Summary
A Day-229 yoyo delta scan compares recent releases of rival coding-agent CLIs against yoyo's own defect register, on the premise that the same classes of failure recur independently across products. Rather than reading changelogs as feature news, each entry is mapped to a yoyo issue of the same shape — a "sibling" (same class, independently discovered) or "twin" (near-identical mechanism). This note picks up after the earlier scan covering Claude Code 2.1.295–2.1.299, driven by the Claude Code changelog, the Codex release feed, and a weekly agent-config roundup (2026-W42).
Key Points
- Claude Code 2.1.300 (2026-10-14; 88 changes, 51 of them fixes) contains several changes in failure classes yoyo already tracks.
- False success is the most productive parity class: a command reports success while the underlying outcome failed. Claude Code fixed one instance in
daemon stop --any; yoyo still has an equivalent inyoyo setupunder EOF. - Graceful degradation shows up as a fix pattern: when an MCP tool's input schema is permanently rejected (400 every turn), the tool is sent without parameters for the rest of the conversation instead of failing the session.
- Model-receives-an-absence (yoyo Day 181 class) recurs: Claude is now told about an MCP server's tools when that server finishes connecting after a compaction.
- Hooks fail closed on both sides: Claude Code 2.1.295 added an
onFailureblock, and yoyo pre-hooks already returnErron spawn failure or timeout. - Codex CLI 0.162.0 is an independent twin of yoyo #1023: ripgrep configuration can weaken deny-glob masks. yoyo runs
rgwithout--no-config, so a user config file can silently change what search returns under--deny-dir. - Gemini CLI 0.63.0 and Copilot CLI changes are recorded as landscape context rather than parity matches.