Merge pull request 'Fixes/request deduplication' (#44) from fixes/request-deduplication into main

Reviewed-on: #44

docs/GIT_WORKFLOW.md

@@ -1,592 +0,0 @@
-# Git Workflow and Branching Strategy
-
-This document outlines the git workflow, branching strategy, commit conventions, and code review guidelines for the glyphdiff.com project.
-
-## Table of Contents
-
-1. [Branching Strategy](#branching-strategy)
-2. [Branch Naming Conventions](#branch-naming-conventions)
-3. [Commit Message Conventions](#commit-message-conventions)
-4. [Code Splitting and Merge Request Guidelines](#code-splitting-and-merge-request-guidelines)
-5. [Branch Protection Rules](#branch-protection-rules)
-6. [Git Hooks Configuration](#git-hooks-configuration)
-
----
-
-## Branching Strategy
-
-We use a Gitflow-inspired branching strategy adapted for our development workflow. This strategy provides a clear structure for feature development, bug fixes, and releases.
-
-### Branch Types
-
-#### 1. `main` Branch
-- **Purpose**: Production-ready code only
-- **Protection**: Highest level of protection
-- **Rules**:
-  - Only merge `release/*` or `hotfix/*` branches into `main`
-  - No direct commits allowed
-  - Must pass all tests and code reviews
-  - Tags are created from this branch for releases (e.g., `v1.0.0`)
-
-#### 2. `develop` Branch
-- **Purpose**: Integration branch for features
-- **Protection**: High level of protection
-- **Rules**:
-  - Merge `feature/*` and `fix/*` branches into `develop`
-  - No direct commits allowed
-  - Must pass all tests before merging
-  - Serves as the base for `release/*` branches
-
-#### 3. `feature/*` Branches
-- **Purpose**: Develop new features
-- **Naming**: `feature/feature-name` (e.g., `feature/font-catalog`, `feature/comparison-grid`)
-- **Base**: Always branch from `develop`
-- **Merge**: Merge back into `develop` via Merge Request (MR)
-- **Rules**:
-  - One feature per branch
-  - Keep branches focused and small
-  - Delete after merging
-
-#### 4. `fix/*` Branches
-- **Purpose**: Fix bugs discovered during development
-- **Naming**: `fix/issue-description` (e.g., `fix/font-loading-error`, `fix/responsive-layout`)
-- **Base**: Branch from `develop`
-- **Merge**: Merge back into `develop` via MR
-- **Rules**:
-  - One fix per branch
-  - Include tests that verify the fix
-  - Delete after merging
-
-#### 5. `hotfix/*` Branches
-- **Purpose**: Critical fixes for production issues
-- **Naming**: `hotfix/critical-fix` (e.g., `hotfix/security-patch`, `hotfix-production-crash`)
-- **Base**: Branch from `main`
-- **Merge**: Merge into both `main` and `develop`
-- **Rules**:
-  - Use only for production emergencies
-  - Must be thoroughly tested
-  - Create a release tag after merging to `main`
-
-#### 6. `release/*` Branches
-- **Purpose**: Prepare for a new release
-- **Naming**: `release/vX.Y.Z` (e.g., `release/v1.0.0`, `release/v1.1.0`)
-- **Base**: Branch from `develop`
-- **Merge**: Merge into both `main` and `develop`
-- **Rules**:
-  - Finalize release notes
-  - Update version numbers
-  - Perform final testing
-  - Create release tag after merging to `main`
-
-### Branch Workflow Diagram
-
-```
-main (production)
-  ↑
-  │ hotfix/*, release/*
-  │
-develop (integration)
-  ↑
-  │ feature/*, fix/*
-  │
-feature branches
-```
-
----
-
-## Branch Naming Conventions
-
-### Feature Branches
-- Format: `feature/feature-name`
-- Examples:
-  - `feature/font-catalog`
-  - `feature/comparison-grid`
-  - `feature/dark-mode`
-  - `feature/google-fonts-integration`
-
-### Fix Branches
-- Format: `fix/issue-description`
-- Examples:
-  - `fix/font-loading-error`
-  - `fix/responsive-layout`
-  - `fix/state-persistence`
-  - `fix-accessibility-contrast`
-
-### Hotfix Branches
-- Format: `hotfix/critical-fix`
-- Examples:
-  - `hotfix/security-patch`
-  - `hotfix-production-crash`
-  - `hotfix-api-rate-limit`
-
-### Release Branches
-- Format: `release/vX.Y.Z`
-- Examples:
-  - `release/v1.0.0`
-  - `release/v1.1.0`
-  - `release/v2.0.0`
-
-### Naming Guidelines
-- Use lowercase letters
-- Use hyphens to separate words
-- Be descriptive but concise
-- Avoid special characters (except hyphens)
-- Keep names under 50 characters
-
----
-
-## Commit Message Conventions
-
-We follow the [Conventional Commits](https://www.conventionalcommits.org/) specification. This format enables automated changelog generation and better commit history readability.
-
-### Format
-
-```
-<type>(<scope>): <subject>
-
-<body>
-
-<footer>
-```
-
-### Commit Types
-
-| Type | Description | Examples |
-|------|-------------|----------|
-| `feat` | New feature | `feat(fonts): add Google Fonts integration` |
-| `fix` | Bug fix | `fix(comparison): resolve font loading race condition` |
-| `docs` | Documentation changes | `docs(readme): update installation instructions` |
-| `style` | Code style changes (formatting, etc.) | `style(components): format with Prettier` |
-| `refactor` | Code refactoring | `refactor(stores): simplify state management` |
-| `test` | Adding or updating tests | `test(fonts): add unit tests for font mapper` |
-| `chore` | Maintenance tasks | `chore(deps): update Tailwind CSS to v4.0` |
-| `perf` | Performance improvements | `perf(catalog): implement lazy loading for fonts` |
-
-### Scope
-
-The scope provides context about which part of the codebase is affected. Common scopes for this project:
-
-- `fonts` - Font-related functionality
-- `comparison` - Font comparison features
-- `catalog` - Font catalog pages
-- `stores` - State management stores
-- `components` - UI components
-- `routes` - SvelteKit routes
-- `services` - External API services
-- `utils` - Utility functions
-- `types` - TypeScript type definitions
-- `ui` - UI-related changes (theme, layout, etc.)
-- `config` - Configuration files
-
-### Subject
-
-- Use imperative mood ("add" not "added", "fix" not "fixed")
-- Keep it short (50 characters or less)
-- Don't end with a period
-- Be specific and descriptive
-
-### Body
-
-- Use imperative mood
-- Explain **what** and **why**, not **how**
-- Wrap at 72 characters
-- Include references to issues (e.g., `Closes #123`)
-
-### Footer
-
-- Reference breaking changes with `BREAKING CHANGE:`
-- Reference issues with `Closes #123` or `Fixes #456`
-- Include co-authors if needed
-
-### Examples
-
-#### Feature Commit
-```
-feat(fonts): add Google Fonts API integration
-
-Implement Google Fonts API service to fetch and display available fonts.
-This includes the fetchGoogleFonts function and font mapper utilities.
-
-Closes #12
-```
-
-#### Bug Fix Commit
-```
-fix(comparison): resolve font loading race condition
-
-The comparison grid was attempting to render fonts before they were fully
-loaded. Added loading state checks to prevent this issue.
-
-Fixes #45
-```
-
-#### Refactor Commit
-```
-refactor(stores): simplify state management with Svelte 5 runes
-
-Migrated from Svelte stores to Svelte 5's $state runes for better
-performance and simpler code. This change affects all stores in the
-project.
-
-BREAKING CHANGE: Store API has changed from subscribe() to direct
-property access. Update all store consumers accordingly.
-```
-
-#### Documentation Commit
-```
-docs(git-workflow): add commit message conventions
-
-Document the conventional commits format with examples and guidelines
-for the team.
-```
-
-#### Chore Commit
-```
-chore(deps): update Tailwind CSS to v4.0.0
-
-Update Tailwind CSS to the latest version and adjust configuration
-files accordingly.
-```
-
----
-
-## Code Splitting and Merge Request Guidelines
-
-### Merge Request Size Guidelines
-
-- **Maximum MR size**: < 500 lines changed (additions + deletions)
-- **Ideal MR size**: 100-300 lines changed
-- **Files per MR**: < 10 files
-
-### When to Split a Feature into Multiple MRs
-
-Split a feature into multiple MRs when:
-
-1. **The feature is large** (> 500 lines or > 10 files)
-2. **Multiple concerns are involved** (e.g., UI + API + state management)
-3. **Independent parts can be tested separately**
-4. **The feature has logical phases** (e.g., setup → implementation → polish)
-
-### Example: Splitting a Feature
-
-**Feature**: Font Catalog with Filtering
-
-**MR 1**: `feature/font-catalog-setup`
-- Create basic catalog page structure
-- Set up routing
-- Add placeholder components
-- ~150 lines
-
-**MR 2**: `feature/font-catalog-data`
-- Implement Google Fonts API integration
-- Create font data fetching logic
-- Add font mapper utilities
-- ~200 lines
-
-**MR 3**: `feature/font-catalog-ui`
-- Build FontCard component
-- Implement grid layout
-- Add loading states
-- ~250 lines
-
-**MR 4**: `feature/font-catalog-filtering`
-- Implement filter store
-- Build FilterBar component
-- Connect filters to catalog
-- ~180 lines
-
-### Merge Request Description Template
-
-Every MR must include a comprehensive description:
-
-```markdown
-## Description
-Brief description of what this MR changes and why.
-
-## Changes Made
-- [ ] Change 1
-- [ ] Change 2
-- [ ] Change 3
-
-## Type of Change
-- [ ] Bug fix
-- [ ] New feature
-- [ ] Breaking change
-- [ ] Documentation update
-- [ ] Refactoring
-- [ ] Performance improvement
-
-## Testing
-- [ ] Unit tests pass
-- [ ] Manual testing completed
-- [ ] Tested on Chrome
-- [ ] Tested on Firefox
-- [ ] Tested on Safari
-- [ ] Tested on mobile (responsive)
-
-## Screenshots (if applicable)
-Add screenshots or GIFs showing the changes.
-
-## Checklist
-- [ ] Code follows project style guidelines
-- [ ] Self-review completed
-- [ ] Comments added for complex logic
-- [ ] Documentation updated
-- [ ] No new warnings generated
-- [ ] Tests added/updated
-- [ ] All tests passing
-
-## Related Issues
-Closes #123
-Related to #456
-```
-
-### Code Review Checklist
-
-Reviewers should check:
-
-#### Functionality
-- [ ] Does the code work as intended?
-- [ ] Are edge cases handled?
-- [ ] Is error handling appropriate?
-
-#### Code Quality
-- [ ] Is the code readable and maintainable?
-- [ ] Are variable/function names descriptive?
-- [ ] Is there unnecessary complexity?
-- [ ] Are there code duplications?
-
-#### Best Practices
-- [ ] Does it follow project conventions?
-- [ ] Are TypeScript types properly defined?
-- [ ] Are Svelte best practices followed?
-- [ ] Is Tailwind CSS used appropriately?
-
-#### Testing
-- [ ] Are tests included?
-- [ ] Do tests cover edge cases?
-- [ ] Are tests meaningful and not redundant?
-
-#### Documentation
-- [ ] Is the code self-documenting?
-- [ ] Are complex functions commented?
-- [ ] Is the MR description clear?
-
-#### Performance
-- [ ] Are there performance concerns?
-- [ ] Is lazy loading used where appropriate?
-- [ ] Are unnecessary re-renders avoided?
-
-### Merge Request Approval Process
-
-1. **Author**: Creates MR with complete description
-2. **Reviewer**: Reviews code using the checklist above
-3. **Discussion**: Address any concerns or suggestions
-4. **Approval**: At least one approval required
-4. **Merge**: Squash and merge into target branch
-5. **Cleanup**: Delete source branch after merge
-
----
-
-## Branch Protection Rules
-
-### `main` Branch Protection
-
-- **Require pull request reviews**: Yes
-  - Required approvers: 1
-  - Dismiss stale reviews: Yes
-- **Require status checks**: Yes
-  - Required checks: All tests, linting
-  - Require branches to be up to date: Yes
-- **Restrict who can push**: Only maintainers
-- **Require linear history**: Yes (squash and merge)
-- **Block force pushes**: Yes
-
-### `develop` Branch Protection
-
-- **Require pull request reviews**: Yes
-  - Required approvers: 1
-  - Dismiss stale reviews: Yes
-- **Require status checks**: Yes
-  - Required checks: All tests, linting
-  - Require branches to be up to date: Yes
-- **Restrict who can push**: Only developers and maintainers
-- **Require linear history**: Yes (squash and merge)
-- **Block force pushes**: Yes
-
-### Implementation Notes
-
-These rules should be configured in your Git hosting platform (GitHub, GitLab, or Bitbucket). The exact configuration steps vary by platform:
-
-- **GitHub**: Settings → Branches → Add rule
-- **GitLab**: Settings → Repository → Protected branches
-- **Bitbucket**: Repository settings → Branch restrictions
-
----
-
-## Git Hooks Configuration
-
-Git hooks are automated scripts that run at specific points in the git workflow. They help maintain code quality and consistency.
-
-### Recommended Hooks
-
-#### 1. Pre-commit Hook
-**Purpose**: Run linter and formatter before committing
-
-**Tools**: ESLint, Prettier
-
-**Implementation**:
-```bash
-#!/bin/sh
-# .git/hooks/pre-commit
-
-# Run Prettier
-npm run format:check
-
-# Run ESLint
-npm run lint
-
-# Exit with error if any check fails
-if [ $? -ne 0 ]; then
-  echo "❌ Pre-commit checks failed. Please fix the issues before committing."
-  exit 1
-fi
-
-echo "✅ Pre-commit checks passed."
-```
-
-**Setup**:
-```bash
-# Install husky (recommended)
-npm install --save-dev husky
-
-# Initialize husky
-npx husky install
-
-# Add pre-commit hook
-npx husky add .husky/pre-commit "npm run lint && npm run format:check"
-```
-
-#### 2. Commit-msg Hook
-**Purpose**: Validate commit message format
-
-**Tools**: commitlint
-
-**Implementation**:
-```bash
-#!/bin/sh
-# .git/hooks/commit-msg
-
-# Validate commit message with commitlint
-npx --no -- commitlint --edit $1
-```
-
-**Setup**:
-```bash
-# Install commitlint
-npm install --save-dev @commitlint/cli @commitlint/config-conventional
-
-# Create commitlint config
-echo "module.exports = { extends: ['@commitlint/config-conventional'] };" > commitlint.config.js
-
-# Add commit-msg hook
-npx husky add .husky/commit-msg "npx --no -- commitlint --edit \$1"
-```
-
-#### 3. Pre-push Hook
-**Purpose**: Run tests before pushing
-
-**Tools**: Vitest, SvelteKit test runner
-
-**Implementation**:
-```bash
-#!/bin/sh
-# .git/hooks/pre-push
-
-# Run tests
-npm run test
-
-# Exit with error if tests fail
-if [ $? -ne 0 ]; then
-  echo "❌ Tests failed. Please fix the failing tests before pushing."
-  exit 1
-fi
-
-echo "✅ All tests passed."
-```
-
-**Setup**:
-```bash
-# Add pre-push hook
-npx husky add .husky/pre-push "npm run test"
-```
-
-### Alternative: Using Husky
-
-[Husky](https://typicode.github.io/husky/) is a popular tool for managing git hooks. It's easier to maintain and works across different operating systems.
-
-**Installation**:
-```bash
-npm install --save-dev husky
-npx husky install
-npm pkg set scripts.prepare="husky install"
-```
-
-**Adding hooks**:
-```bash
-# Pre-commit hook
-npx husky add .husky/pre-commit "npm run lint && npm run format:check"
-
-# Commit-msg hook
-npx husky add .husky/commit-msg "npx --no -- commitlint --edit \$1"
-
-# Pre-push hook
-npx husky add .husky/pre-push "npm run test"
-```
-
-### Hook Scripts for This Project
-
-Once the project is set up with SvelteKit, add these scripts to `package.json`:
-
-```json
-{
-  "scripts": {
-    "format": "prettier --write .",
-    "format:check": "prettier --check .",
-    "lint": "eslint .",
-    "lint:fix": "eslint . --fix",
-    "test": "vitest run",
-    "test:watch": "vitest",
-    "prepare": "husky install"
-  }
-}
-```
-
-### Benefits of Git Hooks
-
-1. **Consistency**: Enforce code style and formatting
-2. **Quality**: Catch bugs before they're committed
-3. **Efficiency**: Fail fast, fix early
-4. **Automation**: Reduce manual checks
-5. **Team alignment**: Ensure everyone follows the same standards
-
----
-
-## Summary
-
-This git workflow provides a structured approach to development for the glyphdiff.com project:
-
-- **Clear branching strategy** with defined purposes for each branch type
-- **Conventional commits** for readable and automated changelogs
-- **Code splitting guidelines** to keep MRs focused and reviewable
-- **Comprehensive review process** to maintain code quality
-- **Git hooks** to automate quality checks
-
-Following this workflow will help the team:
-- Develop features in parallel without conflicts
-- Maintain a clean git history
-- Catch issues early in the development process
-- Ensure code quality and consistency
-- Streamline the release process
-
-For questions or suggestions about this workflow, please discuss with the team or create an issue in the project repository.

src/entities/Font/api/proxy/proxyFonts.test.ts

@@ -21,6 +21,7 @@ vi.mock('$shared/api/api', () => ({
 import { api } from '$shared/api/api';
 import { queryClient } from '$shared/api/queryClient';
 import { fontKeys } from '$shared/api/queryKeys';
+import { FontResponseError } from '../../lib/errors/errors';
 import {
     fetchFontsByIds,
     fetchProxyFontById,
@@ -86,16 +87,20 @@ describe('proxyFonts', () => {
             expect(calledUrl).toContain('offset=0');
         });
 
-        test('should throw on invalid response (missing fonts array)', async () => {
+        test('should throw FontResponseError on invalid response (missing fonts array)', async () => {
             mockApiGet({ total: 0 });
 
-            await expect(fetchProxyFonts()).rejects.toThrow('Proxy API returned invalid response');
+            await expect(fetchProxyFonts()).rejects.toSatisfy(
+                e => e instanceof FontResponseError && e.field === 'response.fonts',
+            );
         });
 
-        test('should throw on null response data', async () => {
+        test('should throw FontResponseError on null response data', async () => {
             vi.mocked(api.get).mockResolvedValueOnce({ data: null, status: 200 });
 
-            await expect(fetchProxyFonts()).rejects.toThrow('Proxy API returned invalid response');
+            await expect(fetchProxyFonts()).rejects.toSatisfy(
+                e => e instanceof FontResponseError && e.field === 'response',
+            );
         });
     });
 

src/entities/Font/api/proxy/proxyFonts.ts

@@ -15,6 +15,7 @@ import { queryClient } from '$shared/api/queryClient';
 import { fontKeys } from '$shared/api/queryKeys';
 import { buildQueryString } from '$shared/lib/utils';
 import type { QueryParams } from '$shared/lib/utils';
+import { FontResponseError } from '../../lib/errors/errors';
 import type { UnifiedFont } from '../../model/types';
 
 /**
@@ -96,11 +97,16 @@ export interface ProxyFontsParams extends QueryParams {
 /**
  * Proxy API response
  *
- * Includes pagination metadata alongside font data
+ * Includes pagination metadata alongside font data.
+ *
+ * Contract: `fonts` is always an array — never `null` or omitted, even when
+ * `total === 0`. Returning `null` on the wire is a backend regression and
+ * surfaces as FontResponseError (non-retryable) on the client.
  */
 export interface ProxyFontsResponse {
     /**
-     * List of font objects returned by the proxy
+     * List of font objects returned by the proxy.
+     * Always an array; empty when no matches.
      */
     fonts: UnifiedFont[];
 
@@ -156,8 +162,11 @@ export async function fetchProxyFonts(
 
     const response = await api.get<ProxyFontsResponse>(url);
 
-    if (!response.data || !Array.isArray(response.data.fonts)) {
-        throw new Error('Proxy API returned invalid response');
+    if (!response.data) {
+        throw new FontResponseError('response', response.data);
+    }
+    if (!Array.isArray(response.data.fonts)) {
+        throw new FontResponseError('response.fonts', response.data.fonts);
     }
 
     return response.data;

src/entities/Font/lib/errors/errors.ts

@@ -1,3 +1,5 @@
+import { NonRetryableError } from '$shared/api/queryClient';
+
 /**
  * Thrown when the network request to the proxy API fails.
  * Wraps the underlying fetch error (timeout, DNS failure, connection refused, etc.).
@@ -12,11 +14,13 @@ export class FontNetworkError extends Error {
 
 /**
  * Thrown when the proxy API returns a response with an unexpected shape.
+ * Extends NonRetryableError because schema mismatches are not transient —
+ * retrying will produce the same failure and only delay surfacing the bug.
  *
  * @property field - The name of the field that failed validation (e.g. `'response'`, `'response.fonts'`).
  * @property received - The actual value received at that field, for debugging.
  */
-export class FontResponseError extends Error {
+export class FontResponseError extends NonRetryableError {
     readonly name = 'FontResponseError';
 
     constructor(

src/entities/Font/model/store/fontCatalogStore/fontCatalogStore.svelte.spec.ts

@@ -84,9 +84,10 @@ describe('FontCatalogStore', () => {
             store.destroy();
         });
 
-        it('starts with isEmpty false — initial fetch is in progress', () => {
-            // The observer starts fetching immediately on construction.
-            // isEmpty must be false so the UI shows a loader, not "no results".
+        it('starts with isEmpty false — observer is gated until setParams enables it', () => {
+            // The observer is disabled on construction (no auto-fetch) — see
+            // `#enabled` in the store. isEmpty must still be false so the UI
+            // doesn't flash "no results" before bindings configures the query.
             const store = makeStore();
             expect(store.isEmpty).toBe(false);
             store.destroy();

src/entities/Font/model/store/fontCatalogStore/fontCatalogStore.svelte.ts

@@ -31,6 +31,13 @@ type FontStoreResult = InfiniteQueryObserverResult<InfiniteData<ProxyFontsRespon
 
 export class FontCatalogStore {
     #params = $state<FontStoreParams>({ limit: 50 });
+    /**
+     * Gates the initial fetch. The observer starts disabled so the constructor
+     * cannot race ahead of the bindings module — which is the single source of
+     * truth for query params. The first setParams flips this on, producing a
+     * single fetch with the correctly merged queryKey.
+     */
+    #enabled = $state(false);
     #result = $state<FontStoreResult>({} as FontStoreResult);
     #observer: InfiniteQueryObserver<
         ProxyFontsResponse,
@@ -45,6 +52,8 @@ export class FontCatalogStore {
     constructor(params: FontStoreParams = {}) {
         this.#params = { limit: 50, ...params };
         this.#observer = new InfiniteQueryObserver(this.#qc, this.buildOptions());
+        // Seed result synchronously; subscribe may not fire on disabled observers.
+        this.#result = this.#observer.getCurrentResult();
         this.#unsubscribe = this.#observer.subscribe(r => {
             this.#result = r;
         });
@@ -88,10 +97,13 @@ export class FontCatalogStore {
         return this.#result.error ?? null;
     }
     /**
-     * True if no fonts were found for the current filter criteria
+     * True if no fonts were found for the current filter criteria.
+     * Always false until the observer has been enabled (via setParams) — otherwise
+     * the UI would briefly render "no results" on mount before bindings configures
+     * the query.
      */
     get isEmpty(): boolean {
-        return !this.isLoading && !this.isFetching && this.fonts.length === 0;
+        return this.#enabled && !this.isLoading && !this.isFetching && this.fonts.length === 0;
     }
 
     /**
@@ -129,10 +141,12 @@ export class FontCatalogStore {
     }
 
     /**
-     * Merge new parameters into existing state and trigger a refetch
+     * Merge new parameters into existing state and trigger a refetch.
+     * The first call also enables the observer (see `#enabled`).
      */
     setParams(updates: Partial<FontStoreParams>) {
         this.#params = { ...this.#params, ...updates };
+        this.#enabled = true;
         this.#observer.setOptions(this.buildOptions());
     }
     /**
@@ -431,6 +445,7 @@ export class FontCatalogStore {
                 const next = lastPage.offset + lastPage.limit;
                 return next < lastPage.total ? { offset: next } : undefined;
             },
+            enabled: this.#enabled,
             staleTime: hasFilters ? 0 : DEFAULT_QUERY_STALE_TIME_MS,
             gcTime: DEFAULT_QUERY_GC_TIME_MS,
         };
@@ -441,6 +456,11 @@ export class FontCatalogStore {
         try {
             response = await fetchProxyFonts(params);
         } catch (cause) {
+            // Preserve non-retryable validation errors so the query client doesn't
+            // burn the retry budget on a deterministic schema mismatch.
+            if (cause instanceof FontResponseError) {
+                throw cause;
+            }
             throw new FontNetworkError(cause);
         }
 

src/entities/Font/ui/FontVirtualList/FontVirtualList.svelte

@@ -40,6 +40,10 @@ interface Props extends
      * Skeleton snippet
      */
     skeleton?: Snippet;
+    /**
+     * Empty-state snippet rendered when the query settled with zero fonts
+     */
+    empty?: Snippet;
 }
 
 let {
@@ -47,6 +51,7 @@ let {
     onVisibleItemsChange,
     weight,
     skeleton,
+    empty,
     ...rest
 }: Props = $props();
 
@@ -59,6 +64,8 @@ let isCatchingUp = $state(false);
 
 const showInitialSkeleton = $derived(!!skeleton && isLoading && fontCatalogStore.fonts.length === 0);
 const showCatchupSkeleton = $derived(!!skeleton && isCatchingUp);
+// Settled query with no matches — empty state replaces the (otherwise blank) list.
+const showEmpty = $derived(!!empty && !isLoading && !isCatchingUp && fontCatalogStore.fonts.length === 0);
 
 function handleInternalVisibleChange(items: UnifiedFont[]) {
     visibleFonts = items;
@@ -163,6 +170,10 @@ function handleNearBottom(_lastVisibleIndex: number) {
         <div class="overflow-hidden h-full" transition:fade={{ duration: 300 }}>
             {@render skeleton()}
         </div>
+    {:else if showEmpty && empty}
+        <div class="h-full" transition:fade={{ duration: 200 }}>
+            {@render empty()}
+        </div>
     {:else}
         <!-- VirtualList persists during pagination - no destruction/recreation -->
         <VirtualList

src/features/FilterAndSortFonts/api/filters/filters.ts

@@ -9,6 +9,7 @@
 
 import { api } from '$shared/api/api';
 import { API_ENDPOINTS } from '$shared/api/endpoints';
+import { NonRetryableError } from '$shared/api/queryClient';
 
 const PROXY_API_URL = API_ENDPOINTS.filters;
 
@@ -37,7 +38,8 @@ export interface FilterMetadata {
     type: 'enum' | 'string' | 'array';
 
     /**
-     * Available filter options
+     * Available filter options.
+     * Always an array; empty when the group has no options.
      */
     options: FilterOption[];
 }
@@ -68,11 +70,16 @@ export interface FilterOption {
 }
 
 /**
- * Proxy filters API response
+ * Proxy filters API response.
+ *
+ * Contract: `filters` (and each nested `options`) is always an array — never
+ * `null` or omitted. Wire-level `null` here is a backend regression and
+ * surfaces as a non-retryable error on the client.
  */
 export interface ProxyFiltersResponse {
     /**
-     * Array of filter metadata
+     * Array of filter metadata.
+     * Always an array; empty when no filter groups are configured.
      */
     filters: FilterMetadata[];
 }
@@ -99,7 +106,7 @@ export async function fetchProxyFilters(): Promise<FilterMetadata[]> {
     const response = await api.get<FilterMetadata[]>(PROXY_API_URL);
 
     if (!response.data || !Array.isArray(response.data)) {
-        throw new Error('Proxy API returned invalid response');
+        throw new NonRetryableError('Proxy API returned invalid filters response');
     }
 
     return response.data;

src/features/FilterAndSortFonts/model/store/bindings.svelte.ts

@@ -42,20 +42,19 @@ $effect.root(() => {
     });
 
     /**
-     * Mirror filter selections + debounced search query into fontCatalogStore params.
+     * Mirror filter selections + debounced search query + sort into fontCatalogStore params.
+     *
+     * Filters and sort are merged into one setParams call to avoid a startup race:
+     * two separate effects each issued setOptions with a different queryKey on the
+     * first flush, producing an orphaned `?limit=50&offset=0` fetch immediately
+     * followed by the real `?limit=50&sort=popularity&offset=0` fetch.
+     *
      * untrack the write so fontCatalogStore's internal $state reads don't feed back
      * into this effect's dependency graph.
      */
     $effect(() => {
         const params = mapAppliedFiltersToParams(appliedFilterStore);
-        untrack(() => fontCatalogStore.setParams(params));
-    });
-
-    /**
-     * Mirror sort selection into fontCatalogStore.
-     */
-    $effect(() => {
-        const apiSort = sortStore.apiValue;
-        untrack(() => fontCatalogStore.setSort(apiSort));
+        const sort = sortStore.apiValue;
+        untrack(() => fontCatalogStore.setParams({ ...params, sort }));
     });
 });

src/shared/api/queryClient.ts

@@ -1,5 +1,15 @@
 import { QueryClient } from '@tanstack/query-core';
 
+/**
+ * Marker base class for errors that retrying will never fix — schema-validation
+ * failures, unauthorized responses, contract violations, etc.
+ *
+ * The queryClient retry handler short-circuits when it sees this; without it,
+ * a non-transient backend bug pins the UI through the full retry budget
+ * (default 3× exponential backoff ≈ 7s).
+ */
+export class NonRetryableError extends Error {}
+
 /**
  * Data remains fresh for this long after fetch. Stores that override
  * staleness (e.g. filtered queries) can use 0 to bypass.
@@ -51,7 +61,12 @@ export const queryClient = new QueryClient({
              * Refetch on mount if data is stale
              */
             refetchOnMount: true,
-            retry: QUERY_RETRY_COUNT,
+            retry: (failureCount, error) => {
+                if (error instanceof NonRetryableError) {
+                    return false;
+                }
+                return failureCount < QUERY_RETRY_COUNT;
+            },
             /**
              * Exponential backoff: 1s, 2s, 4s, 8s... capped at 30s
              */

src/widgets/ComparisonView/ui/FontList/FontList.svelte

@@ -104,6 +104,12 @@ function isFontReady(font: UnifiedFont): boolean {
             gap={2}
             class="bg-transparent min-h-0 h-full scroll-stable py-2 pl-6 pr-4"
         >
+            {#snippet empty()}
+                <div class="px-6 py-12 flex items-center justify-center">
+                    <Label variant="muted" size="sm">No typefaces found</Label>
+                </div>
+            {/snippet}
+
             {#snippet skeleton()}
                 <div class="py-2.5 md:py-3 px-7">
                     {#each { length: 50 } as _, index (index)}