Context

A3S Code treats context as a budgeted resource. The model should see the smallest useful context for the current decision, not every available file, skill, memory, and tool log.

Sources

Context can come from:

• user prompt and conversation history
• AGENTS.md project instructions
• skills and agent definitions
• memory stores
• file search and direct tool results
• MCP tools and context providers
• AHP harness responses
• delegated task summaries
• trace events

AGENTS.md injection, skills discovery, memory APIs, direct tool results, delegated task helpers, and traceEvents() are part of the documented Node SDK surface. Validate MCP/AHP context behavior against your own live integrations before documenting it as product behavior.

Assembly

sources -> ContextItem -> rank -> dedupe -> budget -> render

Long grep output, logs, and child transcripts should be preserved outside the prompt and summarized into prompt-safe evidence. Use session.traceEvents() for compact runtime evidence.

Compaction

Enable automatic compaction for long sessions:

const session = agent.session('/repo', {
  autoCompact: true,
  autoCompactThreshold: 0.75,
});

Validate the exact compaction behavior for any product workflow that depends on it.