[Bug] Providing an initial prompt causes engine to prematurely terminate

[Jake Smith (jsmith13)]

Which Microsoft Discovery surface?

Microsoft Discovery app (Windows desktop client)

For Services bugs only — which area in this repo?

N/A — this is an app bug

Specific catalog item (Services only)

No response

Microsoft Discovery app version

No response

OS version (app only)

No response

What were you trying to do?

Assign an engine to a task

Steps to reproduce

1. Create a gh cli engine
2. Start an engine instance through the "play" icon
3. Enter the initial prompt for the engine in the command pallet

Expected behavior

The engine runs until the task is complete, then terminates.

Actual behavior

The engine makes a small number of tool calls then stop itself throught this mechanism.
[3:23:30 PM] 🏁 Done: Stop reason: end_turn
[3:23:34 PM] 🏁 Done: Stop reason: end_turn
[3:23:38 PM] 🏁 Done: Stop reason: end_turn
[3:23:38 PM] 🏁 Done: Engine completed — 3 consecutive idle turns detected.

Engines without an initial prompt provided do not show this behavior.

Logs and diagnostics

No response

Severity

Major — Workaround exists, but it's painful

Confirmations

• I have searched existing Bugs discussions before posting.
• This report contains no sensitive, regulated, or proprietary data (no subscription IDs, tenant IDs, tokens, customer data, etc.).
• If this is a Services bug, it concerns catalog content in this repo (agent, starter-kit, tool, skill, docs, or utility) — not general Discovery services platform issues. (Tick N/A if this is an app bug.)

[Steven Truitt (stevetru1)]

This is a very interesting bug. Are you using the default "Mission Control" engine or providing your own system prompt? If you are providing your own, do you mind sharing it or giving a sanitized summary? Also, do you have any tools enabled?

I suspect that the engine is not provided any tools or direction in some way so the only thing it sees is it's own "end session" default tool.

If you can share the engine definition json or a screensnap of the settings panel we can look into it more.

[Jake Smith (jsmith13)]

test-agent.json
Of course - here is the engine JSON.

Run without a user prompt, it picks up and executes a task, then runs into issue #78

Run with a user prompt, e.g. "Please pick up design task A", the behavior here is observed.