System Prompt

System Prompt

Edge adaptation of the upstream system prompt assembly pipeline.

Upstream reference: System Prompt

What Upstream Provides

The system prompt subsystem (ctx.systemPrompt) manages a cooperative assembly pipeline where multiple plugins contribute ordered sections that combine into the final system prompt sent to the model.

• Section registry — plugins register named sections with a numeric order. Convention: -100 for harness identity, 0 for deployment persona, 100–199 for tool guidance.
• Assembly waterfall — assemble() gathers global and scoped providers, sorts by order, resolves dynamic text, and produces the final prompt.
• Persona — the deployment-level identity section at order 0, set via plugin config.
• Change notifications — emitted when any provider changes, triggering re-assembly for the next turn.

What Edge Changed

SystemPrompt plugin

SystemPrompt is installed as-is. The section registry, assembly waterfall, change notifications, and tool schema integration are entirely upstream code.

EDGE_SYSTEM_PROMPT

Edge provides its own persona string at order 0:

You are dsh-edge, a coding agent running in a Cloudflare Worker.
Use the bash tool when you need to inspect or modify workspace files,
then answer with the result. Each session has a persistent working
directory that the bash tool defaults to.
The shell is just-bash, not Linux: native binaries and background
processes are unavailable.

This tells the model three critical things about the Edge environment: (1) it's a Cloudflare Worker, (2) the workspace is persistent across turns, (3) the shell is just-bash with no native binaries. Without this, the model would attempt apt-get, pip install, or other Linux commands that don't exist in the Edge runtime.

Plugin sections

Upstream tool plugins inject their own sections on top of the persona via the standard ctx.systemPrompt.section() API:

| Section | Order | Plugin | Content|

tool:read	100	ToolFs	Use read tool, not cat. Results include line numbers.
tool:write	101	ToolFs	Use write to create/replace files. Read first.
---	---	---	---
tool:edit	102	ToolFs	Use edit for targeted changes. old_string must be unique.
---	---	---	---
tool:web_search	110	ToolWeb	Search guidance. Adapts text based on fetch availability.
---	---	---	---
tool:goal	114	ToolGoal	Goal creation policy, round limits, blocked threshold.

Edge does not modify any of these sections. They register themselves when their plugins are installed and unregister when plugins are disposed.

What Edge Did NOT Change

• Section registry, ordering, and assembly waterfall
• Tool schema integration and knownNames visibility filtering
• Change notification and re-assembly triggers
• Compression integration (snapshots only record when content differs)
• All upstream tool guidance sections

Performance Characteristics

Prompt token budget

The assembled system prompt consumes a fixed token budget on every turn. Edge's persona is short (~60 tokens). Each tool section adds 20–50 tokens. With all current plugins (bash, read, write, edit, web_search, goal), the total system prompt is approximately 300–400 tokens — well within DeepSeek's context window.

Assembly cost

Assembly runs once per turn start, sorting registered sections and resolving dynamic text. With ~6 sections, this is sub-millisecond. The result is cached until a provider changes.

Architecture Summary

| Component | Category | Edge Code|

SystemPrompt plugin		One ctx.plugin() call
EDGE_SYSTEM_PROMPT persona		5-line string in agent.ts
---	---	---
Tool guidance sections		Auto-registered by upstream plugins

Key observation: Edge's only customization is a 5-line persona string that describes the Cloudflare runtime environment. Everything else — section ordering, assembly pipeline, tool guidance, change notifications — is upstream code. The persona is the smallest possible adapter: it tells the model what's different about this deployment without reimplementing any prompt logic.

TODO

Update persona for 0.7.x capabilities. (#106) The current persona only mentions bash and workspace. It should describe file tools (read/write/edit), goal tracking, and web search. While these tools register their own sections via ctx.systemPrompt.section(), the persona overview at order 0 gives outdated advice ("Use the bash tool when you need to inspect or modify workspace files").

系统提示词

上游系统提示词组装管线在 Edge 中的适配。

上游参考：System Prompt

上游提供了什么

系统提示词子系统（ctx.systemPrompt）管理一个协作组装管线，多个插件贡献有序的段落，合并为发送给模型的最终系统提示词。

• 段落注册表 — 插件注册命名段落，带数字排序。约定：-100 为 harness 身份，0 为部署 persona，100–199 为工具指导。
• 组装瀑布 — assemble() 收集全局和作用域提供者，按顺序排列，解析动态文本，生成最终提示词。
• Persona — 部署级身份段落，排序 0，通过插件配置设置。
• 变更通知 — 任何提供者变更时发出，触发下一轮的重新组装。

Edge 改了什么

SystemPrompt 插件

SystemPrompt 原封安装。段落注册表、组装瀑布、变更通知和工具 schema 集成完全是上游代码。

EDGE_SYSTEM_PROMPT

Edge 提供自己的 persona 字符串（排序 0）：

You are dsh-edge, a coding agent running in a Cloudflare Worker.
Use the bash tool when you need to inspect or modify workspace files,
then answer with the result. Each session has a persistent working
directory that the bash tool defaults to.
The shell is just-bash, not Linux: native binaries and background
processes are unavailable.

这告诉模型三件关于 Edge 环境的关键信息：(1) 运行在 Cloudflare Worker 上，(2) workspace 跨 turn 持久，(3) shell 是 just-bash，没有原生二进制。没有这个，模型会尝试 apt-get、pip install 等 Edge 运行时不存在的 Linux 命令。

插件段落

上游工具插件通过标准 ctx.systemPrompt.section() API 在 persona 之上注入自己的段落：

| 段落 | 排序 | 插件 | 内容|

tool:read	100	ToolFs	用 read 工具，不用 cat。结果含行号。
tool:write	101	ToolFs	用 write 创建/替换文件。先读取。
---	---	---	---
tool:edit	102	ToolFs	用 edit 做定向修改。old_string 必须唯一。
---	---	---	---
tool:web_search	110	ToolWeb	搜索指导。根据 fetch 可用性调整文本。
---	---	---	---
tool:goal	114	ToolGoal	目标创建策略、轮次限制、阻塞阈值。

Edge 不修改这些段落。它们在插件安装时自动注册，插件卸载时自动取消。

Edge 没有改什么

• 段落注册表、排序和组装瀑布
• 工具 schema 集成和 knownNames 可见性过滤
• 变更通知和重新组装触发
• 压缩集成（快照仅在内容变化时记录）
• 所有上游工具指导段落

性能特征

提示词 token 预算

组装后的系统提示词在每轮消耗固定的 token 预算。Edge persona 很短（约 60 token）。每个工具段落增加 20–50 token。当前所有插件（bash、read、write、edit、web_search、goal）的总系统提示词约 300–400 token——远在 DeepSeek 上下文窗口之内。

组装开销

组装在每轮开始时运行一次，排序已注册段落并解析动态文本。约 6 个段落，亚毫秒完成。结果缓存直到提供者变更。

架构总结

| 组件 | 分类 | Edge 代码|

SystemPrompt 插件		一行 ctx.plugin() 调用
EDGE_SYSTEM_PROMPT persona		agent.ts 中的 5 行字符串
---	---	---
工具指导段落		上游插件自动注册

关键观察：Edge 唯一的定制是一个 5 行的 persona 字符串，描述了 Cloudflare 运行时环境。其他一切——段落排序、组装管线、工具指导、变更通知——都是上游代码。persona 是最小的适配件：告诉模型这个部署有什么不同，不重新实现任何提示词逻辑。

TODO

更新 persona 以反映 0.7.x 能力。（#106）当前 persona 只提到了 bash 和 workspace，应该描述文件工具（read/write/edit）、目标追踪和 web 搜索。虽然这些工具通过 ctx.systemPrompt.section() 注册了自己的策略段，但 order 0 的 persona 概述给出了过时的建议（"Use the bash tool when you need to inspect or modify workspace files"）。