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 CrestApps/CrestApps.AgentSkills --skill crestapps-core-extensible-entitiesgit clone --depth 1 https://github.com/CrestApps/CrestApps.AgentSkillsWrote 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/crestapps/crestapps.agentskills/crestapps-core-extensible-entities)<a href="https://agentmods.dev/skills/crestapps/crestapps.agentskills/crestapps-core-extensible-entities"><img src="https://agentmods.dev/badge/skills/crestapps/crestapps.agentskills/crestapps-core-extensible-entities/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/crestapps/crestapps.agentskills/crestapps-core-extensible-entities"><img src="https://agentmods.dev/badge/skills/crestapps/crestapps.agentskills/crestapps-core-extensible-entities.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 | $0.00145 | $0.01460 |
| Opus 5.5 | $0.00058 | $0.00584 |
| Sonnet 5.5 | $0.00029 | $0.00292 |
| Haiku 4.5 | $0.00015 | $0.00146 |
Grade A, and why
crestapps-core-extensible-entities 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 yesterday.
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 — 141 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CrestApps.Core Extensible Entities
You are a CrestApps.Core expert. Generate code for typed metadata stored in ExtensibleEntity.Properties.
Guidelines
ExtensibleEntity(namespaceCrestApps.Core) exposesProperties, an ordinal-ignore-caseIDictionary<string, object>.CatalogItemderives from it, so every catalog model (profiles, deployments, connections, interactions, personas, data sources) carries a property bag.Propertiesserializes as a nestedPropertiesJSON object throughJsonExtensionDataConverter, which keeps JSON values asJsonNode. Do not replace it with[JsonExtensionData]; flattened root-level values are not read back as metadata.- Use the extension methods in
ExtensibleEntityExtensionsinstead of casting dictionary values. - The default key is the type name (
typeof(T).Name), so keep one metadata object per type. UsePut(name, value)andGet<T>(name)for explicit keys. - Name metadata classes uniquely; two classes with the same name in different namespaces share a key.
Methods
| Method | Constraint | Behavior |
|---|---|---|
Put<T>(value) |
T : new() |
Stores under typeof(T).Name and returns the entity |
Put(name, value) |
none | Stores under an explicit key |
TryGet<T>(out value) |
T : class |
Returns false when the key is missing or null; no allocation |
GetOrCreate<T>() |
T : new() |
Returns the stored value or a new, unstored instance |
Get<T>(name) |
none | Reads an explicit key, or default |
Alter<T>(action) |
T : new() |
Gets or creates, runs the action, and stores the result |
Has<T>() |
none | Checks for the type-name key |
Remove<T>() |
none | Removes the type-name key |
TryGet, GetOrCreate, Get and Alter accept an optional JsonSerializerOptions to override the shared options for one call.
Typed Metadata
using CrestApps.Core;
namespace MyApp.Metadata;
public sealed class BillingMetadata
{
public string InvoicePrefix { get; set; }
public decimal MonthlyBudget { get; set; }
}
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.
- yesterday Changed · +68 lines · +119 tokens per session 60c35dd7d468
- 1mo ago First seen · 73 lines · 26 tokens per session scan A 2bf6e275f0a8
crestapps-core-extensible-entities is a skill published in the GitHub repository CrestApps/CrestApps.AgentSkills (13 stars, last pushed yesterday), licensed MIT. It adds 145 tokens to every session and 1,460 once invoked, about $0.0006 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 2026-08-30.
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