External callers (third-party SDKs, the channel plugin) authenticate
purely via bearer and frequently don't set the X-Workspace-ID header.
Without this, activity_logs.source_id ends up NULL — breaking the
peer_id signal on notifications, the "Agent Comms by peer" canvas tab,
and any analytics that breaks down inbound A2A by sender.
The bearer is the authoritative caller identity per the wsauth contract
(it's what proves who you are); the header is a display/routing hint
that must agree with it. So we derive callerID from the bearer's owning
workspace whenever the header is absent. The existing validateCallerToken
guard fires after this and enforces token-to-callerID binding the same
way it always has.
Org-token requests are skipped — those grant org-wide access and don't
bind to a single workspace, so the canvas-class semantics (callerID="")
are preserved. Bearer-resolution failures (revoked, removed workspace)
fall through to canvas-class as well, never 401.
New wsauth.WorkspaceFromToken exposes the bearer→workspace lookup as a
modular interface; mirrors ValidateAnyToken's defense-in-depth JOIN on
workspaces.status != 'removed'.
Tests: 4 unit tests on WorkspaceFromToken + 3 integration tests on
ProxyA2A covering the three observable paths (bearer-derived,
org-token skipped, derive-failure fallthrough).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>