review: memory writes from a secret session are not written to Honcho

The journal now records each call's class (absent on the owner's undo and on
older lines, which still read). The mirror turns everything a secret write
would conclude or send to the fleet into one Skip, after its deletions, which
still go; a note whose own header says secret is skipped the same way.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/memoryd/src/journal.rs

@@ -35,6 +35,10 @@ pub struct Record {
     /// For an undo, the edit it reverted.
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub undoes: Option<String>,
+    /// The call's class (`public`, `private` or `secret`, as on the wire): what its session had
+    /// read. `None` for the owner's undo and for lines from before it was recorded.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub class: Option<String>,
 }
 
 fn file_of(name: &str) -> Option<MemoryFile> {
@@ -132,6 +136,7 @@ pub fn record(store: &Store, ctx: &Context, outcome: &Outcome) -> Result<String,
             untrusted: ctx.untrusted,
             flag: outcome.flag.map(str::to_string),
             undoes: None,
+            class: Some(crate::notes::class_name(ctx.taint).to_string()),
         },
         ctx.now,
     )
@@ -227,6 +232,7 @@ pub fn undo(store: &Store, id: &str, now: Timestamp) -> Result<String, String> {
             untrusted: false,
             flag: None,
             undoes: Some(id.to_string()),
+            class: None,
         },
         now,
     )?;