chore(openspec): drop 9 superseded proposals + 11 stub archive files

Drop 9 batch proposals that are superseded by the boocode-lift-analysis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-eval-sandbox-agent-runtime/specs/pregel-execution/spec.md

@@ -0,0 +1,49 @@
+## ADDED Requirements
+
+### Requirement: Pregel execution engine
+
+The system SHALL implement a Pregel-style superstep execution engine where:
+
+- Each "superstep" executes all ready nodes concurrently
+- Nodes communicate through typed channels (not direct function calls)
+- Channel writes from one superstep are visible as reads in the next
+- The engine supports `PULL` (edge-triggered) and `PUSH` (dynamic Send) task scheduling
+
+#### Scenario: Nodes execute in dependency order
+
+- **WHEN** node B subscribes to channel A
+- **THEN** node B SHALL execute in the superstep after node A writes to channel A
+
+#### Scenario: Concurrent nodes run in parallel
+
+- **WHEN** two nodes have no dependencies between them
+- **THEN** they SHALL execute concurrently within the same superstep
+
+#### Scenario: Dynamic Send spawns new node executions
+
+- **WHEN** a node calls `send("node_c", { ... })` via `Command`
+- **THEN** `node_c` SHALL be scheduled for execution in the current or next superstep
+
+### Requirement: Graph compilation
+
+The system SHALL provide `graph.compile()` that produces a runnable compiled graph.
+
+Parameters:
+- `checkpointer?: Checkpointer` — optional persistence
+- `interruptBefore?: string[]` — nodes to pause before
+- `interruptAfter?: string[]` — nodes to pause after
+- `name?: string` — graph name
+
+#### Scenario: Compiled graph can be invoked
+
+- **WHEN** `compiled_graph.invoke({ messages: [] })` is called
+- **THEN** it SHALL execute all nodes and return the final state
+
+### Requirement: Recursion limit
+
+The system SHALL enforce a configurable recursion limit to prevent infinite loops.
+
+#### Scenario: Exceeding recursion limit throws
+
+- **WHEN** a graph exceeds the recursion limit
+- **THEN** a `GraphRecursionError` SHALL be thrown