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.
npx skills add ychampion/cskill-agents --skill main-agent-vs-background-memory-extraction-exclusiongit clone --depth 1 https://github.com/ychampion/cskill-agentsWrote 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/ychampion/cskill-agents/main-agent-vs-background-memory-extraction-exclusion)<a href="https://agentmods.dev/skills/ychampion/cskill-agents/main-agent-vs-background-memory-extraction-exclusion"><img src="https://agentmods.dev/badge/skills/ychampion/cskill-agents/main-agent-vs-background-memory-extraction-exclusion/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/ychampion/cskill-agents/main-agent-vs-background-memory-extraction-exclusion"><img src="https://agentmods.dev/badge/skills/ychampion/cskill-agents/main-agent-vs-background-memory-extraction-exclusion.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00034 | $0.00410 |
| Opus 5 | $0.00017 | $0.00205 |
| Sonnet 5 | $0.00007 | $0.00082 |
| Haiku 4.5 | $0.00003 | $0.00041 |
Grade A, and why
main-agent-vs-background-memory-extraction-exclusion 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 7d 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.
What it actually says
SKILL: Main Agent Vs Background Memory Extraction Exclusion
Domain: context-management
Trigger: Apply whenever the background memory agent must determine whether the parent already saved the same memories so it can safely skip processing.
Source Pattern: Distilled from reviewed context, compaction, and memory-governance patterns.
Core Method
Track a cursor UUID pointing to the last assistant message where an auto-memory write occurred and compare incoming messages to that cursor before running extraction. If the parent thread already wrote to memory paths after the cursor, skip launching the background agent. Otherwise, proceed with the forked extraction and reset the cursor to the new save point so the next turn knows what’s already handled.
Key Rules
- Keep the cursor state outside the extraction loop so the check is read-only and does not mutate shared context.
- Only permit a single background extraction per turn; once the main agent wrote to a memory path, mark the cursor so the forked agent sees the change and bails out.
- When detection fails (cursor missing or memory writes unknown), default to running the extractor but emit telemetry so the system tracks unexpected duplications.
- Always update the cursor when the background agent runs successfully, so future turns know the latest covered UUID.
Example Application
Use this skill by having the background extractor call hasMemoryWritesSince before proceeding; if it returns true, emit a “already handled” log and skip, otherwise continue persistence and store the current assistant UUID for the next check.
Anti-Patterns (What NOT to do)
- Don’t let the forked agent write memories unconditionally; that duplicates entries and races with the parent.
- Don’t reset the cursor until after successful writes; resetting prematurely can cause the system to skip future required extractions.
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.
- 7d ago First seen · 28 lines · 34 tokens per session scan A 5920b9a457bf
main-agent-vs-background-memory-extraction-exclusion is a skill published in the GitHub repository ychampion/cskill-agents (36 stars, last pushed 5mo ago), licensed MIT. It adds 34 tokens to every session and 410 once invoked, about $0.0002 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 2026-09-03.
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