deepseek-harness/packages/core/system-prompt

dsh-system-prompt

System prompt assembly registry. Plugins contribute ordered text sections and tool-schema providers; the agent loop calls assemble() once per step.

Service: SystemPrompt (ctx key: systemPrompt)

Public API

• ctx.systemPrompt.section(section: PromptSection): () => void Contribute a section. Disposed with the calling fiber.
• ctx.systemPrompt.tools(provider: () => ToolSchema[]): () => void Contribute tool schemas (evaluated at each assembly). Disposed with the calling fiber.
• ctx.systemPrompt.assemble(): Promise<PromptAssembly> Assemble the current prompt. Runs through the system-prompt/assemble waterfall.

Events

Event	Mode	Purpose
system-prompt/assemble	waterfall	Mutate/extend the assembly before it reaches the model
system-prompt/change	emit	A section or tool provider was registered or unregistered

Key types

• PromptSection — { name, order, text: string | (() => string) }. Sections are concatenated in ascending order.
• PromptAssembly — { sections: PromptSection[], tools: ToolSchema[] }. Tool schemas are part of the assembly by design: "what the model is told it can do" is one coherent thing, even though adapters transmit schemas as a separate wire field.
• renderPrompt(assembly) — joins section texts with blank lines.

Merge-extensible: plugins can declare extra fields on PromptAssembly via declaration merging.

Extension points

• Section providers: AGENTS.md reader, cwd notifier, persona config, etc.
• Tool schema providers: ToolRegistry registers itself as a tool provider automatically.
• The system-prompt/assemble waterfall: mutate or replace the assembly (system-prompt configurability, dynamic tool filtering).

What is NOT here

• Any hardcoded prompt text — every section comes from plugins.
• Prompt compaction (belongs on the agent/request seam in dsh-agent).