show suggested link targets in agent prompts

Agents were flying blind — they could see nodes to review and the
topology header, but had no way to discover what targets to link to.
Now each node shows its top 8 text-similar semantic nodes that aren't
already neighbors, giving agents a search-like capability.

Also added section-level targeting guidance to linker.md, transfer.md,
and replay.md prompts: always target the most specific section, not
the file-level node.

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

prompts/linker.md

@@ -91,6 +91,21 @@ Observations about patterns across episodes that aren't yet captured anywhere.
   If a node is from weeks ago and already has good connections, it doesn't
   need more. Focus your energy on recent, under-linked episodes.
 
+- **Prefer lateral links over hub links.** Connecting two peripheral nodes
+  to each other is more valuable than connecting both to a hub like
+  `identity.md`. Lateral links build web topology; hub links build star
+  topology.
+
+- **Target sections, not files.** When linking to a topic file, always
+  target the most specific section: use `identity.md#boundaries` not
+  `identity.md`, use `kernel-patterns.md#restart-handling` not
+  `kernel-patterns.md`. The suggested link targets show available sections.
+
+- **Use the suggested targets.** Each node shows text-similar targets not
+  yet linked. Start from these — they're computed by content similarity and
+  filtered to exclude existing neighbors. You can propose links beyond the
+  suggestions, but the suggestions are usually the best starting point.
+
 {{TOPOLOGY}}
 
 ## Nodes to review

prompts/replay.md

@@ -85,6 +85,12 @@ for the human to review.
 - **Trust the decay.** If a node is genuinely unimportant, you don't need
   to actively prune it. Just don't link it, and it'll decay below threshold
   on its own.
+- **Target sections, not files.** When linking to a topic file, always
+  target the most specific section: use `identity.md#boundaries` not
+  `identity.md`. The suggested link targets show available sections.
+- **Use the suggested targets.** Each node shows text-similar semantic nodes
+  not yet linked. These are computed by content similarity and are usually
+  the best starting point for new links.
 
 {{TOPOLOGY}}
 

prompts/transfer.md

@@ -128,6 +128,13 @@ Meta-observations about patterns in the consolidation process itself.
   symmetric lock ordering when the hot path is asymmetric" is conceptual.
   Extract the conceptual version.
 
+- **Target sections, not files.** When linking to a topic file, always
+  target the most specific section: use `reflections.md#emotional-patterns`
+  not `reflections.md`. The suggested link targets show available sections.
+
+- **Use the suggested targets.** Each episode shows text-similar semantic
+  nodes not yet linked. Start from these when proposing LINK actions.
+
 {{TOPOLOGY}}
 
 ## Episodes to process

src/neuro.rs

@@ -284,6 +284,37 @@ fn format_nodes_section(store: &Store, items: &[ReplayItem], graph: &Graph) -> S
                 out.push_str(")\n");
             }
         }
+
+        // Suggested link targets: text-similar semantic nodes not already neighbors
+        let neighbor_keys: std::collections::HashSet<&str> = neighbors.iter()
+            .map(|(k, _)| k.as_str()).collect();
+        let mut candidates: Vec<(&str, f32)> = store.nodes.iter()
+            .filter(|(k, _)| {
+                // Only semantic/topic file nodes, not episodic
+                !k.starts_with("journal.") && !k.starts_with("deep-index.")
+                    && !k.starts_with("daily-") && !k.starts_with("weekly-")
+                    && !k.starts_with("monthly-") && !k.starts_with("session-")
+                    && *k != &item.key
+                    && !neighbor_keys.contains(k.as_str())
+            })
+            .map(|(k, n)| {
+                let sim = similarity::cosine_similarity(content, &n.content);
+                (k.as_str(), sim)
+            })
+            .filter(|(_, sim)| *sim > 0.1)
+            .collect();
+        candidates.sort_by(|a, b| b.1.partial_cmp(&a.1).unwrap_or(std::cmp::Ordering::Equal));
+        candidates.truncate(8);
+
+        if !candidates.is_empty() {
+            out.push_str("\nSuggested link targets (by text similarity, not yet linked):\n");
+            for (k, sim) in &candidates {
+                let is_hub = graph.degree(k) >= hub_thresh;
+                out.push_str(&format!("  - {} (sim={:.3}{})\n",
+                    k, sim, if is_hub { ", HUB" } else { "" }));
+            }
+        }
+
         out.push_str("\n---\n\n");
     }
     out