fix: [nomad-step-2] S2.3 review round 1 — document new helper + script, drop unused vault CLI precondition (#881)

Review feedback from PR #895 round 1:

- lib/AGENTS.md (hvault.sh row): add hvault_get_or_empty(PATH) to the
  public-function list; replace the "not sourced at runtime yet" note
  with the three actual callers (vault-apply-policies.sh,
  vault-apply-roles.sh, vault-nomad-auth.sh).
- lib/AGENTS.md (lib/init/nomad/ row): add a one-line description of
  vault-nomad-auth.sh (Step 2, this PR); relabel the row header from
  "Step 0 installer scripts" to "installer scripts" since it now spans
  Step 0 + Step 2.
- lib/init/nomad/vault-nomad-auth.sh: drop the `vault` CLI from the
  binary precondition check — hvault.sh's helpers are all curl-based,
  so the CLI is never invoked. The precondition would spuriously die on
  a Nomad-client-only node that has Vault server reachable but no
  `vault` binary installed. Inline comment preserves the rationale.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/AGENTS.md

@@ -34,5 +34,5 @@ sourced as needed.
 | `lib/sprint-filer.sh` | Post-merge sub-issue filer for sprint PRs. Invoked by the `.woodpecker/ops-filer.yml` pipeline after a sprint PR merges to ops repo `main`. Parses `<!-- filer:begin --> ... <!-- filer:end -->` blocks from sprint PR bodies to extract sub-issue definitions, creates them on the project repo using `FORGE_FILER_TOKEN` (narrow-scope `filer-bot` identity with `issues:write` only), adds `in-progress` label to the parent vision issue, and handles vision lifecycle closure when all sub-issues are closed. Uses `filer_api_all()` for paginated fetches. Idempotent: uses `<!-- decomposed-from: #<vision>, sprint: <slug>, id: <id> -->` markers to skip already-filed issues. Requires `FORGE_FILER_TOKEN`, `FORGE_API`, `FORGE_API_BASE`, `FORGE_OPS_REPO`. | `.woodpecker/ops-filer.yml` (CI pipeline on ops repo) |
 | `lib/hire-agent.sh` | `disinto_hire_an_agent()` — user creation, `.profile` repo setup, formula copying, branch protection, and state marker creation for hiring a new agent. Requires `FORGE_URL`, `FORGE_TOKEN`, `FACTORY_ROOT`, `PROJECT_NAME`. Extracted from `bin/disinto`. | bin/disinto (hire) |
 | `lib/release.sh` | `disinto_release()` — vault TOML creation, branch setup on ops repo, PR creation, and auto-merge request for a versioned release. `_assert_release_globals()` validates required env vars. Requires `FORGE_URL`, `FORGE_TOKEN`, `FORGE_OPS_REPO`, `FACTORY_ROOT`, `PRIMARY_BRANCH`. Extracted from `bin/disinto`. | bin/disinto (release) |
-| `lib/hvault.sh` | HashiCorp Vault helper module. `hvault_kv_get(PATH, [KEY])` — read KV v2 secret, optionally extract one key. `hvault_kv_put(PATH, KEY=VAL ...)` — write KV v2 secret. `hvault_kv_list(PATH)` — list keys at a KV path. `hvault_policy_apply(NAME, FILE)` — idempotent policy upsert. `hvault_jwt_login(ROLE, JWT)` — exchange JWT for short-lived token. `hvault_token_lookup()` — returns TTL/policies/accessor for current token. All functions use `VAULT_ADDR` + `VAULT_TOKEN` from env (fallback: `/etc/vault.d/root.token`), emit structured JSON errors to stderr on failure. Tests: `tests/lib-hvault.bats` (requires `vault server -dev`). | Not sourced at runtime yet — pure scaffolding for Nomad+Vault migration (#799) |
-| `lib/init/nomad/` | Nomad+Vault Step 0 installer scripts. `cluster-up.sh` — idempotent orchestrator that runs all steps in order (installs packages, writes HCL, enables systemd units, unseals Vault); uses `poll_until_healthy()` helper for deduped readiness polling. `install.sh` — installs pinned Nomad+Vault apt packages. `vault-init.sh` — initializes Vault (unseal keys → `/etc/vault.d/`), creates dev-persisted unseal unit. `lib-systemd.sh` — shared systemd unit helpers. `systemd-nomad.sh`, `systemd-vault.sh` — write and enable service units. Idempotent: each step checks current state before acting. Sourced and called by `cluster-up.sh`; not sourced by agents. | `bin/disinto init --backend=nomad` |
+| `lib/hvault.sh` | HashiCorp Vault helper module. `hvault_kv_get(PATH, [KEY])` — read KV v2 secret, optionally extract one key. `hvault_kv_put(PATH, KEY=VAL ...)` — write KV v2 secret. `hvault_kv_list(PATH)` — list keys at a KV path. `hvault_get_or_empty(PATH)` — GET /v1/PATH; 200→raw body, 404→empty, else structured error + return 1 (used by sync scripts to distinguish "absent, create" from hard failure without tripping errexit, #881). `hvault_policy_apply(NAME, FILE)` — idempotent policy upsert. `hvault_jwt_login(ROLE, JWT)` — exchange JWT for short-lived token. `hvault_token_lookup()` — returns TTL/policies/accessor for current token. All functions use `VAULT_ADDR` + `VAULT_TOKEN` from env (fallback: `/etc/vault.d/root.token`), emit structured JSON errors to stderr on failure. Tests: `tests/lib-hvault.bats` (requires `vault server -dev`). | `tools/vault-apply-policies.sh`, `tools/vault-apply-roles.sh`, `lib/init/nomad/vault-nomad-auth.sh` |
+| `lib/init/nomad/` | Nomad+Vault installer scripts. `cluster-up.sh` — idempotent Step-0 orchestrator that runs all steps in order (installs packages, writes HCL, enables systemd units, unseals Vault); uses `poll_until_healthy()` helper for deduped readiness polling. `install.sh` — installs pinned Nomad+Vault apt packages. `vault-init.sh` — initializes Vault (unseal keys → `/etc/vault.d/`), creates dev-persisted unseal unit. `lib-systemd.sh` — shared systemd unit helpers. `systemd-nomad.sh`, `systemd-vault.sh` — write and enable service units. `vault-nomad-auth.sh` — Step-2 script that enables Vault's JWT auth at path `jwt-nomad`, writes the JWKS/algs config pointing at Nomad's workload-identity signer, delegates role sync to `tools/vault-apply-roles.sh`, installs `/etc/nomad.d/server.hcl`, and SIGHUPs `nomad.service` if the file changed (#881). Idempotent: each step checks current state before acting. Sourced and called by `cluster-up.sh`; not sourced by agents. | `bin/disinto init --backend=nomad` |

lib/init/nomad/vault-nomad-auth.sh

@@ -63,7 +63,11 @@ if [ "$(id -u)" -ne 0 ]; then
   die "must run as root (writes ${SERVER_HCL_DST} + signals nomad)"
 fi
 
-for bin in curl jq vault systemctl; do
+# curl + jq are used directly; hvault.sh's helpers are also curl-based, so
+# the `vault` CLI is NOT required here — don't add it to this list, or a
+# Vault-server-present / vault-CLI-absent box (e.g. a Nomad-client-only
+# node) would die spuriously. systemctl is required for SIGHUPing nomad.
+for bin in curl jq systemctl; do
   command -v "$bin" >/dev/null 2>&1 \
     || die "required binary not found: ${bin}"
 done