[Bug] /feedback fails with HTTP 413 — bundles oversized conversation context

Bug Report

The /feedback command fails with "Could not submit feedback. Please try again later." The actual error (visible only in --debug logs) is HTTP 413 Request Entity Too Large on POST /v1/messages.

Steps to Reproduce

1. Run Claude Code with a non-trivial conversation (ours has images, tool calls, compacted context)
2. Type /feedback Test submission
3. Submit

Expected Behavior

Feedback submitted. If payload is too large, truncate context or submit without it.

Actual Behavior

• Red text: "Could not submit feedback. Please try again later."
• Prompt: "Edit and press Enter to retry, or Esc to cancel"
• Retry produces identical 413 — will never succeed for this conversation size
• No diagnostic info shown to user. Root cause only visible in --debug logs:

``
[API REQUEST] /v1/messages source=feedback
[ERROR] Error: AxiosError: Request failed with status code 413
``

Problems

1. Misleading error message — "try again later" implies transient failure, but it's a permanent payload size issue
2. Retry loop is futile — pressing Enter resubmits the same oversized payload
3. No fallback — should truncate context or submit feedback-only without full conversation
4. No diagnostics — user sees generic message, actual HTTP 413 hidden in debug logs

Impact

Cannot file bugs through the intended channel. This has blocked reporting:

• Computer Use MCP bugs (filed via gh — #41099, #41101, #41104)
• Browser MCP / Claude in Chrome issues (filing separately)
• MCP health check stale status (filing separately)
• Significant discrepancies in Weekly/Session limits between a Team account and a Personal Max20 account — raised at the request of @bcherny on X/Twitter (reporter's handle: @AgencyGroupAI)

Environment

• macOS Darwin 25.2.0
• Claude Code 2.1.88, Opus 4.6