Menu

Individual skill

immutable-constants

Proper use of immutable and constant variables for gas savings and correctness. Use when deploying contracts with fixed configuration, optimizing gas, or deciding between constant, immutable, and storage variables.

skills/immutable-constants/SKILL.md

Read pinned source

Source commit a53141f10a1bbf9c634e44af6bc5a29dd1660697

What was checked

Matches the observed repository HEAD
Yes
Scanner rules are current
Yes
Repository scan complete
No
Skill scan complete
Yes
Observed behavior
Instructions only
Last checked
Nov 7, 2026

These are observations at the recorded commit, not a guarantee of safety. Review the source before running it.

Install this skill

Choose an agent in your Stack or copy a command below. Commands fetch the pinned commit and copy only this skill directory. Existing destinations are refused. Copying a command does not install anything.

An install command is unavailable: current rules, complete repository and skill scans, an eligible behavior level and a permitted license are required.

Repository context

Repository stars (not skill ratings)
132
Repository last updated
Oct 23, 2026
License
MIT

Observed agent integration: No specific integration evidence. Standard SKILL.md installation does not imply verified compatibility.

Files and excerpt

File metadata and permitted, redacted excerpts come from the recorded scan. Source links are pinned to that commit.

Browse files
Read excerpt

# Immutable & Constant Variables

## When to Use Each

| Type | Set At | Stored In | SLOAD Cost | Use Case |
|------|--------|-----------|------------|----------|
| `constant` | Compile time | Bytecode (inlined) | 0 gas | Known at write time: math constants, hashes, selectors |
| `immutable` | Deploy time (constructor) | Bytecode (appended) | 0 gas | Known at deploy: addresses, chain IDs, config |
| Storage | Runtime | Storage slot | 2,100 cold / 100 warm | Must change after deployment |

## Constant Variables

Must be known at compile time. Value is inlined everywhere it's used.