fix(ui): module page as master→detail screen (clear which module you're in)

Selecting a module used to dump a stack of panels below the list with no indication of
which module — confusing (founder feedback on 'Fields — Mobile App'). Now clicking a
module opens its OWN screen: a breadcrumb + big header naming the module (name · code ·
SAC · kinds), a Back button, then clearly-labelled sections — Details (editable),
Clients on this module, Fields (plain-language: 'the details you record for each client
on this module'), Quote content, Price book. The list hides while you're in a module.
Row action is now 'Open →'. typecheck + build clean.

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

apps/hq-web/src/pages/Modules.tsx

@@ -26,9 +26,10 @@ export function Modules() {
   const isOwner = role() === 'owner'
   const modules = useData(getModules, [])
   const [creating, setCreating] = useState(false)
-  const [selected, setSelected] = useState<Module | undefined>()
-  const [editingId, setEditingId] = useState<string | undefined>() // inline "Edit module" form
-  const editingModule = modules.data?.find((m) => m.id === editingId)
+  // Master → detail: selecting a module opens its own screen (derive from fresh data so the
+  // header + fields reflect edits immediately after a reload).
+  const [selectedId, setSelectedId] = useState<string | undefined>()
+  const selected = modules.data?.find((m) => m.id === selectedId)
   // How many clients sit on each module — one lightweight roster count per module,
   // best-effort so a slow/failed one never blocks the table (cell shows '…' until then).
   const [clientCounts, setClientCounts] = useState<Record<string, number>>({})
@@ -44,11 +45,34 @@ export function Modules() {
     return () => { live = false }
   }, [modules.data])
 
+  // --- Detail screen: one module at a time, clearly headed, with a Back button. ---
+  if (selected !== undefined) {
+    return (
+      <div className="wf-page">
+        <div className="wf-crumbs">
+          <button type="button" className="wf" style={{ border: 'none', background: 'none', cursor: 'pointer', padding: 0 }}
+            onClick={() => setSelectedId(undefined)}>← All modules</button>
+          <span>/</span><span className="mono">{selected.code}</span>
+        </div>
+        <PageHeader
+          title={`${selected.name}  ·  ${selected.code}`}
+          desc={`SAC ${selected.sac} · ${selected.allowedKinds.map((k) => KIND_LABEL[k]).join(' · ')} · ${selected.active ? 'active' : 'inactive'}`}
+          actions={<Button onClick={() => setSelectedId(undefined)}>← Back to all modules</Button>}
+        />
+        <ModuleDetails key={`md-${selected.id}`} module={selected} isOwner={isOwner} onSaved={() => modules.reload()} />
+        <ModuleClients key={`mc-${selected.id}`} module={selected} />
+        <FieldSpecEditor key={`fs-${selected.id}`} module={selected} isOwner={isOwner} onSaved={() => modules.reload()} />
+        <QuoteContent key={selected.id} module={selected} isOwner={isOwner} onSaved={() => modules.reload()} />
+        <PriceBook module={selected} isOwner={isOwner} />
+      </div>
+    )
+  }
+
   return (
     <div className="wf-page">
       <PageHeader
         title="Modules"
-        desc="What we sell — each with a dated price book. Use Edit to change a module's details; click a row to see its clients, fields, quote content and prices."
+        desc="What we sell — each with a dated price book. Click a module to open it: its clients, install details, fields, quote content and prices."
         actions={isOwner
           ? <Button tone="primary" onClick={() => setCreating(true)}>New module</Button>
           : <Badge>read-only (staff)</Badge>}
@@ -64,31 +88,17 @@ export function Modules() {
             { key: 'multi', label: 'Multi-sub' }, { key: 'active', label: 'Active' },
             { key: 'act', label: '' },
           ]}
-          onRowClick={(_row, i) => setSelected(modules.data![i])}
+          onRowClick={(_row, i) => setSelectedId(modules.data![i]!.id)}
           rows={modules.data.map((m) => ({
             code: m.code, name: m.name, sac: m.sac,
             clients: clientCounts[m.id] !== undefined ? clientCounts[m.id] : '…',
             kinds: m.allowedKinds.map((k) => KIND_LABEL[k]).join(' · '),
             multi: m.multiSubscription ? <Badge tone="accent">yes</Badge> : '—',
             active: m.active ? <Badge tone="ok">active</Badge> : <Badge>inactive</Badge>,
-            act: isOwner
-              ? <span onClick={(e) => e.stopPropagation()}><Button onClick={() => setEditingId(m.id)}>Edit</Button></span>
-              : null,
+            act: <span onClick={(e) => e.stopPropagation()}><Button onClick={() => setSelectedId(m.id)}>Open →</Button></span>,
           }))}
         />
       )}
-      {editingModule !== undefined && (
-        <ModuleDetails key={`md-${editingModule.id}`} module={editingModule} isOwner={isOwner}
-          onSaved={() => modules.reload()} onClose={() => setEditingId(undefined)} />
-      )}
-      {selected !== undefined && (
-        <>
-          <ModuleClients key={`mc-${selected.id}`} module={selected} />
-          <QuoteContent key={selected.id} module={selected} isOwner={isOwner} onSaved={() => modules.reload()} />
-          <FieldSpecEditor key={`fs-${selected.id}`} module={selected} isOwner={isOwner} onSaved={() => modules.reload()} />
-          <PriceBook module={selected} isOwner={isOwner} />
-        </>
-      )}
       {isOwner && (
         <NewModuleDialog
           open={creating}
@@ -328,7 +338,7 @@ function ModuleClients(props: { module: Module }) {
 /** Edit a module's core details (owner only): name, SAC, billing kinds, multi-sub, active.
  *  Code is the identity and is not editable. Field-spec / quote-content / prices have their
  *  own panels below. */
-function ModuleDetails(props: { module: Module; isOwner: boolean; onSaved: () => void; onClose: () => void }) {
+function ModuleDetails(props: { module: Module; isOwner: boolean; onSaved: () => void; onClose?: () => void }) {
   const toast = useToast()
   const m = props.module
   const [name, setName] = useState(m.name)
@@ -348,7 +358,7 @@ function ModuleDetails(props: { module: Module; isOwner: boolean; onSaved: () =>
     if (kinds.length === 0) { setError('Pick at least one billing kind'); return }
     setError(undefined); setBusy(true)
     patchModule(m.id, { name: name.trim(), sac: sac.trim(), allowedKinds: kinds, multiSubscription: multi, active })
-      .then(() => { toast.ok('Module saved'); props.onSaved(); props.onClose() })
+      .then(() => { toast.ok('Module saved'); props.onSaved() })
       .catch((e: Error) => setError(e.message))
       .finally(() => setBusy(false))
   }
@@ -356,7 +366,7 @@ function ModuleDetails(props: { module: Module; isOwner: boolean; onSaved: () =>
   if (!props.isOwner) return null
   return (
     <>
-      <h3 style={{ marginTop: 20 }}>Edit module — <span className="mono">{m.code}</span></h3>
+      <h3 style={{ marginTop: 20 }}>Details</h3>
       <div className="wf-card" style={{ padding: 14 }}>
         <div style={{ display: 'flex', gap: 14, flexWrap: 'wrap', alignItems: 'flex-end' }}>
           <Field label="Name"><input className="wf" style={{ width: 260 }} value={name} onChange={(e) => setName(e.target.value)} /></Field>
@@ -378,7 +388,7 @@ function ModuleDetails(props: { module: Module; isOwner: boolean; onSaved: () =>
         </div>
         <Toolbar>
           <Button tone="primary" disabled={busy} onClick={save}>{busy ? 'Saving…' : 'Save module'}</Button>
-          <Button onClick={props.onClose}>Cancel</Button>
+          {props.onClose !== undefined && <Button onClick={props.onClose}>Cancel</Button>}
         </Toolbar>
         {error !== undefined && <Notice tone="err">{error}</Notice>}
       </div>
@@ -402,7 +412,7 @@ function QuoteContent(props: { module: Module; isOwner: boolean; onSaved: () =>
 
   return (
     <>
-      <h3 style={{ marginTop: 20 }}>Quote content — {props.module.name}</h3>
+      <h3 style={{ marginTop: 20 }}>Quote content <span style={{ fontWeight: 400, fontSize: 13, opacity: 0.65 }}>— the “what’s included” lines printed on quotes</span></h3>
       {props.isOwner ? (
         <div style={{ display: 'flex', gap: 16, alignItems: 'flex-start', flexWrap: 'wrap' }}>
           <div style={{ flex: '0 0 560px', minWidth: 0 }}>
@@ -483,7 +493,7 @@ function FieldSpecEditor(props: { module: Module; isOwner: boolean; onSaved: ()
 
   return (
     <>
-      <h3 style={{ marginTop: 20 }}>Fields — {props.module.name}</h3>
+      <h3 style={{ marginTop: 20 }}>Fields <span style={{ fontWeight: 400, fontSize: 13, opacity: 0.65 }}>— the details you record for each client on this module</span></h3>
       {!props.isOwner ? (
         props.module.fieldSpec.length === 0 ? <EmptyState>No fields defined.</EmptyState> : (
           <DataTable