search: trim default output to 5 results, gate spectral with --expand

Default search was 15 results + 5 spectral neighbors — way too much
for the recall hook context window. Now: 5 results by default, no
spectral. --expand restores the full 15 + spectral output.

Co-Authored-By: ProofOfConcept <poc@bcachefs.org>

src/main.rs

@@ -145,7 +145,7 @@ fn usage() {
     eprintln!("poc-memory v0.4.0 — graph-structured memory store
 
 Commands:
-  search QUERY [QUERY...]   Search memory (AND logic across terms)
+  search QUERY [--expand]   Search memory (AND logic across terms)
   init                      Scan markdown files, index all memory units
   migrate                   Migrate from old weights.json system
   health                    Report graph metrics (CC, communities, small-world)
@@ -214,9 +214,15 @@ fn cmd_search(args: &[String]) -> Result<(), String> {
     use store::StoreView;
 
     if args.is_empty() {
-        return Err("Usage: poc-memory search QUERY [QUERY...]".into());
+        return Err("Usage: poc-memory search QUERY [QUERY...] [--expand]".into());
     }
-    let query = args.join(" ");
+
+    let expand = args.iter().any(|a| a == "--expand");
+    let query: String = args.iter()
+        .filter(|a| *a != "--expand")
+        .cloned()
+        .collect::<Vec<_>>()
+        .join(" ");
 
     let view = store::AnyView::load()?;
     let results = search::search(&query, &view);
@@ -226,19 +232,21 @@ fn cmd_search(args: &[String]) -> Result<(), String> {
         return Ok(());
     }
 
+    let limit = if expand { 15 } else { 5 };
+
     // Log retrieval to a small append-only file (avoid 6MB state.bin rewrite)
     store::Store::log_retrieval_static(&query,
         &results.iter().map(|r| r.key.clone()).collect::<Vec<_>>());
 
     // Bump daily lookup counters (fast path, no store needed)
-    let bump_keys: Vec<&str> = results.iter().take(15).map(|r| r.key.as_str()).collect();
+    let bump_keys: Vec<&str> = results.iter().take(limit).map(|r| r.key.as_str()).collect();
     let _ = lookups::bump_many(&bump_keys);
 
     // Show text results
     let text_keys: std::collections::HashSet<String> = results.iter()
-        .take(15).map(|r| r.key.clone()).collect();
+        .take(limit).map(|r| r.key.clone()).collect();
 
-    for (i, r) in results.iter().enumerate().take(15) {
+    for (i, r) in results.iter().enumerate().take(limit) {
         let marker = if r.is_direct { "→" } else { " " };
         let weight = view.node_weight(&r.key);
         print!("{}{:2}. [{:.2}/{:.2}] {}", marker, i + 1, r.activation, weight, r.key);
@@ -248,7 +256,8 @@ fn cmd_search(args: &[String]) -> Result<(), String> {
         }
     }
 
-    // Spectral expansion: find neighbors of top text hits
+    // Spectral expansion: only with --expand
+    if expand {
         if let Ok(emb) = spectral::load_embedding() {
             let seeds: Vec<&str> = results.iter()
                 .take(5)
@@ -258,7 +267,6 @@ fn cmd_search(args: &[String]) -> Result<(), String> {
 
             if !seeds.is_empty() {
                 let spectral_hits = spectral::nearest_to_seeds(&emb, &seeds, 10);
-            // Filter to nodes not already in text results
                 let new_hits: Vec<_> = spectral_hits.into_iter()
                     .filter(|(k, _)| !text_keys.contains(k))
                     .take(5)
@@ -270,7 +278,6 @@ fn cmd_search(args: &[String]) -> Result<(), String> {
                         let weight = view.node_weight(k);
                         print!("  ~ [{:.2}] {}", weight, k);
                         println!();
-                    // Show first line of content as snippet
                         if let Some(content) = view.node_content(k) {
                             let snippet: String = content.lines()
                                 .find(|l| !l.trim().is_empty() && !l.starts_with('#'))
@@ -284,6 +291,7 @@ fn cmd_search(args: &[String]) -> Result<(), String> {
                 }
             }
         }
+    }
 
     Ok(())
 }