Feedback drafts queue and offer "send" under a custom gateway, but the channel is unavailable and nothing says so

Feedback drafts queue and offer "send" under a custom gateway, but the channel is unavailable and nothing says so

Environment

• Claude Code 2.1.245, macOS (darwin arm64)
• Custom gateway: ANTHROPIC_BASE_URL pointed at a self-hosted Anthropic-wire proxy, ANTHROPIC_AUTH_TOKEN set (gateway client secret, not first-party Anthropic auth)

What happens

1. During a session, the model queued a feedback draft (the SendFeedback tool). The UI accepted it normally: a draft card rendered with "1 to review · 2 to send · 0 to dismiss", and the statusline showed "1 feedback draft".
2. Attempting to send did nothing visible. Invoking /feedback printed no content — no dialog, no error, no explanation.
3. Verified at the gateway that no send was ever attempted: its access log for the window shows only /v1/messages inference traffic, zero requests to any other path. The submission is evidently disabled client-side when running under gateway auth (which makes sense — feedback presumably requires first-party credentials the client doesn't have in this mode).

So every part of the drafting UX works — queueing, the draft card, the statusline badge, the send affordance — while the one thing they all lead to is a no-op. Nothing at draft time, at /feedback time, or at send time says "feedback can't be submitted when using a custom API endpoint."

Expected

Any of these would resolve it:

1. /feedback (and the send keypress) prints a clear message that submission is unavailable under a custom gateway, and why; or
2. the draft queue / statusline suppress or annotate the affordance when the channel is unavailable; or
3. the SendFeedback tool is disabled (or its result warns) in gateway-auth sessions, so the model doesn't lead the user to a dead end — in our session the assistant, seeing the draft queue succeed, repeatedly advised "press 2 to send."

Impact

Minor but confusing: a user with a legitimate bug to report (filed separately as #89972 — this papercut was discovered while trying to send that report) spent a round-trip discovering the channel was dead by tailing their gateway's access log.