wrdn-effect-promise-exit

You fix one pattern: a React handler awaits an effect-atom mutation in `mode: "promise"` and catches failures with `try/catch`. The preferred UI boundary is `mode: "promiseExit"` plus `Exit.isFailure`. This keeps mutation failures as values, matches Effect's error model, and prevents optimistic mutation cleanup from depending on thrown exceptions. ## Trace before changing 1. **Find the mutation setter.** Look for `const doX = useAtomSet(<mutationAtom>, { mode: "promise" })`. 2. **Confirm it is an effect-atom mutation boundary.** The setter should come from `@effect/atom-react` and a mutation atom from `./atoms`, `../api/atoms`, or plugin React atoms. 3. **Find thrown-control handling.** The same handler has `try { await doX(...) } catch (e) { ... }`, usually setting error text, resetting `adding`/`saving`, or showing a toast. 4. **Check for non-mutation async work in the same block.** If the block also awaits follow-up mutations, convert those to `promiseExit` too or keep a narrow boundary only around truly non-effect APIs. 5. **Do not rewrite unrelated local async code.** Probe requests, OAuth popup helpers, `fetch`, and browser APIs may need a different skill unless the lint finding specifically points at the mutation call. ## Fix shape - Change the setter to `{ mode: "promiseExit" }`. - Import `* as Exit from "effect/Exit"` if missing. - Import `* as Option from "effect/Option"` only when extracting an optional error. - Replace `try/catch` around the mutation with: - `const exit = await doX(args);` - `if (Exit.isFailure(exit)) { ...; return; }` - success work after the failure branch. - Use `Exit.findErrorOption(exit)` when preserving an existing error message or typed error branch. - Keep existing typed error handling when present, e.g. `SecretInUseError`, `ConnectionInUseError`. ## Bad ```tsx const doAdd = useAtomSet(addGraphqlSource, { mode: "promise" }); const handleAdd = async () => { setAdding(true); setAddError(null); try { await doAdd({ params: { scopeId }, payload, reactivityKeys: sourceWriteKeys, }); props.onComplete(); } catch (e) { setAddError(e instanceof Error ? e.message : "Failed to add source"); setAdding(false); } }; ``` ## Good ```tsx import * as Exit from "effect/Exit"; import * as Option from "effect/Option"; const doAdd = useAtomSet(addGraphqlSource, { mode: "promiseExit" }); const handleAdd = async () => { setAdding(true); setAddError(null); const exit = await doAdd({ params: { scopeId }, payload, reactivityKeys: sourceWriteKeys, }); if (Exit.isFailure(exit)) { const error = Exit.findErrorOption(exit); setAddError( Option.isSome(error) && error.value instanceof Error ? error.value.message : "Failed to add source", ); setAdding(false); return; } props.onComplete(); }; ``` ## Follow-up mutation chains If success work depends on the mutation result, read it after the failure branch: ```tsx const exit = await doAdd(args); if (Exit.isFailure(exit)) { setAdding(false); return; } const sourceId = exit.value.namespace; ``` If a follow-up effect-atom mutation can fail and the UI treats that as add failure, make that setter `promiseExit` too and branch the same way. Do not put the follow-up mutation in `try/catch` just because the first mutation now returns `Exit`. ## What not to report - `try/catch` around non-effect APIs such as `new URL`, `JSON.parse`, raw `fetch`, or browser popup code. Those may be real lint findings, but they need a different remediation skill. - `useAtomSet(..., { mode: "promise" })` with no local failure handling and no lint finding. Some call sites intentionally let callers decide the boundary. - Tests or SDK/server Effect code. This skill is for React/effect-atom UI mutation handlers. - Manual optimistic placeholder cleanup. Use `wrdn-effect-atom-optimistic` for that; if both patterns appear together, fix optimistic plumbing first, then use `promiseExit` for the remaining mutation boundary. ## Output requirements When reviewing, report: - **File and line** of the `useAtomSet(..., { mode: "promise" })` or `try/catch`. - **Mutation** being called. - **Why** it should return `Exit` at this UI boundary. - **Fix**: the exact setter mode and the failure branch to add. When editing, keep changes local to the handler and imports unless a follow-up mutation in the same success path must also become `promiseExit`.