Does a Microsoft 365 Copilot seat cover GitHub Copilot harness agents?

You’re right to challenge the marketing shorthand. “Copilot Studio” is now a multi-harness platform — and the bill depends on which harness, not the product logo on the slide.

Here’s what’s going on. Learn’s cost table is explicit: GitHub Copilot harness agents are not covered by a Microsoft 365 Copilot licence. Creation, testing, evaluation, and runtime all consume Copilot Credits, billed for all usage. By contrast, standard harness employee-facing agents in Microsoft 365 channels can be zero-rated when the authenticated user holds Microsoft 365 Copilot (with the usual footnotes for channels, flows, and fair use). Computer use (CUA) is also never included. Filter Manage → Copilot Studio inventory by the Harness column (GitHub Copilot / Standard / Copilot Chat) to see which estate is on the always-metered path. Separately, developer and trial environments moved to usage-based billing on 1 September 2026 — prior “non-billed” figures are directional only, not a promise. When credits run out, makers and users can hit enforcement (“You need credits to continue”) until you reallocate, buy capacity, or attach pay-as-you-go.

This is First Law for money: don’t put workload into a harness until you can see how the credits come back out — prepaid allocation, PAYG, and per-agent limits. 12 Panes Steady Cost treats harness choice as a funding decision, not a maker preference.

Options that actually work:

1. Classify by harness before you fund. Standard harness for predictable B2E Q&A on licensed seats; GitHub harness only where multi-step reasoning justifies a capacity owner, environment allocation, and monthly agent limits. Best Steady posture.
2. Contain GitHub harness sandboxes. Allocate prepaid credits, clear Draw from the available capacity in my tenant, set agent limits with notifications (and hard stop where appropriate), Azure budgets on PAYG. Required hygiene after 1 Sep 2026 for former free-feeling developer/trial estates.
3. Assume “everyone has Copilot so Studio is free.” False for GitHub harness, CUA, unlicensed audiences, and many non-M365 channels. Don’t put that sentence in a board pack.
4. Ban the GitHub harness outright. Simple; may block legitimate complex workflows. Prefer funded production environments with owners over a blanket ban.

12 Panes action / comms: One FinOps slide: agent → harness → covered by M365 Copilot? → monthly credit expectation → owner. Message to makers: seats cover standard B2E paths; GitHub harness is always a meter — ask before you build.

Benefits / risks: Clear harness labelling stops surprise invoices; hard enforcement mid-sprint demoralises makers if you never told them developer environments now bill. Roadmap cost-visibility items in Studio help, but they don’t invent free capacity.

I’d suggest this week: filter inventory by Harness = GitHub Copilot, review non-billed history as a hint, then put capacity and limits on those environments before the next invoice cycle. You’ll have a calmer story when Finance and makers share the same table.

DIGITAL SKILL WORKS LTD / 12 PANES · You ask, we answer