bermudalamb
c058b3ed2e
TypeScript's strict mode checks types and nothing else, so nothing enforced the React hook rules, the SonarJS rules, or unhandled-promise detection. Adds a flat config per workspace, a lint script in each, and a lint job in tests.yml. The rule selection is the substance of this change and is measured rather than guessed. A full-strength config reports 435 violations across 50 files, but 325 of those are the no-unsafe-* family from recommendedTypeChecked, every one downstream of pool.query() returning any rows and untyped fetch responses. Typing those boundaries is the whole of #65, so enabling the rules here would ship a linter whose output is three-quarters another issue's backlog — the reliable way to teach everyone to ignore lint output. This enables recommended plus the two type-aware rules that catch defects rather than describe type debt, which leaves 110 findings. Both configs downgrade every preset to a warning and then list the error rules explicitly at the bottom, so the CI gate is readable in one place instead of inferred from four presets' defaults. Errors are no-floating-promises, no-misused-promises, rules-of-hooks, exhaustive-deps and jsx-a11y/alt-text; everything else warns. No --max-warnings flag is needed because ESLint already exits non-zero on errors and zero on warnings. no-misused-promises runs with checksVoidReturn.attributes false, since onClick={async () => ...} is idiomatic React and safe when the handler catches its own errors — at the default it flags every antd button in the admin screens, 25 of its 28 hits, and a rule that is 89% noise gets switched off within a week. The 37 errors this surfaced were mostly not the mechanical fix they looked like. The plan assumed the 30 floating promises were fire-and-forget loaders that already handled their own failures, which was true of the one sampled when writing the design and false for most of the rest: Admin, Categories, Customers, Tags, Settings, Account and CustomerAuthContext all had no rejection handling at all, so `void` on them would have hidden real failures rather than annotated deliberate ones. Each of those loaders now catches and surfaces the failure before the call site voids it. The CustomerAuthContext one was a live bug — a rejected fetchMe left loading true forever, rendering as a permanent spinner instead of a signed-out page. Admin's load became a useCallback so its effect can name it honestly rather than suppress the dependency, Categories' drop handler was split so the function antd receives returns void as its type says, and Cart's effect now names refreshCartContext, which is a useCallback with an empty dependency list and so cannot re-run it. The only disable added is in asyncRoute, where returning a promise where Express expects void is the entire point of the wrapper and the promise cannot reject. Two of the issue's premises did not survive measurement, both recorded in the spec: exhaustive-deps flags 2 cases rather than the 10 inferred from empty dependency arrays, and the backend was already clean on the defect rules because #59 wrapped every async route. Verified: lint, build, 78 unit, 134 integration and 83 e2e all pass in both workspaces, and the CI gate was confirmed to fail by introducing a deliberate violation rather than by assuming the job is wired correctly. Closes #60
156 lines
12 KiB
Markdown
156 lines
12 KiB
Markdown
# ESLint — Design
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**Issue:** [#60 — No ESLint anywhere](https://gitea.bermudalamb.synology.me/bermudalamb/redefined-designs/issues/60)
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**Date:** 2026-08-19
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**Status:** Implemented
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## Goal
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Put a linter in front of the code that catches, at authoring time, the classes of defect this project has already shipped and then fixed by hand. Two workspaces, one CI job, green on the day it lands.
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The issue's own framing is the target: TypeScript's `strict: true` checks types and nothing else, so `rules-of-hooks`, `exhaustive-deps`, `no-floating-promises` and the SonarJS rules currently run either never or on a server after the fact.
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## What the code actually reports
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Every number below comes from running the candidate rule set against `backend/src` and `frontend/src` before writing any config, rather than from estimating. A full-strength config — `typescript-eslint` recommendedTypeChecked, `sonarjs`, `react-hooks` v7, `jsx-a11y` — reports **435 violations across 50 files**.
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| Rule family | Count | Disposition |
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| --- | --- | --- |
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| `@typescript-eslint/no-unsafe-*` (5 rules) | 325 | **Deferred to #65** |
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| `no-floating-promises` | 30 | Error — fix here |
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| `no-misused-promises` | 28 | Error, but 25 disappear under `checksVoidReturn: { attributes: false }` |
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| `sonarjs/prefer-read-only-props` | 16 | Warn |
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| `react-hooks` compiler rules (`set-state-in-effect`, `purity`) | 9 | Warn |
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| `no-explicit-any`, `no-unnecessary-type-assertion` | 11 | Warn |
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| `sonarjs/no-nested-conditional`, `cognitive-complexity` | 7 | Warn |
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| `react-hooks/exhaustive-deps` | 2 | Error — fix here |
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| `jsx-a11y/alt-text` | 2 | Error — fix here |
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| `rules-of-hooks` | 0 | Error (nothing to fix) |
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| Remaining singles | 5 | Warn |
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### Two of the issue's premises do not survive measurement
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**`exhaustive-deps` flags 2, not 10.** The issue inferred ten suspects from ten empty dependency arrays. The rule's own analysis clears eight of them — an empty array is only wrong when the effect closes over something that changes, and most of these genuinely do not. The two real ones are `Admin.tsx:62` (missing `load`) and `Cart.tsx:132` (missing `refreshCartContext`). The "decide case by case rather than blanket-autofix" instinct in the issue is still right; it applies to two cases.
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**The backend is already clean on the defect rules.** #59 wrapped every async route, and it shows: zero floating promises in `backend/src`. Its three `no-misused-promises` hits are all benign, and each was read rather than assumed — `asyncRoute.ts:13` is the wrapper performing its entire purpose, and the two `server.ts` scheduled jobs (`setInterval` cart sweep, `cron.schedule` reminder emails) already `try`/`catch` internally, so no rejection escapes.
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## Decisions
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| Area | Decision |
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| --- | --- |
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| Config format | Flat config (`eslint.config.mjs`), one per workspace |
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| Config location | `backend/` and `frontend/` separately — not a root config |
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| Type-aware linting | On, but narrowly: `recommended`, **not** `recommendedTypeChecked` |
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| `no-unsafe-*` family | Deferred to #65 |
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| `no-misused-promises` | `checksVoidReturn: { attributes: false }` |
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| React Compiler rules | Warn |
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| CI | New `lint` job in `tests.yml` |
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| Fail/warn split | Defect rules error; stylistic and advisory rules warn |
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### Why not `recommendedTypeChecked`
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It is the obvious choice and it is the wrong one here. Its `no-unsafe-*` family accounts for 325 of the 435 findings — 75% — and every one of them traces back to two untyped boundaries: `pool.query()` returning `any` rows on the backend, and `fetch(...).json()` on the frontend. Fixing them means typing those boundaries, which is the entire content of [#65](https://gitea.bermudalamb.synology.me/bermudalamb/redefined-designs/issues/65).
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Turning them on here would produce a lint run whose output is 75% another issue's backlog, which is the reliable way to teach everyone to ignore lint output. Instead this issue enables `recommended` plus the two type-aware rules that catch defects rather than describe type debt:
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```js
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'@typescript-eslint/no-floating-promises': 'error',
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'@typescript-eslint/no-misused-promises': ['error', { checksVoidReturn: { attributes: false } }],
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```
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Both need type information, so `parserOptions.projectService` is still required — the cost of type-aware linting is paid either way. This is a choice about which findings to surface, not about whether to run the type-aware engine.
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Issue #65 turns the `no-unsafe-*` rules on as it types those boundaries. That is the change that makes them green, so that is the change that should own them.
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### Why `checksVoidReturn: { attributes: false }`
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Left at its default, `no-misused-promises` flags every `onClick={async () => …}` — 25 of its 28 hits, all antd buttons in the admin screens. Passing an async function to a React event handler is idiomatic and safe when the function handles its own errors, which these do. typescript-eslint's own documentation recommends this option for React codebases. Without it the rule is 89% noise and would be switched off within a week; with it, the three remaining hits are all real signal.
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### Why the React Compiler rules only warn
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`eslint-plugin-react-hooks` v7 ships the React Compiler rule set — `set-state-in-effect`, `purity`, `static-components` and others — alongside the two classic rules. This is React 18 with no compiler in the build, so those rules are advising on a stricter model than the code is written against.
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They are not worthless: `purity` correctly flags `Date.now()` being called during render in `Cart.tsx:160`. That is a genuine render-purity smell worth seeing. It is not worth failing a build over in a codebase that never opted into the model, and fixing all nine would mean restructuring effects that behave correctly today — behaviour change well outside what #60 asked for.
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Warn keeps the finding visible and the build honest.
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### Why the files are named `.mjs`
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Neither `package.json` sets `"type": "module"`, so an `eslint.config.js` would be parsed as CommonJS and every `import` in it would fail. `.mjs` is the supported flat-config filename for exactly this case. Adding `"type": "module"` to either package instead would change how every other `.js` file in it is interpreted, which is a much larger change than a linter should make.
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### Why per-workspace configs rather than one at the root
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CI already runs `npm install` separately in `backend` and `frontend`, and the two have genuinely different rule needs — React and a11y rules are meaningless in `backend/src`, and each workspace has its own `tsconfig.json` that type-aware linting must point at. A root config would need file-pattern overrides to express a split the directory structure already expresses, and would put React plugins in the backend's dependency tree for no reason.
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The cost is a small amount of duplication between the two config files. That is cheaper than the alternative, and the files are short.
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## Fail/warn split
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The issue asks whether to fail CI on day one or start as warnings, and names the middle path: fail on the rules with real defect-catching value, warn on the rest. That is what this does.
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**Error — build fails (≈37 sites to fix):**
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| Rule | Sites | Fix |
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| --- | --- | --- |
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| `no-floating-promises` | 30 | `.catch` on six loaders, then `void` at the call sites |
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| `no-misused-promises` | 3 | Two restructured, one disabled with a reason |
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| `exhaustive-deps` | 2 | Triage individually |
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| `jsx-a11y/alt-text` | 2 | Add `alt` |
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| `rules-of-hooks` | 0 | — |
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**Warn — visible, does not block (≈73 sites):** SonarJS complexity and style, remaining jsx-a11y, React Compiler rules, `no-explicit-any`.
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No `--max-warnings` flag is needed: ESLint exits non-zero on errors and zero on warnings, so the split falls out of rule severity alone.
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### On `void load()` being a real fix rather than a disguised suppression
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**Corrected during implementation.** The paragraph below was written after reading one loader — `App.tsx`'s, which does catch — and generalised from it. That generalisation was wrong. Checking the other nine sites found that most of the admin loaders (`Admin.tsx`, `Categories.tsx`, `Customers.tsx`, `Tags.tsx`, `Settings.tsx`), plus `Account.tsx` and `CustomerAuthContext.tsx`, had no rejection handling at all. `void` on those would have been exactly the disguised suppression this section warns against.
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So the fix was larger than planned: each of those loaders got a `.catch` that surfaces the failure — `message.error(...)` in the admin screens, and in `CustomerAuthContext` a `.finally` that clears the loading flag, since a rejected `fetchMe()` previously left the app on a permanent spinner rather than showing a signed-out page. Only then does `void` at the call site state something true.
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This is the linter finding real defects on its first run, which is the outcome the issue predicted. It is recorded here because the original reasoning was sound but its premise was not checked widely enough — the per-site check is what caught it.
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Thirty floating promises sounds like thirty bugs; it is not, and the distinction matters because `void` can be either an honest annotation or a way to silence a rule without thinking.
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These are fire-and-forget calls to `load()`-style `useCallback`s in effects and event handlers. The callbacks were read before choosing this fix: each one sets its own error state — `App.tsx`'s `load` calls `setFailed(true)` — so a rejection is already handled inside, and nothing is being swallowed. `void` states "deliberately not awaited," which is exactly true here.
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Had any of them lacked internal handling, the fix for that one would be a `.catch`, not a `void`. The implementation plan checks each site rather than applying `void` mechanically.
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## Files
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| File | Change |
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| --- | --- |
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| `backend/eslint.config.mjs` | New |
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| `frontend/eslint.config.mjs` | New |
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| `backend/package.json` | `lint` script, devDependencies |
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| `frontend/package.json` | `lint` script, devDependencies |
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| `.gitea/workflows/tests.yml` | New `lint` job |
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| `frontend/src/**` (10 files) | ≈37 violation fixes |
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| `backend/src/asyncRoute.ts`, `server.ts` | 3 targeted disables |
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| `.claude/project-context.md` | Record the linter and the deferral to #65 |
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## Testing
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The linter is its own test: `npm run lint` in each workspace must exit 0. Success criteria:
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1. `npm run lint` passes in both workspaces with zero errors.
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2. The warning count is reported, not zero, and that is expected.
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3. `npm run build` still passes in both workspaces.
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4. Backend unit and integration suites still pass — the `void` and disable edits touch frontend files almost exclusively, but `server.ts` and `asyncRoute.ts` are on the backend.
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5. Playwright e2e passes, since ≈37 edits land in rendered components.
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6. The `lint` job runs in CI and fails the build when a rule in the error set is violated.
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Point 6 is verified by deliberately introducing a violation locally and confirming a non-zero exit, not by assuming the job's configuration is correct.
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## Out of scope
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- **The `no-unsafe-*` family and the `any` backlog** — #65.
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- **Prettier or any formatting tool.** The issue asks for defect detection. Formatting is a separate argument with separate churn.
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- **Linting `tests/` and Playwright specs.** Worth doing; a second step once the source is green, so that this change's error count stays the measured one.
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- **Replacing SonarQube.** The CI scan stays. This puts the same rule families in the editor, where they are cheaper to act on.
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## Follow-ups this creates
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- **#65 owns turning on `no-unsafe-*`** as it types `pool.query` results and `fetch` responses.
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- **`routesAreWrapped.test.ts` can retire** once `no-misused-promises` runs on the backend in CI. The test predates the linter and covers the same ground by scanning source; it is more targeted and its failure message is better, so this is a judgement call for whoever next touches either. Recorded here so the duplication is deliberate rather than forgotten.
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