claude: add secret/Vaultwarden credential-store tool + store-durable-creds directive

home_root/.claude/CLAUDE.md

@@ -537,6 +537,26 @@ note says otherwise. On other boxes, check first.)
   `services/booth/` (`scripts/booth {new|add|url|ls|rm}`); user-level systemd
   on nh3-dev (`systemctl --user status booth.service`).
 
+- **`secret` — Vaultwarden credential store (per dev box)** — a CLI for stashing
+  and looking up secrets that shouldn't live in a git repo, backed by
+  **`vaultwarden.phasefinal.com`** (the `infra-ops` org, visible from the operator's
+  primary account). On nh3-dev the CLI is
+  `~/development/eshpfi-management/services/secrets-broker/secret` (bw-backed; auth
+  bootstraps from `~/.config/secrets-broker/bootstrap.env`, `0600`). Usage:
+  `secret put <name> (--file P | --stdin) [--folder C] [--field k=v]`,
+  `secret get <name> [--field F] [--file OUT]` (the only command that prints a
+  value), `secret list [--prefix P]`, `secret backfill [--dry-run]` (scans THIS
+  box's `~/development/*/{env.sh,.env}` + `~/.config` creds and upserts each).
+  Items are hostname-namespaced (`<host>/…`); small text → item note, small binary
+  → base64 hidden field, >6000 B → a bw attachment. **STANDING DIRECTIVE: store
+  durable credentials in the vault.** Any token / API key / cert / env-secret worth
+  keeping — not ephemeral, doesn't belong in git — should be `secret put` into the
+  vault so it survives and is findable, never left single-copy on a box. The one
+  exception is `bootstrap.env` itself (secrets-zero — it unlocks the vault, so it
+  can't live inside it; keep it `0600`). **Not a fleet service / no daemon** — each
+  new dev box duplicates this stack against its own local secrets (setup steps in
+  the service `README.md`). Details: auto-memory `reference_secrets_broker_cli`.
+
 ## DevOps delegation
 
 For all DevOps work — deployments, infrastructure provisioning,