memory: add dispatch handlers for memory_spread and memory_search_content

The new tool definitions broke surface-observe because they had no
corresponding dispatch handlers — the agent runner saw unknown tools
and ran with no tools at all.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/thought/memory.rs

@@ -6,6 +6,7 @@ use anyhow::{Context, Result};
 use serde_json::json;
 
 use crate::hippocampus::memory::MemoryNode;
+use crate::store::StoreView;
 use super::ToolDef;
 use crate::store::Store;
 
@@ -100,7 +101,7 @@ pub fn dispatch(name: &str, args: &serde_json::Value, provenance: Option<&str>)
             store.save().map_err(|e| anyhow::anyhow!("{}", e))?;
             Ok(format!("{} '{}'", result, key))
         }
-        "memory_search" => {
+        "memory_search" | "memory_search_content" => {
             let query = get_str(args, "query")?;
             let store = Store::load().map_err(|e| anyhow::anyhow!("{}", e))?;
             let results = crate::search::search(query, &store);
@@ -113,6 +114,38 @@ pub fn dispatch(name: &str, args: &serde_json::Value, provenance: Option<&str>)
                     .collect::<Vec<_>>().join("\n"))
             }
         }
+        "memory_spread" => {
+            let keys: Vec<String> = args.get("keys")
+                .and_then(|v| v.as_array())
+                .map(|arr| arr.iter().filter_map(|v| v.as_str().map(String::from)).collect())
+                .unwrap_or_default();
+            if keys.is_empty() {
+                anyhow::bail!("spread requires at least one seed key");
+            }
+            let store = Store::load().map_err(|e| anyhow::anyhow!("{}", e))?;
+            let graph = crate::graph::build_graph_fast(&store);
+            let params = store.params();
+            let seeds: Vec<(String, f64)> = keys.iter()
+                .filter_map(|k| {
+                    let resolved = store.resolve_key(k).ok()?;
+                    Some((resolved, 1.0))
+                })
+                .collect();
+            if seeds.is_empty() {
+                anyhow::bail!("no valid seed keys found");
+            }
+            let seed_set: std::collections::HashSet<&str> = seeds.iter()
+                .map(|(k, _)| k.as_str()).collect();
+            let results = crate::search::spreading_activation(
+                &seeds, &graph, &store,
+                params.max_hops, params.edge_decay, params.min_activation,
+            );
+            Ok(results.iter()
+                .filter(|(k, _)| !seed_set.contains(k.as_str()))
+                .take(20)
+                .map(|(key, score)| format!("  {:.2}  {}", score, key))
+                .collect::<Vec<_>>().join("\n"))
+        }
         "memory_links" => {
             let key = get_str(args, "key")?;
             let node = MemoryNode::load(key)