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

Start by reviewing COPILOT_INCIDENT_EVIDENCE_2026-04-27.md and COPILOT_INCIDENT_EVIDENCE_2026-04-27.html, then correlate the Copilot chat transcript and debug-log paths with the Copilot Request ID and GH Request ID. Done means documenting the RCA, determining whether token invalidation was caused by platform degradation, and recording recurrence, mitigation, and SLA findings.

Rédigé par le modèle d'indexation à partir du texte de l'issue.