feat(browser): polish embedded browser pane, sidebar parity, OSS auth gates

[BunsDev]

Summary

Closes the user-reported polish items on the embedded browser pane and aligns its toggle with the rest of the workspace chrome.

Browser pane

• Default search engine is now Google (was DuckDuckGo) with a new user-level setting `general.default_search_engine` (Google / DuckDuckGo / Bing / Kagi / Brave), plumbed through the URL bar's resolver.
• URL bar gets a `URL_BAR_MIN_WIDTH` so it never collapses to icon width in narrow splits.
• Layout invariant documented for why the GPUI toolbar stays clickable above the native wry overlay (Flex column places the webview strictly below the toolbar, so hit-testing routes correctly).
• Toggle-close bug fix. Under `FeatureFlag::UndoClosedPanes`, `PaneGroup::close_pane` detaches into a hidden-for-close shadow instead of destroying the pane — toggle was leaving the `wry::WebView` alive and the next toggle short-circuited on the "already hidden" early-return. `toggle_browser_pane` now filters lookups to visible panes, follows `close_pane` with `cleanup_closed_pane` on the close path, and proactively cleans up stale shadows on the open path. The tab-bar button's active state and `navigate_or_open_browser_pane` use the same filter so icon state matches reality. Cmd+W still uses the undo-friendly path.

Tab-bar parity

• Tab-bar settings cog replaced with a Globe browser-pane toggle on non-wasm builds. Settings remain reachable via Cmd+, the app menu, and the command palette. Wasm keeps the cog because it has no embedded browser.
• `workspace:toggle_left_panel` now defaults to Cmd+B / Ctrl+B, matching the convention used by the right-panel and browser-pane toggles.

Link handoff

• New `WorkspaceAction::NavigateBrowserPane { url }`. Terminal-output URL clicks now load in the embedded pane (navigating an existing pane or opening one if none is visible). On wasm the handler falls back to `open_url`.
• `BrowserView::navigate` promoted to `pub(crate)` so the workspace can drive it.

OSS auth gates

• `root_view.rs` `requires_login` now also requires `ChannelState::cloud_services_available()`, so the public CastCodes OSS build never blocks agent/Cast Drive onboarding behind a Warp account.
• Remote-control chip in the agent input footer skips the login gate on OSS builds — there are no hosted services to authenticate to.

Test plan

• `./script/check_rebrand` — CastCodes rebrand guard passes.
• `cargo check -p warp-app --lib` — clean.
• `cargo check -p warp-app --bin cast-codes --features gui` — clean.
• `cargo test -p warp-app --lib browser::url_input::` — 9 passing (default-Google behavior, per-engine selection, all-prefixes-distinct invariant).
• All commits signed (ED25519); verified `git log main..HEAD --pretty='%H %G?'` reports `G` on every commit.
• Manual: open browser pane (Cmd+Alt+B), type a query, confirm it routes to Google by default and to the chosen engine after changing the setting.
• Manual: toggle browser pane closed via the tab-bar Globe / Cmd+Alt+B and confirm the wry webview is fully gone (no orphaned overlay, next toggle opens a fresh pane).
• Manual: click a URL in terminal output with the browser pane open and confirm the pane navigates to it instead of the system browser opening.
• Manual: on the public `cast-codes` binary, start agent / remote-control flows without logging in and confirm no login gate is hit.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR polishes the embedded browser-pane UX and aligns workspace chrome behavior by fixing toggle-close lifecycle issues (especially under UndoClosedPanes), adding a configurable default search engine for the URL bar, routing terminal URL clicks into the embedded browser, and relaxing login gating for OSS builds where cloud services aren’t available.

Changes:

• Fix browser pane toggle-close behavior by ignoring hidden-for-close panes and force-cleaning up stale shadows; add NavigateBrowserPane { url } for internal link handoff.
• Add general.default_search_engine (default Google) and plumb it through URL resolution; introduce a URL bar minimum width and document toolbar/webview layout invariant.
• Update tab-bar controls (Globe toggle on native, settings cog on wasm) and adjust left-panel default keybinding to Cmd/Ctrl+B; update OSS login gating for onboarding and remote-control chip.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
app/src/workspace/view.rs	Fixes browser pane toggle lifecycle; adds navigate-or-open action handler; updates tab-bar button rendering (Globe vs settings)
app/src/workspace/util.rs	Adds mouse state handle for the new browser toggle icon (native) and gates settings icon to wasm
app/src/workspace/mod.rs	Adds default keybindings for toggling the left panel (Cmd/Ctrl+B)
app/src/workspace/action.rs	Introduces WorkspaceAction::NavigateBrowserPane and excludes it from app-state persistence
app/src/terminal/view.rs	Routes URL link clicks to the workspace’s embedded browser instead of the system browser
app/src/terminal/general_settings.rs	Adds general.default_search_engine setting backed by SearchEngine
app/src/root_view.rs	Skips login gating in OSS builds by also requiring cloud_services_available()
app/src/browser/url_input.rs	Adds SearchEngine enum and resolver that uses the selected engine; expands tests
app/src/browser/browser_view.rs	Uses selected default search engine; adds URL bar min width; exposes navigate to workspace
app/src/ai/blocklist/agent_view/agent_input_footer/mod.rs	Skips remote-control login gate on OSS builds via cloud_services_available()

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