Function build_forge_server 

pub fn build_forge_server(
    facades: ForgeServerFacades,
    families: &BTreeSet<McpFamily>,
    slot: &SessionSlot,
    kind: SessionKind,
) -> McpServer

Build the per-session forge MCP server. ONE McpServer named forge carrying the coordination tool groups appropriate for the calling session’s SessionKind:

• SessionKind::Lead → agents (all seven) + the selected families.
• SessionKind::Worker → agents (the shared three) + the selected families.

families narrows the toggleable groups: only the selected ones register. The agents core is unconditional, and systemone is doubly gated - the family and a configured client.

review, cron, tasks, gotify and slack are any-caller, so they register for both kinds - unlike the four lead-only agents__* verbs. What each acts on is scoped rather than gated on session kind: a review conversation belongs to a project and branch, crons and subscriptions to the caller that made them, and tasks to the caller’s project. A review nudge lands on a worker seat, so the family must be offered to workers and the nudge must stay usable when it is withheld.

All submodules share the server name so the LLM sees a single namespace (mcp__forge__<group>__*) and the auto-approve fast-path in forge-sdk::control_dispatch matches every tool group with one mcp__forge__ prefix check.

Building two separate McpServer::builder("forge") instances and pushing both into OptionsBuilder::mcp_server would collide on the duplicate name and the CLI would reject one - so the right shape is to combine the (selected) tool sets into a single builder here.

slot is the calling session’s slot. Each tool holds its own clone of it, which is safe because a slot is stable across /new and /resume - those swap the occupant and leave the slot alone.