Summary

Gives FlipperServerTransport control over three things that previously required a manual Flipper desktop app:

• Configurable browser open/URL — open/url constructor options (env vars PLAYER_DEVTOOLS_FLIPPER_OPEN/PLAYER_DEVTOOLS_FLIPPER_URL in the CLI). Off by default; when enabled, opens a caller-supplied URL instead of always opening http://localhost:52342. flipper-server itself is always launched with --open=false and browser-opening is now driven by the transport.
• Plugin installation — ensurePluginInstalled() uses Flipper's own documented plugin-management RPCs (plugins-get-installed-plugins, plugins-install-from-npm) — the same commands the desktop UI's "Install Plugin" button calls — instead of reaching into ~/.flipper/installed-plugins or shelling out to this repo's local just install-flipper-client recipe. flipper-plugin-player-ui-devtools is already published to npm, so this works for any consumer of @player-devtools/mcp, not just repo checkouts.
• Plugin activation — enablePlugin(clientId?)/disablePlugin(clientId?) send the init/deinit handshake Flipper's device SDK requires before it will open a live plugin connection and relay messages. Nothing in flipper-server sends this automatically for a non-background, foreground-only plugin like ours without a full desktop Flipper app attached with the plugin's tab selected — these methods let a caller trigger the same handshake directly. enablePlugin() always calls ensurePluginInstalled() first (the plugin can be installed/removed on the attached flipper-server independently of this transport, so there's no "already installed" snapshot that stays trustworthy across calls), and skips clients it already believes are active; disablePlugin() without a clientId only targets clients it believes are active. An opt-in autoEnablePlugin constructor flag (used by bin/run) calls enablePlugin(clientId) automatically for every connecting client.

The CLI (player-devtools-mcp/bin/run) sets autoEnablePlugin: true, so every connecting client gets the plugin installed (if needed) and activated automatically as it connects — no manual Flipper UI interaction or separate startup step required.

Test plan

• bazel test //devtools/client/flipper:flipper_eslint //devtools/client/flipper:flipper_vitest //devtools/mcp:mcp_eslint //devtools/mcp:mcp_vitest — all pass
• bazel build //devtools/mcp:mcp_ts_types_transitive_typecheck_test — passes across both packages
• Manual: run player-devtools-mcp with a Player app instance connected as a device and no Flipper desktop UI running; confirm list_players/get_player_status succeed without any manual Flipper UI interaction
• Manual: confirm PLAYER_DEVTOOLS_FLIPPER_OPEN=true PLAYER_DEVTOOLS_FLIPPER_URL=https://player-ui.tools:52342 opens the custom URL instead of localhost:52342

Release Notes

@player-devtools/mcp no longer requires any manual Flipper desktop app interaction to install or activate the Player UI Devtools plugin — the MCP server now installs the plugin (via Flipper's own plugin-management API) and activates it automatically for each connecting device. FlipperServerTransport gains open/url options for controlling whether/where a browser UI opens (env vars PLAYER_DEVTOOLS_FLIPPER_OPEN/PLAYER_DEVTOOLS_FLIPPER_URL for the CLI), and new ensurePluginInstalled()/enablePlugin()/disablePlugin() methods for consumers embedding the transport directly.