Redrob Browser (Chromium base)

Redrob Browser is an AI-native browser built as a patch-based fork of Chromium. This branch starts from nothing on purpose: the previous base was a Zen/Firefox fork, and Korean banking and public-sector sites depend on Chrome extensions and native messaging rather than on rendering, which is a dependency only a real Chromium browser satisfies.

What is ours

CHROMIUM_VERSION    the release we build, and the only place it is written down
patches/            surgical edits to files that stay Chromium's, one patch per file
branding/           files we replace wholesale: the BRANDING file and every icon
sources/            code we own outright, mirrored at its destination path
build/args/         gn args per build flavour
scripts/redrob.py   the whole fork workflow: bootstrap, sync, brand, apply, build, run, export, derive
agent/              the agent extension, side panel, onboarding, agent server (bun + Rust)
vendor/browseros/   the upstream BrowserOS patch set and build system this fork imports

The Chromium checkout is fetched, never committed. That is the lesson from the last fork: a tree with 258 patches buried in it could not answer "what do we own" without counting files. Here ls patches/ plus branding/manifest is the answer, and each file has exactly one owner -- a change that lives in both is what made the first clean reproduce fail with git apply: does not match index.

Getting to a build

./scripts/redrob.py bootstrap     # depot_tools into ./depot_tools (once)
./scripts/redrob.py sync          # fetch Chromium at CHROMIUM_VERSION, run its hooks
./scripts/redrob.py apply         # our own sources, then patches/
./scripts/redrob.py brand         # overlay branding/: BRANDING and the icons
./scripts/redrob.py build         # gn gen + autoninja, dev flavour
./scripts/redrob.py run           # launch it with a scratch profile

Expect tens of gigabytes and hours, not minutes. docs/BUILD.md has the real numbers and the host constraints.

Changing Chromium

Edit the checkout in chromium/src like a normal tree, then:

./scripts/redrob.py export

patches/ is rewritten from what you actually changed. Patches are never hand-maintained, and a new file you added is reported rather than patched in -- files that are ours belong in this repository as files, not as a diff against Chromium.

Moving to a new Chromium

# edit CHROMIUM_VERSION, then
./scripts/redrob.py sync
./scripts/redrob.py apply          # conflicts here name the files to look at
./scripts/redrob.py derive         # re-generate the branding edits against the new tree
./scripts/redrob.py export         # store them as patches again

derive exists so that a 768-substitution strings patch is never conflict-resolved by hand: it is generated from the new tree instead, and it fails loudly if upstream moved the file rather than producing a stale patch. brand is not part of this -- overlay files do not conflict, they just land.

Where the product lives

docs/ARCHITECTURE.md is the map of this repository: what you own and what is merely fetched, which of the four owners a file belongs to, how one feature travels from the page to the engine and back, which patches register our code into Chromium's build, and where to make a given change. Read it before reading code.

docs/UI.md maps the designed interface onto the three layers this fork has -- a WebUI page, the C++ browser UI, and a local sidecar process -- and says which of them each piece belongs in. The short version: the AI surfaces are web technology and should stay that way; only the tab strip and the agent tab plumbing need C++.

docs/DESIGN-SYSTEM.md says where the browser's colours come from. Every other Redrob product imports @redrob-labs/ui; this one cannot -- C++ has no var() and build_webui has no resolver -- so the values are vendored into the tree from a pinned release and two checks keep the copy honest. Read it before changing a colour, because a hex typed into the chrome is a hex that disagrees with the website.

Licence

AGPL-3.0-or-later as a whole (LICENSE), because the browser carries work derived from BrowserOS. NOTICE lists the provenance and the parts under other licences: ungoogled-chromium patches (BSD 3-Clause), two agent packages (MIT) and the bundled fonts (SIL OFL 1.1).