Copilot outage impact: token invalid 401 during GitHub service disruption (2026-04-27)

## Summary
Copilot failed during active deployment operations on 2026-04-27 with an authenticated chat request error while GitHub platform services were degraded.

Observed UI failure:
- "Sorry, your request failed. Please try again."
- "Reason: token expired or invalid: 401"
- "GitHub is currently experiencing a service disruption. This may be affecting Copilot."

This incident caused repeated interruption and retry during critical-path execution.

## Impact
- Delivery flow interruption during Phase 2 deployment execution.
- Increased manual workaround and operator intervention.
- Reduced confidence in Copilot reliability for critical-path operations.

## Incident Window (UTC)
GitHub status updates during the same window indicated broad degradation across search, issues, pull requests, projects, packages, and Actions.

Representative updates captured:
- 16:31 Investigating degraded performance for Actions
- 16:33 Search failures/timeouts
- 16:53 Pull Requests degraded performance
- 17:35 Intermittent failures across issues/PRs/projects/Actions
- 18:19 Pull Requests degraded availability
- 20:06 Pull Requests still degraded

## Evidence
- Session evidence pack (markdown): `COPILOT_INCIDENT_EVIDENCE_2026-04-27.md`
- Founder-ready evidence pack (html): `COPILOT_INCIDENT_EVIDENCE_2026-04-27.html`
- Copilot chat transcript log (local):
- `c:/Users/korer/AppData/Roaming/Code/User/workspaceStorage/963986299598b5858f7c812f34398b6e/GitHub.copilot-chat/transcripts/40c6cfd0-1be7-4776-a0d3-a132b671504c.jsonl`
- Copilot debug logs (local):
- `c:/Users/korer/AppData/Roaming/Code/User/workspaceStorage/963986299598b5858f7c812f34398b6e/GitHub.copilot-chat/debug-logs/40c6cfd0-1be7-4776-a0d3-a132b671504c/`

## Requested Action
1. Provide RCA for the Copilot request failure mapped to Copilot Request ID and GH Request ID.
2. Confirm whether token invalidation was a symptom of platform degradation or a separate auth path fault.
3. Provide recurrence risk and concrete mitigation actions.
4. Clarify SLA/credit posture for Copilot service impact during this outage window.

## Operational Decision (Current)
Until reliability posture is restored, Copilot is restricted to low-risk drafting/read-only exploration and removed from critical-path deployment/incident-response execution.

## Priority
High

## Labels
- incident
- reliability
- copilot
- outage