+  '## 字体与间距', '',
+  '这是一段用于核对正文的文本，包含 **加粗文字** 和 `inline code`。', '',
+  '下一段文字保持相同的正文规则。字号改变时，段落间距使用公共间距变量。', '',
+  '- 一级列表', '  - 二级列表', '- 第二项', '',
+  '> 引用内容，用于检查继承的字号和行高。', '',
+  '| 项目 | 内容 |', '| --- | --- |', '| 字体 | 统一字号 |', '| 间距 | 公共变量 |', '',
+  '```ts', 'const greeting = "你好，WorkBuddy"', 'console.log(greeting)', '```'
+].join('\n')
+export const typographyFixture = {
+  sessions: [{ id: 'typography', title: '字体与间距核对', createdAt: now, updatedAt: now }],
+  messages: { typography: [
+    { id: 'typography-user', role: 'user', content: '核对正文、代码和控件在六档字号下的表现。', status: 'done', createdAt: now },
+    { id: 'typography-assistant', role: 'assistant', content, parts: [{ type: 'text', text: content }], tools: [], status: 'done', createdAt: now }
+  ] }
+}
+
+// Off-canvas measurement probes for the unified handler, not product UI.
+export const typographyProbes = `<style id="typography-fixture-style">
+#typography-probes { position: fixed; left: -10000px; top: 0; }
+.typography-probe-static { font-size: 13px; }
+.typography-probe-semantic { font-size: var(--yc-text-body-size); line-height: var(--yc-text-body-line-height); }
+.typography-probe-wb { font-size: var(--wb-font-body-size); }
+</style><div id="typography-probes" aria-hidden="true"><span class="typography-probe-static">static</span><span class="typography-probe-semantic">semantic</span><span class="typography-probe-wb">wb</span><div class="cb-font-size-fixed"><span class="typography-probe-static">fixed static</span><span class="typography-probe-semantic">fixed semantic</span><span class="typography-probe-wb">fixed wb</span></div></div>`