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.
Plug Mailtrap into your AI workflow and let it handle the email.
Connect Mailtrap MCP →
Agent, run crypto. Access onchain data & trade routes via 1inch.
Install now →
Make coding agent sessions - Searchable, Shareable, Vendor-neutral & Scored.
Try For Free →
Your agent targets a perfect 10 Code Health score. Deterministic. Every commit.
Try For Free →
Integrate web data into your AI product. One API to scrape website & brand data.
Get API Key Now →
belt cli automatically finds the best tools and skills for your agent. image, video, music, tts...
one prompt install →
Files
SKILL.md
Select a file.
Featured
Plug Mailtrap into your AI workflow and let it handle the email.
Connect Mailtrap MCP →Agent, run crypto. Access onchain data & trade routes via 1inch.
Install now →Make coding agent sessions - Searchable, Shareable, Vendor-neutral & Scored.
Try For Free →Your agent targets a perfect 10 Code Health score. Deterministic. Every commit.
Try For Free →Integrate web data into your AI product. One API to scrape website & brand data.
Get API Key Now →belt cli automatically finds the best tools and skills for your agent. image, video, music, tts...
one prompt install →
