ruvector_list_agents() and ruvector_sparql_json() crash PostgreSQL backend

[grparry]

Hi! I've been testing the PostgreSQL extension and found two issues that crash the backend process (killing the client connection):

1. ruvector_list_agents() / ruvector_find_agents_by_capability()
The SQL in ruvector--2.0.0.sql declares RETURNS SETOF jsonb, but the Rust functions return a TableIterator with named composite columns. PostgreSQL expects a single JSONB datum per row and crashes on the mismatch.

2. ruvector_sparql_json() with invalid input
An invalid SPARQL query causes a Rust panic that bypasses pgrx's error handler. This is partly because the workspace Cargo.toml sets panic = "abort" in the release profile, which makes catch_unwind a no-op and also prevents pgrx from converting Result::Err into PostgreSQL errors (pgrx relies on unwinding).

I have a working fix for both if you'd like a PR. Happy to adjust it to match your preferred style.

[ruvnet]

Fix Applied in PR #172 (merged)

All three crashes identified and fixed:

1. SQL/Rust type mismatch — ruvector_list_agents() and ruvector_find_agents_by_capability()

SQL declared RETURNS SETOF jsonb but Rust returns TableIterator with named composite columns. PostgreSQL expected a single JSONB datum per row and crashed on the mismatch.

Fix in ruvector--2.0.0.sql:

-- Before (crashes):
RETURNS SETOF jsonb

-- After (matches Rust signature):
RETURNS TABLE(name text, agent_type text, capabilities text[],
  cost_per_request real, avg_latency_ms real, quality_score real,
  success_rate real, total_requests bigint, is_active boolean)

2. SPARQL panic on invalid input

Fix: Added empty query validation before parsing:

if query.trim().is_empty() {
    return Err("SPARQL query cannot be empty".to_string());
}

3. panic = "abort" in release profile

The workspace Cargo.toml had panic = "abort" which prevents pgrx from catching panics via catch_unwind. Any Rust panic kills the PostgreSQL backend process.

Fix: Changed to panic = "unwind" so pgrx can convert panics to PostgreSQL ERROR messages.

Would welcome your PR for additional SPARQL validation if you have one ready!

Version: ruvector-postgres 2.0.2 | PR: #172

[ruvnet]

Fixed in ruvector-postgres v2.0.2 (PR #172). SQL type signatures corrected, SPARQL validation added, panic=unwind enabled.

[grparry]

Thanks for the fast turnaround on #172 — really appreciate it!

Your fix took a different (and totally valid) approach on the type mismatch — changing the SQL to match the Rust signatures rather than the other way around. Nice.

While testing, we found a few additional things in the SPARQL subsystem that #172 didn't cover, so I've put them in PR #180 for your review:

1. Parser backtrack bug — the saturating_sub(6) in parse_query_body() assumes all update keywords are 6 characters, but LOAD/DROP are 4 and CLEAR is 5. Replaced with a saved_pos variable.
2. Memory leak in executor — Box::leak is used in the GraphPattern::Graph handler to create &'static str references, but those allocations are never freed. Switched default_graph to Option<String> instead.
3. catch_unwind safety net — the empty-query check catches one case, but a non-empty malformed query can still panic deeper in the parser/executor chain. Wrapped the whole parse/execute/format path in catch_unwind so any remaining panics become PostgreSQL ERRORs rather than backend crashes.

Happy to adjust anything to match your conventions. Thanks again for creating and maintaining this project!