♻️ Split shared config utilities (#257)

Why: move the shared config, CI, git, and output utilities into a smaller production-ready foundation before the command and server slices build on them. This keeps the behavior easy to review and catches real stale-dependency cleanup before merge.\n\nWhat changed:\n- Simplified config merge/serialization helpers and config-service behavior.\n- Tightened CI/git/output helper behavior with outcome-focused tests.\n- Removed the unused build-history helper.\n- Kept the active colors utility after fresh review showed CLI, TDD, output, and tests still depend on it.\n\nVerification:\n- npm run lint\n- npm run build\n- node --test tests/config/core.test.js tests/services/config-service.test.js tests/unit/ci-env.test.js tests/unit/output.test.js tests/utils/ci-env.test.js tests/utils/colors.test.js tests/utils/config-loader.test.js tests/utils/git.test.js\n- GitHub CI: CI Status, Node 22, Node 24, SDK E2E, SDK Unit Status, and GitHub visual workflows all passed.\n\nNote: external Vizzly CLI Reporter requested review for one mobile visual diff on a reporter screen outside this PR's code scope; GitHub visual workflows passed.

Author: Robdel12

src/config/core.js

@@ -22,7 +22,7 @@ export const CONFIG_DEFAULTS = {
     batchSize: 10,
     timeout: 30000,
   },
-  comparison: { threshold: 2.0 },
+  comparison: { threshold: 2.0, minClusterSize: 2 },
   tdd: { openReport: false },
   plugins: [],
 };
@@ -81,32 +81,44 @@ export function validateWriteScope(scope) {
 // Deep Merge
 // ============================================================================
 
+function isPlainConfigObject(value) {
+  return value && typeof value === 'object' && !Array.isArray(value);
+}
+
+function cloneConfigValue(value) {
+  if (Array.isArray(value)) {
+    return value.map(cloneConfigValue);
+  }
+
+  if (isPlainConfigObject(value)) {
+    let cloned = {};
+    for (let key of Object.keys(value)) {
+      cloned[key] = cloneConfigValue(value[key]);
+    }
+    return cloned;
+  }
+
+  return value;
+}
+
 /**
  * Deep merge two objects
  * @param {Object} target - Target object
  * @param {Object} source - Source object
  * @returns {Object} Merged object (new object, inputs not mutated)
  */
 export function deepMerge(target, source) {
-  let output = { ...target };
+  let output = cloneConfigValue(target);
 
   for (let key of Object.keys(source)) {
-    if (
-      source[key] &&
-      typeof source[key] === 'object' &&
-      !Array.isArray(source[key])
-    ) {
-      if (
-        target[key] &&
-        typeof target[key] === 'object' &&
-        !Array.isArray(target[key])
-      ) {
+    if (isPlainConfigObject(source[key])) {
+      if (isPlainConfigObject(target[key])) {
         output[key] = deepMerge(target[key], source[key]);
       } else {
-        output[key] = source[key];
+        output[key] = cloneConfigValue(source[key]);
       }
     } else {
-      output[key] = source[key];
+      output[key] = cloneConfigValue(source[key]);
     }
   }
 
@@ -123,12 +135,22 @@ export function deepMerge(target, source) {
  * @returns {Object} The value if it's an object, empty object otherwise
  */
 function ensureObject(value) {
-  if (value && typeof value === 'object' && !Array.isArray(value)) {
+  if (isPlainConfigObject(value)) {
     return value;
   }
   return {};
 }
 
+function applyConfigLayer(config, sources, layer, sourceName) {
+  let merged = deepMerge(config, layer);
+
+  for (let key of Object.keys(layer)) {
+    sources[key] = sourceName;
+  }
+
+  return merged;
+}
+
 /**
  * Build merged config from layers with source tracking
  * @param {Object} options - Config layers
@@ -147,37 +169,31 @@ export function buildMergedConfig({
   let safeGlobalConfig = ensureObject(globalConfig);
   let safeEnvOverrides = ensureObject(envOverrides);
 
-  let mergedConfig = {};
+  let mergedConfig = cloneConfigValue(CONFIG_DEFAULTS);
   let sources = {};
 
-  // Layer 1: Defaults
   for (let key of Object.keys(CONFIG_DEFAULTS)) {
-    mergedConfig[key] = CONFIG_DEFAULTS[key];
     sources[key] = 'default';
   }
 
-  // Layer 2: Global config (auth, project mappings, user preferences)
-  if (safeGlobalConfig.auth) {
-    mergedConfig.auth = safeGlobalConfig.auth;
-    sources.auth = 'global';
-  }
-
-  if (safeGlobalConfig.projects) {
-    mergedConfig.projects = safeGlobalConfig.projects;
-    sources.projects = 'global';
-  }
-
-  // Layer 3: Project config file
-  for (let key of Object.keys(safeProjectConfig)) {
-    mergedConfig[key] = safeProjectConfig[key];
-    sources[key] = 'project';
-  }
-
-  // Layer 4: Environment variables
-  for (let key of Object.keys(safeEnvOverrides)) {
-    mergedConfig[key] = safeEnvOverrides[key];
-    sources[key] = 'env';
-  }
+  mergedConfig = applyConfigLayer(
+    mergedConfig,
+    sources,
+    safeGlobalConfig,
+    'global'
+  );
+  mergedConfig = applyConfigLayer(
+    mergedConfig,
+    sources,
+    safeProjectConfig,
+    'project'
+  );
+  mergedConfig = applyConfigLayer(
+    mergedConfig,
+    sources,
+    safeEnvOverrides,
+    'env'
+  );
 
   return { config: mergedConfig, sources };
 }

src/services/config-service.js

@@ -12,30 +12,10 @@ import { existsSync } from 'node:fs';
 import { writeFile } from 'node:fs/promises';
 import { join } from 'node:path';
 import { cosmiconfigSync } from 'cosmiconfig';
+import { CONFIG_DEFAULTS } from '../config/core.js';
 import { loadGlobalConfig, saveGlobalConfig } from '../utils/global-config.js';
 import * as output from '../utils/output.js';
 
-/**
- * Default configuration values
- */
-let DEFAULT_CONFIG = {
-  comparison: {
-    threshold: 2.0,
-    minClusterSize: 2,
-  },
-  server: {
-    port: 47392,
-    timeout: 30000,
-  },
-  build: {
-    name: 'Build {timestamp}',
-    environment: 'test',
-  },
-  tdd: {
-    openReport: false,
-  },
-};
-
 /**
  * Create a config service instance
  * @param {Object} options
@@ -77,7 +57,7 @@ export function createConfigService({ workingDir }) {
    * Get merged configuration with source tracking
    */
   async function getMergedConfig() {
-    let config = { ...DEFAULT_CONFIG };
+    let config = cloneConfigValue(CONFIG_DEFAULTS);
     let sources = {};
 
     // Layer 1: Global config
@@ -102,18 +82,17 @@ export function createConfigService({ workingDir }) {
 
     // Layer 3: Environment variables
     if (process.env.VIZZLY_THRESHOLD) {
-      config.comparison.threshold = parseFloat(process.env.VIZZLY_THRESHOLD);
+      config.comparison.threshold = Number(process.env.VIZZLY_THRESHOLD);
       sources.comparison = 'env';
     }
     if (process.env.VIZZLY_MIN_CLUSTER_SIZE) {
-      config.comparison.minClusterSize = parseInt(
-        process.env.VIZZLY_MIN_CLUSTER_SIZE,
-        10
+      config.comparison.minClusterSize = Number(
+        process.env.VIZZLY_MIN_CLUSTER_SIZE
       );
       sources.comparison = 'env';
     }
     if (process.env.VIZZLY_PORT) {
-      config.server.port = parseInt(process.env.VIZZLY_PORT, 10);
+      config.server.port = Number(process.env.VIZZLY_PORT);
       sources.server = 'env';
     }
 
@@ -240,7 +219,11 @@ export default defineConfig(${JSON.stringify(newConfig, null, 2)});
     // Validate threshold
     if (config.comparison?.threshold !== undefined) {
       let threshold = config.comparison.threshold;
-      if (typeof threshold !== 'number' || threshold < 0) {
+      if (
+        typeof threshold !== 'number' ||
+        !Number.isFinite(threshold) ||
+        threshold < 0
+      ) {
         errors.push('comparison.threshold must be a non-negative number');
       } else if (threshold > 100) {
         warnings.push(
@@ -299,7 +282,7 @@ export default defineConfig(${JSON.stringify(newConfig, null, 2)});
  * Deep merge two objects
  */
 function mergeDeep(target, source) {
-  let result = { ...target };
+  let result = cloneConfigValue(target);
 
   for (let key in source) {
     if (
@@ -308,6 +291,8 @@ function mergeDeep(target, source) {
       !Array.isArray(source[key])
     ) {
       result[key] = mergeDeep(result[key] || {}, source[key]);
+    } else if (Array.isArray(source[key])) {
+      result[key] = [...source[key]];
     } else {
       result[key] = source[key];
     }
@@ -316,21 +301,45 @@ function mergeDeep(target, source) {
   return result;
 }
 
+function cloneConfigValue(value) {
+  if (Array.isArray(value)) {
+    return value.map(cloneConfigValue);
+  }
+
+  if (value && typeof value === 'object') {
+    let clone = {};
+    for (let key in value) {
+      clone[key] = cloneConfigValue(value[key]);
+    }
+    return clone;
+  }
+
+  return value;
+}
+
 /**
  * Merge config with source tracking
  */
-function mergeWithTracking(target, source, sources, sourceName) {
+function mergeWithTracking(target, source, sources, sourceName, sectionName) {
   for (let key in source) {
+    let sourceSection = sectionName || key;
+
     if (
       source[key] &&
       typeof source[key] === 'object' &&
       !Array.isArray(source[key])
     ) {
       if (!target[key]) target[key] = {};
-      mergeWithTracking(target[key], source[key], sources, sourceName);
+      mergeWithTracking(
+        target[key],
+        source[key],
+        sources,
+        sourceName,
+        sourceSection
+      );
     } else {
       target[key] = source[key];
-      sources[key] = sourceName;
+      sources[sourceSection] = sourceName;
     }
   }
 }