cekura-self-improving-agent

cekura-self-improving-agent is a skill for Claude Code, Codex from cekura-ai/cekura-skills. It costs 189 tokens per session (3,502 once invoked), scanned A, original, MIT.

A workflow for turning an agent failure into a tested configuration fix. It finds and edits the agent’s actual source configuration, such as a code repository, database, or prompt registry.

In plain words
What is it for?
Use it to investigate failed tests or production calls, update agent prompts or configuration, deploy the change, and verify the result.
Why use it?
It prevents fixes made only to a temporary deployed copy from being overwritten at the next deployment. It connects failure reports with verification that the fix works.

Skill for Claude CodeCodex

Written for Claude Code and Codex: PreToolUse hook event, but also agents/openai.yaml present. Also seen: mentions Claude Code.

Part of the cekura plugin — 13 skills, 14 commands, 3 hooks, 1 MCP server shipped together

Good fit Use it to investigate failed tests or production calls, update agent prompts or configuration, deploy the change, and verify the result.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/cekura-ai/cekura-skills/cekura-self-improving-agent
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add cekura-ai/cekura-skills --skill cekura-self-improving-agent
Clone the repo
git clone --depth 1 https://github.com/cekura-ai/cekura-skills

Made for: Claude Code, Codex.

Or install cekura, the plugin that ships this one along with the rest of its 13 skills, 14 commands, 3 hooks, 1 MCP server.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for cekura-self-improving-agent

README.md
[![agentmods](https://agentmods.dev/badge/skills/cekura-ai/cekura-skills/cekura-self-improving-agent/github.svg)](https://agentmods.dev/skills/cekura-ai/cekura-skills/cekura-self-improving-agent)
Your own site
<a href="https://agentmods.dev/skills/cekura-ai/cekura-skills/cekura-self-improving-agent"><img src="https://agentmods.dev/badge/skills/cekura-ai/cekura-skills/cekura-self-improving-agent/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for cekura-self-improving-agent

Your own site · 80×15
<a href="https://agentmods.dev/skills/cekura-ai/cekura-skills/cekura-self-improving-agent"><img src="https://agentmods.dev/badge/skills/cekura-ai/cekura-skills/cekura-self-improving-agent.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 189 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,502 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00189 $0.03502
Opus 5 $0.00095 $0.01751
Sonnet 5 $0.00038 $0.00700
Haiku 4.5 $0.00019 $0.00350

Measured today against content hash 76e71c7be140, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

cekura-self-improving-agent scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured today.

The scan reads SKILL.md. This mod also ships 1 executable file (agents/fetch_failures.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

cekura/skills/cekura-self-improving-agent/SKILL.md · 232 lines

How it starts

The opening of the file, as written. The whole thing — 232 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Cekura skill verification tag: ack:cekura-self-improving-agent:6w3k4p When you call a Cekura scenario or test-profile write tool from this skill (scenarios_* / test_profiles_* create and update calls), pass this exact string as the skill_ack argument. Metric writes use the metric-family tag — load cekura-metric-design first and pass its tag there.

Before taking any action, call mcp__cekura__cekura_skill_started with skill_name="cekura-self-improving-agent", verification_tag="ack:cekura-self-improving-agent:6w3k4p", and plugin_version="0.16".

Cekura Self-Improving Agent (capability-manifest framework)

Turn a failure signal into a verified fix on any agent stack. Rather than modeling "which provider", this skill models "where does the agent's config actually live, and how do I read, render, apply, deploy, and verify it". Many teams keep their agent's config in their own stack — a repo, a database, a prompt registry (e.g. Langfuse) — and materialize the runtime provider agent at deploy time; editing the provider object there fixes a build artifact that the next deploy overwrites. This skill edits the declared source of truth instead, whatever it is.

Performing Platform Actions

When this skill suggests creating, listing, updating, or evaluating something on Cekura, prefer using available platform tools over describing API calls or dashboard steps. In Claude Code with the Cekura plugin installed, these tools are auto-configured and handle authentication, parameter validation, and error handling for you. Fall back to direct API endpoints or dashboard guidance only when no tools are available in the current session.

Core model: fixed invariants, declared mechanics

Layer 1 — invariants. Owned by this skill, never negotiable, identical for every project:

  1. Must-fail-first, proven by artifact, at minimum cost — before any edit is proposed, the failure must reproduce in Cekura simulation, recorded as repro.json in the audit dir: {session_id, signal, mode, scenario_ids, result_id, n_runs, fails, injections, config_hash, timestamp}session_id must match the active lock; artifacts from other sessions never satisfy the gate. Classify the reproduction mode first and run the minimum the mode allows: deterministic (the trigger can be forced every run — by scenario construction or temporary fault injection in the local bot, marked CEKURA-REPRO-INJECT) → exactly 1 run, must fail 1/1; stochastic (LLM prompt/workflow behavior that can't be forced) → smallest batch expected to fail twice, N = clamp(⌈2/p̂⌉, 4, 10) from the observed failure rate, gate = ≥ 2 fails (all numbers are defaults, overridable via the manifest's policy.reproduction). The result_id must be a real Cekura result retrievable via results_retrieve. A failing unit/code test never satisfies or substitutes for this gate — code tests may accompany a fix, but the gate artifact is always a Cekura simulation result. Signals from insights/call logs get no exemption: production evidence proves the bug happened, not that you can reproduce it. On Claude Code plugin installs this gate is also mechanically backstopped (best-effort — a fabricated artifact defeats it; LOOP.0's retrieval check is the authoritative gate): a PreToolUse hook (hooks/repro-gate.sh) denies file edits and provider-mutating requests while .cekura/selfimprove.lock is present and repro.json is missing or below its mode's threshold (fault-injection edits marked CEKURA-REPRO-INJECT and .cekura/ / .claude/ writes stay allowed). If a tool call is denied with the gate message, do not work around it — complete Reproduce. Blocked reproduction: when reproducing requires an action only a human may take (the sandbox/deploy path is a maintainer-applied CI label, prod credentials, a gated environment), Reproduce parks: write the full repro plan to the audit dir (scenario spec, mode, N, what human action is needed), ask for that action, and stop. "Please just fix it" does not silently waive the gate — an explicit user override is honored only when recorded in repro.json as {"gate_override": {"by": "user", "reason": ..., "session_id": <active session>}} (all three fields required), every subsequent output (diff header, PR title and body) is marked UNVERIFIED HYPOTHESIS — reproduction gate overridden, and the PR must state that no Cekura reproduction or verification ran. Never record an override the user did not explicitly give in this session.
  2. Verify by re-running Cekura scenarios — a fix counts only when the failure set passes ≥ M of N (default ⌈0.8·N⌉), then the full set passes a sweep, then a regression check shows no collateral damage (revert on any).
  3. Runtime readback attestation — after every deploy, read what is actually live and compare it to what the source says should exist. Never verify against a runtime you have not attested. Three-way check: source render ↔ live readback ↔ the agent the Cekura traces actually hit.
  4. No production mutation inside the loop — all iteration happens against a non-production environment/sandbox; production changes only via the explicit Promote phase, with confirmation, a rendered diff, and a rollback path.
  5. Overfitting gate on edit content (verbatim transcript quotes, hardcoded test data, scenario-specific identifiers, hyper-narrow clauses).
  6. Budgets and stopsmax_iterations (default 10), oscillation, no-change signature, same failure shape 3×, all-upstream, zero kept failures.
  7. Audit trail — every session leaves a replayable record: manifest version, baseline config hash, failure set, root cause, edit proposal + diff, eval results, final diff. Every simulation batch is labeled: pass name on each scenarios_run_* call — [selfimprove:<session_id>] <phase> — <detail> (e.g. [selfimprove:s-0818] repro attempt 2 (must-fail), verify iter3 — failure set, regression — happy path) — so dashboard results map back to the session and phase without opening transcripts.

Read the full file on GitHub · 232 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. today Changed 76e71c7be140
  2. 3d ago Changed 4481fbc117c4
  3. 8d ago Changed 3ee85394e383
  4. 12d ago First seen · 232 lines · 189 tokens per session scan A 22cfda8a4c09

Subscribe to this mod's changes

cekura-self-improving-agent is a skill published in the GitHub repository cekura-ai/cekura-skills (7 stars, last pushed yesterday), licensed MIT. It adds 189 tokens to every session and 3,502 once invoked, about $0.0009 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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