Summary
If you're building on Internet Computer, this is your guide to not losing user data when you upgrade a canister. It covers the persistent actor pattern in Motoko (where `let` and `var` just work automatically) and StableBTreeMap with MemoryManager in Rust (because thread_local RefCell gets wiped on every deploy). The mistakes section is genuinely useful: it walks through the pre_upgrade instruction trap that bricks canisters, the type change gotchas in Motoko, and why Bound::Unbounded beats Bound::Bounded for forward compatibility. Includes working code for both languages with CBOR serialization. Read this before your first canister upgrade, not after you've lost production data.
Install to Claude Code
npx -y skills add dfinity/icskills --skill stable-memory --agent claude-codeInstalls into .claude/skills of the current project.
Keeps your Mac awake while Claude Code, Codex or Cursor works. Lets it sleep when they are done.
Try free for 7 days →
Block distracting apps from your iPhone permanently without a 3rd party app. Free and open source.
Block now (100% free) →
Notes, actions and memory. Without a meeting bot. First month 100% off.
Download for free →
belt cli automatically finds the best tools and skills for your agent. image, video, music, tts...
one prompt install →
Free an open-source skills that make AI coding agents easier to understand, verify, and control.
Download for free →
Connect your Claude agent to live crypto prices and trading routes via 1inch
Get the MCP →Files
SKILL.md
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Keeps your Mac awake while Claude Code, Codex or Cursor works. Lets it sleep when they are done.
Try free for 7 days →Block distracting apps from your iPhone permanently without a 3rd party app. Free and open source.
Block now (100% free) →Notes, actions and memory. Without a meeting bot. First month 100% off.
Download for free →belt cli automatically finds the best tools and skills for your agent. image, video, music, tts...
one prompt install →Free an open-source skills that make AI coding agents easier to understand, verify, and control.
Download for free →Connect your Claude agent to live crypto prices and trading routes via 1inch
Get the MCP →
