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)
- Open Settings → Plugins → Fusion Plugins.
- In Bundled Plugins, click Install on Compound Engineering.
- 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/textturns, - surfaces a structured
questionand pauses inawaiting_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
Session updates are pushed over the shared /api/events SSE stream. The
orchestrator emits observable events via ctx.emitEvent (turn / question /
completed / error / interrupted); the host forwards them to connected clients as
project-scoped plugin:custom events, and the view subscribes through the
subscribePluginEvents context capability — refetching the session on each event
(no raw EventSource; no deep dashboard import). Client polling of
GET /sessions/:id remains as a fallback while a turn is mid-flight, so a
missed event still converges. Session identity is project-scoped: the projectId
used at start is threaded through every later answer/resume/poll so they
resolve the same store and live handle.
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.