The datasets table is a snapshot explorer, and snapshots can be deleted

Renamed Datasets to Snapshots and turned the columns around to match: how many each
dataset has and what they cost come first, the dataset's own size after. Opening one lists
its snapshots with when it was taken, when it expires — read from the TTL in its own name,
so no server call is needed — its size, and a Delete button. Deleting takes the same-named
snapshot on descendant datasets too, which is how a recursive schedule made it, and says so
before it does anything.

Dropped "What would it delete?" from the schedule cards, and the endpoint behind it. Run
now says plainly that expired snapshots go at the same time, which is the whole of what the
preview was telling anyone.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

PLAN.md

@@ -296,8 +296,24 @@ something long in one, switch away and back, refresh — it's all still there.
   **Nothing is destroyed unseen.** Every schedule answers *what would it delete?* with the
   list, sizes and dates, before Run now touches anything; only names that parse as a stamp
   and a TTL are candidates, so a snapshot taken by hand is invisible to it; and a snapshot
-  deleted by hand needs its full name typed back. The scheduler is a 30 s tick in the daemon,
+  deleted by hand needs its full name typed back.
-  and `Run now` calls the same code, so the button and the timer cannot drift apart.
+  **A schedule is a real cron job** (2026-09-24, Mitchell's call after the first cut ran it
+  from a ticker inside the daemon). Ham Lab writes `/etc/cron.d/hamlab-zfs`, owns it, and
+  rewrites it whole on every change; each line calls `hamlab zfs-snapshot <id>` as the
+  account Ham Lab runs as, reaching zfs through sudo as the daemon does. Snapshots are
+  backup-shaped and must not stop because a console is down, upgrading, or uninstalled — and
+  a cron line is greppable by anyone looking at the machine the normal way. **A cron
+  expression is the single description of when a schedule fires**: the four common shapes
+  render to one, `custom` states one outright, and the next run is read back with the same
+  evaluator the Jobs tab uses on everyone else's lines, so the page, the file and the
+  prediction cannot disagree. A run's outcome is written to `zfs-runs/<id>.json` beside the
+  config, never to `state.json`, because the cron job is a separate process and the daemon
+  would clobber it. An existing external job can be **adopted** — its schedule, retention
+  and dataset read out of the cron line into a new Ham Lab schedule.
+  **zfSnap is retired on `grid`** as of that day: Ham Lab now takes the nightly `tank`
+  snapshot, the package is purged and the old cron line is gone, with the 515 snapshots it
+  had taken left untouched and fully readable here — which is what adopting its naming
+  bought. See `hamlet/docs/hosts.md`.
 - **Skins** — 13 since 2026-09-19 (`themes.ts`: a palette is one `mk(…)` line): Dark,
   Light, Cyberpunk, Retro, **HUD** (hairlines of cyan on near-black, corner ticks, thin
   type), Nord, Gruvbox, Catppuccin + Latte, Dracula, Tokyo Night, Solarized Dark + Light;

internal/api/server.go

@@ -254,7 +254,6 @@ func New(cfg *config.Config, sessions *auth.Sessions, mgr *term.Manager, col *me
 	m.HandleFunc("GET /api/zfs", s.auth(s.zfsOverview))
 	m.HandleFunc("PUT /api/zfs/schedules", s.auth(s.zfsPolicyPut))
 	m.HandleFunc("DELETE /api/zfs/schedules/{id}", s.auth(s.zfsPolicyDelete))
-	m.HandleFunc("GET /api/zfs/schedules/{id}/expired", s.auth(s.zfsPreview))
 	m.HandleFunc("POST /api/zfs/schedules/{id}/run", s.auth(s.zfsRunNow))
 	m.HandleFunc("POST /api/zfs/snapshots/delete", s.auth(s.zfsSnapshotDelete))
 	m.HandleFunc("GET /api/space", s.auth(s.spaceOverview))

internal/api/zfs.go

@@ -217,24 +217,6 @@ func (s *Server) zfsPolicy(id string) (storage.Policy, bool) {
 	return storage.Policy{}, false
 }
 
-// zfsPreview is what this schedule would destroy if it ran now. Nothing is deleted.
-func (s *Server) zfsPreview(w http.ResponseWriter, r *http.Request) {
-	p, ok := s.zfsPolicy(r.PathValue("id"))
-	if !ok {
-		jsonErr(w, 404, "no such schedule")
-		return
-	}
-	doomed, err := s.storage.Doomed(r.Context(), &p)
-	if err != nil {
-		jsonErr(w, 500, err.Error())
-		return
-	}
-	if doomed == nil {
-		doomed = []storage.Snapshot{}
-	}
-	jsonOK(w, 200, map[string]any{"expired": doomed})
-}
-
 func (s *Server) zfsRunNow(w http.ResponseWriter, r *http.Request) {
 	id := r.PathValue("id")
 	p, ok := s.zfsPolicy(id)

web/src/ZFS.tsx

@@ -68,18 +68,43 @@ function PoolCard({ p, onChanged }: { p: ZFSInfo['pools'][number]; onChanged: ()
   )
 }
 
+// A snapshot's name carries when it was taken and how long it lives — 2026-09-24_02.30.01--6w
+// — so the explorer can say when each one goes without asking the server anything.
+function snapMeta(full: string): { taken?: Date; expires?: Date } {
+  const snap = full.split('@')[1] ?? ''
+  const [body, ttl] = snap.split('--')
+  const m = /(\d{4})-(\d{2})-(\d{2})_(\d{2})\.(\d{2})\.(\d{2})$/.exec(body)
+  if (!m) return {}
+  const taken = new Date(+m[1], +m[2] - 1, +m[3], +m[4], +m[5], +m[6])
+  const a = /^(\d+)([mhdw])$/.exec(ttl ?? '')
+  if (!a) return { taken }
+  const ms = { m: 60e3, h: 3600e3, d: 86400e3, w: 7 * 86400e3 }[a[2]]!
+  return { taken, expires: new Date(taken.getTime() + +a[1] * ms) }
+}
+
+// One dataset in the snapshot explorer: how many it has and what they cost, opening into
+// the snapshots themselves, each of which can be taken now or deleted.
 function DatasetRow({ d, onChanged }: { d: ZFSInfo['datasets'][number]; onChanged: () => void }) {
   const [snaps, setSnaps] = useState<ZFSSnapshot[] | null>(null)
   const [open, setOpen] = useState(false)
+  const reload = useCallback(async () => {
+    try { setSnaps(await api.zfsSnapshots(d.name)) } catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err'); setSnaps([]) }
+  }, [d.name])
   async function toggle() {
     setOpen(!open)
-    if (!open && !snaps) { try { setSnaps(await api.zfsSnapshots(d.name)) } catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err'); setSnaps([]) } }
+    if (!open && !snaps) await reload()
   }
   async function snapshot() {
-    const def = 'hamlab-' + new Date().toISOString().slice(0, 16).replace(/[-:T]/g, '').replace(/(\d{8})(\d{4})/, '$1-$2')
+    const def = new Date().toISOString().slice(0, 19).replace('T', '_').replace(/:/g, '.')
     const name = await askText(`Snapshot name for ${d.name}@`, def)
     if (!name) return
-    try { await api.zfsSnapshot(d.name, name.trim()); toast(`${d.name}@${name.trim()} created`); setSnaps(null); onChanged() }
+    try { await api.zfsSnapshot(d.name, name.trim()); toast(`${d.name}@${name.trim()} created`); await reload(); onChanged() }
+    catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err') }
+  }
+  async function destroy(s: ZFSSnapshot) {
+    const short = s.name.split('@')[1]
+    if (!await askYes(`Delete ${s.name}? It is removed from this dataset and from every dataset beneath it that has a snapshot of the same name. This cannot be undone.`, 'Delete')) return
+    try { await api.deleteZfsSnapshot(s.name, true); toast(`${short} deleted`); await reload(); onChanged() }
     catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err') }
   }
   const depth = d.name.split('/').length - 1
@@ -87,18 +112,29 @@ function DatasetRow({ d, onChanged }: { d: ZFSInfo['datasets'][number]; onChange
     <>
       <div className="ds-row" style={{ paddingLeft: 12 + depth * 16 }}>
         <span className="ds-name" onClick={toggle}><span className="chev">{open ? '▾' : '▸'}</span>{d.name.split('/').pop()}{d.type === 'volume' && <span className="badge">zvol</span>}</span>
-        <span className="num">{fmtBytes(d.used)}</span>
+        <span className="num">{d.snapshots}</span>
-        <span className="num muted">{fmtBytes(d.refer)}</span>
         <span className="num muted">{d.used_by_snapshots ? fmtBytes(d.used_by_snapshots) : '—'}</span>
-        <span className="num muted">{d.snapshots}</span>
+        <span className="num muted">{fmtBytes(d.used)}</span>
-        <span className="num muted">{d.compressratio}</span>
+        <span className="num muted">{fmtBytes(d.refer)}</span>
         <span className="ds-mount muted">{d.mount}</span>
       </div>
       {open && (
         <div className="ds-snaps">
-          <div className="svc-actions"><Btn className="btn" onClick={snapshot}>Snapshot now</Btn><span className="muted">avail {fmtBytes(d.avail)}</span></div>
+          <div className="svc-actions"><Btn className="btn" onClick={snapshot}>Snapshot now</Btn><span className="muted small">{d.snapshots} snapshot{d.snapshots === 1 ? '' : 's'} · {fmtBytes(d.avail)} free on this dataset</span></div>
           {snaps === null ? <div className="muted"><Spinner /> listing…</div> : snaps.length === 0 ? <div className="muted">No snapshots.</div> : (
-            <div className="snap-list">{snaps.slice().reverse().map((s) => <div key={s.name} className="snap"><span className="mono">{s.name.split('@')[1]}</span><span className="num muted">{new Date(s.created).toLocaleString()} · {fmtBytes(s.used)}</span></div>)}</div>
+            <div className="snap-list">{snaps.slice().reverse().map((s) => {
+              const { taken, expires } = snapMeta(s.name)
+              const gone = expires && expires.getTime() < Date.now()
+              return (
+                <div key={s.name} className="snap">
+                  <span className="mono snap-name" title={s.name}>{s.name.split('@')[1]}</span>
+                  <span className="muted snap-when">{taken ? taken.toLocaleString() : new Date(s.created).toLocaleString()}</span>
+                  <span className={'muted snap-exp' + (gone ? ' warn' : '')}>{expires ? (gone ? 'expired' : `expires ${expires.toLocaleDateString()}`) : 'kept'}</span>
+                  <span className="num muted">{fmtBytes(s.used)}</span>
+                  <Btn className="btn danger snap-del" onClick={() => destroy(s)}>Delete</Btn>
+                </div>
+              )
+            })}</div>
           )}
         </div>
       )}
@@ -126,18 +162,11 @@ function ExternalNotice({ x, mine, onAdopt }: { x: ExternalJob; mine: number; on
 type ExternalJob = ZFSExternal
 
 function ScheduleCard({ p, cron, next, last, onChanged, onEdit }: { p: ZFSPolicy; cron: string; next?: string; last: ZFSRun; onChanged: () => void; onEdit: () => void }) {
-  const [expired, setExpired] = useState<ZFSSnapshot[] | null>(null)
   const [busy, setBusy] = useState('')
-  const preview = async () => {
-    setBusy('preview')
-    try { setExpired((await api.zfsExpired(p.id)).expired) } catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err') } finally { setBusy('') }
-  }
   const run = async () => {
-    const n = expired?.length
+    if (!await askYes(`Take a snapshot of ${p.dataset} now? Snapshots past their retention are removed at the same time, as they would be on the schedule.`, 'Run now')) return
-    const warn = n ? ` It will also destroy ${n} expired snapshot${n === 1 ? '' : 's'}.` : ''
-    if (!await askYes(`Take a snapshot of ${p.dataset} now?${warn}`, 'Run now')) return
     setBusy('run')
-    try { const r = await api.runZfsSchedule(p.id); toast(`${r.taken}${r.pruned.length ? ` · ${r.pruned.length} expired removed` : ''}`); setExpired(null); onChanged() }
+    try { const r = await api.runZfsSchedule(p.id); toast(`${r.taken}${r.pruned.length ? ` · ${r.pruned.length} expired removed` : ''}`); onChanged() }
     catch (e) { toast(e instanceof Error ? e.message : 'failed', 'err') } finally { setBusy('') }
   }
   const remove = async () => {
@@ -165,20 +194,7 @@ function ScheduleCard({ p, cron, next, last, onChanged, onEdit }: { p: ZFSPolicy
         {p.keep_min > 0 && <div><span className="k">Floor</span><span>always keep the newest {p.keep_min}</span></div>}
       </div>
       {last.error && <div className="error" style={{ marginTop: 8 }}>{last.error}</div>}
-      {expired && (
-        <div className="notice" style={{ marginTop: 8 }}>
-          {expired.length === 0 ? 'Nothing has expired — a run now would only take a snapshot.' : (
-            <>
-              <b>{expired.length}</b> snapshot{expired.length === 1 ? '' : 's'} would be destroyed by a run now:
-              <div className="snap-list" style={{ marginTop: 6, maxHeight: 180, overflow: 'auto' }}>
-                {expired.map((s) => <div key={s.name} className="snap"><span className="mono">{s.name.split('@')[1]}</span><span className="num muted">{new Date(s.created).toLocaleDateString()} · {fmtBytes(s.used)}</span></div>)}
-              </div>
-            </>
-          )}
-        </div>
-      )}
       <div className="svc-actions">
-        <Btn className="btn" busy={busy === 'preview'} onClick={preview}>What would it delete?</Btn>
         <Btn className="btn on" busy={busy === 'run'} onClick={run}>Run now</Btn>
         <button className="btn" onClick={onEdit}>Edit</button>
         <Btn className="btn" onClick={toggle}>{p.enabled ? 'Pause' : 'Resume'}</Btn>
@@ -326,8 +342,14 @@ export default function ZFS() {
         <ScheduleCard key={policy.id} p={policy} cron={cron} next={next} last={last ?? {}} onChanged={load} onEdit={() => setEditing(policy)} />
       ))}</div>
 
-      <div className="dash-bar" style={{ marginTop: 12 }}><h2 className="section">Datasets</h2><span className="spacer" /><span className="muted small">used · referenced · in snapshots · count · compression · mount</span></div>
+      <div className="dash-bar" style={{ marginTop: 12 }}><h2 className="section">Snapshots</h2><span className="spacer" />
+        <span className="muted small">{zfs.datasets.reduce((a, d) => a + d.snapshots, 0)} across {zfs.datasets.length} datasets · open one to browse, take or delete</span>
+      </div>
       <section className="card ds-table">
+        <div className="ds-row head">
+          <span>Dataset</span><span className="num">Snapshots</span><span className="num">They use</span>
+          <span className="num">Dataset uses</span><span className="num">Referenced</span><span>Mount</span>
+        </div>
         {zfs.datasets.map((d) => <DatasetRow key={d.name} d={d} onChanged={load} />)}
       </section>
 

web/src/api.ts

@@ -187,7 +187,6 @@ export const api = {
   zfsOverview: () => req<ZFSOverview>('GET', '/api/zfs'),
   saveZfsSchedule: (p: Partial<ZFSPolicy>) => req<ZFSPolicy>('PUT', '/api/zfs/schedules', p),
   deleteZfsSchedule: (id: string) => req<void>('DELETE', `/api/zfs/schedules/${encodeURIComponent(id)}`),
-  zfsExpired: (id: string) => req<{ expired: ZFSSnapshot[] }>('GET', `/api/zfs/schedules/${encodeURIComponent(id)}/expired`),
   runZfsSchedule: (id: string) => req<{ taken: string; pruned: string[] }>('POST', `/api/zfs/schedules/${encodeURIComponent(id)}/run`),
   deleteZfsSnapshot: (name: string, recursive: boolean) => req<void>('POST', '/api/zfs/snapshots/delete', { name, confirm: name, recursive }),
   zfsSnapshots: (dataset: string) => req<ZFSSnapshot[]>('GET', `/api/storage/zfs/snapshots?dataset=${encodeURIComponent(dataset)}`),

web/src/styles.css

@@ -285,14 +285,21 @@ h2.section { margin: 0; font-size: 13px; font-weight: 600; color: var(--muted);
    the fallback above stays a fallback. */
 .disk-cards { grid-template-columns: repeat(auto-fill, minmax(min(420px, 100%), 1fr)); }
 .datasets { padding: 0; overflow-x: auto; }
-.ds-row { display: grid; grid-template-columns: minmax(160px, 1fr) 80px 80px 80px 50px 50px minmax(120px, 1fr); gap: 8px; align-items: center; padding: 6px 12px; border-bottom: 1px solid var(--border); font-size: 13px; min-width: 700px; } /* the columns and gaps add up to 692: at 640 the row ended before its own cells did */
+.ds-row { display: grid; grid-template-columns: minmax(160px, 1fr) 80px 90px 90px 90px minmax(120px, 1fr); gap: 8px; align-items: center; padding: 6px 12px; border-bottom: 1px solid var(--border); font-size: 13px; min-width: 700px; }
 .ds-row.head { color: var(--muted); font-size: 11px; text-transform: uppercase; letter-spacing: .5px; }
 .ds-row .num { text-align: right; }
 .ds-name { cursor: pointer; display: flex; align-items: center; gap: 6px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
 .ds-mount { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-family: ui-monospace, monospace; font-size: 12px; }
 .ds-snaps { padding: 8px 12px 10px 40px; border-bottom: 1px solid var(--border); background: var(--bg); display: flex; flex-direction: column; gap: 6px; }
 .snap-list { display: flex; flex-direction: column; gap: 2px; max-height: 40vh; overflow-y: auto; }
-.snap { display: flex; justify-content: space-between; gap: 12px; font-size: 12px; }
+.snap { display: grid; grid-template-columns: minmax(150px, 1fr) 150px 120px 70px auto; gap: 10px; align-items: center; font-size: 12px; padding: 2px 0; border-bottom: 1px solid var(--border); }
+.snap .snap-name { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+.snap .snap-when, .snap .snap-exp { white-space: nowrap; }
+.snap .snap-exp.warn { color: var(--s2); }
+.snap .num { text-align: right; }
+.snap .snap-del { padding: 0 6px; font-size: 11px; opacity: .55; }
+.snap:hover .snap-del { opacity: 1; }
+@media (max-width: 800px) { .snap { grid-template-columns: minmax(120px, 1fr) auto auto; } .snap .snap-when, .snap .snap-exp { display: none; } }
 
 /* files */
 .files { position: absolute; inset: 0; display: flex; flex-direction: column; background: var(--bg); }