chore(openspec): drop 9 superseded proposals + 11 stub archive files

Drop 9 batch proposals that are superseded by the boocode-lift-analysis
(boocontext-audit, conductor upgrades, self-healing/verify-gate skills):
add-3tier-memory, import-llm-evaluator, import-pregel-engine, plugin-platform,
conductor-evolution, code-intelligence-upgrade, dev-workflow, ui-overhaul,
agent-reliability.

Delete 11 stub archive files (49-66B each, 'Status: Shipped. Archived.' only)
that provide zero documentation value over the existing CHANGELOG.md + git tags.

openspec/changes/archived/2026-06-07-hybrid-workflow-engine/specs/event-sourcing/spec.md

@@ -0,0 +1,59 @@
+## ADDED Requirements
+
+### Requirement: Append-only event log
+Workflow runs SHALL produce append-only event records. Events SHALL NOT be modified after creation.
+
+#### Scenario: Events are chronological
+- **WHEN** a workflow executes
+- **THEN** events SHALL be stored with monotonically increasing timestamps or sequence numbers
+- **THEN** event order SHALL match execution order
+
+#### Scenario: Events are immutable
+- **WHEN** an event has been persisted
+- **THEN** it SHALL NOT be updated or deleted
+
+### Requirement: Event types
+The event log SHALL support exactly 8 event types: `workflow_started`, `workflow_completed`, `workflow_failed`, `workflow_cancelled`, `node_started`, `node_completed`, `node_failed`, `node_skipped`.
+
+#### Scenario: Workflow lifecycle events
+- **WHEN** a workflow run begins
+- **THEN** a `workflow_started` event SHALL be recorded
+- **WHEN** a workflow run completes successfully
+- **THEN** a `workflow_completed` event SHALL be recorded
+- **WHEN** a workflow run fails
+- **THEN** a `workflow_failed` event SHALL be recorded
+
+#### Scenario: Node lifecycle events
+- **WHEN** a node begins execution
+- **THEN** a `node_started` event SHALL be recorded
+- **WHEN** a node completes successfully
+- **THEN** a `node_completed` event SHALL record the node's output
+- **WHEN** a node fails
+- **THEN** a `node_failed` event SHALL record the error
+- **WHEN** a node is skipped (trigger_rule not met)
+- **THEN** a `node_skipped` event SHALL be recorded
+
+### Requirement: Deterministic replay for crash recovery
+When a workflow run is resumed after an interruption, the engine SHALL load completed node outputs from the event log and skip re-execution of completed nodes.
+
+#### Scenario: Resume skips completed nodes
+- **WHEN** a workflow run is resumed after a crash
+- **THEN** all nodes with a `node_completed` event SHALL be skipped
+- **THEN** execution SHALL begin from the first node without a completed event
+
+#### Scenario: Resume after partial execution
+- **WHEN** a workflow had 5 nodes and the first 3 completed before the crash
+- **THEN** nodes 1-3 SHALL be skipped (outputs loaded from event log)
+- **THEN** node 4 SHALL be re-executed
+
+### Requirement: Event storage via plugable backend
+Events SHALL be persisted through the `IWorkflowStore` interface, with at least a filesystem backend.
+
+#### Scenario: Filesystem event store
+- **WHEN** using the filesystem backend
+- **THEN** each run SHALL have a JSON file at `{runId}/events.jsonl`
+- **THEN** events SHALL be appended as newline-delimited JSON
+
+#### Scenario: SQLite event store
+- **WHEN** using the SQLite backend
+- **THEN** events SHALL be stored in a `workflow_events` table with columns for run_id, sequence, event_type, timestamp, and payload