chore(openspec): drop 9 superseded proposals + 11 stub archive files

Drop 9 batch proposals that are superseded by the boocode-lift-analysis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/dag-engine/spec.md

@@ -0,0 +1,54 @@
+## ADDED Requirements
+
+### Requirement: DAG topological execution
+The engine SHALL execute workflow nodes in topological order determined by `depends_on` edges using Kahn's algorithm.
+
+#### Scenario: Independent nodes run concurrently
+- **WHEN** a workflow has nodes A and B with no `depends_on`
+- **THEN** both A and B SHALL execute in the same topological layer, concurrently
+
+#### Scenario: Dependent nodes run sequentially
+- **WHEN** node B lists `depends_on: [A]`
+- **THEN** A SHALL complete before B begins
+
+#### Scenario: Cycle detection
+- **WHEN** nodes form a cycle (A → B → C → A)
+- **THEN** the loader SHALL reject the workflow with a cycle detection error
+
+### Requirement: Trigger rules
+The engine SHALL support 4 trigger rules for join semantics.
+
+#### Scenario: all_success (default)
+- **WHEN** a node has multiple upstream dependencies and no explicit `trigger_rule`
+- **THEN** it SHALL only run if ALL upstream nodes completed successfully
+- **THEN** it SHALL be skipped if any upstream node failed
+
+#### Scenario: one_success
+- **WHEN** a node sets `trigger_rule: one_success`
+- **THEN** it SHALL run if at least one upstream node completed successfully
+
+#### Scenario: all_done
+- **WHEN** a node sets `trigger_rule: all_done`
+- **THEN** it SHALL run when all upstream nodes have finished (any status), regardless of success/failure
+
+#### Scenario: none_failed_min_one_success
+- **WHEN** a node sets `trigger_rule: none_failed_min_one_success`
+- **THEN** it SHALL run only if no upstream node failed AND at least one succeeded
+
+### Requirement: when conditions
+Nodes SHALL support a `when:` string that evaluates to a boolean condition.
+
+#### Scenario: when condition prevents execution
+- **WHEN** a node has `when: "false"` or any expression that evaluates falsy
+- **THEN** the node SHALL be skipped as if its trigger_rule prevented execution
+
+### Requirement: Node retry with configurable policy
+Nodes SHALL support a `retry` config with `max_attempts`, `delay_ms`, and `on_error` (transient|all).
+
+#### Scenario: retry on transient error
+- **WHEN** a node with `retry: { max_attempts: 3 }` fails with a transient error
+- **THEN** it SHALL retry up to 3 times with configured delay between attempts
+
+#### Scenario: retry exhausted
+- **WHEN** all retry attempts fail
+- **THEN** the node SHALL be marked as failed and trigger_rule evaluation proceeds