Agentic Context Engine is an open-source engine that gives AI agents a persistent learning loop, helping them remember successful strategies and learn from failures across sessions. It is used to improve production agents, and also powers Kayba’s hosted service. Catalogue add-ons support workflows for operating and configuring the engine.
Borrowing it
Nothing to install: this file belongs to kayba-ai/agentic-context-engine. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/kayba-ai/agentic-context-engine/main/.claude/skills/kayba-pipeline/stage-3-metrics/SKILL.mdgit clone --depth 1 https://github.com/kayba-ai/agentic-context-engineWrote 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.
[](https://agentmods.dev/skills/kayba-ai/agentic-context-engine/stage-3-metrics)<a href="https://agentmods.dev/skills/kayba-ai/agentic-context-engine/stage-3-metrics"><img src="https://agentmods.dev/badge/skills/kayba-ai/agentic-context-engine/stage-3-metrics/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.
<a href="https://agentmods.dev/skills/kayba-ai/agentic-context-engine/stage-3-metrics"><img src="https://agentmods.dev/badge/skills/kayba-ai/agentic-context-engine/stage-3-metrics.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00092 | $0.03166 |
| Opus 5 | $0.00046 | $0.01583 |
| Sonnet 5 | $0.00018 | $0.00633 |
| Haiku 4.5 | $0.00009 | $0.00317 |
Grade A, and why
kayba-stage-3-metrics 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 9d ago.
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.
How it starts
The opening of the file, as written. The whole thing — 181 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Stage 3: Metrics and Programmatic Analysis
Define metrics from insights, implement as code, run, review, iterate.
Inputs
TRACES_FOLDER— path to directory containing trace JSON fileseval/stage1_insights_summary.md— output from Stage 1eval/stage2_domain_context.md— output from Stage 2
Read both input files before starting.
Process
This stage is iterative. You cycle through define → implement → run → review, with a hard cap of 3 iterations. A metric set is "clean" when ALL of the following hold:
- No small-sample metrics in the priority set — every metric used for priority ranking has denominator >= 5. Metrics with denominator < 5 are kept but labeled
"confidence": "directional-only"and excluded from priority sorting. - No unexplained extremes — no metric reads 0% or 100% unless you can write a one-sentence justification (e.g., "0% is correct because the agent never calls send_certificate anywhere in the dataset"). Record the justification in the metric's
"extreme_justification"field. - No redundant pairs — no two metrics share > 70% of their denominator events. Check this: for each pair, compute
|events_A ∩ events_B| / min(|events_A|, |events_B|). If > 0.70, merge or drop one. - Script runs without errors on the full trace set.
If after 3 iterations the set is not fully clean, ship what you have and log remaining issues in eval/baseline_metrics.json under a top-level "warnings" key.
Step 1: Define metrics
For each insight from the Kayba analysis, use the evidence fields to identify observable signals in the traces:
- Read the insights summary — focus on evidence citations, error strings, behavioral patterns
- For each valid insight, determine what trace signal would change if the agent followed the skill
- Classify each metric by detector pattern type:
Recovery detectors — consecutive calls to the same function where first has error, next succeeds
def has_recovery(calls, function_name):
for i in range(len(calls) - 1):
if calls[i]['name'] == function_name and is_error(calls[i]['output']):
if calls[i+1]['name'] == function_name and is_success(calls[i+1]['output']):
return True
return False
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.
- 9d ago First seen · 181 lines · 92 tokens per session scan A 80a1e8a64c6c
kayba-stage-3-metrics is a skill published in the GitHub repository kayba-ai/agentic-context-engine (2,565 stars, last pushed 11d ago), licensed Apache-2.0. It adds 92 tokens to every session and 3,166 once invoked, about $0.0005 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 2026-08-30.
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