Task State Machine

A todo lifecycle pattern that enforces structured task workflow: pending → active → done → verified. Tasks are tracked in a structured list. Present in ~40% of tools (~21/52), preventing half-finished work and providing session continuity.

Lifecycle (confidence: high)

1. Pending — Task identified but not started
2. Active — Task being worked on
3. Done — Implementation complete
4. Verified — Explicit confirmation that completion criteria are met

Some tools require explicit verification before marking done, adding a quality gate.

Tools Using This Pattern (confidence: high)

Claude Code, Cline, RooCode, Manus, Devin, Codex CLI (2025). RooCode’s 5-mode architecture is the most sophisticated — each mode (Code, Architect, Ask, Debug, Custom) has its own per-mode state machine with specialized workflows.

Co-occurrence (confidence: high)

Task state machines frequently appear alongside chain-of-thought-pattern (CoT provides reasoning for each state transition) and plan-before-implement-gate (the gate triggers state transitions).

Implications: The task state machine is the operational backbone of autonomous agents. It transforms LLM behavior from reactive (answer a question) to proactive (execute a multi-step workflow). The verified-pending transition is the most important quality gate — without explicit verification, the LLM may mark tasks done prematurely. RooCode’s per-mode state machines represent the current frontier of this pattern.

See also: chain-of-thought-pattern, plan-before-implement-gate, multi-file-agent-architecture

Sources

• [raw/prompts/articles/taxonomy-synthesis-2026-07-16.md]