jellytau/eslint.config.js

// ESLint flat config for the JellyTau frontend (Svelte 5 + TypeScript strict).
//
// TRACES: | DR-205
//
// Scope: `src/` (the presentation layer), `scripts/` (build tooling), and the
// root config files. The Rust backend is linted by clippy, not by this config.
//
// Formatting is NOT ESLint's job here — `eslint-config-prettier` is applied last
// and switches off every stylistic rule that would fight `prettier`. Run
// `bun run format` / `bun run format:check` for layout.
import js from "@eslint/js";
import ts from "typescript-eslint";
import svelte from "eslint-plugin-svelte";
import globals from "globals";
import prettier from "eslint-config-prettier";
import svelteConfig from "./svelte.config.js";

export default ts.config(
  {
    // Kept in one place so `npx eslint .` and editor integrations agree.
    ignores: [
      "node_modules/",
      ".svelte-kit/",
      // Scratch worktrees (git-ignored) hold full checkouts of this repo,
      // including their own generated .svelte-kit trees. Without this, `eslint .`
      // lints every in-flight branch and reports its generated code as ours.
      ".claude/",
      "build/",
      "dist/",
      "coverage/",
      "package/",
      "src-tauri/",
      // Generated by tauri-specta on every Rust build — never hand-edited, and
      // its shape is dictated by the Rust command definitions.
      "src/lib/api/bindings.ts",
    ],
  },

  js.configs.recommended,
  ...ts.configs.recommended,
  ...svelte.configs.recommended,
  prettier,
  ...svelte.configs.prettier,

  {
    languageOptions: {
      globals: {
        ...globals.browser,
        ...globals.es2021,
      },
    },
    rules: {
      // The logger-facade migration this rule was waiting on is done: the ~468
      // `console.*` calls that used to live in `src/` are gone, replaced by
      // `createLogger(...)` from src/lib/utils/logger.ts (DR-204), which is now
      // the single sink. Nothing is allowed through — not even warn/error —
      // because the facade's own `warn`/`error` levels are always emitted, so a
      // raw call has no capability the facade lacks. It only loses the scope tag
      // and the runtime level control.
      //
      // The sink itself is exempted below, as are tests (a test that asserts on
      // logging has to be able to talk about `console`).
      "no-console": "error",

      // Unused values are a real signal, but `_`-prefixed args are the
      // established way to say "this parameter exists for the signature".
      //
      // ⚠️ warn, not error: the tree carries ~94 genuinely dead bindings (stale
      // imports, `$state` left over from refactors, unused `catch (e)`). Every
      // one is a real finding, but fixing them here would mean ~50 unrelated
      // files in this tooling commit. Clear the backlog, then promote to
      // "error".
      "@typescript-eslint/no-unused-vars": [
        "warn",
        {
          argsIgnorePattern: "^_",
          varsIgnorePattern: "^_",
          caughtErrorsIgnorePattern: "^_",
          destructuredArrayIgnorePattern: "^_",
        },
      ],

      // Warn-only rules: each flags something real, but the existing tree has
      // more instances than can be fixed without swamping unrelated diffs.
      // Drive these to zero and promote them to "error" — do not delete them.
      //
      // `any` at the Tauri IPC boundary, mostly in code predating the
      // tauri-specta bindings (~25 sites outside tests).
      "@typescript-eslint/no-explicit-any": "warn",
      // Empty catch/if bodies that swallow an error.
      "no-empty": ["warn", { allowEmptyCatch: true }],

      // Prefer `import type` so type-only imports are erased cleanly by the
      // bundler instead of pulling a module in at run time.
      "@typescript-eslint/consistent-type-imports": "off",

      // Not applicable to this app (~130 hits, all no-ops). SvelteKit's
      // `resolve()` exists so hrefs keep working under a non-empty
      // `kit.paths.base`; JellyTau is an adapter-static SPA served from the
      // Tauri webview root and svelte.config.js sets no `base`. Re-enable this
      // the day a base path is introduced — the rule is otherwise correct.
      // (Declared here, not in the *.svelte block: `goto()` is also called from
      // plain .ts modules such as src/lib/utils/navigation.ts.)
      "svelte/no-navigation-without-resolve": "off",
    },
  },

  {
    // Svelte components: the parser needs the project's svelte.config.js so it
    // resolves preprocessors and Svelte 5 runes the same way the build does.
    files: ["**/*.svelte", "**/*.svelte.ts", "**/*.svelte.js"],
    languageOptions: {
      parserOptions: {
        parser: ts.parser,
        svelteConfig,
      },
    },
    rules: {
      // Warn-only — real findings, but each fix is a behavioural refactor that
      // does not belong in a tooling commit:
      //   require-each-key      keyed {#each} changes DOM reuse semantics
      //   prefer-svelte-reactivity  Set/Map -> SvelteSet/SvelteMap changes
      //                             reactivity, not just syntax
      //   prefer-writable-derived   $state + $effect -> writable $derived
      //   no-at-html-tags           {@html} sites need an XSS review each
      "svelte/require-each-key": "warn",
      "svelte/prefer-svelte-reactivity": "warn",
      "svelte/prefer-writable-derived": "warn",
      "svelte/no-at-html-tags": "warn",

      // Warn-only: this rule cannot see the Svelte *compiler's* warning set, so
      // it reports `<!-- svelte-ignore a11y_… -->` as unused when the compiler
      // may still be emitting the warning it suppresses. Verify against a real
      // `bun run check` before deleting any of them.
      "svelte/no-unused-svelte-ignore": "warn",
    },
  },

  {
    // The logging facade is the one place allowed to touch `console` — it *is*
    // the sink every other module reaches it through (see the `no-console`
    // comment above). `createLogger`'s `console[method](...)` dispatch is a
    // computed member access, which the rule flags like any other.
    files: ["src/lib/utils/logger.ts"],
    rules: {
      "no-console": "off",
    },
  },

  {
    // Node-side tooling: build/test scripts and root config files run under
    // Bun/Node, not in the webview.
    files: [
      "scripts/**/*.{ts,js}",
      "*.config.{ts,js}",
      "*.config.*.{ts,js}",
      "svelte.config.js",
      "eslint.config.js",
    ],
    languageOptions: {
      globals: {
        ...globals.node,
      },
    },
    rules: {
      // These are command-line tools (extract-traces, release-notes, ...) whose
      // stdout IS the product — `bun run traces:markdown > docs/traceability.md`
      // depends on it. The logging facade is a webview concern; a CLI printing
      // its result is not a stray debug statement.
      "no-console": "off",
    },
  },

  {
    // Test files: vitest globals are enabled in vitest.config.ts.
    files: ["**/*.{test,spec}.{ts,js}", "src/test/**/*.{ts,js}"],
    languageOptions: {
      globals: {
        ...globals.node,
        ...globals.vitest,
      },
    },
    rules: {
      // Tests are allowed to talk about `console` — several spy on it to assert
      // what the logging facade emits, and scripts/ tooling tests capture output.
      "no-console": "off",
      // Test doubles legitimately use `any` for partial mocks.
      "@typescript-eslint/no-explicit-any": "off",
      // `vi.mock` factories are hoisted above the import graph, so a lazy
      // `require()` inside one is the documented escape hatch.
      "@typescript-eslint/no-require-imports": "off",
      // Several tests deliberately replay a production assignment sequence
      // (`currentStreamUrl = newStreamUrl; hasSeeked = false;`) to document the
      // `$effect` they stand in for. The "useless" write is the subject under
      // test, not dead code.
      "no-useless-assignment": "off",
    },
  },
);