Architecture explorer

Chromium 144.0.7559.261 embedded via the CEF binary distribution (CEF 144.0.34), selected in ADR-001. Provides the full Chromium navigation, rendering, and network stack with the upstream process model — browser, renderer, GPU, and network service processes — left intact.

• CEF C++ API (libcef + libcef_dll_wrapper)
• CefBrowserView per tab (Views framework)
• CefRequestContext for profile and cache isolation
• CefPermissionHandler for permission routing

Chromium sandbox and Site Isolation preserved at upstream defaults. On Windows the sandbox is kept intact via the bootstrap.exe + application-DLL launch pattern. No --no-sandbox, no --disable-web-security, no single-process mode.

The browser's own chrome — tab strip, omnibox, panels — implemented as trusted HTML/CSS/JS served over the internal itisyou:// scheme inside a dedicated privileged view, separate from all web content views.

• itisyou:// internal scheme handler
• origin-gated JS-to-native message router
• window and tab management commands

Privileged UI is separated from untrusted web content at three independent layers: renderer-side bindings are only installed for itisyou:// frames, the browser-side message router rejects queries from non-internal origins, and content tabs are blocked from navigating to the privileged host.

Tab Mode: the classic multi-tab browsing model. Manages tab lifecycle (create, close, activate, reorder) with one sandboxed browser view per tab, and feeds session snapshots to the storage layer for crash recovery.

• TabManager (create / close / activate / move)
• per-tab navigation state
• session snapshot feed for recovery

Each tab hosts untrusted web content in its own sandboxed renderer with no privileged bindings and no filesystem or native API surface.

Workspace foundation: named contexts that group tabs so research, development, and personal browsing can be kept apart. Phase 1 delivers the foundation only; the full persistent Workspace Mode grows in Phase 2.

• WorkspaceManager (create / switch / persist)
• workspace-scoped tab lists

Workspace metadata is local-only. There is no sync service, no cloud component, and no account system.

Omnibox input handling: distinguishing URLs from search queries, dispatching navigations, resolving internal itisyou:// pages, and recording visits into local history.

• omnibox parse and dispatch
• per-tab navigation controller
• internal page routing (itisyou://)

Web content cannot navigate a tab to the privileged itisyou://chrome host; internal pages are reachable only through trusted UI paths.

Local persistence with deliberately separate datasets: session state (for crash recovery), browsing history, and workspace data each live behind their own boundary rather than in one merged profile blob.

• session store (crash recovery)
• local history store
• workspace store

All datasets are local to the machine and separated by purpose. Nothing is transmitted anywhere; there is no sync, telemetry, or cloud backup path in the codebase.

A central PermissionService that all site permission requests (camera, microphone, location, notifications, and the rest) route through. The policy is deny-by-default: nothing is granted unless the user explicitly says yes.

• CefPermissionHandler integration
• default-deny policy engine
• structured decision log (local)

Web content cannot bypass the service: permission prompts are resolved in the browser process, and unanswered or unsupported requests are denied.

Chromium's network service via CEF, wrapped in a network-mode abstraction. Phase 1 implements standard mode only. The abstraction exists so future modes (proxy, Tor) can be added in Phase 2/3 without rearchitecting.

• network-mode abstraction (standard mode only)
• proxy configuration surface (reserved, unused)
• scheme and resource handlers

The network service runs inside Chromium's sandboxed process model. Tor and proxy modes are planned and not implemented — no anonymity properties are claimed today.

Interface definitions for future, optional AI assistance — and nothing more. In Phase 1 the AI runtime exists only as disabled interfaces: no provider is configured, no API keys exist anywhere in the project, and zero provider calls are made.

• AI runtime interface definitions (disabled)
• global enable/disable state (fixed OFF in Phase 1)

OFF by default and structurally inert: there is no code path that contacts an AI provider. Any future AI capability (Phase 3) will be opt-in, explicit per action, and auditable — never granted silent access to browsing data.

A planned system for user-defined automation ('skills') that would run under explicit user grants. Not designed in detail yet; listed here so the boundary it must respect is on record before any code exists.

• not yet defined

Will follow the same deny-by-default grant model as the PermissionService. Nothing exists today.

Planned extension support. CEF's Chrome runtime style offers partial extension support; full Chrome-store-level support may require moving to a Chromium source derivative, a path documented in ADR-001.

• not yet defined

Extensions will be sandboxed and permission-gated when they arrive. Nothing exists today.

Isolates OS-specific behavior — paths, process launch, windowing — behind adapters so the core stays portable. The Windows adapter is being developed and verified now; Linux and macOS layouts are architecture-ready in the build system but unverified.

• platform adapter contract (src/platform/)
• Windows launch path: bootstrap.exe + itisyou.dll

Windows sandbox preserved via the CEF bootstrap pattern. The Linux chrome-sandbox and macOS helper-bundle patterns are wired in CMake but remain unverified until those environments are available.

Structured local logging and diagnostics used as development evidence: milestone events, permission decisions, crash data. Exists so every claim about the browser can point at a verifiable record.

• structured log sink (local files)
• progress event records

Diagnostics never leave the machine. There is no telemetry endpoint in the codebase, and crash data is not uploaded anywhere.