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 reatlat/fullstory-claude-plugin --skill retention-analyzergit clone --depth 1 https://github.com/reatlat/fullstory-claude-pluginWrote 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/reatlat/fullstory-claude-plugin/retention-analyzer)<a href="https://agentmods.dev/skills/reatlat/fullstory-claude-plugin/retention-analyzer"><img src="https://agentmods.dev/badge/skills/reatlat/fullstory-claude-plugin/retention-analyzer/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/reatlat/fullstory-claude-plugin/retention-analyzer"><img src="https://agentmods.dev/badge/skills/reatlat/fullstory-claude-plugin/retention-analyzer.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 | $0.00048 | $0.01193 |
| Opus 5 | $0.00024 | $0.00596 |
| Sonnet 5 | $0.00010 | $0.00239 |
| Haiku 4.5 | $0.00005 | $0.00119 |
Grade A, and why
retention-analyzer 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 12d 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 — 136 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Retention Analyzer
Measure user retention — how many users come back, how often, and who's at risk of churning.
When to Use
- "What's our 7-day retention rate?"
- "How many new users from last month are still active?"
- "Are enterprise users more sticky than free users?"
- "Show me users who haven't returned in 30 days"
- "What's the churn rate for users who signed up in Q2?"
- "Compare retention between users who completed onboarding vs those who didn't"
Mental Model
Retention is about returning users. There are three common lenses:
- N-day retention: What percentage of users who were active on Day 0 came back on Day N? (e.g., Day 1, Day 7, Day 30)
- Cohort retention: Of users who signed up/started in a period, what percentage are still active N days later?
- Stickiness: How many days per week/month do active users engage? (DAU/MAU ratio)
Fullstory doesn't have a native retention report, so you build it from segments and metrics.
Workflow
Step 1: Define the retention window
Clarify what the user wants:
- N-day return: "Are users active on Day 7 and Day 30?"
- Ongoing engagement: "How many sessions per week do active users have?"
- Churn detection: "Which users haven't returned in 30+ days?"
Step 2: Build a retention cohort
For N-day retention from signup:
fullstory:build_segment("users with first_seen between July 1 and July 7") → cohort_segment
For ongoing activity:
fullstory:build_segment("users with last_seen in last 7 days") → active_users
fullstory:build_segment("users with last_seen before last 30 days") → churned_users
Step 3: Measure return rate
Build a metric that counts users who were active in both the cohort window AND the return window:
fullstory:build_metric(
query="users who were active between July 1-7 AND active between Aug 1-7",
output_type="single_number"
)
Compare to the total cohort size to get the retention rate: "1,200 of 5,000 July Week 1 users were active in August (24% 30-day retention)."
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.
- 12d ago First seen · 136 lines · 48 tokens per session scan A 1ac178b670e4
retention-analyzer is a skill published in the GitHub repository reatlat/fullstory-claude-plugin (62 stars, last pushed 1mo ago), licensed MIT. It adds 48 tokens to every session and 1,193 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 2026-08-30.
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