On EC2 tenant instances, Caddy serves Canvas (:3000) and API (:8080) under
the same domain. Canvas makes same-origin requests without X-Molecule-Org-Id
or Fly-Replay-Src headers, causing TenantGuard to 404 every API route.
- Add isSameOriginCanvas() as tertiary check in TenantGuard — when
CANVAS_PROXY_URL is set and Referer/Origin matches Host, pass through.
- Enhance isSameOriginCanvas() to also check Origin header (WebSocket
upgrade requests send Origin but may not send Referer).
- Add 3 new tests: Referer bypass, Origin bypass (WS), inactive without env.
Fixes all 404s on /workspaces, /templates, /org/templates, /approvals/pending,
/canvas/viewport, and /ws WebSocket on tenant EC2 instances.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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