[Critical]: Copilot Agent session keeps running indefinitely, cannot stop session or send replies

[erbanku]

Describe the bug

Note

Sorry for submitting the issue here; the reason is that I could not find a place to submit it otherwise.

Copilot Coding Agent sessions in organization repositories can get stuck indefinitely. The session shows only the initial plan (draft PR) with no commits or file changes, even after almost 2 weeks.

In this state:

• The session cannot be stopped from the UI
• No progress is made
• No additional output or updates occur

This appears to happen when the GitHub Actions runner is deleted while the agent session is still running, leaving the session orphaned.

For more context: https://github.com/orgs/community/discussions/190936#discussioncomment-16354984

Affected version

1.0.10

Steps to reproduce the behavior

Precondition:

• Organization Actions policy is set to restrict external actions:
  Organization Settings → Actions → General → Actions permissions
  Select: "Allow enterprise and select non-enterprise actions"
  AND do NOT include required actions in the allowlist (e.g. actions/checkout, actions/upload-artifact, github/gh-aw/actions/setup-cli)

Expected behavior

The session should either fail gracefully when the runner is removed
Or automatically terminate after detecting the runner is unavailable
The user should be able to stop or clean up the session from the UI

Additional context

Some error info:

17:58:44.551 chunk-EPOLDU6W.mjs:193 No `HydrateFallback` element provided to render during initial hydration
p @ chunk-EPOLDU6W.mjs:193
17:58:58.118 api.business.githubcopilot.com/agents/repos/VOLT-BOX/doc-backend/tasks/5aea9865-456a-413c-a36c-e6aa53ed5b81/sessions:1  Failed to load resource: the server responded with a status of 409 ()
17:59:21.370 api.business.githubcopilot.com/agents/swe/jobs/VOLT-BOX/doc-backend/session/983c59ca-3538-450f-a9a9-194874abaa3f/cancel:1  Failed to load resource: the server responded with a status of 404 ()
17:59:48.178 fetch-patch.ts:10  POST https://api.business.githubcopilot.com/agents/repos/VOLT-BOX/doc-backend/tasks/1db7984a-255c-4a96-888b-126ab85c46d2/sessions 409 (Conflict)
o.cg.o.cg.fetch @ fetch-patch.ts:10
window.fetch @ fetch-patch.ts:86
k @ copilot-chat-helpers.ts:179
u @ fetch-capi.ts:140
await in u
c @ fetch-capi.ts:106
t6 @ use-create-api-session.ts:125
a @ use-create-api-session.ts:56
fn @ mutation.js:74
v @ retryer.js:77
start @ retryer.js:119
execute @ mutation.js:113
await in execute
mutate @ mutationObserver.js:61
(anonymous) @ useMutation.js:33
r @ use-create-api-session.ts:94
eg @ TaskChatInputV2.tsx:316
n @ ChatInputDisplay.tsx:60
s6 @ react-dom-client.production.js:12317
(anonymous) @ react-dom-client.production.js:12867
tP @ react-dom-client.production.js:1498
un @ react-dom-client.production.js:12455
cd @ react-dom-client.production.js:15306
cc @ react-dom-client.production.js:15274