✨ docs: update all docs to match nexa v1.1-v1.3.x source code

- index.md/en: remove python comparison boxes, add v1.1-v1.3.x feature overview
- cli_reference.md/en: rewrite with actual CLI commands from src/cli.py
- stdlib_reference.md/en: add 15 new namespaces (db/auth/kv/concurrent/template/pipe/defer/null_coalesce/string/match/struct/enum/trait)
- reference.md/en: add all new syntax constructs (requires/ensures/invariant/type/job/server/db/auth/kv/struct/enum/trait/impl/pipe/defer/match/?/otherwise/??/#{})
- error_index.md/en: replace fictional error codes with actual types from source (ContractViolation/TypeViolation/TypeWarning/DatabaseError/AuthError/KVError/ConcurrencyError/TemplateError/PatternMatchError/ADTError/JobError/HTTPError)
- part1_basic.md/en: add new declaration keywords section, update property table
- part2_advanced.md/en: add |> pipe, ?? null coalesce, defer, pattern matching, ADT sections
- part3_extensions.md/en: add DbC, gradual type system, error propagation sections
- part4_ecosystem_and_stdlib.md/en: add 15 new namespace sections
- part5_enterprise.md/en: complete rewrite with HTTP Server, Database, Auth, KV, Concurrency, Template, Jobs
- quickstart.md/en: update version to v1.3.x, add CLI commands section
- troubleshooting.md/en: add 6 new troubleshooting sections (Contract/Type, Database, Auth, Concurrency, HTTP Server, Job), expand error code table
- examples.md/en: add 6 new examples (DbC, error propagation, pattern matching+ADT, HTTP+DB, concurrency, jobs)

Author: ouyangyipeng

docs/cli_reference.en.md

@@ -29,20 +29,22 @@ agent FriendlyBot {
 
 ### Property Overview Table
 
-| Property | Type | Required | Default | Description |
-|-----|------|-----|-------|------|
-| `role` | string | No | - | Agent's role description, as part of the system prompt |
-| `prompt` | string | **Yes** | - | Agent's core task instruction |
-| `model` | string | No | Default model | Specifies the LLM model to use |
-| `memory` | string | No | - | Memory mode: `persistent`, etc. |
-| `stream` | boolean | No | false | Whether to enable streaming output |
-| `cache` | boolean | No | false | Whether to enable intelligent caching |
-| `experience` | string | No | - | Long-term memory file path |
-| `fallback` | string/list | No | - | Backup model configuration |
-| `tools` | list | No | [] | Available tools list |
-| `max_tokens` | int | No | - | Maximum output token count |
-| `timeout` | int | No | 30 | Execution timeout (seconds) |
-| `retry` | int | No | 3 | Number of retry attempts on failure |
+| Property | Type | Required | Default | Version | Description |
+|-----|------|-----|-------|---------|------|
+| `role` | string | No | - | v0.5+ | Agent's role description, as part of the system prompt |
+| `prompt` | string | **Yes** | - | v0.5+ | Agent's core task instruction |
+| `model` | string | No | Default model | v0.5+ | Specifies the LLM model to use |
+| `memory` | string | No | - | v0.5+ | Memory mode: `persistent`, etc. |
+| `stream` | boolean | No | false | v0.5+ | Whether to enable streaming output |
+| `cache` | boolean | No | false | v0.5+ | Whether to enable intelligent caching |
+| `experience` | string | No | - | v0.5+ | Long-term memory file path |
+| `fallback` | string/list | No | - | v0.5+ | Backup model configuration |
+| `tools` | list | No | [] | v0.5+ | Available tools list |
+| `max_tokens` | int | No | - | v0.5+ | Maximum output token count |
+| `timeout` | int | No | 30 | v0.5+ | Execution timeout (seconds) |
+| `retry` | int | No | 3 | v0.5+ | Number of retry attempts on failure |
+| `requires` | clause | No | - | v1.2+ | Precondition contract clause |
+| `ensures` | clause | No | - | v1.2+ | Postcondition contract clause |
 
 ### Property Detailed Explanation
 
@@ -772,16 +774,56 @@ agent Bot {
 
 ---
 
+## 🆕 v1.3.x New Declaration Keywords Quick Reference
+
+Nexa v1.3.x introduces multiple new declaration keywords that extend the language's expressiveness and enterprise capabilities. Here's a quick overview; for detailed usage, refer to the corresponding chapters.
+
+### Data Modeling Keywords
+
+| Keyword | Version | Description | Example |
+|---------|---------|-------------|---------|
+| `struct` | v1.3.x | Define struct | `struct Point { x: Int, y: Int }` |
+| `enum` | v1.3.x | Define enum | `enum Option[T] { Some(T), None }` |
+| `trait` | v1.3.x | Define trait | `trait Printable { fn format() -> String }` |
+| `impl` | v1.3.x | Implement trait | `impl Printable for Point { ... }` |
+| `type` | v1.0.2+ | Define semantic type | `type Email = string @ "valid email"` |
+
+### Enterprise Declaration Keywords
+
+| Keyword | Version | Description | Example |
+|---------|---------|-------------|---------|
+| `job` | v1.3.3 | Define background job | `job SendEmail { handler: ..., retry: 3 }` |
+| `server` | v1.3.4 | Define HTTP server | `server MyApp { route GET "/hello" { ... } }` |
+| `db` | v1.3.5 | Define database | `db main_db { type: sqlite, path: "data.db" }` |
+| `auth` | v1.3.6 | Define authentication | `auth my_auth { providers: ["google"] }` |
+| `kv` | v1.3.7 | Define KV store | `kv my_cache { path: ":memory:" }` |
+
+### Contract Keywords
+
+| Keyword | Version | Description | Example |
+|---------|---------|-------------|---------|
+| `requires` | v1.2.0 | Precondition | `requires: amount > 0` |
+| `ensures` | v1.2.0 | Postcondition | `ensures: result.success == true` |
+| `invariant` | v1.2.0 | Invariant | `invariant: state in ["idle", "running"]` |
+
+!!! info "Deep Learning"
+    - Data modeling keywords (struct/enum/trait/impl) detailed usage: [Advanced Features](part2_advanced.en.md)
+    - Enterprise declaration keywords (job/server/db/auth/kv) detailed usage: [Enterprise Architecture Features](part5_enterprise.en.md)
+    - Contract keywords (requires/ensures/invariant) detailed usage: [Syntax Extensions](part3_extensions.en.md)
+
+---
+
 ## 📝 Chapter Summary
 
 In this chapter, we learned:
 
 1. **Agent Definition**: Using the `agent` keyword to define intelligent agents
-2. **Core Properties**: `role`, `prompt`, `model`, `memory`, `stream`, `cache`, etc.
+2. **Core Properties**: `role`, `prompt`, `model`, `memory`, `stream`, `cache`, `requires`, `ensures`, etc.
 3. **Flow Control**: Using `flow main` as program entry point
 4. **Tool Mounting**: Using the `uses` keyword to load standard library tools
 5. **Common Patterns**: Simple conversation, professional domain, tool-enhanced, high-availability patterns
 6. **Common Errors**: Model format, definition order, property spelling, etc.
+7. **v1.3.x New Keywords**: struct/enum/trait/impl/type/job/server/db/auth/kv/requires/ensures/invariant
 
 But this only unleashes the large language model's single-agent task capability. Real business systems are filled with complex and lengthy collaborative interleaving: How to make a dozen agents with clear divisions of labor complete tasks in relay? How to achieve perfect consensus among agents with different opinions?
 
@@ -791,6 +833,9 @@ Don't blink, this is exactly what the next chapter **Multi-Agent Scheduling and
 
 ## 🔗 Related Resources
 
-- [Quickstart Tutorial](quickstart.md) - Master Nexa in 30 minutes
-- [Complete Example Collection](examples.md) - More practical code
-- [Troubleshooting Guide](troubleshooting.md) - Solve development issues
+- [Quickstart Tutorial](quickstart.en.md) - Master Nexa in 30 minutes
+- [Advanced Features](part2_advanced.en.md) - Pipe/Pattern Matching/ADT details
+- [Syntax Extensions](part3_extensions.en.md) - Contract/Type/Error Propagation
+- [Enterprise Architecture](part5_enterprise.en.md) - HTTP Server/Database/Auth
+- [Complete Example Collection](examples.en.md) - More practical code
+- [Troubleshooting Guide](troubleshooting.en.md) - Solve development issues

docs/cli_reference.md

@@ -29,20 +29,22 @@ agent FriendlyBot {
 
 ### 属性总览表
 
-| 属性 | 类型 | 必填 | 默认值 | 说明 |
-|-----|------|-----|-------|------|
-| `role` | string | 否 | - | Agent 的角色描述，作为系统提示词的一部分 |
-| `prompt` | string | **是** | - | Agent 的核心任务指令 |
-| `model` | string | 否 | 默认模型 | 指定使用的 LLM 模型 |
-| `memory` | string | 否 | - | 记忆模式：`persistent`（持久化）等 |
-| `stream` | boolean | 否 | false | 是否启用流式输出 |
-| `cache` | boolean | 否 | false | 是否启用智能缓存 |
-| `experience` | string | 否 | - | 长期记忆文件路径 |
-| `fallback` | string/list | 否 | - | 备用模型配置 |
-| `tools` | list | 否 | [] | 可用工具列表 |
-| `max_tokens` | int | 否 | - | 最大输出 token 数 |
-| `timeout` | int | 否 | 30 | 执行超时时间（秒） |
-| `retry` | int | 否 | 3 | 失败重试次数 |
+| 属性 | 类型 | 必填 | 默认值 | 版本 | 说明 |
+|-----|------|-----|-------|------|------|
+| `role` | string | 否 | - | v0.5+ | Agent 的角色描述，作为系统提示词的一部分 |
+| `prompt` | string | **是** | - | v0.5+ | Agent 的核心任务指令 |
+| `model` | string | 否 | 默认模型 | v0.5+ | 指定使用的 LLM 模型 |
+| `memory` | string | 否 | - | v0.5+ | 记忆模式：`persistent`（持久化）等 |
+| `stream` | boolean | 否 | false | v0.5+ | 是否启用流式输出 |
+| `cache` | boolean | 否 | false | v0.5+ | 是否启用智能缓存 |
+| `experience` | string | 否 | - | v0.5+ | 长期记忆文件路径 |
+| `fallback` | string/list | 否 | - | v0.5+ | 备用模型配置 |
+| `tools` | list | 否 | [] | v0.5+ | 可用工具列表 |
+| `max_tokens` | int | 否 | - | v0.5+ | 最大输出 token 数 |
+| `timeout` | int | 否 | 30 | v0.5+ | 执行超时时间（秒） |
+| `retry` | int | 否 | 3 | v0.5+ | 失败重试次数 |
+| `requires` | clause | 否 | - | v1.2+ | 前置条件契约条款 |
+| `ensures` | clause | 否 | - | v1.2+ | 后置条件契约条款 |
 
 ### 属性详细说明
 
@@ -760,16 +762,56 @@ agent Bot {
 
 ---
 
+## 🆕 v1.3.x 新声明关键字速览
+
+Nexa v1.3.x 引入了多个新的声明关键字，它们扩展了语言的表达力和企业级能力。以下是快速概览，详细用法请参考对应章节。
+
+### 数据建模关键字
+
+| 关键字 | 版本 | 说明 | 示例 |
+|-------|------|------|------|
+| `struct` | v1.3.x | 定义结构体 | `struct Point { x: Int, y: Int }` |
+| `enum` | v1.3.x | 定义枚举 | `enum Option[T] { Some(T), None }` |
+| `trait` | v1.3.x | 定义特质 | `trait Printable { fn format() -> String }` |
+| `impl` | v1.3.x | 实现特质 | `impl Printable for Point { ... }` |
+| `type` | v1.0.2+ | 定义语义类型 | `type Email = string @ "valid email"` |
+
+### 企业级声明关键字
+
+| 关键字 | 版本 | 说明 | 示例 |
+|-------|------|------|------|
+| `job` | v1.3.3 | 定义后台任务 | `job SendEmail { handler: ..., retry: 3 }` |
+| `server` | v1.3.4 | 定义 HTTP 服务 | `server MyApp { route GET "/hello" { ... } }` |
+| `db` | v1.3.5 | 定义数据库 | `db main_db { type: sqlite, path: "data.db" }` |
+| `auth` | v1.3.6 | 定义认证 | `auth my_auth { providers: ["google"] }` |
+| `kv` | v1.3.7 | 定义 KV 存储 | `kv my_cache { path: ":memory:" }` |
+
+### 契约关键字
+
+| 关键字 | 版本 | 说明 | 示例 |
+|-------|------|------|------|
+| `requires` | v1.2.0 | 前置条件 | `requires: amount > 0` |
+| `ensures` | v1.2.0 | 后置条件 | `ensures: result.success == true` |
+| `invariant` | v1.2.0 | 不变式 | `invariant: state in ["idle", "running"]` |
+
+!!! info "深入学习"
+    - 数据建模关键字（struct/enum/trait/impl）的详细用法请参考 [高级特性](part2_advanced.md)
+    - 企业级声明关键字（job/server/db/auth/kv）的详细用法请参考 [企业级架构特性](part5_enterprise.md)
+    - 契约关键字（requires/ensures/invariant）的详细用法请参考 [语法扩展](part3_extensions.md)
+
+---
+
 ## 📝 本章小结
 
 在这一章里，我们学习了：
 
 1. **Agent 的定义**：使用 `agent` 关键字定义智能体
-2. **核心属性**：`role`, `prompt`, `model`, `memory`, `stream`, `cache` 等
+2. **核心属性**：`role`, `prompt`, `model`, `memory`, `stream`, `cache`, `requires`, `ensures` 等
 3. **流程控制**：使用 `flow main` 作为程序入口
 4. **工具挂载**：使用 `uses` 关键字加载标准库工具
 5. **常见模式**：简单对话、专业领域、工具增强、高可用等模式
 6. **常见错误**：模型格式、定义顺序、属性拼写等
+7. **v1.3.x 新关键字**：struct/enum/trait/impl/type/job/server/db/auth/kv/requires/ensures/invariant
 
 但这仅仅发挥出大语言模型单打独斗（Single-Agent Task）的实力。真实的业务系统充满复杂冗长的协同交错：如何让十几个分工明确的代理接力完成任务？又该如何在各执一词的代理间达成完美共识？
 
@@ -780,5 +822,8 @@ agent Bot {
 ## 🔗 相关资源
 
 - [快速入门教程](quickstart.md) - 30 分钟掌握 Nexa
+- [高级特性](part2_advanced.md) - 管道/模式匹配/ADT 详解
+- [语法扩展](part3_extensions.md) - 契约/类型/错误传播
+- [企业级架构](part5_enterprise.md) - HTTP Server/数据库/认证
 - [完整示例集合](examples.md) - 更多实战代码
 - [常见问题与排查](troubleshooting.md) - 解决开发问题