naming agent: resolve node names before creation

Any time an agent creates a new node (WRITE_NODE) or the fact miner
stores extracted facts, a naming sub-agent now checks for conflicts
and ensures the key is meaningful:

- find_conflicts() searches existing nodes via component matching
- Haiku LLM decides: CREATE (good name), RENAME (better name),
  or MERGE_INTO (fold into existing node)
- WriteNode actions may be converted to Refine on MERGE_INTO

Also updates the rename agent to handle _facts-<UUID> nodes —
these are no longer skipped, and the prompt explains how to name
them based on their domain/claim content.

poc-memory/src/agents/fact_mine.rs

@@ -245,7 +245,7 @@ pub fn mine_and_store(
         .map(|n| n.to_string_lossy().to_string())
         .unwrap_or_else(|| "unknown".into());
 
-    let key = format!("_facts-{}", filename.trim_end_matches(".jsonl"));
+    let proposed_key = format!("_facts-{}", filename.trim_end_matches(".jsonl"));
 
     // Always write a marker so we don't re-queue empty transcripts
     let json = if facts.is_empty() {
@@ -256,6 +256,25 @@ pub fn mine_and_store(
     };
 
     let mut store = store::Store::load()?;
+
+    // Run naming resolution to get a good key (and possibly merge into existing)
+    let resolution = super::knowledge::resolve_naming(&store, &proposed_key, &json);
+    let key = match resolution {
+        super::knowledge::NamingResolution::Create(k) => k,
+        super::knowledge::NamingResolution::MergeInto(existing_key) => {
+            // Merge: append facts to existing node's content
+            eprintln!("  Merging facts into existing node: {}", existing_key);
+            if let Some(node) = store.nodes.get(existing_key.as_str()) {
+                let merged = format!("{}\n\n{}", node.content, json);
+                store.upsert_provenance(&existing_key, &merged, Provenance::AgentFactMine)?;
+                store.save()?;
+                return Ok(facts.len());
+            }
+            // Fallback if existing node disappeared
+            proposed_key
+        }
+    };
+
     store.upsert_provenance(&key, &json, Provenance::AgentFactMine)?;
     store.save()?;