diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 0000000..b010027
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,14 @@
+node_modules
+dist
+.git
+.github
+test
+docs
+media
+examples
+*.md
+.husky
+hooks
+skills
+.claude-plugin
+marketplace.json
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..fc0de18
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,36 @@
+name: CI
+
+on:
+  push:
+    branches: [main, master]
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        node: ['18', '20', '22']
+    name: test (Node ${{ matrix.node }})
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node }}
+          cache: npm
+      - run: npm ci
+      - run: npm run build
+      - run: npm test
+
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: npm
+      - run: npm ci
+      - run: npm run lint
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 799913b..d12fdc2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,25 @@
 
 All notable changes to capcut-cli are documented here. The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/); the project follows [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.6.0] — 2026-05-29
+
+Distribution and integration release. No breaking changes to existing commands; everything stays zero-dep, JSON-by-default, and pipeable.
+
+### Added
+
+- **`capcut doctor`** — environment preflight that inspects the machine, not a draft: Node version (hard requirement, ≥ 18), a whisper binary on `PATH` (for `caption`), `ANTHROPIC_API_KEY` (for `translate`), and the default per-OS CapCut/JianYing project directory. JSON by default, `-H` for a human checklist. Exits `1` only on a hard failure.
+- **Importable Node library** — `import { loadDraft, saveDraft, findSegment, findMaterial, getTracksByType, extractText, updateTextContent, lintDraft, detectVersion, runDoctor } from "capcut-cli"`, with types. New `src/lib.ts` entry point; `package.json` `exports`/`main`/`types` map to `dist/lib.js`; `tsconfig` now emits `.d.ts`. Importing the package no longer executes the CLI.
+- **Dockerfile + `.dockerignore`** — zero-dep multi-stage build; the final image is Node + `dist/` + `templates/`. Drafts mount at `/work`. Also runs `serve` over a stdin pipe.
+- **GitHub Action (`action.yml`)** — composite action wrapping `capcut lint` so drafts can be gated in CI; `lint` exit code `2` (errors) fails the job. `uses: renezander030/capcut-cli@v0.6`.
+- **Three new shipped templates** — `caption-pop` (bold white center subtitle), `lower-third` (handle/name attribution), `hook-question` (large top-of-frame hook). Catalogue grows 3 → 6, all validated by the roundtrip suite.
+- **`serve-automation.md` example** — JSONL job/result contract and four integration paths (local pipe, n8n Execute Command, cloud builders via webhook→queue-file, Docker).
+
+### CI / Quality
+
+- **GitHub Actions CI** — test matrix across Node 18 / 20 / 22 plus a Biome lint job, on every push and pull request.
+- **Fuzz / injection test suite** — 12 malformed `draft_content.json` inputs (non-JSON, truncated, wrong-shape, prototype-pollution attempts, deep nesting) across six read commands assert graceful failure: no hang, no leaked stack trace, single-line JSON error on stderr. Plus a prototype-pollution non-regression check.
+- Test suite grew to 113 passing tests (doctor, fuzz, library, and the three new templates added their own coverage).
+
 ## [0.5.0] — 2026-05-25
 
 Six new commands voted in from [Discussion #1](https://github.com/renezander030/capcut-cli/discussions/1), shipped as a single release. All keep the zero-dep, JSON-by-default, pipeable design.
diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..9f34b6e
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,23 @@
+# capcut-cli — zero runtime deps, so the final image is just Node + dist/.
+# Build:  docker build -t capcut-cli .
+# Run:    docker run --rm -v "$PWD:/work" capcut-cli info /work/draft_content.json
+#         cat jobs.jsonl | docker run --rm -i -v "$PWD:/work" capcut-cli serve
+
+FROM node:20-alpine AS build
+WORKDIR /app
+COPY package.json package-lock.json ./
+RUN npm ci
+COPY tsconfig.json biome.json ./
+COPY src ./src
+RUN npm run build
+
+FROM node:20-alpine
+WORKDIR /app
+# No `npm install` here: the package declares zero runtime dependencies.
+COPY --from=build /app/dist ./dist
+COPY templates ./templates
+COPY package.json ./
+# Drafts are mounted at runtime; /work is the conventional mount point.
+WORKDIR /work
+ENTRYPOINT ["node", "/app/dist/index.js"]
+CMD ["--help"]
diff --git a/README.md b/README.md
index cf8a6c8..be5746f 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,6 @@
 # capcut-cli
 
+[![CI](https://github.com/renezander030/capcut-cli/actions/workflows/ci.yml/badge.svg)](https://github.com/renezander030/capcut-cli/actions/workflows/ci.yml)
 [![npm version](https://img.shields.io/npm/v/capcut-cli.svg)](https://www.npmjs.com/package/capcut-cli)
 [![npm downloads](https://img.shields.io/npm/dm/capcut-cli.svg)](https://www.npmjs.com/package/capcut-cli)
 [![node](https://img.shields.io/node/v/capcut-cli.svg)](https://nodejs.org)
@@ -7,15 +8,25 @@
 
 English | [中文](./README.zh-CN.md)
 
-**The CapCut/JianYing toolkit that survives the next ByteDance update — and auto-captions with real caption objects.**
+**The CapCut/JianYing CLI any LLM agent can drive — zero dependencies, no server, both namespaces in one binary.**
 
-A pure CLI any LLM can drive: no MCP server, no HTTP daemon, no state. Inspect drafts, build from scratch, add media, modify subtitles, auto-caption with whisper, translate to N languages, cut long-form to shorts. Zero runtime deps, both CapCut and JianYing namespaces in one binary, JSON output by default.
+Every command reads and writes `draft_content.json` directly: JSON in, JSON out, no MCP server, no HTTP daemon, no state to babysit. That makes it a deterministic boundary any model (Claude, DeepSeek, GLM, Kimi) can call from a pipeline. Inspect drafts, build from scratch, add media, edit subtitles, auto-caption with whisper, translate to N languages, and cut long-form to shorts. Because there is no private API in the loop, it keeps working across ByteDance updates — and `caption` writes real caption objects, not the text-segment mimics other tools settle for.
+
+**Use it three ways:**
+
+- **CLI** — `npm install -g capcut-cli`, then `capcut <command> <project>`
+- **Library** — `import { loadDraft, lintDraft, saveDraft } from "capcut-cli"` (typed, zero-dep)
+- **Queue runner** — `capcut serve` reads JSONL jobs from stdin and drops into [n8n / Make / Coze](./examples/serve-automation.md)
+
+Run `capcut doctor` first to verify your environment (Node, whisper, draft directory).
+
+**New in v0.6** — `doctor` (environment preflight), an importable Node library (`import { … } from "capcut-cli"`), an official [Dockerfile](./Dockerfile), a [GitHub Action](./action.yml) that lints drafts in CI, three new shipped templates (`caption-pop`, `lower-third`, `hook-question`), and a CI matrix across Node 18/20/22.
 
 **New in v0.4** — `caption` (whisper → real caption objects, not the import-srt text-mimics), `migrate` (mask ↔ common_masks across CapCut/JianYing version jumps), `lint` (schema-aware checks: overlaps, line length, missing files), `version` (detect support status), `translate` (Anthropic-API multi-language draft clone), `add-sfx`, `chroma`, `serve` (stateless JSONL queue runner for n8n/Coze/Make), and `export --batch` (EXPERIMENTAL macOS UI-automated render queue).
 
-## v0.5 — vote on what ships next
+## v0.5 — shipped, community-voted
 
-Open for community vote on **[Discussion #1](https://github.com/renezander030/capcut-cli/discussions/1)**. 👍 the comments for the features you want most — I ship the top 3-5 as a single v0.5 release within ~2 weeks.
+All six features below were voted in on **[Discussion #1](https://github.com/renezander030/capcut-cli/discussions/1)** and shipped together in v0.5. Want a say in what lands next? 👍 the comments there, or open a new discussion.
 
 - ✅ `audio-fade <project> <id> --in <s> --fade-out <s>` — fade-in / fade-out on audio segments (proper `audio_fades` objects, not volume keyframes) **shipped in v0.5**
 - ✅ `bubble-text <project> <id> --bubble <slug>` / 花字 — bubble / decorative text effects + `enums --bubbles` discovery **shipped in v0.5**
@@ -24,7 +35,7 @@ Open for community vote on **[Discussion #1](https://github.com/renezander030/ca
 - ✅ `import-ass <project> <ass-path>` — ASS subtitle import alongside existing `import-srt` **shipped in v0.5**
 - ✅ `mix-mode <project> <id> <mode>` — blend modes per video segment (multiply, screen, overlay, …) **shipped in v0.5**
 
-> Voting closes when v0.5 ships. If your feature is missing, drop a comment on Discussion #1.
+> All six shipped in v0.5.0. If the feature you want is missing, drop a comment on Discussion #1.
 
 ## Workflow
 
@@ -129,7 +140,15 @@ Status of every feature shipped. ✅ = implemented, ⬜ = roadmap. Section ancho
 - ✅ `caption` — whisper shell-out (openai-whisper / whisper.cpp / faster-whisper) → real caption-track segments with `sub_type` + `caption_template_info` (addresses pyJianYingDraft #148 — no more text-segment mimics)
 - ✅ `translate` — Anthropic-API multi-language draft clone, zero runtime deps (uses built-in `fetch`). `--dry-run` for safe inspection. Original stays untouched
 
-### v0.5 — new commands (in progress)
+### v0.6 — distribution & integration
+- ✅ `doctor` — environment preflight: Node version, whisper binary (for `caption`), `ANTHROPIC_API_KEY` (for `translate`), default CapCut/JianYing project directory. Exits 1 only on hard failures
+- ✅ Node **library** — `import { loadDraft, lintDraft, saveDraft, detectVersion, runDoctor } from "capcut-cli"` — the core, typed and zero-dep, importable without running the CLI
+- ✅ [**Dockerfile**](./Dockerfile) — zero-dep multi-stage image; `docker run --rm -v "$PWD:/work" capcut-cli info /work/draft_content.json`
+- ✅ [**GitHub Action**](./action.yml) — `uses: renezander030/capcut-cli@v0.6` to lint drafts in CI (exit 2 on errors fails the job)
+- ✅ Three new templates — `caption-pop`, `lower-third`, `hook-question` (six shipped templates total)
+- ✅ CI matrix across Node 18 / 20 / 22 + Biome lint on every push and PR
+
+### v0.5 — new commands (shipped)
 - ✅ `mix-mode` — set blend mode on a video segment (normal · multiply · screen · overlay · soft-light · hard-light · color-dodge · color-burn · darken · lighten · difference · exclusion)
 - ✅ `audio-fade` — fade-in / fade-out on an audio segment via `materials.audio_fades[]` (real fade material, not `volume` keyframes)
 - ✅ `add-cover` — set the draft's cover frame (thumbnail) to a local image (PNG/JPG); `--time <ms>` defaults to 0
@@ -187,6 +206,49 @@ Add the marketplace, then enable the plugin:
 
 This gives Claude Code the `/capcut-cli:capcut-edit` skill -- it learns every command, the progressive disclosure navigation pattern, and how to find your CapCut projects on macOS/Windows. Auto-installs the CLI on first enable.
 
+### Use as a Node library
+
+The core is importable and typed — no shelling out, no CLI process:
+
+```ts
+import { loadDraft, lintDraft, saveDraft, detectVersion } from "capcut-cli";
+
+const { draft, filePath } = loadDraft("./my-project/draft_content.json");
+console.log(detectVersion(draft).support.status);   // supported | untested | known-broken
+const issues = lintDraft(draft);                     // [{ severity, code, message, location }]
+saveDraft(filePath, draft);
+```
+
+Importing the package never runs the CLI. Exposed: `loadDraft`, `saveDraft`, `findSegment`, `findMaterial`, `getTracksByType`, `extractText`, `updateTextContent`, `lintDraft`, `detectVersion`, `runDoctor`, plus their types.
+
+### Docker
+
+Zero runtime deps, so the image is just Node + the build output. Mount your drafts at `/work`:
+
+```bash
+docker build -t capcut-cli .
+docker run --rm -v "$PWD:/work" capcut-cli info /work/draft_content.json
+cat jobs.jsonl | docker run --rm -i -v "$PWD:/work" capcut-cli serve
+```
+
+### GitHub Action — lint drafts in CI
+
+Gate caption quality (overlaps, line length, missing files) on every push. `lint` exits `2` on errors, which fails the job:
+
+```yaml
+- uses: renezander030/capcut-cli@v0.6
+  with:
+    project: ./drafts/my-short
+    args: --max-chars 32 --max-cue-secs 6
+```
+
+### Verify your environment
+
+```bash
+capcut doctor          # JSON report; exit 1 only on a hard failure (Node < 18)
+capcut doctor -H       # human-readable checklist
+```
+
 ### Why a CLI, not an MCP server
 
 Other CapCut / JianYing tooling exposes an HTTP API or MCP server. `capcut-cli` deliberately does not:
diff --git a/README.zh-CN.md b/README.zh-CN.md
index 4d5ec57..b60a660 100644
--- a/README.zh-CN.md
+++ b/README.zh-CN.md
@@ -1,5 +1,6 @@
 # capcut-cli
 
+[![CI](https://github.com/renezander030/capcut-cli/actions/workflows/ci.yml/badge.svg)](https://github.com/renezander030/capcut-cli/actions/workflows/ci.yml)
 [![npm version](https://img.shields.io/npm/v/capcut-cli.svg)](https://www.npmjs.com/package/capcut-cli)
 [![npm downloads](https://img.shields.io/npm/dm/capcut-cli.svg)](https://www.npmjs.com/package/capcut-cli)
 [![node](https://img.shields.io/node/v/capcut-cli.svg)](https://nodejs.org)
@@ -7,15 +8,25 @@
 
 [English](./README.md) | 中文
 
-**剪映 / CapCut 工具链，扛得住字节跳动下次改版 —— 自动加的字幕也是真字幕对象（不是 import-srt 那种文本伪装）。**
+**任何大模型 Agent 都能驱动的剪映 / CapCut 命令行 —— 零依赖、无服务、CapCut + 剪映共用一个二进制。**
 
-任何能输出 JSON 的大模型都能驱动它：不用 MCP 服务，不用 HTTP 守护进程，无状态。命令行查看工程、从零搭草稿、加素材、改字幕、用 whisper 自动打字幕、一键克隆成多语言版本、把长视频切成短片。直接读写 `draft_content.json`，零运行时依赖，CapCut + 剪映两个命名空间共用一个二进制。
+每个命令都直接读写 `draft_content.json`：JSON 进、JSON 出，不用 MCP 服务，不用 HTTP 守护进程，无状态。任何模型（Claude、DeepSeek、GLM、Kimi）都能在流水线里直接调用这个确定性边界。命令行查看工程、从零搭草稿、加素材、改字幕、用 whisper 自动打字幕、一键克隆成多语言版本、把长视频切成短片。因为链路里没有任何私有 API，所以扛得住字节跳动下次改版 —— 而且 `caption` 写的是真字幕对象，不是别的工具那种文本伪装。
+
+**三种用法：**
+
+- **命令行** —— `npm install -g capcut-cli`，然后 `capcut <command> <project>`
+- **代码库** —— `import { loadDraft, lintDraft, saveDraft } from "capcut-cli"`（带类型、零依赖）
+- **队列执行器** —— `capcut serve` 从 stdin 读 JSONL 任务，可对接 [n8n / Make / 扣子 Coze](./examples/serve-automation.md)
+
+先跑 `capcut doctor` 检查环境（Node、whisper、草稿目录）。
+
+**v0.6 新增** —— `doctor`（环境预检）、可导入的 Node 代码库（`import { … } from "capcut-cli"`）、官方 [Dockerfile](./Dockerfile)、在 CI 里检查草稿的 [GitHub Action](./action.yml)、三个新模板（`caption-pop`、`lower-third`、`hook-question`），以及覆盖 Node 18/20/22 的 CI 矩阵。
 
 **v0.4 新增** —— `caption`（whisper → 真字幕对象，不再是 import-srt 那种文本伪装）、`migrate`（剪映 5.9 / CapCut 9.6 之间的 `mask` ↔ `common_masks` schema 迁移）、`lint`（字幕检查：重叠、行长、缺失素材文件）、`version`（检测兼容状态）、`translate`（多语言草稿克隆，走 Anthropic API）、`add-sfx`、`chroma`、`serve`（无状态 JSONL 队列 —— 对接 n8n / Coze / 扣子 / Make）、`export --batch`（**实验性** macOS UI 自动化批量导出）。
 
-## v0.5 投票决定下一步
+## v0.5 已发布（社区投票决定）
 
-下面是 v0.5 候选功能，欢迎到 **[Discussion #1](https://github.com/renezander030/capcut-cli/discussions/1)** 给你想要的功能 👍 —— 我会按票数把前 3-5 个打包进一个 v0.5 release（目标 2 周内出）。
+下面六个功能都是在 **[Discussion #1](https://github.com/renezander030/capcut-cli/discussions/1)** 投票选出、并在 v0.5 一起发布的。想决定下一步加什么？去那里给评论点 👍，或者开一个新 discussion。
 
 - `audio-fade <project> <id> --in <秒> --out <秒>` —— 音频淡入淡出（写真正的 `audio_fades` 对象，不再用音量关键帧凑）
 - `bubble-text <project> <id> --bubble <slug>` / 花字 —— 文本气泡 / 花字特效 + `enums --bubbles` 枚举发现
@@ -24,7 +35,7 @@
 - `import-ass <project> <ass-path>` —— ASS 字幕导入（跟现有 `import-srt` 并存）
 - `mix-mode <project> <id> <模式>` —— 视频片段混合模式（正片叠底 / 滤色 / 叠加 …）
 
-> 投票截止到 v0.5 发布为止。如果你想要的功能不在列表里，去 Discussion #1 留言。
+> 六个功能都已在 v0.5.0 发布。如果你想要的功能不在列表里，去 Discussion #1 留言。
 
 > **想要完整的国产大模型 + 剪映短视频流水线？** `capcut-cli` 是引擎，配套的 **[病毒短视频蓝图（完整教程 + 蓝图下载）](https://renezander.com/zh-cn/guides/automate-xiaohongshu-capcut-cli/?utm_source=capcut-cli&utm_medium=readme&utm_campaign=hero-cn)** 给你完整方法 —— DeepSeek / GLM / Kimi / Qwen 都能跑，专为 **小红书 + 抖音** 优化（不是 YouTube），**支付宝 / 微信支付** 通过 Stripe 直接下单。
 
diff --git a/action.yml b/action.yml
new file mode 100644
index 0000000..ba8cd1a
--- /dev/null
+++ b/action.yml
@@ -0,0 +1,30 @@
+name: capcut-cli
+description: Lint CapCut/JianYing drafts in CI — caption overlaps, line length, cue duration, missing material refs and files.
+author: renezander030
+branding:
+  icon: check-square
+  color: green
+
+inputs:
+  project:
+    description: Path to draft_content.json (or its parent directory) to lint.
+    required: true
+  args:
+    description: 'Extra flags passed to `capcut lint` (e.g. "--max-chars 32 --max-cue-secs 6").'
+    required: false
+    default: ''
+  version:
+    description: capcut-cli version to install from npm.
+    required: false
+    default: latest
+
+runs:
+  using: composite
+  steps:
+    - name: Install capcut-cli
+      shell: bash
+      run: npm install -g "capcut-cli@${{ inputs.version }}"
+    - name: Lint draft
+      shell: bash
+      # `lint` exits 0 (clean) / 1 (warnings) / 2 (errors) — exit 2 fails the job.
+      run: capcut lint "${{ inputs.project }}" ${{ inputs.args }} -H
diff --git a/examples/README.md b/examples/README.md
index 78d0ffc..8c9c771 100644
--- a/examples/README.md
+++ b/examples/README.md
@@ -12,6 +12,7 @@ Copy-paste recipes for common CapCut / JianYing workflows. Every recipe is one s
 | [keyframe-zoom.md](./keyframe-zoom.md) | Programmatic Ken Burns zoom-in/out keyframes on one segment |
 | [keyframe-pan.md](./keyframe-pan.md) | Unfinished-pan keyframe pattern for epilogue / payoff stills |
 | [verify-vo-alignment.md](./verify-vo-alignment.md) | Pre-flight check on ElevenLabs voiceover + word-level timestamps |
+| [serve-automation.md](./serve-automation.md) | Wire the stateless JSONL queue runner into n8n / Make / Coze / Docker |
 
 All shell-only recipes assume `capcut` is on your `$PATH` (`npm install -g capcut-cli`).
 The three keyframe / VO recipes ship with companion Python scripts under [`./scripts/`](./scripts/) — Python 3.9+, no external deps.
diff --git a/examples/serve-automation.md b/examples/serve-automation.md
new file mode 100644
index 0000000..baea8cf
--- /dev/null
+++ b/examples/serve-automation.md
@@ -0,0 +1,82 @@
+# Wire capcut-cli into n8n / Make / Coze — no HTTP server
+
+`capcut serve` is a **stateless JSONL queue runner**. It reads one job per line from
+stdin (or a `--queue` file), dispatches each to the CLI, and writes one JSON result
+per line to stdout. No daemon, no port, no state between runs. That makes it a clean
+fit for any automation tool that can run a shell command or pipe bytes.
+
+## The job format
+
+One JSON object per line. `cmd` is required; `project` and `args` are optional:
+
+```jsonl
+{"cmd":"info","project":"/work/draft_content.json"}
+{"cmd":"add-text","project":"/work/draft_content.json","args":["8s","2s","Subscribe","--font-size","16"]}
+{"cmd":"import-srt","project":"/work/draft_content.json","args":["/work/captions.srt"]}
+{"cmd":"lint","project":"/work/draft_content.json"}
+```
+
+Each result line is `{ok, cmd, args, status, stdout, stderr}`. `ok` is `true` when the
+command exited `0`; `stdout` is the parsed JSON the command would have printed. Because
+`lint` exits `2` on errors, a lint job comes back `{"ok":false,"status":2,...}` — handle
+that in your flow to gate a render.
+
+## Local / cron
+
+```bash
+cat jobs.jsonl | capcut serve > results.jsonl
+# or read from a file the upstream step wrote:
+capcut serve --queue jobs.jsonl > results.jsonl
+```
+
+Add `--fail-fast` to stop at the first failing job.
+
+## n8n (self-hosted — Execute Command node)
+
+n8n's **Execute Command** node runs on the n8n host, so `capcut` just needs to be on its
+`PATH` (`npm install -g capcut-cli`, or use the Docker image below). Build the JSONL in a
+Function node, then pipe it in:
+
+```
+Command:  capcut serve
+Input:    {{ $json.jobs }}        // a JSONL string from the previous node
+```
+
+A Function node to turn structured items into JSONL:
+
+```js
+// one n8n item per job → a single JSONL string
+return [{ json: { jobs: items.map(i => JSON.stringify(i.json)).join("\n") } }];
+```
+
+Parse `results.jsonl` back out in the next Function node by splitting on newlines and
+`JSON.parse`-ing each line.
+
+## Make / Coze (cloud) — webhook → queue file → serve
+
+Cloud builders can't run a binary directly. The stateless model still fits: have the
+cloud scenario **write a queue file** (or POST JSONL to a tiny endpoint on a host you
+control), then run `capcut serve --queue` on that host from cron or a file-watch. The
+boundary is the JSONL file — the cloud side never needs to know about the CLI internals.
+
+```bash
+# on your host: drain whatever the cloud scenario dropped, every minute
+* * * * * test -s /srv/capcut/inbox.jsonl && \
+  capcut serve --queue /srv/capcut/inbox.jsonl > /srv/capcut/outbox.jsonl && \
+  : > /srv/capcut/inbox.jsonl
+```
+
+## Docker (no global install)
+
+The published image runs `serve` over a stdin pipe — drafts are mounted at `/work`:
+
+```bash
+cat jobs.jsonl | docker run --rm -i -v "$PWD:/work" capcut-cli serve > results.jsonl
+```
+
+Build the image from this repo with `docker build -t capcut-cli .`.
+
+> **Why no HTTP mode?** A long-lived server adds a port to secure, state to reset, and a
+> process to babysit. A queue runner that starts, drains, and exits composes with the
+> retry/idempotency model your automation tool already has. If you genuinely need HTTP,
+> put `serve` behind a one-line handler that pipes the request body to it.
diff --git a/media/og-card.png b/media/og-card.png
new file mode 100644
index 0000000..ab390a8
Binary files /dev/null and b/media/og-card.png differ
diff --git a/package.json b/package.json
index 0896f45..c891c3a 100644
--- a/package.json
+++ b/package.json
@@ -1,12 +1,21 @@
 {
   "name": "capcut-cli",
-  "version": "0.5.0",
+  "version": "0.6.0",
   "description": "CLI to create and edit CapCut projects — build drafts from scratch, add video/audio/text, subtitles, timing, speed, volume, templates, cut long-form to shorts. No API needed.",
   "type": "module",
   "bin": {
     "capcut": "dist/index.js",
     "capcut-cli": "dist/index.js"
   },
+  "main": "./dist/lib.js",
+  "types": "./dist/lib.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/lib.d.ts",
+      "import": "./dist/lib.js"
+    },
+    "./package.json": "./package.json"
+  },
   "files": [
     "dist",
     "examples",
diff --git a/src/doctor.ts b/src/doctor.ts
new file mode 100644
index 0000000..03ce412
--- /dev/null
+++ b/src/doctor.ts
@@ -0,0 +1,116 @@
+import { existsSync } from "node:fs";
+import { homedir, platform, release } from "node:os";
+import { delimiter, join } from "node:path";
+
+export type CheckStatus = "ok" | "warn" | "missing";
+
+export interface DoctorCheck {
+  name: string;
+  status: CheckStatus;
+  detail: string;
+  /** Commands degraded or unavailable when this check is not "ok". */
+  affects?: string[];
+  /** How to fix, when not "ok". */
+  fix?: string;
+}
+
+export interface DoctorReport {
+  ok: boolean;
+  platform: string;
+  node: string;
+  checks: DoctorCheck[];
+}
+
+/** Minimal cross-platform PATH lookup — no `which`/`where` shell-out. */
+function onPath(cmd: string): string | null {
+  const dirs = (process.env.PATH ?? "").split(delimiter).filter(Boolean);
+  const exts = platform() === "win32" ? ["", ".exe", ".cmd", ".bat"] : [""];
+  for (const dir of dirs) {
+    for (const ext of exts) {
+      const full = join(dir, cmd + ext);
+      if (existsSync(full)) return full;
+    }
+  }
+  return null;
+}
+
+function nodeMajor(): number {
+  return Number.parseInt(process.versions.node.split(".")[0] ?? "0", 10);
+}
+
+/** Default per-OS CapCut/JianYing project directories. */
+function draftDirs(): { label: string; path: string }[] {
+  const home = homedir();
+  if (platform() === "darwin") {
+    return [
+      { label: "CapCut (macOS)", path: join(home, "Movies/CapCut/User Data/Projects/com.lveditor.draft") },
+      { label: "JianYing (macOS)", path: join(home, "Movies/JianyingPro/User Data/Projects/com.lveditor.draft") },
+    ];
+  }
+  if (platform() === "win32") {
+    const local = process.env.LOCALAPPDATA ?? join(home, "AppData/Local");
+    return [
+      { label: "CapCut (Windows)", path: join(local, "CapCut/User Data/Projects/com.lveditor.draft") },
+      { label: "JianYing (Windows)", path: join(local, "JianyingPro/User Data/Projects/com.lveditor.draft") },
+    ];
+  }
+  return [];
+}
+
+export function runDoctor(): DoctorReport {
+  const checks: DoctorCheck[] = [];
+
+  // Node runtime — hard requirement.
+  const major = nodeMajor();
+  checks.push({
+    name: "node",
+    status: major >= 18 ? "ok" : "missing",
+    detail: `Node ${process.versions.node}${major >= 18 ? "" : " (capcut-cli needs >= 18)"}`,
+    affects: major >= 18 ? undefined : ["*"],
+    fix: major >= 18 ? undefined : "Upgrade to Node 18 or newer.",
+  });
+
+  // whisper — needed by `caption`.
+  const whisper = onPath("whisper") ?? onPath("whisper-cli") ?? onPath("faster-whisper");
+  checks.push({
+    name: "whisper",
+    status: whisper ? "ok" : "warn",
+    detail: whisper ? `found: ${whisper}` : "no whisper binary on PATH",
+    affects: ["caption"],
+    fix: whisper ? undefined : "pip install openai-whisper · brew install whisper-cpp · or pass --whisper-cmd <path>",
+  });
+
+  // ANTHROPIC_API_KEY — needed by `translate`.
+  const hasKey = Boolean(process.env.ANTHROPIC_API_KEY);
+  checks.push({
+    name: "anthropic-api-key",
+    status: hasKey ? "ok" : "warn",
+    detail: hasKey ? "ANTHROPIC_API_KEY is set" : "ANTHROPIC_API_KEY not set",
+    affects: ["translate"],
+    fix: hasKey ? undefined : "export ANTHROPIC_API_KEY=… (or pass --api-key) to use `translate`.",
+  });
+
+  // CapCut / JianYing project directories — informational.
+  const dirs = draftDirs();
+  if (dirs.length === 0) {
+    checks.push({
+      name: "draft-dir",
+      status: "warn",
+      detail: `no default project directory for ${platform()} — pass the draft path explicitly`,
+    });
+  } else {
+    for (const d of dirs) {
+      const found = existsSync(d.path);
+      checks.push({
+        name: "draft-dir",
+        status: found ? "ok" : "warn",
+        detail: `${d.label}: ${found ? "found" : "not found"} (${d.path})`,
+        fix: found ? undefined : "Open a project in CapCut/JianYing once, or pass the draft path directly.",
+      });
+    }
+  }
+
+  // `ok` reflects only hard failures (missing), not optional-tool warnings.
+  const ok = !checks.some((c) => c.status === "missing");
+  return { ok, platform: `${platform()} ${release()}`, node: process.versions.node, checks };
+}
diff --git a/src/index.ts b/src/index.ts
index 199952b..c6c7971 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -32,6 +32,7 @@ import {
   transitionSlugs,
 } from "./decorators.js";
 import { detectEncryption } from "./decrypt.js";
+import { type DoctorCheck, runDoctor } from "./doctor.js";
 import type { Draft, Segment, Track } from "./draft.js";
 import {
   extractText,
@@ -305,6 +306,10 @@ Encryption (v0.6 — detection scaffold):
   decrypt    <project>
              Detect JianYing 6.0+ encryption and report next steps.
              (Decryption algorithm not bundled; clear error UX + workaround docs.)
+  doctor
+             Check the environment, not a draft: Node version, whisper binary
+             (for caption), ANTHROPIC_API_KEY (for translate), and the default
+             CapCut/JianYing project directory. Exit 1 only on hard failures.
 
 Stateless queue runner (v0.5):
   serve      [--queue <path>] [--fail-fast]
@@ -1901,6 +1906,25 @@ function cmdBatch(draft: Draft, filePath: string, flags: Flags): void {
   out({ ok: true, succeeded: ok, failed: fail }, flags);
 }
 
+function cmdDoctor(flags: Flags): boolean {
+  const report = runDoctor();
+  if (flags.human) {
+    const glyph: Record<DoctorCheck["status"], string> = { ok: "✓", warn: "!", missing: "✗" };
+    console.log(`Platform:  ${report.platform}`);
+    console.log(`Node:      ${report.node}`);
+    console.log("");
+    for (const c of report.checks) {
+      console.log(`[${glyph[c.status]}] ${c.name.padEnd(18)} ${c.detail}`);
+      if (c.status !== "ok" && c.fix) console.log(`      → ${c.fix}`);
+    }
+    console.log("");
+    console.log(report.ok ? "Ready." : "Missing a hard requirement — see ✗ above.");
+  } else {
+    out(report, flags);
+  }
+  return report.ok;
+}
+
 // --- Main ---
 
 async function main(): Promise<void> {
@@ -1920,6 +1944,11 @@ async function main(): Promise<void> {
     process.exit(0);
   }
 
+  // `doctor` inspects the environment, not a draft — no project needed.
+  if (cmd === "doctor") {
+    process.exit(cmdDoctor(flags) ? 0 : 1);
+  }
+
   // `serve` reads jobs from stdin/queue file — no project needed.
   if (cmd === "serve") {
     await cmdServe(flags);
diff --git a/src/lib.ts b/src/lib.ts
new file mode 100644
index 0000000..c971949
--- /dev/null
+++ b/src/lib.ts
@@ -0,0 +1,47 @@
+/**
+ * Public library entry point for capcut-cli.
+ *
+ * The CLI lives in `index.ts` (it runs `main()` on import, so it is not
+ * importable as a library). This module re-exports the stable, side-effect-free
+ * core so other tools can read, inspect, lint, and write CapCut/JianYing drafts
+ * programmatically:
+ *
+ *   import { loadDraft, saveDraft, lintDraft } from "capcut-cli";
+ *
+ *   const { draft, filePath } = loadDraft("./draft_content.json");
+ *   const issues = lintDraft(draft);
+ *   saveDraft(filePath, draft);
+ */
+
+export type { CheckStatus, DoctorCheck, DoctorReport } from "./doctor.js";
+export { runDoctor } from "./doctor.js";
+export type {
+  Draft,
+  MaterialAudio,
+  MaterialText,
+  MaterialVideo,
+  Segment,
+  Timerange,
+  Track,
+} from "./draft.js";
+export {
+  extractText,
+  findDraft,
+  findMaterial,
+  findMaterialGlobal,
+  findSegment,
+  getMaterialTypes,
+  getTracksByType,
+  loadDraft,
+  saveDraft,
+  updateTextContent,
+} from "./draft.js";
+export type { LintIssue, LintOptions, Severity } from "./lint.js";
+export {
+  DEFAULT_LINT_OPTIONS,
+  lintDraft,
+  lintExitCode,
+  summarize,
+} from "./lint.js";
+export type { AppSource, VersionInfo } from "./version.js";
+export { detectVersion } from "./version.js";
diff --git a/templates/caption-pop.json b/templates/caption-pop.json
new file mode 100644
index 0000000..9f953f6
--- /dev/null
+++ b/templates/caption-pop.json
@@ -0,0 +1,79 @@
+{
+  "name": "caption-pop",
+  "type": "text",
+  "segment": {
+    "id": "a1b2c3d4-0001-4a01-9001-000000000001",
+    "material_id": "a1b2c3d4-0002-4a02-9002-000000000002",
+    "raw_segment_id": "a1b2c3d4-0003-4a03-9003-000000000003",
+    "target_timerange": { "start": 0, "duration": 2500000 },
+    "source_timerange": { "start": 0, "duration": 2500000 },
+    "speed": 1,
+    "volume": 1,
+    "visible": true,
+    "reverse": false,
+    "clip": {
+      "alpha": 1,
+      "rotation": 0,
+      "scale": { "x": 1, "y": 1 },
+      "transform": { "x": 0, "y": -0.75 },
+      "flip": { "horizontal": false, "vertical": false }
+    },
+    "render_index": 15000,
+    "track_render_index": 0,
+    "track_attribute": 0,
+    "extra_material_refs": [
+      "a1b2c3d4-0004-4a04-9004-000000000004",
+      "a1b2c3d4-0005-4a05-9005-000000000005",
+      "a1b2c3d4-0006-4a06-9006-000000000006",
+      "a1b2c3d4-0007-4a07-9007-000000000007"
+    ],
+    "common_keyframes": [],
+    "keyframe_refs": []
+  },
+  "material": {
+    "type": "texts",
+    "data": {
+      "id": "a1b2c3d4-0002-4a02-9002-000000000002",
+      "type": "text",
+      "content": "{\"styles\":[{\"range\":[0,7],\"size\":15,\"bold\":true,\"italic\":false,\"underline\":false,\"fill\":{\"alpha\":1,\"content\":{\"render_type\":\"solid\",\"solid\":{\"alpha\":1,\"color\":[1,1,1]}}}}],\"text\":\"CAPTION\"}",
+      "alignment": 1,
+      "font_size": 15,
+      "text_color": "#FFFFFF",
+      "typesetting": 0,
+      "letter_spacing": 0,
+      "line_spacing": 0.02,
+      "line_feed": 1,
+      "line_max_width": 0.82,
+      "force_apply_line_max_width": false,
+      "check_flag": 7,
+      "fixed_width": -1,
+      "fixed_height": -1,
+      "has_shadow": true,
+      "shadow_alpha": 0.8,
+      "shadow_color": "#000000",
+      "shadow_distance": 6,
+      "border_width": 0.08,
+      "border_color": "#000000",
+      "border_alpha": 1,
+      "has_border": true
+    }
+  },
+  "extra_materials": [
+    {
+      "type": "speeds",
+      "data": { "id": "a1b2c3d4-0004-4a04-9004-000000000004", "type": "speed", "speed": 1, "mode": 0, "curve_speed": null }
+    },
+    {
+      "type": "placeholder_infos",
+      "data": { "id": "a1b2c3d4-0005-4a05-9005-000000000005", "type": "placeholder_info", "error_path": "", "error_text": "", "meta_type": "none", "res_path": "", "res_text": "" }
+    },
+    {
+      "type": "sound_channel_mappings",
+      "data": { "id": "a1b2c3d4-0006-4a06-9006-000000000006", "type": "none", "audio_channel_mapping": 0, "is_config_open": false }
+    },
+    {
+      "type": "vocal_separations",
+      "data": { "id": "a1b2c3d4-0007-4a07-9007-000000000007", "type": "vocal_separation", "choice": 0, "enter_from": "", "final_algorithm": "", "production_path": "", "removed_sounds": [], "time_range": null }
+    }
+  ]
+}
diff --git a/templates/hook-question.json b/templates/hook-question.json
new file mode 100644
index 0000000..6be4dd7
--- /dev/null
+++ b/templates/hook-question.json
@@ -0,0 +1,79 @@
+{
+  "name": "hook-question",
+  "type": "text",
+  "segment": {
+    "id": "c1b2c3d4-0001-4c01-9c01-000000000001",
+    "material_id": "c1b2c3d4-0002-4c02-9c02-000000000002",
+    "raw_segment_id": "c1b2c3d4-0003-4c03-9c03-000000000003",
+    "target_timerange": { "start": 0, "duration": 3000000 },
+    "source_timerange": { "start": 0, "duration": 3000000 },
+    "speed": 1,
+    "volume": 1,
+    "visible": true,
+    "reverse": false,
+    "clip": {
+      "alpha": 1,
+      "rotation": 0,
+      "scale": { "x": 1, "y": 1 },
+      "transform": { "x": 0, "y": 0.55 },
+      "flip": { "horizontal": false, "vertical": false }
+    },
+    "render_index": 15000,
+    "track_render_index": 0,
+    "track_attribute": 0,
+    "extra_material_refs": [
+      "c1b2c3d4-0004-4c04-9c04-000000000004",
+      "c1b2c3d4-0005-4c05-9c05-000000000005",
+      "c1b2c3d4-0006-4c06-9c06-000000000006",
+      "c1b2c3d4-0007-4c07-9c07-000000000007"
+    ],
+    "common_keyframes": [],
+    "keyframe_refs": []
+  },
+  "material": {
+    "type": "texts",
+    "data": {
+      "id": "c1b2c3d4-0002-4c02-9c02-000000000002",
+      "type": "text",
+      "content": "{\"styles\":[{\"range\":[0,16],\"size\":19,\"bold\":true,\"italic\":false,\"underline\":false,\"fill\":{\"alpha\":1,\"content\":{\"render_type\":\"solid\",\"solid\":{\"alpha\":1,\"color\":[1,1,1]}}}}],\"text\":\"Wait for it...?\"}",
+      "alignment": 1,
+      "font_size": 19,
+      "text_color": "#FFFFFF",
+      "typesetting": 0,
+      "letter_spacing": 0,
+      "line_spacing": 0.02,
+      "line_feed": 1,
+      "line_max_width": 0.82,
+      "force_apply_line_max_width": false,
+      "check_flag": 7,
+      "fixed_width": -1,
+      "fixed_height": -1,
+      "has_shadow": true,
+      "shadow_alpha": 0.8,
+      "shadow_color": "#000000",
+      "shadow_distance": 7,
+      "border_width": 0.07,
+      "border_color": "#000000",
+      "border_alpha": 1,
+      "has_border": true
+    }
+  },
+  "extra_materials": [
+    {
+      "type": "speeds",
+      "data": { "id": "c1b2c3d4-0004-4c04-9c04-000000000004", "type": "speed", "speed": 1, "mode": 0, "curve_speed": null }
+    },
+    {
+      "type": "placeholder_infos",
+      "data": { "id": "c1b2c3d4-0005-4c05-9c05-000000000005", "type": "placeholder_info", "error_path": "", "error_text": "", "meta_type": "none", "res_path": "", "res_text": "" }
+    },
+    {
+      "type": "sound_channel_mappings",
+      "data": { "id": "c1b2c3d4-0006-4c06-9c06-000000000006", "type": "none", "audio_channel_mapping": 0, "is_config_open": false }
+    },
+    {
+      "type": "vocal_separations",
+      "data": { "id": "c1b2c3d4-0007-4c07-9c07-000000000007", "type": "vocal_separation", "choice": 0, "enter_from": "", "final_algorithm": "", "production_path": "", "removed_sounds": [], "time_range": null }
+    }
+  ]
+}
diff --git a/templates/lower-third.json b/templates/lower-third.json
new file mode 100644
index 0000000..cf76bd7
--- /dev/null
+++ b/templates/lower-third.json
@@ -0,0 +1,79 @@
+{
+  "name": "lower-third",
+  "type": "text",
+  "segment": {
+    "id": "b1b2c3d4-0001-4b01-9b01-000000000001",
+    "material_id": "b1b2c3d4-0002-4b02-9b02-000000000002",
+    "raw_segment_id": "b1b2c3d4-0003-4b03-9b03-000000000003",
+    "target_timerange": { "start": 0, "duration": 4000000 },
+    "source_timerange": { "start": 0, "duration": 4000000 },
+    "speed": 1,
+    "volume": 1,
+    "visible": true,
+    "reverse": false,
+    "clip": {
+      "alpha": 1,
+      "rotation": 0,
+      "scale": { "x": 1, "y": 1 },
+      "transform": { "x": -0.42, "y": -0.62 },
+      "flip": { "horizontal": false, "vertical": false }
+    },
+    "render_index": 15000,
+    "track_render_index": 0,
+    "track_attribute": 0,
+    "extra_material_refs": [
+      "b1b2c3d4-0004-4b04-9b04-000000000004",
+      "b1b2c3d4-0005-4b05-9b05-000000000005",
+      "b1b2c3d4-0006-4b06-9b06-000000000006",
+      "b1b2c3d4-0007-4b07-9b07-000000000007"
+    ],
+    "common_keyframes": [],
+    "keyframe_refs": []
+  },
+  "material": {
+    "type": "texts",
+    "data": {
+      "id": "b1b2c3d4-0002-4b02-9b02-000000000002",
+      "type": "text",
+      "content": "{\"styles\":[{\"range\":[0,9],\"size\":8,\"bold\":true,\"italic\":false,\"underline\":false,\"fill\":{\"alpha\":1,\"content\":{\"render_type\":\"solid\",\"solid\":{\"alpha\":1,\"color\":[1,1,1]}}}}],\"text\":\"@handle\"}",
+      "alignment": 0,
+      "font_size": 8,
+      "text_color": "#FFFFFF",
+      "typesetting": 0,
+      "letter_spacing": 0,
+      "line_spacing": 0.02,
+      "line_feed": 1,
+      "line_max_width": 0.82,
+      "force_apply_line_max_width": false,
+      "check_flag": 7,
+      "fixed_width": -1,
+      "fixed_height": -1,
+      "has_shadow": true,
+      "shadow_alpha": 0.6,
+      "shadow_color": "#000000",
+      "shadow_distance": 4,
+      "border_width": 0.04,
+      "border_color": "#000000",
+      "border_alpha": 1,
+      "has_border": true
+    }
+  },
+  "extra_materials": [
+    {
+      "type": "speeds",
+      "data": { "id": "b1b2c3d4-0004-4b04-9b04-000000000004", "type": "speed", "speed": 1, "mode": 0, "curve_speed": null }
+    },
+    {
+      "type": "placeholder_infos",
+      "data": { "id": "b1b2c3d4-0005-4b05-9b05-000000000005", "type": "placeholder_info", "error_path": "", "error_text": "", "meta_type": "none", "res_path": "", "res_text": "" }
+    },
+    {
+      "type": "sound_channel_mappings",
+      "data": { "id": "b1b2c3d4-0006-4b06-9b06-000000000006", "type": "none", "audio_channel_mapping": 0, "is_config_open": false }
+    },
+    {
+      "type": "vocal_separations",
+      "data": { "id": "b1b2c3d4-0007-4b07-9b07-000000000007", "type": "vocal_separation", "choice": 0, "enter_from": "", "final_algorithm": "", "production_path": "", "removed_sounds": [], "time_range": null }
+    }
+  ]
+}
diff --git a/test/doctor.test.mjs b/test/doctor.test.mjs
new file mode 100644
index 0000000..cee799e
--- /dev/null
+++ b/test/doctor.test.mjs
@@ -0,0 +1,42 @@
+import assert from "node:assert/strict";
+import { describe, it } from "node:test";
+import { spawnCli } from "./helpers/spawn-cli.mjs";
+
+describe("capcut doctor", () => {
+  it("runs without a project and emits a structured report", () => {
+    const r = spawnCli(["doctor"]);
+    // Exit 0 because the test runner is Node >= 18 (the only hard requirement).
+    assert.equal(r.status, 0, `stderr: ${r.stderr}`);
+    assert.ok(r.json, "stdout should be valid JSON");
+    assert.equal(r.json.ok, true);
+    assert.equal(typeof r.json.platform, "string");
+    assert.equal(typeof r.json.node, "string");
+    assert.ok(Array.isArray(r.json.checks));
+    assert.ok(r.json.checks.length > 0);
+  });
+
+  it("reports the node check as ok on a supported runtime", () => {
+    const r = spawnCli(["doctor"]);
+    const node = r.json.checks.find((c) => c.name === "node");
+    assert.ok(node, "should include a node check");
+    assert.equal(node.status, "ok");
+  });
+
+  it("includes whisper, anthropic-api-key, and draft-dir checks with valid statuses", () => {
+    const r = spawnCli(["doctor"]);
+    const names = new Set(r.json.checks.map((c) => c.name));
+    assert.ok(names.has("whisper"));
+    assert.ok(names.has("anthropic-api-key"));
+    for (const c of r.json.checks) {
+      assert.ok(["ok", "warn", "missing"].includes(c.status), `bad status: ${c.status}`);
+    }
+  });
+
+  it("renders a human-readable layout with -H", () => {
+    const r = spawnCli(["doctor", "-H"]);
+    assert.equal(r.status, 0);
+    assert.match(r.stdout, /Platform:/);
+    assert.match(r.stdout, /Node:/);
+    assert.match(r.stdout, /whisper/);
+  });
+});
diff --git a/test/fuzz.test.mjs b/test/fuzz.test.mjs
new file mode 100644
index 0000000..4b07b45
--- /dev/null
+++ b/test/fuzz.test.mjs
@@ -0,0 +1,68 @@
+import assert from "node:assert/strict";
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { after, describe, it } from "node:test";
+import { spawnCli } from "./helpers/spawn-cli.mjs";
+
+/** Write a draft_content.json with arbitrary raw bytes; return the dir path. */
+function draftWith(raw) {
+  const dir = mkdtempSync(join(tmpdir(), "capcut-cli-fuzz-"));
+  writeFileSync(join(dir, "draft_content.json"), raw);
+  return dir;
+}
+
+// Read-only commands should never crash, hang, or leak a stack trace on bad input.
+const READ_CMDS = ["info", "version", "lint", "texts", "tracks", "segments"];
+
+const MALFORMED = {
+  "not JSON at all": "}{ this is not json",
+  "empty file": "",
+  "truncated JSON": '{"tracks": [',
+  "JSON array, not object": "[]",
+  "JSON scalar": "42",
+  "JSON null": "null",
+  "object missing tracks": '{"id": "x", "name": "y"}',
+  "tracks not an array": '{"tracks": {"nope": true}}',
+  "segment missing fields": '{"tracks": [{"segments": [{}]}]}',
+  "prototype-pollution attempt": '{"__proto__": {"polluted": true}, "tracks": []}',
+  "constructor-pollution attempt": '{"constructor": {"prototype": {"x": 1}}, "tracks": []}',
+  "deeply nested garbage": `{"tracks": ${"[".repeat(50)}${"]".repeat(50)}}`,
+};
+
+describe("fuzz: malformed draft_content.json", () => {
+  const dirs = [];
+  after(() => {
+    for (const d of dirs) rmSync(d, { recursive: true, force: true });
+  });
+
+  for (const [label, raw] of Object.entries(MALFORMED)) {
+    it(`handles "${label}" gracefully across read commands`, () => {
+      const dir = draftWith(raw);
+      dirs.push(dir);
+      for (const cmd of READ_CMDS) {
+        const r = spawnCli([cmd, dir], { timeout: 10_000 });
+        // Must terminate (not hang → status null) — either clean (0) or a handled error.
+        assert.notEqual(r.status, null, `${cmd} on "${label}" timed out / was killed`);
+        // A non-zero exit must carry a single-line JSON error on stderr, not a raw stack.
+        if (r.status !== 0) {
+          assert.doesNotMatch(r.stderr, /\n\s+at\s/, `${cmd} on "${label}" leaked a stack trace`);
+          const firstLine = r.stderr.trim().split("\n")[0];
+          assert.doesNotThrow(
+            () => JSON.parse(firstLine),
+            `${cmd} on "${label}" should report a JSON error, got: ${firstLine}`,
+          );
+        }
+      }
+    });
+  }
+
+  it("does not pollute Object.prototype when parsing a hostile draft", () => {
+    const dir = draftWith('{"__proto__": {"pwned": true}, "tracks": []}');
+    dirs.push(dir);
+    const r = spawnCli(["info", dir]);
+    assert.notEqual(r.status, null);
+    // The test process must be unaffected regardless of what the child did.
+    assert.equal({}.pwned, undefined);
+  });
+});
diff --git a/test/lib.test.mjs b/test/lib.test.mjs
new file mode 100644
index 0000000..abf6609
--- /dev/null
+++ b/test/lib.test.mjs
@@ -0,0 +1,26 @@
+import assert from "node:assert/strict";
+import { dirname, join } from "node:path";
+import { describe, it } from "node:test";
+import { fileURLToPath } from "node:url";
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const LIB = join(__dirname, "..", "dist", "lib.js");
+const FIXTURE = join(__dirname, "draft_content.json");
+
+describe("library entry point (dist/lib.js)", () => {
+  it("exports the stable core API and importing it does not run the CLI", async () => {
+    const lib = await import(LIB);
+    for (const name of ["loadDraft", "saveDraft", "lintDraft", "detectVersion", "runDoctor", "findSegment"]) {
+      assert.equal(typeof lib[name], "function", `missing export: ${name}`);
+    }
+  });
+
+  it("can load, inspect, and lint a draft programmatically", async () => {
+    const { loadDraft, lintDraft, detectVersion } = await import(LIB);
+    const { draft, filePath } = loadDraft(FIXTURE);
+    assert.ok(Array.isArray(draft.tracks));
+    assert.equal(typeof filePath, "string");
+    assert.ok(Array.isArray(lintDraft(draft)));
+    assert.ok(["CapCut", "JianYing", "unknown"].includes(detectVersion(draft).app));
+  });
+});
diff --git a/test/template.test.mjs b/test/template.test.mjs
index 1bc6cc5..2c1855f 100644
--- a/test/template.test.mjs
+++ b/test/template.test.mjs
@@ -47,7 +47,7 @@ describe("capcut save-template + apply-template", () => {
 });
 
 describe("shipped templates apply cleanly", () => {
-  for (const name of ["gold-title", "end-card", "subscribe-cta"]) {
+  for (const name of ["gold-title", "end-card", "subscribe-cta", "caption-pop", "lower-third", "hook-question"]) {
     it(`templates/${name}.json roundtrips into a fresh draft`, () => {
       const fix = tmpDraft();
       try {
diff --git a/tsconfig.json b/tsconfig.json
index 3946cf5..470dfc5 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -7,7 +7,7 @@
     "rootDir": "src",
     "strict": true,
     "esModuleInterop": true,
-    "declaration": false,
+    "declaration": true,
     "sourceMap": false
   },
   "include": ["src"]