restructure: hippocampus/ for memory, subconscious/ for agents

hippocampus/ — memory storage, retrieval, and consolidation:
  store, graph, query, similarity, spectral, neuro, counters,
  config, transcript, memory_search, lookups, cursor, migrate

subconscious/ — autonomous agents that process without being asked:
  reflect, surface, consolidate, digest, audit, etc.

All existing crate::X paths preserved via re-exports in lib.rs.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

src/subconscious/agents/enrich.rs

@@ -0,0 +1,40 @@
+// Conversation extraction from JSONL transcripts
+//
+// extract_conversation  — parse JSONL transcript to messages
+// split_on_compaction   — split messages at compaction boundaries
+
+/// Extract conversation messages from a JSONL transcript file.
+/// Returns (line_number, role, text, timestamp) tuples.
+pub fn extract_conversation(jsonl_path: &str) -> Result<Vec<(usize, String, String, String)>, String> {
+    let path = std::path::Path::new(jsonl_path);
+    let messages = super::transcript::parse_transcript(path)?;
+    Ok(messages.into_iter()
+        .map(|m| (m.line, m.role, m.text, m.timestamp))
+        .collect())
+}
+
+pub const COMPACTION_MARKER: &str = "This session is being continued from a previous conversation that ran out of context";
+
+/// Split extracted messages into segments at compaction boundaries.
+/// Each segment represents one continuous conversation before context was compacted.
+pub fn split_on_compaction(messages: Vec<(usize, String, String, String)>) -> Vec<Vec<(usize, String, String, String)>> {
+    let mut segments: Vec<Vec<(usize, String, String, String)>> = Vec::new();
+    let mut current = Vec::new();
+
+    for msg in messages {
+        if msg.1 == "user" && msg.2.starts_with(COMPACTION_MARKER) {
+            if !current.is_empty() {
+                segments.push(current);
+                current = Vec::new();
+            }
+            current.push(msg);
+        } else {
+            current.push(msg);
+        }
+    }
+    if !current.is_empty() {
+        segments.push(current);
+    }
+
+    segments
+}