Finalize canonical API description + add BRAND.md

Aligns SDK/plugin subline to 'The video search API for agents — meaning-based, grounded, timestamped' and adds BRAND.md as single source of truth.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: JessyTsui

BRAND.md

@@ -0,0 +1,53 @@
+# Cerul Brand Copy — Canonical Reference
+
+> Single source of truth for all public-facing slogans and descriptions.
+> Locked 2026-07-07. Do not invent new variants — reuse these verbatim.
+
+## Two slogans (the ONLY two)
+
+**Identity** — use where readers are *learning who we are*
+(deck cover, site footer, GitHub/repo descriptions, About page, splash, bio, press boilerplate):
+
+- EN: **Cerul: where video becomes citable.**
+- ZH: **Cerul：让视频有出处**
+
+**Action** — use where readers are *being persuaded*
+(site hero H1, ads, App Store subtitle, in-app home heading, tweet closers, merch):
+
+- EN: **Stop scrubbing. Start searching.**
+- ZH: **别拖进度条了，直接搜**
+
+## Two product descriptions (pick by product, follows the slogan)
+
+**API / platform** — cerul.ai, SDK/CLI READMEs, developer docs, plugin marketplace:
+
+- EN: **The video search API for agents — meaning-based, grounded, timestamped.**
+- ZH: **给 agent 的视频搜索 API——按语义、有出处、带时间码。**
+
+**App** — app.cerul.ai, App Store, in-app onboarding, cerul-app README:
+
+- EN: **Ask anything about what you've watched and heard — get the exact second.**
+- ZH: **关于你看过、听过的，问一句就有答案——精确到那一秒。**
+
+## Assembly rules
+
+- Full intro = identity slogan **+** the matching product description, concatenated verbatim, not rewritten.
+  e.g. footer: `Cerul: where video becomes citable. The video search API for agents — meaning-based, grounded, timestamped.`
+- **Max one slogan per screen.** Descriptions, buttons, FAQ are normal UI copy, unrestricted.
+- Hero lede may be longer, but only *expand* concepts already in the description — never invent new value phrases.
+- **Never expose "index / 索引"** in user-facing copy (it's implementation). Express local-first as "on your own machine / 全在本机".
+- Repo description formula: `Cerul — where video becomes citable. <one noun phrase>` (CLI / TypeScript SDK / …). Don't cram a description sentence in.
+
+## SEO / GEO keywords (canonical set)
+
+video search API, search video by meaning, video RAG, timestamped video citations,
+grounded video search, ask your videos, search podcasts and videos, video evidence for AI agents,
+local-first video search, cite video, semantic video search.
+(中文：视频搜索 API、按语义搜视频、视频引用、带时间码的检索、给 agent 的视频搜索、本地视频搜索。)
+
+## Retired — never use again
+
+- 视听第二大脑 / A second brain for video & audio
+- The video search layer for AI agents
+- Teach your AI agents to see
+- 找到视频里说过的每一句话 / Find every word said in your videos