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Magnitude is a monorepo with layered packages that power agent behavior, runtime execution, and the terminal interface.

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Package map

CLI (cli/)
  React + OpenTUI terminal interface
  ↓
Agent Core (packages/agent/)
  Team lead + subagents, execution manager, tools, projections integration
  ↓ uses
Agent Definition (packages/agent-definition/)
  Agent definitions, prompts, turn policies, model slot declarations
  ↓ uses
XML-ACT Runtime (packages/xml-act/)
  Streaming XML parser, structured tool execution, refs/composition
  ↓ uses
Tools Framework (packages/tools/)
  Tool definition + bindings
  ↓
Event Core (packages/event-core/)
  Event system primitives used across runtime/projections/workers

Agent Core also depends on:
- `packages/providers/` (provider registry, auth, models)
- `packages/llm-core/` (LLM abstraction and orchestration)
- `packages/browser-harness/` (Playwright browser automation)
- `packages/telemetry/` (anonymous usage events)
- `packages/tracing/` (tracing/debugging)

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Event-driven architecture

Magnitude is event-driven:
  • Events capture all state transitions and actions.
  • Projections derive queryable state from the event stream.
  • Workers react to events and perform side effects.
  • Signals coordinate communication between runtime components.
This architecture makes runs replayable and deterministic, and it enables robust inspection and debug workflows.

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Subagent roles

Magnitude uses a full agent taxonomy with distinct prompts and tool access:
  • Team lead: user-facing coordinator; manages delegation and conversation.
  • Explorer: codebase investigation and evidence gathering.
  • Planner: converts findings into actionable implementation plans.
  • Builder: performs concrete code changes and implementation.
  • Debugger: diagnoses failures and resolves regressions.
  • Reviewer: validates quality, risks, and completion criteria.
  • Browser: visual and web task execution using browser tooling.
These roles are defined in packages/agent/src/agents/.

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XML-ACT runtime

Magnitude agents communicate using structured XML-ACT turns with dedicated sections for reasoning, communication, and actions. Tool calls are expressed as XML elements, and composition supports referencing earlier tool outputs with query-based selection. The XML-ACT runtime in packages/xml-act/ handles streaming parse, validation, execution dispatch, and structured event emission. This is the primary runtime model for agent-tool interaction.

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Forks

Forks are parallel execution units with isolated state. Each fork maintains its own runtime context and activity stream. Subagents run as forks, allowing parallel task execution while keeping agent state scoped and auditable.

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Terminal UI

The CLI uses React with OpenTUI. It renders conversation state, tool activity, and fork and subagent progress in the terminal.