fusion/plugins/fusion-plugin-compound-engineering

Compound Engineering Plugin for Fusion

A dedicated dashboard surface for the compound-engineering (CE) workflow: an artifact hub, interactive in-dashboard ce-* skill sessions, a work→board bridge, and event-driven bidirectional sync between the Fusion board and a plugin-local CE-pipeline state model. It runs alongside Fusion's native pipeline — it does not replace or bypass it.

Install (one-click)

1. Open Settings → Plugins → Fusion Plugins.
2. In Bundled Plugins, click Install on Compound Engineering.
3. Enable the plugin if prompted.

Once installed and enabled, Fusion registers the Compound Engineering dashboard destination automatically and installs the bundled ce-* skills into a plugin-local, discoverable directory.

What it does

Compound engineering normally runs as terminal slash-commands whose artifacts scatter across docs/, with no unified surface and no link between a finished plan and the board work that follows. This plugin surfaces the whole flow inside Fusion while reusing the real skills so the plugin improves as they do.

Artifact hub

The primary dashboard view (viewId: "compound-engineering") discovers and renders CE artifacts from their conventional locations (STRATEGY.md, docs/ideation/, docs/brainstorms/, plan docs, docs/work/, CONCEPTS.md, docs/solutions/) and groups them by stage. Artifacts are read through a plugin route and rendered self-contained (sandboxed preview). The hub renders explicit empty / partial / error states rather than crashing or silently dropping an unreadable artifact.

Artifact HTTP endpoints live under /api/plugins/fusion-plugin-compound-engineering/ and back the hub list/read.

Interactive ce-* sessions

Each pipeline stage maps to a bundled skill via the stage registry (src/session/stage-registry.ts): { stageId, skillId, artifactLocation, icon, label }. Adding a stage is a data entry — no new route, store, or screen.

The launcher lists the registered (and operator-enabled) stages. Launching a stage starts an interactive agent session driven by the host's createInteractiveAiSession seam (a foundational extension added by this plan, because the existing createAiSession is one-shot and cannot pause on a mid-agent question). The session orchestrator (src/session/orchestrator.ts):

• streams thinking / text turns,
• surfaces a structured question and pauses in awaiting_input,
• accepts a structured answer and continues,
• on complete, writes the artifact to the stage's conventional location.

Lifecycle states are launching → active → awaiting_input → completed, plus error and interrupted. On interrupt or error the orchestrator auto-saves progress and emits an observable event — never silent loss — and an interrupted/error session can be resumed/retried back to its current question.

Transport

Plugin routes return { status, body } with no native server-push and the loader emitEvent is a logging stub, so v1 uses polling: clients poll GET /sessions/:id for the current persisted state. No raw EventSource is used. The orchestrator still emits observable events via ctx.emitEvent for the no-silent-loss requirement; turning those into true client push needs a host event-publish seam (a documented carry-forward).

Work → board bridge

When a stage reaches its work phase (ce-work, stage id work), its complete payload may carry a derived task list. The orchestrator creates each as a Fusion board task via ctx.taskStore.createTask, tagged CE-originated (source workflow_step with CE markers in sourceMetadata) and recorded as a pipeline-link row. The link row — not task-row JSON — is the authoritative back-reference from a board task to its originating pipeline/stage/artifact (per the FN-5719 pattern). Created tasks then run the normal lifecycle with no plugin interference. Zero derived tasks is a clean no-op.

Bidirectional sync model

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

• Board-task ownership → the task's 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 (board → pipeline). The onTaskMoved / onTaskCompleted lifecycle hooks do the minimum under the 5s hook budget: resolve the link and enqueueSync(...), then return. Heavy advancement is not done inline.

Reconcile (the convergence guarantee). reconcileCePipelines(ctx) is a single on-demand sweep — not a tight interval poll. It (1) drains the queue and (2) independently re-derives transitions by comparing live board state against pipeline state. Step (2) is why a dropped or never-enqueued hook event still converges: the queue is an optimization; the board↔state comparison is the source of truth.

Outbound (pipeline → board). When a pipeline advances to a stage that produces board work, the reconciler creates the next-stage board task via ctx.taskStore.createTask and links it.

Conflict policy. The reconciler only reads the already-terminal board task columns (board-authoritative) and only writes CE-owned fields plus a brand-new board task — the two writers never contend over the same cell.

Bundled-skills isolation model

The ce-* skills are bundled and pinned inside the plugin (src/skills/<skillId>/SKILL.md), declared via PluginSkillContribution with plugin-root-relative skillFiles. On load they are physically installed (cpSync, idempotent skip-if-exists) into a plugin-local, discoverable directory so an agent session can resolve them. The install is guarded to never touch a global ~/.claude/skills path an operator's own compound-engineering install owns — registering the bundled copy can never clobber a global install.

Settings

Operator-facing settings render in Settings → Plugins → Compound Engineering, grouped as follows. Every setting has a real consumption point in the plugin.

Sessions

Setting	Type	Default	Effect
Default Session Provider (defaultProvider)	string	(host default)	Passed to the interactive-session factory as defaultProvider. Blank → host picks.
Default Session Model (defaultModelId)	string	(host default)	Passed to the factory as defaultModelId. Blank → host picks.
Enabled Stages (enabledStages)	string[]	full registry	Only these stage IDs may be launched; the orchestrator rejects others.

Sync

Setting	Type	Default	Effect
Reconcile on Board Changes (reconcileOnHooks)	boolean	true	When on, the reconcile sweep auto-fires after task move/complete hooks. When off, the hook still enqueues so an on-demand sweep converges later.
Reconcile Cadence (minutes) (reconcileIntervalMinutes)	number	15	Cadence hint for an on-demand refresh surface. Not a continuous poll loop.

Getters live in src/settings.ts (getDefaultProvider, getDefaultModelId, getEnabledStages, getReconcileOnHooks, getReconcileIntervalMinutes), each returning its default when the setting is absent.