custom-features

A guide to creating a reusable TanStack Table v9 feature plugin that adds new state, settings, and methods to table objects. It covers the different places where the feature must be registered and connected.

In plain words
What is it for?
Use it when built-in table features are insufficient and you need reusable behavior that extends tables, columns, rows, cells, or headers.
Why use it?
It prevents a custom feature from working in one part of the table while missing its types, defaults, lifecycle handling, or public methods elsewhere.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/tanstack/table/custom-features
Any agent
npx skills add TanStack/table --skill custom-features
Clone the repo
git clone --depth 1 https://github.com/TanStack/table

Made for: Claude Code, Codex.

Per session 93 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,190 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00093 $0.02190
Opus 5 $0.00046 $0.01095
Sonnet 5 $0.00019 $0.00438
Haiku 4.5 $0.00009 $0.00219

Measured 2d ago against content hash 5591215f2814, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

custom-features 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 2d 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.

packages/table-core/skills/custom-features/SKILL.md · 236 lines

How it starts

The opening of the file, as written. The whole thing — 236 lines — stays where its author put it; the contents beside it link to each section on GitHub.

This skill builds on core, table-features, and typescript. Prefer a built-in feature or typed tableMeta/columnMeta for application callbacks; create a feature only for reusable state or behavior that must augment Table objects.

Extension Surface

Declaration-merge Plugins to register the feature key, then merge only the maps backed by runtime behavior:

Feature map Contribution
TableState_FeatureMap State slices in options, atoms, and store
TableOptions_FeatureMap<TFeatures, TData> Table options and change callbacks
Table_FeatureMap<TFeatures, TData> Public table APIs
ColumnDef_FeatureMap<TFeatures, TData, TValue> Column-definition options
Column_FeatureMap<TFeatures, TData> Public column APIs/data
Row_FeatureMap<TFeatures, TData> Public row APIs/data
Cell_FeatureMap Public cell APIs
Header_FeatureMap Public header APIs
RowModelFns_FeatureMap<TFeatures, TData> Advanced table._rowModelFns registries
CachedRowModels_FeatureMap<TFeatures, TData> Advanced table._rowModels cache getters

assignTableAPIs installs singleton table methods. Use assignPrototypeAPIs inside assignColumnPrototype, assignRowPrototype, assignCellPrototype, or assignHeaderPrototype for shared object methods. Use initColumnInstanceData and initRowInstanceData only for per-instance fields.

Use initTableInstanceData for mutable, non-reactive data owned by one table. It runs once after options, state atoms, and the store exist, and every feature initialization finishes before any constructTableAPIs hook runs. Use resetTableInstanceData to clear transient instance data after internal atoms reset during table.reset(); it does not own state slices or externally controlled state. Keep constructTableAPIs exclusively for method assignment.

Read the full file on GitHub · 236 lines

Changes

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.

  1. 2d ago First seen · 236 lines · 93 tokens per session scan A 5591215f2814

Subscribe to this mod's changes

custom-features is a skill published in the GitHub repository TanStack/table (28,393 stars, last pushed 2d ago), licensed MIT. It adds 93 tokens to every session and 2,190 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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