fusion/docs/plugins/compound-engineering.md

Compound Engineering Plugin

A dedicated dashboard surface for the compound-engineering (CE) workflow — an artifact hub, interactive ce-* skill sessions, a work→board bridge, and event-driven bidirectional sync. It runs alongside Fusion's native pipeline.

Install

1. Open Settings → Plugins → Fusion Plugins.
2. In Bundled Plugins, click Install for Compound Engineering.
3. Enable the plugin if it is not already started.

When installed and enabled, the plugin registers the Compound Engineering dashboard view destination and installs its bundled ce-* skills into a plugin-local, discoverable directory (never a global ~/.claude/skills path).

Dashboard view

The Compound Engineering view is registered as a primary plugin destination (viewId: "compound-engineering").

It provides:

• An artifact hub that discovers CE artifacts from conventional locations (STRATEGY.md, docs/ideation/, docs/brainstorms/, plan docs, docs/work/, CONCEPTS.md, docs/solutions/) grouped by stage, with explicit empty / partial / error states.
• Self-contained artifact previews read through plugin routes under /api/plugins/fusion-plugin-compound-engineering/.
• A stage launcher listing the registered, operator-enabled stages.

Sessions

Each stage maps to a bundled skill via the stage registry ({ stageId, skillId, artifactLocation, icon, label }). Launching a stage starts an interactive agent session on the host's createInteractiveAiSession seam.

The orchestrator streams thinking/text turns, surfaces a structured question (pausing in awaiting_input), accepts a structured answer, and on complete writes the artifact to the stage's conventional location. Lifecycle: launching → active → awaiting_input → completed, plus error and interrupted. Interrupt/error auto-saves progress and emits an observable event; sessions resume/retry back to their current question.

Updates are pushed over the shared /api/events SSE stream: the orchestrator emits via ctx.emitEvent, the host forwards them as project-scoped plugin:custom events, and the view subscribes through the host subscribePluginEvents capability (no raw EventSource). Polling GET /sessions/:id remains a fallback. The projectId from start is threaded through every answer/resume/poll so they resolve the session's owning store.

HTTP endpoints (under /api/plugins/fusion-plugin-compound-engineering/):

• POST /sessions → start a stage session
• POST /sessions/:id/answer → answer the awaiting question (send projectId)
• POST /sessions/:id/resume → resume an awaiting/interrupted session (send projectId)
• GET /sessions/:id → current persisted session state (push + poll fallback)
• GET /sessions → list sessions (filter by status/stage)
• GET /sessions/:id/links → the work→board pipeline-link records for a session

Sync model

Two separate state machines are kept in sync, never merged:

• Board-task ownership → the task column. The board is authoritative for task state.
• CE-pipeline ownership → ce_pipeline_state.{currentStage, status}. The CE flow is authoritative for artifact/pipeline content.

Inbound: onTaskMoved / onTaskCompleted hooks resolve the link and enqueue a sync signal under the 5s hook budget — no inline advancement.

Reconcile: reconcileCePipelines(ctx) is a single on-demand sweep (not a poll loop). It drains the queue and independently re-derives transitions from live board state, so a dropped or never-enqueued event still converges.

Outbound: when a pipeline advances to a stage that produces board work, the reconciler creates the next-stage board task and links it.

Conflict policy: the reconciler only reads already-terminal board columns and only writes CE-owned fields plus a new board task, so the two writers never contend over the same cell.

The work bridge tags every CE-originated board task (source workflow_step with CE markers in sourceMetadata) and records an authoritative pipeline-link row; created tasks then run the normal lifecycle untouched.

Settings

Settings render under Settings → Plugins → Compound Engineering.

Sessions

• defaultProvider (string) — provider for CE interactive sessions; blank uses the host default. Consumed by the orchestrator's factory call.
• defaultModelId (string) — model within the provider; blank uses the host default. Consumed by the orchestrator's factory call.
• enabledStages (string[], default = full registry) — only these stage IDs may be launched; the orchestrator rejects others.

Sync

• reconcileOnHooks (boolean, default true) — auto-fire the reconcile sweep after task move/complete hooks. When off, the hook still enqueues so an on-demand sweep converges later.
• reconcileIntervalMinutes (number, default 15) — cadence hint for an on-demand refresh surface; not a continuous poll loop.