diff --git a/extension/src/ghost-browser-api.d.ts b/extension/src/ghost-browser-api.d.ts
new file mode 100644
index 0000000..d72efee
--- /dev/null
+++ b/extension/src/ghost-browser-api.d.ts
@@ -0,0 +1,718 @@
+/**
+ * Ghost Browser Extension APIs Type Definitions
+ *
+ * Source: Extracted from Ghost Browser.app binary
+ * Location: /Applications/Ghost Browser.app/Contents/Frameworks/Ghost Browser Framework.framework
+ *
+ * These APIs are available to extensions running in Ghost Browser.
+ * Check availability with: typeof chrome.ghostPublicAPI !== 'undefined'
+ */
+
+declare namespace chrome {
+  // ============================================================================
+  // GHOST PUBLIC API (chrome.ghostPublicAPI)
+  // ============================================================================
+
+  export namespace ghostPublicAPI {
+    /** Maximum number of temporary identities allowed */
+    export const MAX_TEMPORARY_IDENTITIES: 25
+
+    /** Use to open tab in new temporary identity. Value: "OpenInNewSession" */
+    export const NEW_TEMPORARY_IDENTITY: 'OpenInNewSession'
+
+    /** Empty string representing default identity. Value: "" */
+    export const DEFAULT_IDENTITY: ''
+
+    export interface OpenTabParams {
+      /** URL to navigate to */
+      url?: string
+      /** Tab position (0-based index) */
+      index?: number
+      /** Whether tab should be active (default: true) */
+      active?: boolean
+      /** Whether tab should be pinned */
+      pinned?: boolean
+      /** Identity ID, NEW_TEMPORARY_IDENTITY, or DEFAULT_IDENTITY */
+      identity?: string
+    }
+
+    /**
+     * Opens a new tab with Ghost Browser identity support
+     * @example
+     * chrome.ghostPublicAPI.openTab({
+     *   url: 'https://example.com',
+     *   identity: chrome.ghostPublicAPI.NEW_TEMPORARY_IDENTITY
+     * }, (tabId) => console.log('Opened tab:', tabId))
+     */
+    export function openTab(
+      params: OpenTabParams,
+      callback?: (tabId: number) => void
+    ): Promise<number>
+  }
+
+  // ============================================================================
+  // GHOST PROXIES API (chrome.ghostProxies)
+  // ============================================================================
+
+  export namespace ghostProxies {
+    /** UUID for direct connection (no proxy) */
+    export const DIRECT_PROXY: '8f513494-8cf5-41c7-b318-936392222104'
+
+    /** UUID for system proxy settings */
+    export const SYSTEM_PROXY: '2485b989-7ffb-4442-a45a-d7f9a10c6171'
+
+    export interface AddProxyParams {
+      /** Display name for the proxy */
+      name?: string
+      /** Proxy URI (e.g., "http://host:port" or "socks5://host:port") */
+      uri: string
+      /** Authentication username */
+      username?: string
+      /** Authentication password */
+      password?: string
+      /** Timezone for this proxy */
+      timezone?: string
+      /** Tags for organization */
+      tags?: string
+    }
+
+    export interface ModifyProxyParams {
+      enabled?: boolean
+      name?: string
+      uri?: string
+      username?: string
+      password?: string
+      timezone?: string
+      tags?: string
+    }
+
+    export interface GhostProxy {
+      id: string
+      name: string
+      uri: string
+      username: string
+      password: string
+      timezone: string
+      tags: string
+      enabled: boolean
+      index: number
+      is_set: boolean
+      is_null: boolean
+    }
+
+    // Proxy CRUD operations
+    export function add(
+      proxy: AddProxyParams,
+      callback?: (proxy: GhostProxy) => void
+    ): Promise<GhostProxy>
+
+    export function import_(
+      proxy: AddProxyParams,
+      callback?: (proxy: GhostProxy) => void
+    ): Promise<GhostProxy>
+
+    export function remove(
+      proxy_id: string,
+      callback?: (success: boolean) => void
+    ): Promise<boolean>
+
+    export function removeAll(callback?: (success: boolean) => void): Promise<boolean>
+
+    export function getList(callback?: (proxies: GhostProxy[]) => void): Promise<GhostProxy[]>
+
+    export function get(
+      proxy_id: string,
+      callback?: (proxy: GhostProxy) => void
+    ): Promise<GhostProxy>
+
+    export function move(
+      proxy_id: string,
+      new_index: number,
+      callback?: (success: boolean) => void
+    ): Promise<boolean>
+
+    export function modify(
+      proxy_id: string,
+      params: ModifyProxyParams,
+      callback?: (proxy: GhostProxy) => void
+    ): Promise<GhostProxy>
+
+    // Set proxy at different levels
+    export function setProjectProxy(
+      proxy_id: string,
+      keep_overrides: boolean,
+      callback?: (success: boolean) => void
+    ): Promise<boolean>
+
+    export function setSessionProxy(
+      session_id: string,
+      proxy_id: string,
+      keep_overrides: boolean,
+      callback?: (success: boolean) => void
+    ): Promise<boolean>
+
+    export function setIdentityProxy(
+      identity_id: string,
+      proxy_id: string,
+      callback?: (success: boolean) => void
+    ): Promise<boolean>
+
+    export function setTabProxy(
+      tab_id: number,
+      proxy_id: string,
+      callback?: (success: boolean) => void
+    ): Promise<boolean>
+
+    // Get proxy at different levels
+    export function getProjectProxy(callback?: (proxy: GhostProxy) => void): Promise<GhostProxy>
+
+    export function getSessionProxy(
+      session_id: string,
+      callback?: (proxy: GhostProxy) => void
+    ): Promise<GhostProxy>
+
+    export function getIdentityProxy(
+      identity_id: string,
+      callback?: (proxy: GhostProxy) => void
+    ): Promise<GhostProxy>
+
+    export function getTabProxy(
+      tab_id: number,
+      callback?: (proxy: GhostProxy) => void
+    ): Promise<GhostProxy>
+
+    // Clear proxy at different levels
+    export function clearProjectProxy(
+      keep_overrides: boolean,
+      callback?: (success: boolean) => void
+    ): Promise<boolean>
+
+    export function clearSessionProxy(
+      session_id: string,
+      keep_overrides: boolean,
+      callback?: (success: boolean) => void
+    ): Promise<boolean>
+
+    export function clearIdentityProxy(
+      identity_id: string,
+      callback?: (success: boolean) => void
+    ): Promise<boolean>
+
+    export function clearTabProxy(
+      tab_id: number,
+      callback?: (success: boolean) => void
+    ): Promise<boolean>
+
+    // Events
+    export const onAdded: chrome.events.Event<(proxy: GhostProxy) => void>
+    export const onRemoved: chrome.events.Event<(proxy_id: string) => void>
+    export const onChanged: chrome.events.Event<(proxy: GhostProxy) => void>
+    export const onMoved: chrome.events.Event<(proxy: GhostProxy, old_index: number) => void>
+    export const onProjectProxyChanged: chrome.events.Event<(proxy: GhostProxy) => void>
+    export const onSessionProxyChanged: chrome.events.Event<
+      (session_id: string, proxy: GhostProxy) => void
+    >
+    export const onTabProxyChanged: chrome.events.Event<
+      (tab_id: number, proxy: GhostProxy) => void
+    >
+    export const onIdentityProxyChanged: chrome.events.Event<
+      (identity_id: string, proxy: GhostProxy) => void
+    >
+  }
+
+  // ============================================================================
+  // GHOST PROJECTS API (chrome.projects)
+  // ============================================================================
+
+  export namespace projects {
+    /** Home project UUID */
+    export const PROJECT_ID_HOME: 'f0673216-13b9-48be-aa41-90763e229e78'
+
+    /** Unsaved project UUID */
+    export const PROJECT_ID_UNSAVED: 'fe061488-8a8e-40f0-9e5e-93a1a5e2c273'
+
+    /** Maximum sessions per project */
+    export const SESSIONS_MAX: 25
+
+    /** Value to create new session. Same as ghostPublicAPI.NEW_TEMPORARY_IDENTITY */
+    export const NEW_SESSION: 'OpenInNewSession'
+
+    /** Global/default session. Empty string. */
+    export const GLOBAL_SESSION: ''
+
+    export type ClearSessionDataType = 'all' | 'cookies' | 'storage'
+    export type ClearIdentityDataType = 'all' | 'cookies' | 'storage'
+    export type IdentitySortCondition = 'name' | 'date' | 'usage'
+
+    export interface GhostProject {
+      id: string
+      name: string
+      description: string
+      locked: boolean
+      enabled: boolean
+      active: boolean
+      index: number
+    }
+
+    export interface GhostSession {
+      id: string
+      project_id: string
+      name: string
+      color: string
+      display_name: string
+      display_color: string
+      opened: boolean
+      enabled: boolean
+    }
+
+    export interface GhostIdentity {
+      id: string
+      name: string
+      color: string
+      tag: string
+      description: string
+      /** URL dedication (site this identity is dedicated to) */
+      dedication: string
+      dedication_is_strict: boolean
+      user_agent: string
+      usage_rate: number
+      creation_time: string
+      index: number
+      enabled: boolean
+    }
+
+    export interface GhostWindow {
+      id: number
+      project_id: string
+      active: boolean
+    }
+
+    export interface GhostTab {
+      id: number
+      project_id: string
+      identity_id: string
+      session_id: string
+      window_id: number
+      index: number
+      index_in_session: number
+      tab_id: number
+      url: string
+      title: string
+      favicon: string
+      active: boolean
+      pinned: boolean
+    }
+
+    export interface AddProjectDetails {
+      project_name?: string
+      project_description?: string
+      clone_current?: boolean
+      add_window?: boolean
+    }
+
+    export interface AddIdentityDetails {
+      name: string
+      color: string
+      dedication: string
+      dedication_is_strict: boolean
+    }
+
+    export interface TabInfo {
+      url?: string
+      title?: string
+      favicon?: string
+      active?: boolean
+      pinned?: boolean
+    }
+
+    export interface AddTabDetails {
+      project_id: string
+      window_id: number
+      index?: number
+      session_id?: string
+      identity_id?: string
+      tab_info: TabInfo
+    }
+
+    export interface AddWindowDetails {
+      project_id: string
+      index?: number
+      active?: boolean
+    }
+
+    export interface ArchivedProject {
+      id: string
+      name: string
+      description: string
+      index: number
+    }
+
+    export interface GhostMultiExtensionOption {
+      id: string
+      name: string
+      value: number
+      identity_id: string
+    }
+
+    // Project functions
+    export function getProjectsList(
+      callback?: (projects: GhostProject[]) => void
+    ): Promise<GhostProject[]>
+
+    export function getProject(
+      project_id: string,
+      callback?: (project: GhostProject) => void
+    ): Promise<GhostProject>
+
+    export function getActiveProject(
+      callback?: (project: GhostProject) => void
+    ): Promise<GhostProject>
+
+    export function addProject(
+      project: AddProjectDetails,
+      callback?: () => void
+    ): Promise<void>
+
+    export function removeProject(project_id: string, callback?: () => void): Promise<void>
+
+    export function moveProject(
+      project_id: string,
+      new_index: number,
+      callback?: () => void
+    ): Promise<void>
+
+    export function renameProject(
+      project_id: string,
+      project_name: string,
+      callback?: () => void
+    ): Promise<void>
+
+    export function setProjectDescription(
+      project_id: string,
+      project_description: string,
+      callback?: () => void
+    ): Promise<void>
+
+    export function lockProject(project_id: string, callback?: () => void): Promise<void>
+    export function unlockProject(project_id: string, callback?: () => void): Promise<void>
+    export function openProject(project_id: string, callback?: () => void): Promise<void>
+
+    // Archived projects
+    export function getArchivedProjects(
+      callback?: (projects: ArchivedProject[]) => void
+    ): Promise<ArchivedProject[]>
+
+    export function archiveProject(project_id: string, callback?: () => void): Promise<void>
+
+    export function restoreArchivedProject(
+      project_id: string,
+      callback?: () => void
+    ): Promise<void>
+
+    export function deleteArchivedProject(
+      project_id: string,
+      callback?: () => void
+    ): Promise<void>
+
+    // Session functions
+    export function getSessionsList(
+      project_id: string,
+      callback?: (sessions: GhostSession[]) => void
+    ): Promise<GhostSession[]>
+
+    export function getSession(
+      project_id: string,
+      session_id: string,
+      callback?: (session: GhostSession) => void
+    ): Promise<GhostSession>
+
+    export function renameSession(
+      project_id: string,
+      session_id: string,
+      session_name: string,
+      callback?: () => void
+    ): Promise<void>
+
+    export function changeSessionColor(
+      project_id: string,
+      session_id: string,
+      session_color: string,
+      callback?: () => void
+    ): Promise<void>
+
+    export function clearSessionData(
+      project_id: string,
+      session_id: string,
+      type: ClearSessionDataType,
+      callback?: () => void
+    ): Promise<void>
+
+    // Identity functions
+    export function getIdentitiesList(
+      callback?: (identities: GhostIdentity[]) => void
+    ): Promise<GhostIdentity[]>
+
+    export function sortIdentitiesList(
+      condition: IdentitySortCondition,
+      desc: boolean,
+      callback?: (identities: GhostIdentity[]) => void
+    ): Promise<GhostIdentity[]>
+
+    export function getIdentity(
+      identity_id: string,
+      callback?: (identity: GhostIdentity) => void
+    ): Promise<GhostIdentity>
+
+    export function addIdentity(
+      identity: AddIdentityDetails,
+      callback?: (identity: GhostIdentity) => void
+    ): Promise<GhostIdentity>
+
+    export function removeIdentity(identity_id: string, callback?: () => void): Promise<void>
+
+    export function moveIdentity(
+      identity_id: string,
+      new_index: number,
+      callback?: () => void
+    ): Promise<void>
+
+    export function renameIdentity(
+      identity_id: string,
+      identity_name: string,
+      callback?: () => void
+    ): Promise<void>
+
+    export function changeIdentityColor(
+      identity_id: string,
+      identity_color: string,
+      callback?: () => void
+    ): Promise<void>
+
+    export function setIdentityTag(
+      identity_id: string,
+      identity_tag: string,
+      callback?: () => void
+    ): Promise<void>
+
+    export function setIdentityDescription(
+      identity_id: string,
+      identity_description: string,
+      callback?: () => void
+    ): Promise<void>
+
+    export function setIdentityDedication(
+      identity_id: string,
+      identity_dedication: string,
+      callback?: () => void
+    ): Promise<void>
+
+    export function setIdentityDedicationIsStrict(
+      identity_id: string,
+      identity_dedication_is_strict: boolean,
+      callback?: () => void
+    ): Promise<void>
+
+    export function setIdentityUserAgent(
+      identity_id: string,
+      user_agent: string,
+      callback?: () => void
+    ): Promise<void>
+
+    export function resetIdentity(
+      identity_id: string,
+      callback?: (identity: GhostIdentity) => void
+    ): Promise<GhostIdentity>
+
+    export function clearIdentityData(
+      identity_id: string,
+      type: ClearIdentityDataType,
+      callback?: () => void
+    ): Promise<void>
+
+    export function getIdentityTabsList(
+      project_id: string,
+      identity_id: string,
+      callback?: (tabs: GhostTab[]) => void
+    ): Promise<GhostTab[]>
+
+    /** Opens a new tab in a new identity */
+    export function newIdentityOpenTab(): void
+
+    /** Duplicates current tab into a new identity */
+    export function newIdentityDuplicateTab(): void
+
+    // Window functions
+    export function getWindowsList(
+      project_id: string,
+      callback?: (windows: GhostWindow[]) => void
+    ): Promise<GhostWindow[]>
+
+    export function getWindowTabsList(
+      project_id: string,
+      window_id: number,
+      callback?: (tabs: GhostTab[]) => void
+    ): Promise<GhostTab[]>
+
+    export function addWindow(window: AddWindowDetails, callback?: () => void): Promise<void>
+
+    export function removeWindow(
+      project_id: string,
+      window_id: number,
+      callback?: () => void
+    ): Promise<void>
+
+    // Tab functions
+    export function getSessionTabsList(
+      project_id: string,
+      session_id: string,
+      callback?: (tabs: GhostTab[]) => void
+    ): Promise<GhostTab[]>
+
+    export function getTab(
+      project_id: string,
+      tab_id: number,
+      callback?: (tab: GhostTab) => void
+    ): Promise<GhostTab>
+
+    export function addTab(tab: AddTabDetails, callback?: () => void): Promise<void>
+
+    export function removeTab(
+      project_id: string,
+      tab_id: number,
+      callback?: () => void
+    ): Promise<void>
+
+    export function updateTab(
+      project_id: string,
+      tab_id: number,
+      tab_info: TabInfo,
+      callback?: () => void
+    ): Promise<void>
+
+    // Multi-extension options
+    export function isMultiExtensionEnabled(
+      callback?: (enabled: boolean) => void
+    ): Promise<boolean>
+
+    export function getMultiExtensionOptions(
+      identity_id: string,
+      callback?: (options: GhostMultiExtensionOption[]) => void
+    ): Promise<GhostMultiExtensionOption[]>
+
+    export function setMultiExtensionOption(
+      identity_id: string,
+      id: string,
+      value: number,
+      callback?: (success: boolean) => void
+    ): Promise<boolean>
+
+    export function clearMultiExtensionOptions(
+      identity_id: string,
+      callback?: (success: boolean) => void
+    ): Promise<boolean>
+
+    // Events
+    export const onProjectWillOpen: chrome.events.Event<
+      (project_id: string, first_time: boolean) => void
+    >
+    export const onProjectOpened: chrome.events.Event<
+      (project_id: string, first_time: boolean) => void
+    >
+    export const onProjectClosed: chrome.events.Event<(project_id: string) => void>
+    export const onProjectAdded: chrome.events.Event<(project: GhostProject) => void>
+    export const onProjectRemoved: chrome.events.Event<(project_id: string) => void>
+    export const onProjectNameChanged: chrome.events.Event<
+      (project_id: string, new_name: string) => void
+    >
+    export const onProjectDescriptionChanged: chrome.events.Event<
+      (project_id: string, description: string) => void
+    >
+    export const onProjectLockStateChanged: chrome.events.Event<
+      (project_id: string, locked: boolean) => void
+    >
+
+    export const onIdentityAdded: chrome.events.Event<(identity: GhostIdentity) => void>
+    export const onIdentityRemoved: chrome.events.Event<(identity_id: string) => void>
+    export const onIdentityNameChanged: chrome.events.Event<
+      (identity_id: string, identity_name: string) => void
+    >
+    export const onIdentityColorChanged: chrome.events.Event<
+      (identity_id: string, identity_color: string) => void
+    >
+    export const onIdentityUserAgentChanged: chrome.events.Event<
+      (identity_id: string, identity_user_agent: string) => void
+    >
+    export const onIdentitiesChanged: chrome.events.Event<() => void>
+
+    export const onSessionAdded: chrome.events.Event<(session: GhostSession) => void>
+    export const onSessionRemoved: chrome.events.Event<
+      (project_id: string, session_id: string) => void
+    >
+    export const onSessionNameChanged: chrome.events.Event<
+      (project_id: string, session_id: string, new_name: string) => void
+    >
+    export const onSessionColorChanged: chrome.events.Event<
+      (project_id: string, session_id: string, session_color: string) => void
+    >
+
+    export const onTabAdded: chrome.events.Event<(tab: GhostTab) => void>
+    export const onTabRemoved: chrome.events.Event<
+      (project_id: string, window_id: number, tab_id: number, is_window_closing: boolean) => void
+    >
+    export const onTabUpdated: chrome.events.Event<(project_id: string, tab_id: number) => void>
+
+    export const onWindowAdded: chrome.events.Event<(window: GhostWindow) => void>
+    export const onWindowRemoved: chrome.events.Event<
+      (project_id: string, window_id: number) => void
+    >
+  }
+
+  // ============================================================================
+  // EXTENDED CHROME.TABS (Ghost Browser additions)
+  // ============================================================================
+
+  export namespace tabs {
+    export interface ProjectInfo {
+      project_id?: string
+      session_id?: string
+      tab_id?: number
+    }
+
+    export interface ProxyInfo {
+      proxy_id: string
+      proxy_has_effect: boolean
+    }
+
+    export interface GhostTabPublicAPI {
+      workspace_id: string
+      identity_id: string
+      is_temporary_identity: boolean
+    }
+
+    // Extended Tab interface with Ghost Browser properties
+    export interface Tab {
+      /** Ghost Browser project info */
+      projectInfo?: ProjectInfo
+      /** Ghost Browser proxy info */
+      proxyInfo?: ProxyInfo
+      /** Identity ID (also available in ghostPublicAPI) */
+      identity_id?: string
+      /** Ghost Browser public API properties */
+      ghostPublicAPI?: GhostTabPublicAPI
+    }
+
+    // Extended CreateProperties for chrome.tabs.create()
+    export interface CreateProperties {
+      /** Session ID to open tab in */
+      session_id?: string
+      /** Identity ID to open tab in */
+      identity_id?: string
+    }
+
+    // Extended QueryInfo for chrome.tabs.query()
+    export interface QueryInfo {
+      /** Filter by session ID */
+      session_id?: string
+    }
+  }
+}