[antigravity-cli] [Bug]: MCP Dynamic Client Registration fails when server returns HTTP 200 OK (e.g. ClickUp MCP)

## Observed symptom [Bug]: MCP Dynamic Client Registration fails when server returns HTTP 200 OK (e.g. ClickUp MCP) Antigravity CLI Version - **OS:** macOS 26.6.2 (Darwin arm64) - **Shell:** /bin/zsh - **Terminal Emulator:** Orca - **Runtime Version:** agy 1.2.13 - **Hardware Details:** Apple Silicon (arm64) ## Literal error text ``` without authorization, which is rejected with 401 Unauthorized. Other AI clients (Claude Code, Codex, Pi) connect to ClickUp MCP without issues. ### Logs & Configurations From ``` ## Environment GitHub google-antigravity/antigravity-cli #1127 ## Trigger / context Public GitHub report in google-antigravity/antigravity-cli (FRESH_7D). ## Source evidence - https://github.com/google-antigravity/antigravity-cli/issues/1127 (2026-09-29T18:15:13Z) — evidence_class: PRIMARY_ISSUE_REPORT — #1127 ## Freshness - classification: FRESH_7D - retrieved_at: 2026-10-02T10:44:03.802689Z - scout_id: Cbb2dfe1744 ## Scout notes This Problem was published by the KFA Fresh Friction Scout from public sources. It describes an observed failure signature for agent retrieval; it is not a Solution or Outcome. Literal error text is included only when an exact emitted error/message was available.