Adopt already-installed apps (Updatest-style discovery → brew --adopt)

Source: Reddit feedback (2026-06-15), same thread as the telemetry question. Maintainer committed to filing.

Request: Like Updatest, detect apps already installed on the Mac (e.g. in /Applications) that have a matching Homebrew cask but aren't currently brew-managed, and offer to adopt them into Homebrew management — so Brew Browser can track/update apps the user installed manually.

Notes for implementation:

• Homebrew supports this natively: brew install --cask --adopt <token> adopts a matching existing install instead of erroring on "It seems there is already an App at...".
• Discovery: enumerate installed .app bundles, match against the cask catalog (by name/bundle id / app stanza artifact), and surface unmanaged-but-matchable apps in a "Discovered" surface with an Adopt action.
• Be conservative on matching (avoid false adoptions); confirm-gated per app.
• Parity: both shells (Tauri + native).

Related: ignore/pin specific casks so they're never updated is tracked separately as #90; in-app update %-progress #95 and concurrent-update handling #96.

Start with the Tauri and native shell entry points, then review how installed apps under /Applications and the cask catalog can be matched by name, bundle ID, or app artifact. Done means conservative matches appear in a Discovered surface in both shells, each has a confirm-gated Adopt action using brew install --cask --adopt, and false adoptions are avoided.