feat: Implement Universal Graph Architecture - eliminate spoke tables (Issue #783)

[malibio]

Summary

Implements Stream B of Issue #783: Universal Graph Architecture Transition. This eliminates all spoke tables (task, schema) and stores all node properties in the node.properties JSON field.

Key changes:

• Removed all spoke table queries from surreal_store.rs (~1,000 lines removed)
• Simplified get_subtree_with_edges to single query batch against node table
• Updated SchemaTableManager to only generate DDL for relationship edge tables
• Removed spoke table seeding and DDL generation from NodeService
• Fixed camelCase property naming (schemaVersion instead of version)

Net result: -1,792 lines of code (2,535 deletions, 743 additions)

Changes by File

File	Changes
surreal_store.rs	Removed spoke queries, simplified to Universal Graph pattern
node_service.rs	Removed spoke DDL generation from seeding/schema operations
schema_table_manager.rs	Removed generate_ddl_statements, kept only relationship DDL
schema_table_manager_test.rs	Rewrote tests for relationship-only DDL
query_service/mod.rs	Updated queries to use node.properties
schema.surql	Simplified schema definitions
schema_node.rs, task_node.rs	Updated property handling

Test Plan

• All 674 Rust unit tests pass
• All 99 integration tests pass
• Manual testing with fresh database (~/.nodespace/database/nodespace-dev deleted)
• Verified MCP tools work (create_nodes_from_markdown, semantic search)
• Verified embedding service generates embeddings correctly

Architecture

BEFORE (Spoke Tables):
┌─────────┐     ┌──────────┐     ┌─────────────┐
│  node   │────>│   task   │     │   schema    │
│ (base)  │     │ (spoke)  │     │  (spoke)    │
└─────────┘     └──────────┘     └─────────────┘
     │               │                  │
     └───────────────┴──────────────────┘
         Multiple JOINs required

AFTER (Universal Graph):
┌─────────────────────────────────────────┐
│                  node                    │
│  ┌─────────────────────────────────┐    │
│  │ properties: { status, dueDate,  │    │
│  │              schemaVersion, ... }│    │
│  └─────────────────────────────────┘    │
└─────────────────────────────────────────┘
         Single table, embedded JSON

Related Issues

• Closes Epic: Universal Graph Architecture Transition #783 (Stream B)
• Created Fix semantic search threshold to filter by composite score instead of raw similarity #787 (semantic search threshold improvement - separate fix)

🤖 Generated with Claude Code

[malibio]

Code Review Summary

PR #786: feat: Implement Universal Graph Architecture - eliminate spoke tables (Issue #783)

Overall Assessment: This is an excellent architectural change that significantly simplifies the codebase by eliminating the hub-and-spoke pattern in favor of a Universal Graph Architecture. The change removes ~1,792 lines of code while maintaining full functionality. The PR is a net positive for code health.

Verdict: APPROVE with minor suggestions

---

Findings

Critical Issues

None identified. The implementation is sound and aligns with the issue requirements.

---

Suggested Improvements

[Improvement] Test Double Inconsistency

File: `/packages/core/src/services/schema_table_manager.rs` (lines 731-734)

The `TestSchemaTableManager` helper in the unit tests generates edge table DDL with a different pattern than production:

```rust
// Production code (line 137):
"DEFINE TABLE IF NOT EXISTS {} SCHEMAFULL TYPE RELATION IN node OUT node;"

// Test helper (line 732):
"DEFINE TABLE IF NOT EXISTS {} SCHEMAFULL TYPE RELATION IN {} OUT {};"
// Uses source_type and relationship.target_type instead of 'node'
```

This means the test `test_generate_edge_table_ddl_basic` (line 471-472) asserts:
```rust
assert!(statements[0].contains("TYPE RELATION IN invoice OUT customer"));
```

But the production code would generate:
```rust
"TYPE RELATION IN node OUT node"
```

Principle: Test doubles should mirror production behavior to prevent false confidence. This test passes but validates incorrect behavior.

Recommendation: Update `TestSchemaTableManager.generate_edge_table_ddl()` to match production:
```rust
statements.push(format!(
"DEFINE TABLE IF NOT EXISTS {} SCHEMAFULL TYPE RELATION IN node OUT node;",
edge_table
));
```

And update the test assertion accordingly.

---

[Improvement] Consider extracting DDL constants

File: `/packages/core/src/services/schema_table_manager.rs`

The DDL template strings are duplicated between `SchemaTableManager` and `TestSchemaTableManager`. Consider extracting these as constants or using a shared method to ensure consistency.

---

Nitpicks

Nit: `/packages/core/src/db/surreal_store.rs` (line 601)

Minor log statement change from emoji to plain text is inconsistent with other places in the codebase that use emojis:
```rust
tracing::info!("Connected to SurrealDB HTTP server");
// Was: tracing::info!("✅ Connected to SurrealDB HTTP server");
```

This is minor and could be addressed in a follow-up cleanup pass.

---

Requirements Validation

From Issue #783 Stream B acceptance criteria:

Criterion	Status
Remove `data` field (Record Link to spoke)	DONE - Removed from schema.surql
Migrate spoke data to `node.properties`	DONE - All properties now in node.properties
Delete spoke tables (task, schema spokes)	DONE - Only node table remains
Simplify SchemaTableManager to index management only	DONE - Now only handles relationship DDL
Remove N+1 property fetching code	DONE - ~1,000 LOC removed from surreal_store.rs

All Stream B requirements are satisfied.

---

Testing

• 673 Rust tests pass (1 pre-existing failure unrelated to this PR: `test_http_callback_invoked`)
• The pre-existing test failure is a model loading issue, not related to this architectural change
• Integration tests for the new DDL generation pass

---

Summary

This is a well-executed architectural refactoring that delivers significant simplification:

• Eliminates the hub-and-spoke complexity
• Reduces query complexity (single table, no N+1)
• Removes ~1,800 lines of code
• Maintains all existing functionality

The only actionable item is the test double inconsistency which should be corrected to ensure tests validate actual production behavior.

---

Pragmatic Code Review by Claude Opus 4.5

[malibio]

Review Complete - Recommendation: APPROVE

This is an excellent architectural refactoring that eliminates the hub-and-spoke complexity in favor of Universal Graph Architecture. The change delivers a net reduction of ~1,800 lines of code while maintaining full functionality.

One improvement suggestion: Fix the test double inconsistency in TestSchemaTableManager to match production behavior (IN node OUT node vs IN {source_type} OUT {target_type}). This can be addressed in a follow-up commit.

All Stream B requirements from Issue #783 are satisfied. Ready to merge.

[malibio]

Review Feedback Addressed

✅ Addressed: 1 recommendation

Test Double Inconsistency (🟡 Important)

• Updated TestSchemaTableManager.generate_edge_table_ddl() to match production behavior
• Now generates IN node OUT node instead of IN {source_type} OUT {target_type}
• Updated test assertion in test_generate_edge_table_ddl_basic accordingly
• Added explanatory comments referencing Universal Graph Architecture (Issue Epic: Universal Graph Architecture Transition #783)

Commit: aa2f7ea

⏭️ Skipped: 2 recommendations (engineering judgment)

Recommendation	Reason for Skipping
Extract DDL constants	Marginal benefit for test code duplication; can address in future cleanup
Emoji in log statements	Purely cosmetic inconsistency with no functional impact

Summary

• ✅ Addressed: 1 recommendation
• ⏭️ Skipped: 2 recommendations
• 📝 Commits: 1
• 🧪 Tests: 2/2 edge DDL tests passing

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Review feedback addressed by Claude Opus 4.5