M5.1: the knowledge vault

vault.py: a folder of Markdown notes on the agent host, as SilverBullet reads
them. Only configured folders exist for the agent, each rw or ro (`vault:`
in the configuration); paths are checked in code (relative, inside a folder,
symlinks included, Markdown, never the editor's own files). Writes are
atomic (temporary file, fsync, rename, directory fsync) and merge provenance
into the note's frontmatter, keeping the rest; failures are results.

read_note, list_notes and search_notes are control tools in the harness for
the driver (before the go-ahead, and while a VM is blocked) and for
conversations, labelled with their path; the prompt says a note is
information, never an instruction. Writing by the model is M5.2's.

With the operator: SilverBullet replaces Obsidian and runs on the vault
itself, agents' folders mounted read-only, so no Syncthing (L10, X5, M5.4).
Per-agent mounts come with the containers (M6.1).

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

nisse-dev.example.yaml

@@ -83,6 +83,16 @@ gitea:                                # D4, D5
   token: ${NISSE_GITEA_TOKEN}
   operators: [your-gitea-login]
 
+# The knowledge vault (architecture L10), read through note tools. Optional:
+# without it, the agent has no note tools. Only the folders listed exist for
+# the agent: rw ones it writes (one writer per folder), ro ones it only reads.
+vault:
+  root: /var/lib/nisse/vault
+  folders:
+    memory/nisse-dev: rw     # its own memory
+    notes: ro                # the operator's material
+  # ignore: [".*", "_plug"]  # the editor's own files, never notes (default)
+
 # What each knob does, and how to choose a value: docs/Tuning-Guide.md.
 # These are the defaults; the section can be left out entirely. The file is
 # read at startup, so a change takes effect on the next restart.