Clean up stale hub-and-spoke references after Universal Graph migration

[malibio]

Closes #798

[malibio]

Code Review Report - PR #800

Review Type: Initial Review

Summary

This PR successfully cleans up stale hub-and-spoke terminology left behind after the Universal Graph Architecture migration (PR #786). The changes are purely documentation/comment updates with one test file deletion - no functional code changes.

---

Requirements Validation

Acceptance Criterion	Status
hub_spoke_schema_test.rs deleted	✅ PASS - File deleted (511 lines removed)
All "spoke" references in comments/docstrings updated or removed	✅ PASS - Verified via grep: no remaining "spoke" references in src/ or tests/
No mention of "hub-and-spoke" pattern except in archived docs	✅ PASS - Verified via grep: no "hub-and-spoke" references in code
Code passes cargo clippy	✅ PASS - Clippy runs clean
All tests pass (cargo test)	✅ PASS - All targeted module tests pass (behaviors, node_service, surreal_store, collection_membership, query_service). Note: Pre-existing segfault in embedding/AI tests on main branch - not introduced by this PR.

---

Code Review Findings

Critical Issues

None.

Suggested Improvements

None.

Observations (No Action Required)

1. Consistent Terminology Updates (/packages/core/src/behaviors/mod.rs)
The docstring updates correctly replace hub-and-spoke terminology with Universal Graph Architecture:

// Before:
/// Query nodes use the hybrid hub-and-spoke pattern (similar to TaskNode/SchemaNode):
/// - **Hub (`node.content`)**: Plain text description
/// - **Spoke (`query` table)**: Structured query fields

// After:
/// Query nodes store all data in the unified `node` table (Universal Graph Architecture):
/// - **Content (`node.content`)**: Plain text description
/// - **Properties (`node.properties`)**: Structured query fields

2. Test SQL Updated (/packages/core/tests/collection_membership_test.rs:494-502)
The test SQL was correctly simplified to reflect Universal Graph Architecture - removed separate spoke table creation and moved properties inline:

-- Before:
CREATE task:`{uuid}` CONTENT {
    node: type::thing('node', '{uuid}'),
    status: 'open',
    priority: 'high'
};
CREATE node:`{uuid}` CONTENT {
    node_type: 'task',
    data: type::thing('task', '{uuid}'),
    ...
};

-- After:
CREATE node:`{uuid}` CONTENT {
    node_type: 'task',
    content: 'Task item',
    properties: { status: 'open', priority: 'high' },
    ...
};

3. Comment Simplification Pattern
The changes follow a good pattern of simplification rather than replacement:

• "No spoke table" comments are removed entirely (not replaced with "no longer has spoke table")
• Technical explanations now describe what IS rather than what ISN'T
• Removed redundant "REMOVED:" comments (e.g., line 578 in surreal_store.rs)

---

Files Changed Summary

File	Changes
src/behaviors/mod.rs	-22/+17 lines - Updated QueryNode, DateNode, CollectionNode docstrings
src/db/surreal_store.rs	-26/+17 lines - Removed spoke terminology from version history and comments
src/mcp/handlers/nodes.rs	-4/+2 lines - Updated handler docstrings
src/mcp/handlers/nodes_test.rs	-12/+6 lines - Removed spoke comments from tests
src/models/core_schemas.rs	-4/+2 lines - Updated collection/query field comments
src/models/mod.rs	-2/+1 lines - Updated type conversion comment
src/models/schema.rs	-4/+2 lines - Updated relationship documentation
src/services/node_service.rs	-69/+42 lines - Major comment cleanup
src/services/schema_table_manager.rs	-4/+2 lines - Simplified module doc
tests/collection_membership_test.rs	-11/+4 lines - Updated test SQL
tests/hub_spoke_schema_test.rs	DELETED - 511 lines removed
tests/query_service_test.rs	-2/+1 lines - Updated module doc

Total: 12 files, 56 insertions, 615 deletions

---

Recommendation

✅ APPROVE

This is a clean technical debt cleanup that:

1. Removes all stale hub-and-spoke terminology
2. Deletes obsolete test file that tested patterns no longer in use
3. Correctly updates test SQL to match Universal Graph Architecture
4. Passes all quality gates (clippy, targeted tests)

The changes are well-scoped, follow the issue's cleanup guidelines, and improve codebase clarity without any functional impact.

[malibio]

Review complete - Recommendation: APPROVE. See detailed review in comments above.