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 PostHog/posthog-foss --skill visualizing-change-over-timegit clone --depth 1 https://github.com/PostHog/posthog-fossWrote 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/posthog/posthog-foss/visualizing-change-over-time)<a href="https://agentmods.dev/skills/posthog/posthog-foss/visualizing-change-over-time"><img src="https://agentmods.dev/badge/skills/posthog/posthog-foss/visualizing-change-over-time/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/posthog/posthog-foss/visualizing-change-over-time"><img src="https://agentmods.dev/badge/skills/posthog/posthog-foss/visualizing-change-over-time.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 3 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Prompt Injection · line 27 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 31 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Prompt Injection · line 32 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
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 | $0.00169 | $0.01340 |
| Opus 5.5 | $0.00068 | $0.00536 |
| Sonnet 5.5 | $0.00034 | $0.00268 |
| Haiku 4.5 | $0.00017 | $0.00134 |
Grade A, and why
visualizing-change-over-time 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 1mo 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- streamlit-assessment — 86% identical, 170 lines differ
How it starts
The opening of the file, as written. The whole thing — 98 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Visualizing change over time
When a request is about how something changed, the default reach is a line/area
trend — and that is usually right for a continuous series with many x points. But for
some change-over-time shapes a different chart reads far better. This skill is the
menu to offer, including the slope graph, when building visualizations with
@posthog/quill-charts.
Present the fitting option(s) and let the user choose — none of these is mandatory.
Pick by the shape of the change
| The change is… | Reach for | Why |
|---|---|---|
| A continuous series over many time points (a trend) | TimeSeriesLineChart / LineChart (area fill for emphasis) |
The standard trend; the slope between every pair of points is visible. |
| Two points only (before → after) across several series/categories | SlopeChart |
One line per entity from a left "before" to a right "after" — direction and magnitude of each entity's change, and rank flips, read at a glance. |
| Magnitude comparison at points in time (not the path between them) | BarChart / TimeSeriesBarChart |
Bars compare discrete values; group/stack for sub-series. |
| A single headline number plus its change vs a prior period | MetricCard |
Big number + sparkline + change pill. |
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.
- 1mo ago Changed 3debca18fc9b
- 1mo ago Changed d12ada4df4f8
- 1mo ago Changed · -2 lines 5a1c9abebafe
- 1mo ago First seen · 100 lines · 169 tokens per session scan A 2326c9e4e207
visualizing-change-over-time is a skill published in the GitHub repository PostHog/posthog-foss (724 stars, last pushed today), licensed MIT. It adds 169 tokens to every session and 1,340 once invoked, about $0.0007 per session on Opus 5.5. 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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