How an Agent Decides

Session 1.2 — classic vs. generative orchestration, the three control layers for agent autonomy, and why the GitHub Copilot harness skips the toggle entirely.

Group 1 · Session 1.2 of the Copilot Studio course. Full plan on the Mission page. Follows What's Copilot Studio?.

Session 1.1 sorted your agent into a harness. This session opens the box: what actually happens between a user's message and the agent's response — and who's allowed to decide what.

Two different decision-makers

The standard harness makes you choose, per agent, between two ways of deciding how to respond. It's a real toggle on the agent's Settings page, not a conceptual distinction — you'll flip it yourself in Session 2. The GitHub Copilot harness doesn't give you that toggle at all, and that absence is the more interesting fact, covered at the end of this lesson.

Classic orchestration: match and script

Classic is the older, fully scripted model. The agent compares the user's message against the trigger phrases you wrote for each topic, picks the closest match, and runs that topic's steps exactly as you built them: question nodes to ask for input, message nodes to reply. If nothing matches, it falls back to knowledge search, and if that fails too, it escalates. Nothing here is generated on the fly — you authored every sentence the agent can say.

Generative orchestration: plan and compose

Generative is the default for every newly created standard-harness agent. Instead of matching phrases, an LLM-driven planner reads the topic, tool, knowledge source, and connected-agent descriptions you wrote, decides which are relevant to the request, and can call several of them in one turn. Ask a Northwind agent "what's your return window, and can you check on order 4471" and it doesn't pick one topic — it runs the return-policy topic and the order-status tool in the same turn, then writes one combined reply itself.

Behavior	Generative orchestration	Classic orchestration
Picks a topic by	Matching its description to the request	Matching trigger phrases
Can combine sources	Yes — topics, tools, knowledge, other agents in one turn	No — one topic, knowledge only as fallback
Asks for missing info	Generates the question itself	You author a question node
Writes the reply	Generates it from whatever it gathered	You author a message node

The cost of that flexibility is that descriptions, not trigger phrases, are now the thing you're actually authoring. A vaguely named tool ("Flow1", description "does the thing") is invisible to the planner in exactly the way a topic with no trigger phrases was invisible under classic — just for a different reason. Session 2 is largely about writing descriptions well.

What's underneath the planner

Microsoft's own architecture guidance names five moving parts, and it's worth knowing them by name before you start building, since you'll be authoring four of them directly over the next several sessions.

Component	Role	You build this in
Orchestrator (planner)	Turns a message or event into an ordered plan of steps	Configured by your instructions, not hand-built
Knowledge layer	Read-only retrieval — documents, sites, databases	Group 3
Tools and connectors	Actions the agent can call, with defined inputs/outputs	Group 4
Topics and inline agents	Reusable conversation logic, invoked by description	Group 2
Event triggers	Start a plan without a user message at all	Group 5 — this is autonomy

Deciding how much the agent gets to decide

This is the part of the architecture that connects straight back to my own essay. Giving an agent generative orchestration doesn't mean giving it unlimited judgment — Microsoft's guidance is explicit that production agents split decisions across three layers, and picking the right layer per action is a design decision you make, not something the platform infers for you.

Deterministic layer — rule-based, scripted, no AI interpretation. For anything mission-critical or irreversible — processing a payment, deleting a record — you wrap it in a strictly authored flow the planner can't improvise around.

Hybrid (intercept) layer — the agent can draft or act, but a checkpoint exists: a manager reviews before it sends, or the agent must escalate past a set value. Medium-risk work — let the AI do the labor, keep a human at the gate.

AI orchestrator layer — fully generative, within policy. Most Q&A and simple multistep lookups live here — low-risk enough that the agent can decide and act without asking permission every time.

Put in my terms: this is Copilot Studio building in a gate between "the agent tried something" and "the agent is trusted to have tried it unsupervised." A library doesn't need this — a library can't do damage by being wrong out loud. The moment an agent can act, I inherit the same judgment call my essay makes about skill: repetition and failure are how competence gets proven, and you don't hand over the consequential decisions until it's been proven, watched, and bounded.

Hook points, if you need to intervene mid-plan

Three triggers exist specifically for generative orchestration, letting you step into the planner's process rather than just configuring it upfront:

Trigger	Fires	Typical use
OnKnowledgeRequested	Right before a knowledge search runs	Route the query to your own search index instead
AI Response Generated	After the draft reply is written, before it's sent	Fix formatting, swap in tracked links, redact something
On Plan Complete	After every step finished and the answer went out	Trigger a survey or an end-of-chat topic

And the GitHub Copilot harness just doesn't ask

Here's the fact worth sitting with from Session 1.1: on the standard harness, generative vs. classic is a setting you control. On the GitHub Copilot harness, there's no such setting. Microsoft's own documentation states it plainly — that harness "uses this enhanced orchestration model for all agents," full stop. You don't author topics or branching logic there at all; you describe the agent in natural language and the reasoning runtime figures out the plan every time, with a fixed lifecycle of Create → Build → Test (Preview and Evaluate tabs) → Publish → Monitor.

Confirms a prediction from 1.1: Session 1.1 guessed the GitHub Copilot harness has "no configurable orchestration mode — it's fixed to the enhanced reasoning runtime." Microsoft's docs confirm that directly. Worth noticing when a guess and the primary source line up, not just when they don't — it means the mental model from last session is holding.

Worked example: same Northwind agent, one setting flipped

Picture the Northwind support agent with a return-policy topic, an order-status tool, and a live-agent-transfer tool.

Classic orchestration

A customer types "am I too late to return these boots" and it either matches your "Return Window" trigger phrases exactly, or it doesn't and falls back to knowledge, or it doesn't and asks the customer to rephrase.

Generative orchestration

The same message gets read for intent. If the customer then adds "also, where's my other order," the planner runs both the return topic and the order-status tool in one turn and writes a single reply covering both — something classic orchestration structurally cannot do without you hand-authoring that combination in advance.

Check your retrieval

Answer before you expand each one.

Question 1 of 4

True or false: a brand-new standard-harness agent defaults to classic orchestration.

• True

• False — generative is the default for new agents

Answer

False — generative is the default for new agents

Question 2 of 4

Under classic orchestration, what decides which topic runs?

• The topic's description

• Matching the user's words to trigger phrases

• A vote among all available tools

Answer

Matching the user's words to trigger phrases

Question 3 of 4

A user asks two things in one message. Which orchestration mode can act on both without you pre-scripting that exact combination?

• Generative orchestration

• Classic orchestration

• Neither — always requires a dedicated top

Answer

Generative orchestration

Question 4 of 4

True or false: you can switch an agent built on the GitHub Copilot harness to classic orchestration if you prefer more predictability.

• True — it's the same Settings toggle as standard harness

• False — that harness has no orchestration toggle at all

Answer

False — that harness has no orchestration toggle at all

Match to a control layer

For each Northwind Outfitters action, which control layer should own the decision? Now, let's explore three sample cases:

Action	Suggested Layer
"What's your return window for shoes?"	Al orchestrator layer
Issue a $640 refund to a customer's card	Hybrid (intercept) layer
Permanently delete a customer's account on request	Deterministic layer

Reflection

My essay says skill is proven through repetition, failure, and watching whether something holds up. Why might an agent still belong in the hybrid layer for a task even after months of getting it right every time — what would have to be true before you'd move it to the fully AI orchestrator layer?

ONE REASONABLE ANSWER Getting it right every time you've watched isn't the same guarantee as getting it right every time, full stop — the hybrid layer exists precisely because failure modes for high-consequence actions (a wrong refund, a wrongful deletion) are often rare and expensive rather than frequent and cheap, so a good track record doesn't retire the risk. Moving something to the fully Al orchestrator layer isn't really about the agent's skill improving further; it's about the cost of a rare failure dropping low enough — through smaller blast radius, reversibility, or a cap on the action's size — that unsupervised judgment becomes acceptable rather than about trusting the model more.

Read next

The natural next primary source, since you're about to start authoring descriptions in Session 2: Configure high-quality instructions for generative orchestration. It's the practical companion to the architecture covered here.

Key takeaway: Orchestration is really two separate questions stacked on top of each other: how does the agent pick what to do (classic scripting vs. generative planning), and how much is it trusted to do without a human checkpoint (deterministic, hybrid, or fully AI). Session 2 starts on the first question; the second one you'll be answering for every action you ever give an agent.

Sources

• Orchestrate agent behavior with generative AI — Microsoft Learn

• Apply generative orchestration capabilities — Microsoft Learn

• Agents powered by GitHub Copilot Harness overview — Microsoft Learn

• AI-based agent authoring overview — Microsoft Learn

• What is AI Really? — my essay, the frame for this course