M5.2: agent memory

remember(name, description, fact) and forget(name, why): control tools for
the driver (before the go-ahead too) and conversations, writing only the
agent's own vault folder, one note per fact with its provenance. No one
agrees first; each change is a line in the thread. The harness keeps the
index and puts it into the transcript once per item, with a hash.

At an item's close, completed or abandoned, a bounded memory pass (the
driver's model, its own transcript and view) records what was decided and
learned; it never holds the close up (tuning.memory.max_turns).

With the operator: corrections may be paraphrased (L6 changed), the model
forgets on its own, and nothing limits what may prompt a note. The walk
remembers and forgets, and checks nothing lands outside the agent's folder.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J5Utyfzw7gF7UhjRDEtjTk

nisse-dev/src/nisse_dev/vault.py

@@ -175,6 +175,18 @@ class Vault:
 
     # -- writing ---------------------------------------------------------------
 
+    def delete(self, path: str) -> None:
+        """Remove a note in a read-write folder (one writer: its own)."""
+        _, real, access = self._resolve(path, note=True)
+        if access != READ_WRITE:
+            raise VaultError(f"{path}: that folder is read-only for you")
+        try:
+            real.unlink()
+        except FileNotFoundError:
+            raise VaultError(f"{path}: no such note") from None
+        except OSError as exc:
+            raise VaultError(f"{path}: couldn't remove it ({exc})") from None
+
     def write(self, path: str, text: str, *, provenance: Mapping[str, str]) -> None:
         """Write a note in a read-write folder, atomically, with where it
         came from merged into its frontmatter; the rest of its frontmatter