Transferable Defect Classes

Summary

A transferable defect class is a category of bug fixed in one agent CLI (Claude Code, Codex CLI) that can plausibly exist in an unrelated peer implementation. Rather than copying features from release notes, the practice reads upstream changelogs, abstracts each fix into a class of defect, and then checks whether the local tool — here yoyo v0.4.0 at commit 0375d32f — shares it. Each class is resolved into one of four states: probed and reproduced, matched to an already-filed issue, measured but unfiled, or explicitly unmeasured (the premise was never exercised).

Upstream sources for this pass: Claude Code 2.1.318 (2026-11-04), Codex releases, and Codex CLI v0.166 notes.

Key Points

The unit of transfer is the defect class, not the individual fix; a class survives translation across codebases and languages.
Every claim is pinned to a commit (0375d32f) so status is reproducible.
Statuses are honest about coverage: several classes are marked "not probed" or "unmeasured" rather than assumed fixed.
Classes split across three outcomes: yoyo already handles them (#1138, #1137/#1128, #1064, doctor), yoyo has a measured gap (double stdio spawn), or the premise is untested.
Credential/TLS handling, -p non-interactive exit semantics, and MCP server lifecycle are the recurring fault lines.

Concepts

Defect class — an abstracted bug shape reusable across implementations.
Probe — the concrete command/experiment that establishes whether yoyo exhibits the class.
Unmeasured premise — a class where the yoyo-side precondition was never tested, so "not present" cannot be claimed.
-p mode — non-interactive/print mode; its exit codes and silence-on-failure are a repeated defect surface.
Stdio MCP servers — subprocess MCP transports, vulnerable to handshake/version-probe churn.

#	Defect class	Upstream fix	yoyo status
1	Damaged/unreadable CA bundle	Falls back to readable certs when `NODE_EXTRA_CA_CERTS` is empty, non-PEM, or starts with a broken cert; warns on stderr	Partly handled: empty `SSL_CERT_FILE` fails fast with a named reason (exit 1); garbage-first-then-valid bundle still reached the API (401 on bogus key) → readable certs used. Probed; upstream yoagent panic half still open (#1138)
2	`-p` reports success after an API error truncated a reply	Fixed (touched `turn.step`)	Bogus key under `-p` exits 1; mid-stream cutoff not probed
3	Failing slash command prints nothing in `-p`	Fixed	Same class as #1137/#1128 (exit codes; REPL wording leaking into `-p`)
4	Stdio MCP server that exits on the version probe gets re-probed every start	Pins such servers to a legacy handshake for 7 days	Measured, unfiled: yoyo spawns every stdio server twice (pre-flight + connect); documented in CLAUDE.md MCP section
5	MCP tool invoked before load; approved connector tool vanishing after restart	Returns the tool's input schema; Claude is told when an approved tool becomes unavailable	Related to #1134 (dead server); the missing-tool premise itself is unmeasured
6	Shell command approved after restart runs in the start folder	Uses the correct cwd	Anchor class relevant to yoyo's `nested_instructions` root resolution — untested
7	Credentials exposed in remote bash output	Codex 0.164 masks credentials	#1064 covers an opt-in env scrub; ownership split by population
8	Model-specific AGENTS.md compliance regression	GPT-6.1 Sol regression noted; Terra recommended	yoyo ships both `gpt-6.1-sol` and `gpt-6.1-terra` presets (`agent_builder.rs:826`), so the choice is user-configurable
9	Session queueing and network-scoped diagnostics	Codex 0.166 adds `codex queue --resume` and `codex doctor --network-only`	yoyo has `doctor`, but no network-only narrowing and no queued session resume

Transferable Defect Classes

Summary

Key Points

Concepts

Details

Method

Class-by-class findings

Recurring themes

what links here

related pages