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🧠 AI Agent Architectures

To build superior AI systems, we must move beyond static, single-prompt LLM interactions and master Agentic Workflows. An AI Agent is a system where the LLM is given an instruction and autonomously executes a loop of Planning, Action, Observation, and Reflection to achieve a specific goal.


🔄 1. Agent Reasoning & Cognitive Topologies

An agent's cognitive loop defines how it decomposes problems, reasons about constraints, and selects actions.

A. Reasoning Patterns

  • Zero-Shot ReAct (Reasoning and Action): The foundational loop for modern agents. The agent alternates between a reasoning step (Thought) and execution step (Action) to observe the outcome (Observation).
  • Chain-of-Thought (CoT): Enforces step-by-step reasoning before yielding a final output, significantly reducing logic errors.
  • Plan-and-Execute: The agent drafts a complete multi-step task list before running tools. When an observation violates a plan parameter, the agent replans. Useful for long-running software engineering or complex data analysis.
  • Self-Critique & Reflection: The agent generates a draft, evaluates it against safety or format rules (such as a compiler or automated linter), and rewrites the content iteratively.
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ReAct Execution Trace:
Input: "Analyze TSLA stock and draft a summary."
  ├── 💭 Thought: I need TSLA's current stock price first.
  ├── 🛠️ Action: Call yfinance_tool(ticker="TSLA")
  ├── 👁️ Observation: Price is $182.40, down 2.1% today.
  ├── 💭 Thought: I should check market sentiment.
  ├── 🛠️ Action: Call financial_news_search(query="TSLA")
  ├── 👁️ Observation: "TSLA shares dip amid delivery worries."
  └── ✍️ Final Answer: "TSLA is trading at $182.40 (-2.1%) due to..."

🗄️ 2. Memory Architectures & State Persistence

Agents must maintain context and track system states across multiple turns or asynchronous workflow executions.

A. Short-Term Memory

  • Active Context: The immediate dialogue history loaded into the LLM's context window.
  • Context Compaction: As conversation turns grow, agents use sliding windows or summarization techniques to compress historical tokens, keeping core instructions within context bounds.

B. Long-Term Memory

  • Semantic Memory (Vector DB): Stored embeddings in database tables (e.g. PostgreSQL with pgvector). The agent queries databases via cosine-similarity to retrieve relevant document segments. For implementation mechanics, see Vector Memory & Hybrid Databases (M06).
  • Episodic Memory: Records of past task outcomes. By tracking errors and successful parameters from previous cycles, the agent avoids repeat failures.
  • Entity Relation Graph Memory: Storing structured nodes and relationships (e.g. User -> WorksAt -> Company) to maintain semantic connections across long periods.

👥 3. Orchestration Topologies: Single-Agent vs. Multi-Agent

For complex workflow automations, a single agent model becomes bottlenecked by context limits and tool parameters. We delegate tasks to a team of specialized agents working in concert:

A. Orchestration Patterns

  • Hierarchical (Supervisor/Workers): A manager agent takes user inputs, decomposes them, delegates tasks to specialized worker agents, and reviews their outputs before final compilation. See implementations in [CrewAI Framework](../CrewAI Framework.md) and [Google ADK](../Google ADK.md).
  • Sequential Pipelines: Tasks flow in a linear path where one agent's output becomes the input for the next.
  • Choreography (State Machine Graphs): Agents pass messages dynamically based on transition rules. This cyclical routing is the pattern implemented in LangGraph, where each agent is a node, and the transition rules are conditional edges. For details, see Stateful Multi-Agent Graphs (M11).

🛡️ 4. Production Engineering & Safety Envelopes

To make agentic systems robust, self-healing, and safe for production workloads, we implement structural safety parameters:

  1. Strict JSON Output Guarantees: Force models to output structured data schemas. We use Pydantic v2 or Instructor to validate arguments and reject malformed JSON. See Structured Outputs & Type Safety (M05).
  2. Graceful Self-Healing Loop: If a tool fails (e.g. database times out), the error message should be returned back to the agent as the Observation. The model parses the traceback, determines a remediation path, and executes a different tool or command.
  3. Human-in-the-Loop (HITL) Gates: For high-risk actions (sending emails, executing financial transactions), the agent halts its process and triggers an approval webhook. See [Docker & n8n Services](../Docker & n8n Services.md).
  4. Runtime Sandboxing: Restrict execution boundaries by running subprocesses and skills inside isolated containers or lightweight virtual machines to safeguard host resources.