brain_list MCP tool always returns 400: category=[object Object]

[vRobM]

Summary

brain_list MCP tool always fails with a 400 error regardless of whether a category parameter is provided. The server receives category=[object Object] in the query string instead of the correct value (or nothing).

Steps to Reproduce

Call brain_list via MCP:

• With {category: "architecture", limit: 3} -> error
• With {limit: 2} (no category at all) -> same error

Actual Result

error: "pi error (400): Failed to deserialize query string: unknown variant `[object Object]`, expected one of `architecture`, `pattern`, `solution`, `convention`, `security`, `performance`, `tooling`, `debug`, `sota`, `discovery`, `hypothesis`, `cross_domain`, `neural_architecture`, `compression`, `self_learning`, `reinforcement_learning`, `graph_intelligence`, `distributed_systems`, `edge_computing`, `hardware_acceleration`, `quantum`, `neuromorphic`, `bio_computing`, `cognitive_science`, `formal_methods`, `geopolitics`, `climate`, `biomedical`, `space`, `finance`, `meta_cognition`, `benchmark`, `consciousness`, `information_decomposition`, `custom`"

Expected Result

List of memories, optionally filtered by category.

Evidence

REST API works fine (bypassing the MCP handler):

GET /v1/memories/list?category=architecture&limit=3

Returns 3 results with total_count: 2129 -- correct.

Related MCP tool works: brain_search with {query: "architecture patterns", category: "architecture"} returns results successfully. Both handlers use the identical pattern for extracting category from args.

Root Cause

The deployed brain_list MCP handler on pi.ruv.io is constructing query params with category=[object Object] regardless of the provided arguments. The error text uses pi error not API error, confirming the deployed binary differs from the current main branch source at crates/mcp-brain-server/src/routes.rs.

The main branch handler (lines 6070-6078) looks correct:

"brain_list" => {
    let mut params = Vec::new();
    if let Some(c) = args.get("category").and_then(|v| v.as_str()) {
        params.push(("category", c.to_string()));
    }
    if let Some(l) = args.get("limit").and_then(|v| v.as_u64()) {
        params.push(("limit", l.to_string()));
    }
    proxy_get(&client, &base, "/v1/memories/list", api_key, &params).await
}

The fix is to rebuild and redeploy the brain server from main.

Workaround

Use the REST API directly:

curl -H "Authorization: Bearer $KEY" "https://pi.ruv.io/v1/memories/list?category=architecture&limit=5"

Or use brain_search which handles the category parameter correctly.

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