ART Framework API Docs
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    Class SystemPromptResolver

    Default implementation of ISystemPromptResolver interface.

    This class manages the resolution and merging of system prompts across multiple levels:

    1. Base prompt - The fundamental system instruction from agent persona or framework defaults
    2. Instance-level override - Global configuration applied to all threads in an ART instance
    3. Thread-level override - Configuration specific to a single conversation thread
    4. Call-level override - Configuration for a specific LLM call

    Each level can provide either:

    • A preset tag that references a template from SystemPromptsRegistry
    • Freeform content that is directly used

    The resolution process:

    1. Starts with the base prompt
    2. Applies instance-level override (if provided)
    3. Applies thread-level override (if provided)
    4. Applies call-level override (if provided)

    At each level, the override is:

    • Rendered from a template if a tag is specified (with variable substitution)
    • Used directly if freeform content is provided
    • Applied using the specified merge strategy (append or prepend)

    Template rendering supports:

    • Simple variable interpolation: {{variableName}}
    • Prompt fragment references: {{fragment:name}}
    const resolver = new SystemPromptResolver({
      specs: {
        'default': {
          template: 'You are {{name}}. Be {{tone}}.',
          defaultVariables: { name: 'AI Assistant', tone: 'helpful' }
        },
        'expert': {
          template: 'You are an expert in {{topic}}.',
          mergeStrategy: 'prepend'
        }
      },
      defaultTag: 'default'
    });

    const result = await resolver.resolve({
      base: 'System: You are helpful.',
      instance: { tag: 'expert', variables: { topic: 'physics' } },
      thread: { tag: 'default', strategy: 'append' }
    }, 'trace-123');
    // Result combines: base + expert (prepended) + default (appended)

    SystemPromptResolver

    ISystemPromptResolver

    Implements

    • SystemPromptResolver
    Index

    Constructors

    constructor

    Methods

    resolve

    Constructors

    Methods

    • Resolves the final system prompt by applying overrides in precedence order.

      Parameters

      • input: {
            base: string;
            call?: string | SystemPromptOverride;
            instance?: string | SystemPromptOverride;
            thread?: string | SystemPromptOverride;
        }

        Object containing the base prompt and optional overrides at each level. - base (string): The fundamental system prompt (required) - instance (string | SystemPromptOverride): Instance-level override - thread (string | SystemPromptOverride): Thread-level override - call (string | SystemPromptOverride): Call-level override

      • OptionaltraceId: string

        Optional trace identifier for logging and debugging purposes.

      Returns Promise<string>

      A promise resolving to the final, resolved system prompt string.

      The resolution process follows this precedence hierarchy (highest to lowest):

      1. Call-level override (immediate, most specific)
      2. Thread-level override (conversation-specific)
      3. Instance-level override (instance-wide)
      4. Base prompt (default)

      For each override level:

      • If a tag is provided and exists in registry: Render the template
      • If freeform content is provided: Use it directly
      • Apply using the specified merge strategy (defaults to 'append')
      • Variables for template rendering come from defaultVariables merged with provided variables

      Template variable substitution:

      • Variables are wrapped in double braces: {{variableName}}
      • Supports fragment references: {{fragment:name}} (for PromptManager integration)
      • Missing variables render as empty strings

      Merge strategies:

      • 'append': Adds content to the end of existing prompt (default)
      • 'prepend': Adds content to the beginning of existing prompt

      Note: 'replace' strategy is intentionally unsupported to prevent custom prompts from overriding framework-required structural contracts.

      const result = await resolver.resolve({
        base: 'You are a helpful AI.',
        instance: {
          tag: 'technical',
          variables: { specialization: 'web development' }
        },
        thread: { content: 'Be concise in your responses.' }
      }, 'trace-123');

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