* Robustness for the claude/codex backends on Windows: argv overflow, subprocess encoding, tolerant JSON, test-eval dirs
Fixes surfaced running SkillOpt end-to-end on the bundled `claude` backend
(local Claude CLI) on Windows. None changes the OpenAI/GPT happy path.
1. skillopt/engine/trainer.py — the final test-eval directory
(test_eval_final/) is written to before being created; add
os.makedirs(..., exist_ok=True), matching the two sibling test-eval dirs.
Without it, summary.json raises FileNotFoundError when a rollout yields
zero predictions.
2. skillopt/model/claude_backend.py
a. Pass the prompt via stdin (not argv): on Windows the whole command line
is capped at ~32 KB and a large optimizer prompt (the success-analyst
minibatch carrying several report trajectories) overflows it with
[WinError 206], killing the run after retries.
b. Pass the system prompt via --append-system-prompt-file (a temp file),
not argv. The system prompt here is the skill being optimized, which
SkillOpt grows over training; since the ~32 KB cap applies to the SUM of
all argv, a grown skill would re-hit [WinError 206] even with the prompt
on stdin.
c. Pin the subprocess encoding to utf-8 (errors="replace"). With text=True
and no encoding=, stdin is encoded with the system codepage; on a zh-CN
box (cp936/GBK) a prompt containing an emoji or some Latin-1 characters
raises UnicodeEncodeError before the CLI even starts, failing every retry.
3. skillopt/model/codex_backend.py — the same utf-8 encoding pin on its
subprocess.run(input=...) call (identical unpinned-encoding pattern).
4. skillopt/utils/json_utils.py — extract_json() returned None for valid-
looking JSON that strict json.loads rejects (unescaped ASCII quotes inside
CJK string values, trailing commas), silently dropping the analyst's edits
on non-schema backends (Claude/Qwen): reflect produces N edits, 0 applied.
Add a json_repair fallback, but only on a single unambiguous object — a
balanced-brace extractor plus a refuse-on-multiple-objects guard — so a
chain-of-thought "scratch + final" response can't make repair silently
return the wrong (discarded) object, which would be worse than None (None is
detectable and retryable; a wrong-but-valid edit is applied blind). Declare
json_repair in requirements.txt and the claude/qwen optional extras so the
fallback is actually present (it otherwise no-ops, dropping edits silently).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
(cherry picked from commit dca74a683e)
* fix(json_utils): harden tolerant JSON fallback from PR #77
Follow-up fixes on top of the cherry-picked Windows-robustness change:
1. Make _top_level_brace_objects() fully string-aware in its OUTER scan, not
just inside an object. A '{' inside quoted prose (e.g. '"set it to {x}"')
no longer starts a candidate object, so extract_json() returns None for
prose pseudo-JSON instead of repairing it into a bogus dict — which would
be strictly worse than dropping the edit, since extract_json feeds the
optimizer's skill edits.
2. Pick the repair candidate BEFORE importing json_repair, so the missing-
dependency RuntimeWarning only fires when there is genuinely a single
malformed object that could have been repaired. Ordinary no-JSON / prose
replies (the common case) now return None silently instead of warning on
every call.
3. Resolve dependency-metadata inconsistency: json_repair is optional, so add
it to the `all` extra (it was already in `claude`/`qwen`) and demote it
from a hard requirement to an optional/commented entry in requirements.txt,
matching the project's convention for backend-specific deps.
Adds regression tests for prose-with-braces (-> None), no-warning-on-plain-
text, single-object repair, and multi-object ambiguity. Existing 22 json
tests still pass with and without json_repair installed.
Co-Authored-By: Claude <noreply@anthropic.com>
---------
Co-authored-by: samuelgoofus-boop <260247789+samuelgoofus-boop@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
SkillOpt: Executive Strategy for Self-Evolving Agent Skills
Train agent skills like you train neural networks — with epochs, (mini-)batchsize, learning rates, and validation gates — but without touching model weights.
📖 For installation, data preparation, training/eval commands, the full configuration reference, and framework internals, see the Documentation & Reproduction Guide (rendered on GitHub Pages).
News 🔥🔥🔥
- [2026-06-15] 😴 SkillOpt-Sleep (preview) — a nightly offline self-evolution companion for local coding agents (Claude Code / Codex / Copilot): review past sessions, replay recurring tasks, and consolidate validated skills behind a held-out gate. See
docs/sleep/README.mdfor what it is, how to use it, and results. - [2026-06-03] 🎉 gbrain, gbrain-evals, and darwin-skill have all integrated SkillOpt.
- [2026-06-02] 🎉 SkillOpt v0.1.0 is now available on PyPI! Install with
pip install skillopt. This initial release includes the full training loop (rollout → reflect → aggregate → select → update → evaluate), multi-backend support (OpenAI / Azure / Claude / Qwen / MiniMax), six built-in benchmarks, and WebUI dashboard.
Overview
Modern agent skills are usually hand-crafted, generated one-shot by a strong LLM, or evolved through loosely controlled self-revision — none of which behaves like a deep-learning optimizer for the skill itself, and none of which reliably improves over its starting point under feedback.
SkillOpt treats the skill document as the trainable state of a frozen agent, and trains it with the discipline that makes weight-space optimization reproducible. A separate optimizer model turns scored rollouts into bounded add / delete / replace edits on a single skill document; a candidate edit is accepted only when it strictly improves a held-out validation score. A textual learning-rate budget, a rejected-edit buffer, and an epoch-wise slow / meta update make skill training stable while adding zero inference-time model calls at deployment.
The deployed artifact is a compact best_skill.md (typically 300–2,000
tokens) that runs against the unchanged target model. Across six
benchmarks, seven target models, and three execution harnesses (direct
chat, Codex CLI, Claude Code CLI), SkillOpt is best or tied-best on all
52 evaluated (model, benchmark, harness) cells and on GPT-5.5 lifts the
average no-skill accuracy by +23.5 points in direct chat, +24.8 inside
the Codex agentic loop, and +19.1 inside Claude Code. Optimized skill
artifacts transfer across model scales, between Codex and Claude Code
harnesses, and to nearby benchmarks without further optimization.
For the full method, ablations, and per-cell results see the paper; for a visual walkthrough of the loop see the project page; for deeper API / backend / benchmark docs see docs/.
🎬 Demo Video
https://github.com/user-attachments/assets/eb12d3bc-371c-467f-904d-91b61f339ed7
▶ Watch the full demo on YouTube
Extensibility & WebUI
Adding a new backend
A backend = a chat / exec target (e.g. openai_chat, claude_chat,
qwen_chat, minimax_chat, codex_exec, claude_code_exec). See
docs/guide/new-backend.md for the full
contract; in short you add a skillopt/model/<name>_backend.py module,
register it in skillopt/model/common.py + backend_config.py, and wire
it through the router in skillopt/model/__init__.py. qwen_backend.py
and minimax_backend.py are good templates.
Adding a new benchmark
A benchmark = a skillopt/envs/<name>/ package with a dataloader.py, a
rollout.py, and an initial.md seed skill. See
docs/guide/new-benchmark.md for the full
contract; the simplest reference is skillopt/envs/searchqa/.
WebUI
Launch the monitoring dashboard (optional):
pip install -e ".[webui]"
python -m skillopt_webui.app
| Flag | Default | Description |
|---|---|---|
--port |
7860 | Server port |
--host |
0.0.0.0 |
Bind address |
--share |
off | Create a public Gradio share link |
Citation
@misc{yang2026skilloptexecutivestrategyselfevolving,
title={SkillOpt: Executive Strategy for Self-Evolving Agent Skills},
author={Yifan Yang and Ziyang Gong and Weiquan Huang and Qihao Yang and Ziwei Zhou and Zisu Huang and Yan Li and Xuemei Gao and Qi Dai and Bei Liu and Kai Qiu and Yuqing Yang and Dongdong Chen and Xue Yang and Chong Luo},
year={2026},
eprint={2605.23904},
archivePrefix={arXiv},
primaryClass={cs.AI},
url={https://arxiv.org/abs/2605.23904}
}