fusion-plugin-claude-runtime exposes Claude Code as Fusion runtime claude and CLI provider claude-cli. It communicates through Agent Client Protocol (ACP), preserving streaming updates, tool calls, and multi-turn sessions.

The plugin uses the pinned claude-code-cli-acp bridge (0.1.1). CLI packaging stages its reviewed launcher beside the bundled plugin, while the published @runfusion/fusion dependency installs the matching optional native bridge for the operator's OS and CPU. The runtime never falls back to a same-named executable on PATH.

This is additive to Fusion's experimental pi-claude-cli Route A. Route A remains available; selecting the claude runtime explicitly selects this first-class ACP transport.

Fusion custom-tools bridge

The fusion-custom-tools MCP server launches mcp-schema-server.cjs beside the loaded bridge module. It is kept beside src/ for source loading and copied beside dist/ by pnpm build; do not remove that postbuild copy or dist-loaded sessions will fail initialize with handshake failed: connection closed: initialize response.

When requested Fusion tools cannot start their bridge, the adapter emits FUSION_TOOL_BRIDGE_FAILED: mcp-schema-server-missing or FUSION_TOOL_BRIDGE_FAILED: bridge-start-failed, omits the unusable MCP entry, and the engine stores only the fixed outcome and tool count in session:runtime-resolved run audit metadata.