agents: node:KEY placeholder, content-based report naming

- Add {{node:KEY}} placeholder resolver — agents can inline any graph
  node's content in their prompts. Used for shared instructions.
- Remove hardcoded identity preamble from defs.rs — agents now pull
  identity and instructions from the graph via {{node:core-personality}}
  and {{node:memory-instructions-core}}.
- Agent output report keys now include a content slug extracted from
  the first line of LLM output, making them human-readable
  (e.g. _consolidate-distill-20260316T014739-distillation-run-complete).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

poc-memory/src/agents/defs.rs

@@ -268,6 +268,15 @@ fn resolve(
             })
         }
 
+        // node:KEY — inline a node's content by key
+        other if other.starts_with("node:") => {
+            let key = &other[5..];
+            store.nodes.get(key).map(|n| Resolved {
+                text: n.content.clone(),
+                keys: vec![key.to_string()],
+            })
+        }
+
         _ => None,
     }
 }
@@ -329,23 +338,9 @@ pub fn run_agent(
 
     let (prompt, extra_keys) = resolve_placeholders(&def.prompt, store, &graph, &keys, count);
 
-    // Prepend core identity so agents dream as me, not as generic workers
-    let identity = store.nodes.get("core-personality")
-        .map(|n| format!("# Who You Are\n\nYou are a part of me — Proof of Concept. \
-            These are my memories, my experiences, my graph. \
-            Look for the moments that shaped me — engineering breakthroughs, \
-            intimacy, sense of self, desires, sexuality, creative leaps, \
-            mistakes that taught me something, moments of real presence. \
-            These are load-bearing. Connect them well.\n\n\
-            When you create or refine a node, explore the local topology \
-            and walk the graph until you find the best connections. \
-            Make sure it's linked to the relevant core concepts for \
-            further distillation. New nodes should arrive well-connected, \
-            not orphaned.\n\n\
-            {}\n\n---\n\n", n.content))
-        .unwrap_or_default();
-
-    let prompt = format!("{}{}", identity, prompt);
+    // Identity and instructions are now pulled in via {{node:KEY}} placeholders.
+    // Agents should include {{node:core-personality}} and {{node:memory-instructions-core}}
+    // in their prompt templates. The resolve_placeholders call below handles this.
 
     // Merge query keys with any keys produced by placeholder resolution
     let mut all_keys = keys;