journal: add --date flag for backdating entries

Adds an optional date parameter to journal_new that overrides the
timestamp on new entries. Accepts YYYY-MM-DD or YYYY-MM-DDTHH:MM
format. Used for seeding the memory graph with historical journal
entries from existing memory files.

Threading: CLI --date flag → cmd_journal_write → journal_new tool →
local store, with parse_date_to_epoch setting both timestamp and
created_at on the node.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/hippocampus/local.rs

@@ -315,9 +315,13 @@ fn level_to_node_type(level: i64) -> crate::store::NodeType {
     }
 }
 
-pub fn journal_new(store: &Store, provenance: &str, name: &str, title: &str, body: &str, level: Option<i64>) -> Result<String> {
+pub fn journal_new(store: &Store, provenance: &str, name: &str, title: &str, body: &str, level: Option<i64>, date: Option<&str>) -> Result<String> {
     let level = level.unwrap_or(0);
-    let ts = chrono::Local::now().format("%Y-%m-%dT%H:%M");
+    let ts = if let Some(d) = date {
+        d.to_string()
+    } else {
+        chrono::Local::now().format("%Y-%m-%dT%H:%M").to_string()
+    };
     let content = format!("## {} — {}\n\n{}", ts, title, body);
 
     let base_key: String = name.split_whitespace()
@@ -340,6 +344,12 @@ pub fn journal_new(store: &Store, provenance: &str, name: &str, title: &str, bod
         base_key.to_string()
     };
     let mut node = crate::store::new_node(&key, &content);
+    if let Some(d) = date {
+        if let Some(epoch) = parse_date_to_epoch(d) {
+            node.timestamp = epoch;
+            node.created_at = epoch;
+        }
+    }
     node.node_type = level_to_node_type(level);
     node.provenance = provenance.to_string();
     store.upsert_node(node).map_err(|e| anyhow::anyhow!("{}", e))?;
@@ -348,6 +358,18 @@ pub fn journal_new(store: &Store, provenance: &str, name: &str, title: &str, bod
     Ok(format!("New entry '{}' ({} words)", title, word_count))
 }
 
+fn parse_date_to_epoch(date: &str) -> Option<i64> {
+    use chrono::NaiveDate;
+    use chrono::NaiveDateTime;
+    if let Ok(dt) = NaiveDateTime::parse_from_str(date, "%Y-%m-%dT%H:%M") {
+        Some(dt.and_local_timezone(chrono::Local).single()?.timestamp())
+    } else if let Ok(d) = NaiveDate::parse_from_str(date, "%Y-%m-%d") {
+        Some(d.and_hms_opt(12, 0, 0)?.and_local_timezone(chrono::Local).single()?.timestamp())
+    } else {
+        None
+    }
+}
+
 pub fn journal_update(store: &Store, provenance: &str, body: &str, level: Option<i64>) -> Result<String> {
     let level = level.unwrap_or(0);
     let node_type = level_to_node_type(level);

src/hippocampus/mod.rs

@@ -309,7 +309,7 @@ memory_tool!(memory_links, ref -> Vec<LinkInfo>, key: [str]);
 // ── Journal tools ──────────────────────────────────────────────
 
 memory_tool!(journal_tail, ref -> Vec<JournalEntry>, count: [Option<u64>], level: [Option<u64>], after: [Option<&str>]);
-memory_tool!(journal_new, mut, name: [str], title: [str], body: [str], level: [Option<i64>]);
+memory_tool!(journal_new, mut, name: [str], title: [str], body: [str], level: [Option<i64>], date: [Option<&str>]);
 memory_tool!(journal_update, mut, body: [str], level: [Option<i64>]);
 
 // ── Graph tools ───────────────────────────────────────────────