diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8165dbd5..6da01f9e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,24 @@
 
 Format: [Keep a Changelog](https://keepachangelog.com/)
 
+## [4.4.0] - 2025-11-23
+
+### Changed
+- **BREAKING**: settings.json now shared across profiles via symlinks
+  - Each profile previously had isolated settings.json
+  - Now all profiles share ~/.claude/settings.json
+  - Migration automatic on install (uses ~/.claude/settings.json)
+  - Backups created: `<instance>/settings.json.pre-shared-migration`
+  - Rollback: restore backup manually if needed
+
+### Added
+- Doctor validates settings.json symlink integrity
+- Sync repairs broken settings.json symlinks
+- Migration from isolated to shared settings (automatic)
+
+### Fixed
+- Consistent shared data architecture across all .claude/ items
+
 ## [4.3.10] - 2025-11-23
 
 ### Fixed
diff --git a/README.md b/README.md
index 1285a577..a87bdd69 100644
--- a/README.md
+++ b/README.md
@@ -313,43 +313,21 @@ graph LR
 - Uses `CLAUDE_CONFIG_DIR` for isolated instances
 - Create with `ccs auth create <profile>`
 
-### Shared Data (v3.1+)
+### Shared Data (v4.4+)
 
-**CCS items (v4.1)**: Commands and skills symlinked from `~/.ccs/.claude/` to `~/.claude/` - **single source of truth with auto-propagation**.
+**Shared across instances** (`~/.ccs/shared/` symlinked to `~/.claude/`):
+- commands/ - Slash commands
+- skills/ - Agent skills
+- agents/ - Agent configs
+- **settings.json** - Claude CLI settings (v4.4+)
 
-**Profile access**: `~/.ccs/shared/` symlinks to `~/.claude/` - **no duplication across profiles**.
+**Profile-specific**:
+- sessions/ - Conversation history
+- todolists/ - Todo lists
+- logs/ - Execution logs
 
-```plaintext
-~/.ccs/
-├── .claude/                 # CCS items (ships with package, v4.1)
-│   ├── commands/ccs/        # Delegation commands (/ccs, /ccs:continue)
-│   └── skills/ccs-delegation/  # AI decision framework (replaces deprecated agents)
-├── shared/                  # Symlinks to ~/.claude/ (for profiles)
-│   ├── agents@ → ~/.claude/agents/
-│   ├── commands@ → ~/.claude/commands/
-│   └── skills@ → ~/.claude/skills/
-├── instances/               # Profile-specific data
-│   └── work/
-│       ├── agents@ → shared/agents/
-│       ├── commands@ → shared/commands/
-│       ├── skills@ → shared/skills/
-│       ├── settings.json    # API keys, credentials
-│       ├── sessions/        # Conversation history
-│       └── ...
-
-~/.claude/                   # User's Claude directory
-├── commands/ccs@ → ~/.ccs/.claude/commands/ccs/  # Selective symlink
-├── skills/ccs-delegation@ → ~/.ccs/.claude/skills/ccs-delegation/
-# agents/ccs-delegator.md@ → ~/.ccs/.claude/agents/ccs-delegator.md  # Deprecated in v4.3.2
-```
-
-**Symlink Chain**: `work profile → ~/.ccs/shared/ → ~/.claude/ → ~/.ccs/.claude/` (CCS items)
-
-| Type | Files |
-|:-----|:------|
-| **CCS items** | `~/.ccs/.claude/` (ships with package, selective symlinks to `~/.claude/`) |
-| **Shared** | `~/.ccs/shared/` (symlinks to `~/.claude/`) |
-| **Profile-specific** | `settings.json`, `sessions/`, `todolists/`, `logs/` |
+> [!NOTE]
+> **v4.4 Breaking Change**: settings.json now shared across profiles. Previously each profile had isolated settings. Migration is automatic on install using ~/.claude/settings.json as the authoritative source. Backups created: `<instance>/settings.json.pre-shared-migration`
 
 > [!NOTE]
 > **Windows**: Symlink support requires Developer Mode (v4.2 will add copy fallback)
diff --git a/VERSION b/VERSION
index 5d72fe47..fdc66988 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-4.3.10
+4.4.0
diff --git a/bin/management/doctor.js b/bin/management/doctor.js
index 1f1647b0..bec8d057 100644
--- a/bin/management/doctor.js
+++ b/bin/management/doctor.js
@@ -117,6 +117,7 @@ class Doctor {
     console.log(colored('System Health:', 'bold'));
     this.checkPermissions();
     this.checkCcsSymlinks();
+    this.checkSettingsSymlinks();
     console.log('');
 
     this.showReport();
@@ -502,6 +503,127 @@ class Doctor {
     }
   }
 
+  /**
+   * Check 10: settings.json symlinks
+   */
+  checkSettingsSymlinks() {
+    const spinner = ora('Checking settings.json symlinks').start();
+
+    try {
+      const sharedDir = path.join(this.homedir, '.ccs', 'shared');
+      const sharedSettings = path.join(sharedDir, 'settings.json');
+      const claudeSettings = path.join(this.claudeDir, 'settings.json');
+
+      // Check shared settings exists and points to ~/.claude/
+      if (!fs.existsSync(sharedSettings)) {
+        spinner.warn(`  ${'settings.json (shared)'.padEnd(26)}${colored('[!]', 'yellow')}  Not found`);
+        this.results.addCheck(
+          'Settings Symlinks',
+          'warning',
+          'Shared settings.json not found',
+          'Run: ccs sync'
+        );
+        return;
+      }
+
+      const sharedStats = fs.lstatSync(sharedSettings);
+      if (!sharedStats.isSymbolicLink()) {
+        spinner.warn(`  ${'settings.json (shared)'.padEnd(26)}${colored('[!]', 'yellow')}  Not a symlink`);
+        this.results.addCheck(
+          'Settings Symlinks',
+          'warning',
+          'Shared settings.json is not a symlink',
+          'Run: ccs sync'
+        );
+        return;
+      }
+
+      const sharedTarget = fs.readlinkSync(sharedSettings);
+      const resolvedShared = path.resolve(path.dirname(sharedSettings), sharedTarget);
+
+      if (resolvedShared !== claudeSettings) {
+        spinner.warn(`  ${'settings.json (shared)'.padEnd(26)}${colored('[!]', 'yellow')}  Wrong target`);
+        this.results.addCheck(
+          'Settings Symlinks',
+          'warning',
+          `Points to ${resolvedShared} instead of ${claudeSettings}`,
+          'Run: ccs sync'
+        );
+        return;
+      }
+
+      // Check each instance
+      const instancesDir = path.join(this.ccsDir, 'instances');
+      if (!fs.existsSync(instancesDir)) {
+        spinner.succeed(`  ${'settings.json'.padEnd(26)}${colored('[OK]', 'green')}  Shared symlink valid`);
+        this.results.addCheck('Settings Symlinks', 'success', 'Shared symlink valid', null, {
+          status: 'OK',
+          info: 'Shared symlink valid'
+        });
+        return;
+      }
+
+      const instances = fs.readdirSync(instancesDir).filter(name => {
+        return fs.statSync(path.join(instancesDir, name)).isDirectory();
+      });
+
+      let broken = 0;
+      for (const instance of instances) {
+        const instancePath = path.join(instancesDir, instance);
+        const instanceSettings = path.join(instancePath, 'settings.json');
+
+        if (!fs.existsSync(instanceSettings)) {
+          broken++;
+          continue;
+        }
+
+        try {
+          const stats = fs.lstatSync(instanceSettings);
+          if (!stats.isSymbolicLink()) {
+            broken++;
+            continue;
+          }
+
+          const target = fs.readlinkSync(instanceSettings);
+          const resolved = path.resolve(path.dirname(instanceSettings), target);
+
+          if (resolved !== sharedSettings) {
+            broken++;
+          }
+        } catch (err) {
+          broken++;
+        }
+      }
+
+      if (broken > 0) {
+        spinner.warn(`  ${'settings.json'.padEnd(26)}${colored('[!]', 'yellow')}  ${broken} broken instance(s)`);
+        this.results.addCheck(
+          'Settings Symlinks',
+          'warning',
+          `${broken} instance(s) have broken symlinks`,
+          'Run: ccs sync',
+          { status: 'WARN', info: `${broken} broken instance(s)` }
+        );
+      } else {
+        spinner.succeed(`  ${'settings.json'.padEnd(26)}${colored('[OK]', 'green')}  ${instances.length} instance(s) valid`);
+        this.results.addCheck('Settings Symlinks', 'success', 'All instance symlinks valid', null, {
+          status: 'OK',
+          info: `${instances.length} instance(s) valid`
+        });
+      }
+
+    } catch (err) {
+      spinner.warn(`  ${'settings.json'.padEnd(26)}${colored('[!]', 'yellow')}  Check failed`);
+      this.results.addCheck(
+        'Settings Symlinks',
+        'warning',
+        `Failed to check: ${err.message}`,
+        'Run: ccs sync',
+        { status: 'WARN', info: 'Check failed' }
+      );
+    }
+  }
+
   /**
    * Show health check report
    */
diff --git a/bin/management/instance-manager.js b/bin/management/instance-manager.js
index d317b0c3..f2b57d58 100644
--- a/bin/management/instance-manager.js
+++ b/bin/management/instance-manager.js
@@ -159,14 +159,9 @@ class InstanceManager {
    * @param {string} instancePath - Instance path
    */
   _copyGlobalConfigs(instancePath) {
-    const globalConfigDir = path.join(os.homedir(), '.claude');
-
-    // Copy settings.json only (commands/skills are now symlinked to shared/)
-    const globalSettings = path.join(globalConfigDir, 'settings.json');
-    if (fs.existsSync(globalSettings)) {
-      const instanceSettings = path.join(instancePath, 'settings.json');
-      fs.copyFileSync(globalSettings, instanceSettings);
-    }
+    // No longer needed - settings.json now symlinked via SharedManager
+    // Keeping method for backward compatibility (empty implementation)
+    // Can be removed in future major version
   }
 
   /**
diff --git a/bin/management/shared-manager.js b/bin/management/shared-manager.js
index 2e5a26d3..b5481cb3 100644
--- a/bin/management/shared-manager.js
+++ b/bin/management/shared-manager.js
@@ -17,7 +17,13 @@ class SharedManager {
     this.sharedDir = path.join(this.homeDir, '.ccs', 'shared');
     this.claudeDir = path.join(this.homeDir, '.claude');
     this.instancesDir = path.join(this.homeDir, '.ccs', 'instances');
-    this.sharedDirs = ['commands', 'skills', 'agents', 'plugins'];
+    this.sharedItems = [
+      { name: 'commands', type: 'directory' },
+      { name: 'skills', type: 'directory' },
+      { name: 'agents', type: 'directory' },
+      { name: 'plugins', type: 'directory' },
+      { name: 'settings.json', type: 'file' }
+    ];
   }
 
   /**
@@ -74,18 +80,23 @@ class SharedManager {
     }
 
     // Create symlinks ~/.ccs/shared/* → ~/.claude/*
-    for (const dir of this.sharedDirs) {
-      const claudePath = path.join(this.claudeDir, dir);
-      const sharedPath = path.join(this.sharedDir, dir);
+    for (const item of this.sharedItems) {
+      const claudePath = path.join(this.claudeDir, item.name);
+      const sharedPath = path.join(this.sharedDir, item.name);
 
-      // Create directory in ~/.claude/ if missing
+      // Create in ~/.claude/ if missing
       if (!fs.existsSync(claudePath)) {
-        fs.mkdirSync(claudePath, { recursive: true, mode: 0o700 });
+        if (item.type === 'directory') {
+          fs.mkdirSync(claudePath, { recursive: true, mode: 0o700 });
+        } else if (item.type === 'file') {
+          // Create empty settings.json if missing
+          fs.writeFileSync(claudePath, JSON.stringify({}, null, 2), 'utf8');
+        }
       }
 
       // Check for circular symlink
       if (this._detectCircularSymlink(claudePath, sharedPath)) {
-        console.log(`[!] Skipping ${dir}: circular symlink detected`);
+        console.log(`[!] Skipping ${item.name}: circular symlink detected`);
         continue;
       }
 
@@ -104,18 +115,27 @@ class SharedManager {
           // Continue to recreate
         }
 
-        // Remove existing directory/link
-        fs.rmSync(sharedPath, { recursive: true, force: true });
+        // Remove existing file/directory/link
+        if (item.type === 'directory') {
+          fs.rmSync(sharedPath, { recursive: true, force: true });
+        } else {
+          fs.unlinkSync(sharedPath);
+        }
       }
 
       // Create symlink
       try {
-        fs.symlinkSync(claudePath, sharedPath, 'dir');
+        const symlinkType = item.type === 'directory' ? 'dir' : 'file';
+        fs.symlinkSync(claudePath, sharedPath, symlinkType);
       } catch (err) {
-        // Windows fallback: copy directory
+        // Windows fallback: copy
         if (process.platform === 'win32') {
-          this._copyDirectoryFallback(claudePath, sharedPath);
-          console.log(`[!] Symlink failed for ${dir}, copied instead (enable Developer Mode)`);
+          if (item.type === 'directory') {
+            this._copyDirectoryFallback(claudePath, sharedPath);
+          } else if (item.type === 'file') {
+            fs.copyFileSync(claudePath, sharedPath);
+          }
+          console.log(`[!] Symlink failed for ${item.name}, copied instead (enable Developer Mode)`);
         } else {
           throw err;
         }
@@ -130,23 +150,32 @@ class SharedManager {
   linkSharedDirectories(instancePath) {
     this.ensureSharedDirectories();
 
-    for (const dir of this.sharedDirs) {
-      const linkPath = path.join(instancePath, dir);
-      const targetPath = path.join(this.sharedDir, dir);
+    for (const item of this.sharedItems) {
+      const linkPath = path.join(instancePath, item.name);
+      const targetPath = path.join(this.sharedDir, item.name);
 
-      // Remove existing directory/link
+      // Remove existing file/directory/link
       if (fs.existsSync(linkPath)) {
-        fs.rmSync(linkPath, { recursive: true, force: true });
+        if (item.type === 'directory') {
+          fs.rmSync(linkPath, { recursive: true, force: true });
+        } else {
+          fs.unlinkSync(linkPath);
+        }
       }
 
       // Create symlink
       try {
-        fs.symlinkSync(targetPath, linkPath, 'dir');
+        const symlinkType = item.type === 'directory' ? 'dir' : 'file';
+        fs.symlinkSync(targetPath, linkPath, symlinkType);
       } catch (err) {
         // Windows fallback
         if (process.platform === 'win32') {
-          this._copyDirectoryFallback(targetPath, linkPath);
-          console.log(`[!] Symlink failed for ${dir}, copied instead (enable Developer Mode)`);
+          if (item.type === 'directory') {
+            this._copyDirectoryFallback(targetPath, linkPath);
+          } else if (item.type === 'file') {
+            fs.copyFileSync(targetPath, linkPath);
+          }
+          console.log(`[!] Symlink failed for ${item.name}, copied instead (enable Developer Mode)`);
         } else {
           throw err;
         }
@@ -179,49 +208,56 @@ class SharedManager {
     }
 
     // Copy user modifications from ~/.ccs/shared/ to ~/.claude/
-    for (const dir of this.sharedDirs) {
-      const sharedPath = path.join(this.sharedDir, dir);
-      const claudePath = path.join(this.claudeDir, dir);
+    for (const item of this.sharedItems) {
+      const sharedPath = path.join(this.sharedDir, item.name);
+      const claudePath = path.join(this.claudeDir, item.name);
 
       if (!fs.existsSync(sharedPath)) continue;
 
       try {
         const stats = fs.lstatSync(sharedPath);
-        if (!stats.isDirectory()) continue;
-      } catch (err) {
-        continue;
-      }
 
-      // Create claude dir if missing
-      if (!fs.existsSync(claudePath)) {
-        fs.mkdirSync(claudePath, { recursive: true, mode: 0o700 });
-      }
+        // Handle directories
+        if (item.type === 'directory' && stats.isDirectory()) {
+          // Create claude dir if missing
+          if (!fs.existsSync(claudePath)) {
+            fs.mkdirSync(claudePath, { recursive: true, mode: 0o700 });
+          }
 
-      // Copy files from shared to claude (preserve user modifications)
-      try {
-        const entries = fs.readdirSync(sharedPath, { withFileTypes: true });
-        let copied = 0;
+          // Copy files from shared to claude (preserve user modifications)
+          const entries = fs.readdirSync(sharedPath, { withFileTypes: true });
+          let copied = 0;
 
-        for (const entry of entries) {
-          const src = path.join(sharedPath, entry.name);
-          const dest = path.join(claudePath, entry.name);
+          for (const entry of entries) {
+            const src = path.join(sharedPath, entry.name);
+            const dest = path.join(claudePath, entry.name);
 
-          // Skip if already exists in claude
-          if (fs.existsSync(dest)) continue;
+            // Skip if already exists in claude
+            if (fs.existsSync(dest)) continue;
 
-          if (entry.isDirectory()) {
-            fs.cpSync(src, dest, { recursive: true });
-          } else {
-            fs.copyFileSync(src, dest);
+            if (entry.isDirectory()) {
+              fs.cpSync(src, dest, { recursive: true });
+            } else {
+              fs.copyFileSync(src, dest);
+            }
+            copied++;
+          }
+
+          if (copied > 0) {
+            console.log(`[OK] Migrated ${copied} ${item.name} to ~/.claude/${item.name}`);
           }
-          copied++;
         }
 
-        if (copied > 0) {
-          console.log(`[OK] Migrated ${copied} ${dir} to ~/.claude/${dir}`);
+        // Handle files (settings.json)
+        else if (item.type === 'file' && stats.isFile()) {
+          // Only copy if ~/.claude/ version doesn't exist
+          if (!fs.existsSync(claudePath)) {
+            fs.copyFileSync(sharedPath, claudePath);
+            console.log(`[OK] Migrated ${item.name} to ~/.claude/${item.name}`);
+          }
         }
       } catch (err) {
-        console.log(`[!] Failed to migrate ${dir}: ${err.message}`);
+        console.log(`[!] Failed to migrate ${item.name}: ${err.message}`);
       }
     }
 
@@ -251,6 +287,87 @@ class SharedManager {
     console.log('[OK] Migration to v3.2.0 complete');
   }
 
+  /**
+   * Migrate existing instances from isolated to shared settings.json (v4.4+)
+   * Runs once on upgrade
+   */
+  migrateToSharedSettings() {
+    console.log('[i] Migrating instances to shared settings.json...');
+
+    // Ensure ~/.claude/settings.json exists (authoritative source)
+    const claudeSettings = path.join(this.claudeDir, 'settings.json');
+    if (!fs.existsSync(claudeSettings)) {
+      // Create empty settings if missing
+      fs.writeFileSync(claudeSettings, JSON.stringify({}, null, 2), 'utf8');
+      console.log('[i] Created ~/.claude/settings.json');
+    }
+
+    // Ensure shared settings.json symlink exists
+    this.ensureSharedDirectories();
+
+    // Migrate each instance
+    if (!fs.existsSync(this.instancesDir)) {
+      console.log('[i] No instances to migrate');
+      return;
+    }
+
+    const instances = fs.readdirSync(this.instancesDir).filter(name => {
+      const instancePath = path.join(this.instancesDir, name);
+      return fs.statSync(instancePath).isDirectory();
+    });
+
+    let migrated = 0;
+    let skipped = 0;
+
+    for (const instance of instances) {
+      const instancePath = path.join(this.instancesDir, instance);
+      const instanceSettings = path.join(instancePath, 'settings.json');
+
+      try {
+        // Check if already symlink
+        if (fs.existsSync(instanceSettings)) {
+          const stats = fs.lstatSync(instanceSettings);
+          if (stats.isSymbolicLink()) {
+            skipped++;
+            continue; // Already migrated
+          }
+
+          // Backup existing settings
+          const backup = instanceSettings + '.pre-shared-migration';
+          if (!fs.existsSync(backup)) {
+            fs.copyFileSync(instanceSettings, backup);
+            console.log(`[i] Backed up ${instance}/settings.json`);
+          }
+
+          // Remove old settings.json
+          fs.unlinkSync(instanceSettings);
+        }
+
+        // Create symlink via SharedManager
+        const sharedSettings = path.join(this.sharedDir, 'settings.json');
+
+        try {
+          fs.symlinkSync(sharedSettings, instanceSettings, 'file');
+          migrated++;
+        } catch (err) {
+          // Windows fallback
+          if (process.platform === 'win32') {
+            fs.copyFileSync(sharedSettings, instanceSettings);
+            console.log(`[!] Symlink failed for ${instance}, copied instead`);
+            migrated++;
+          } else {
+            throw err;
+          }
+        }
+
+      } catch (err) {
+        console.log(`[!] Failed to migrate ${instance}: ${err.message}`);
+      }
+    }
+
+    console.log(`[OK] Migrated ${migrated} instance(s), skipped ${skipped}`);
+  }
+
   /**
    * Copy directory as fallback (Windows without Developer Mode)
    * @param {string} src - Source directory
diff --git a/installers/install.ps1 b/installers/install.ps1
index 53754de4..0d0c9fb6 100644
--- a/installers/install.ps1
+++ b/installers/install.ps1
@@ -31,7 +31,7 @@ $InstallMethod = if ($ScriptDir -and ((Test-Path "$ScriptDir\lib\ccs.ps1") -or (
 # IMPORTANT: Update this version when releasing new versions!
 # This hardcoded version is used for standalone installations (irm | iex)
 # For git installations, VERSION file is read if available
-$CcsVersion = "4.3.10"
+$CcsVersion = "4.4.0"
 
 # Try to read VERSION file for git installations
 if ($ScriptDir) {
diff --git a/installers/install.sh b/installers/install.sh
index 49154b5f..e6c79d01 100755
--- a/installers/install.sh
+++ b/installers/install.sh
@@ -32,7 +32,7 @@ fi
 # IMPORTANT: Update this version when releasing new versions!
 # This hardcoded version is used for standalone installations (curl | bash)
 # For git installations, VERSION file is read if available
-CCS_VERSION="4.3.10"
+CCS_VERSION="4.4.0"
 
 # Try to read VERSION file for git installations
 if [[ -f "$SCRIPT_DIR/VERSION" ]]; then
diff --git a/lib/ccs b/lib/ccs
index 89688c87..09344335 100755
--- a/lib/ccs
+++ b/lib/ccs
@@ -2,7 +2,7 @@
 set -euo pipefail
 
 # Version (updated by scripts/bump-version.sh)
-CCS_VERSION="4.3.10"
+CCS_VERSION="4.4.0"
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 readonly CONFIG_FILE="${CCS_CONFIG:-$HOME/.ccs/config.json}"
 readonly PROFILES_JSON="$HOME/.ccs/profiles.json"
diff --git a/lib/ccs.ps1 b/lib/ccs.ps1
index 1bcbc19b..90eee1fe 100644
--- a/lib/ccs.ps1
+++ b/lib/ccs.ps1
@@ -12,7 +12,7 @@ param(
 $ErrorActionPreference = "Stop"
 
 # Version (updated by scripts/bump-version.sh)
-$CcsVersion = "4.3.10"
+$CcsVersion = "4.4.0"
 $ScriptDir = Split-Path -Parent $MyInvocation.MyCommand.Path
 $ConfigFile = if ($env:CCS_CONFIG) { $env:CCS_CONFIG } else { "$env:USERPROFILE\.ccs\config.json" }
 $ProfilesJson = "$env:USERPROFILE\.ccs\profiles.json"
diff --git a/package.json b/package.json
index e363f88f..07079c75 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@kaitranntt/ccs",
-  "version": "4.3.10",
+  "version": "4.4.0",
   "description": "Claude Code Switch - Instant profile switching between Claude Sonnet 4.5 and GLM 4.6",
   "keywords": [
     "cli",
diff --git a/scripts/postinstall.js b/scripts/postinstall.js
index 7d907252..f68571d5 100755
--- a/scripts/postinstall.js
+++ b/scripts/postinstall.js
@@ -97,6 +97,9 @@ function createConfigFiles() {
       const sharedManager = new SharedManager();
       sharedManager.migrateFromV311();
       sharedManager.ensureSharedDirectories();
+
+      // Run v4.4 migration: Migrate instances to shared settings.json
+      sharedManager.migrateToSharedSettings();
     } catch (err) {
       console.warn('[!] Migration warning:', err.message);
       console.warn('    Migration will retry on next run');