swarm-ui: move agent creation into the agents page as a dialog

Adds a generic ui/dialog/Dialog primitive (native <dialog>, no
third-party modal lib and no shadow-DOM custom element per the esbuild
gap on those) and wires a "+ agent" button into AgentsPage that opens
the existing create-agent form inside it, content unchanged from its
former life as a standalone /create-agent route/nav item.

Removes the "new agent" top-level nav entry and the /create-agent
route entirely -- creation now only reachable from the roster that
gets populated by it. CreateAgentPage.tsx/css renamed to
CreateAgentForm.tsx/css to match its new role as a mounted component
rather than a page.

Screenshot-verified the dialog open/closed states against a mock
server.

frontend/packages/swarm-ui/src/App.tsx

@@ -4,7 +4,6 @@ import { Route, Switch } from 'wouter-preact';
 import { Shell } from './shell/Shell.js';
 import { AgentsPage } from './pages/AgentsPage.js';
 import { ComponentsPage } from './pages/ComponentsPage.js';
-import { CreateAgentPage } from './pages/CreateAgentPage.js';
 import { JobsPage } from './pages/JobsPage.js';
 import { HivesPage } from './pages/HivesPage.js';
 import { Panel } from './ui/panel/Panel.js';
@@ -23,7 +22,6 @@ export function App() {
       <Switch>
         <Route path="/" component={HivesPage} />
         <Route path="/agents" component={AgentsPage} />
-        <Route path="/create-agent" component={CreateAgentPage} />
         <Route path="/jobs" component={JobsPage} />
         <Route path="/components" component={ComponentsPage} />
         <Route component={NotFound} />

frontend/packages/swarm-ui/src/pages/AgentsPage.tsx

@@ -11,9 +11,18 @@
 // client-side into one row per agent rather than N per-agent config-PR
 // calls — exactly why the bulk endpoint exists instead of looping the
 // single-agent one.
+//
+// Owns the "+ agent" trigger too: creation used to be its own
+// `/create-agent` route + nav item, but the roster this populates is
+// the natural home for the action that populates it — a separate top-
+// level nav entry was one click of indirection for no benefit. The form
+// itself (`CreateAgentForm`) is unchanged from its page days, just
+// mounted inside a `Dialog` instead of a route.
 import { useState } from 'preact/hooks';
 import { ApiErrorPanel } from '@hive/shared/api-error-panel.js';
 import { readApiError, type ProblemDetails } from '@hive/shared/api-error.js';
+import { Button } from '../ui/button/Button.js';
+import { Dialog } from '../ui/dialog/Dialog.js';
 import { Panel } from '../ui/panel/Panel.js';
 import {
   RefreshIntervalPicker,
@@ -22,6 +31,7 @@ import {
 } from '../ui/refresh-interval/RefreshInterval.js';
 import { StatusChip } from '../ui/status-chip/StatusChip.js';
 import { Table, type TableColumn } from '../ui/table/Table.js';
+import { CreateAgentForm } from './CreateAgentForm.js';
 
 interface ConfigPrStatus {
   pr_number: number;
@@ -67,6 +77,7 @@ export function AgentsPage() {
   const [rows, setRows] = useState<AgentRow[] | null>(null);
   const [error, setError] = useState<ProblemDetails | null>(null);
   const [intervalMs, setIntervalMs] = useState<RefreshIntervalMs>(DEFAULT_INTERVAL_MS);
+  const [createOpen, setCreateOpen] = useState(false);
 
   useRefreshInterval(intervalMs, () => {
     (async () => {
@@ -93,11 +104,21 @@ export function AgentsPage() {
     <Panel
       title="agents"
       icon="👥"
-      actions={<RefreshIntervalPicker id="agents-refresh" value={intervalMs} onChange={setIntervalMs} />}
+      actions={
+        <>
+          <Button variant="primary" onClick={() => setCreateOpen(true)}>
+            + agent
+          </Button>
+          <RefreshIntervalPicker id="agents-refresh" value={intervalMs} onChange={setIntervalMs} />
+        </>
+      }
     >
       {error ? <ApiErrorPanel context="failed to load the agent roster" problem={error} /> : null}
       {!error && rows === null ? <p>loading…</p> : null}
       {rows ? <Table columns={COLUMNS} rows={rows} rowKey={(a) => a.name} /> : null}
+      <Dialog open={createOpen} onClose={() => setCreateOpen(false)} label="create agent">
+        <CreateAgentForm />
+      </Dialog>
     </Panel>
   );
 }

frontend/packages/swarm-ui/src/pages/CreateAgentForm.css

@@ -1,6 +1,8 @@
-/* <CreateAgentPage> — the create-agent form. Input/button chrome now
-   comes from the shared `ui/` form kit (`TextField`/`SelectField`/
-   `Button`); this file only owns the page's own layout + copy. Column,
+/* <CreateAgentForm> — the create-agent form, rendered inside a `Dialog`
+   from `AgentsPage` (see that component's file-top comment for why).
+   Input/button chrome comes from the shared `ui/` form kit
+   (`TextField`/`SelectField`/`Button`); this file only owns this
+   component's own layout + copy. Column,
    not row inside the form itself: with a second field (hive) added, a
    row layout put fields of different natural widths on one baseline and
    looked misaligned — mara: "make it a col". Reuses the same base16

frontend/packages/swarm-ui/src/pages/CreateAgentForm.tsx

@@ -1,20 +1,19 @@
-// <CreateAgentPage> — minimal agent creation form, POSTs to
+// <CreateAgentForm> — minimal agent creation form, POSTs to
 // swarm-controller's `POST /api/agents`. That endpoint only queues a
 // `CreateIdentity` job and returns its node id — the identity isn't
-// guaranteed to exist yet when this page gets a response — so this
-// page shows the queued confirmation and links to the Jobs page to
-// watch it settle, rather than duplicating JobqGraph's per-node
-// polling here. Scope matches the originating issue exactly: name
-// field only, no forge/deploy options (those aren't wired server-side
-// yet either).
+// guaranteed to exist yet when this gets a response — so this shows
+// the queued confirmation and links to the Jobs page to watch it
+// settle, rather than duplicating JobqGraph's per-node polling here.
+// Scope matches the originating issue exactly: name field only, no
+// forge/deploy options (those aren't wired server-side yet either).
 //
-// Lives at `/create-agent`, not `/agents` — a future agent *roster*
-// (listing existing agents) is the natural owner of the bare `/agents`
-// path, and this creation form is a distinct action from that list,
-// not a variant of it. Flat, not `/agents/new`: `index.html`'s asset
-// links are relative (`static/main.js`), which only resolve correctly
-// one path segment deep — a real bug, filed separately rather than
-// fixed here, but reason enough to avoid a nested route today.
+// Rendered inside a `Dialog` from `AgentsPage`'s own "+ agent" button,
+// not a standalone route — the roster it feeds is the natural home for
+// the action that populates it, and a distinct top-level nav item next
+// to it was one click of indirection for no benefit. Kept as its own
+// component (not inlined into AgentsPage) since the two-panel layout
+// below is unchanged from its former life as a page: same content, same
+// review history, just a different mount point.
 //
 // `hive` field added because agent creation had no way to record which
 // hive an agent runs on. `POST /api/agents` now requires it, so the
@@ -34,7 +33,7 @@ import { Panel } from '../ui/panel/Panel.js';
 import { TextField } from '../ui/text-field/TextField.js';
 import { SelectField, type SelectOption } from '../ui/select-field/SelectField.js';
 import { Button } from '../ui/button/Button.js';
-import './CreateAgentPage.css';
+import './CreateAgentForm.css';
 
 // Mirrors swarm-controller's `HiveEntry` — same shape `HivesPage`
 // consumes off `/api/hives/status`, but this page hits the plain
@@ -70,7 +69,7 @@ type SubmitState =
 // exception report on this page.
 const NAME_PATTERN = '[a-z0-9\\-]{1,63}';
 
-export function CreateAgentPage() {
+export function CreateAgentForm() {
   const [name, setName] = useState('');
   const [hive, setHive] = useState('');
   // `null` = still loading, `[]` = loaded but empty (a real, if unusual,

frontend/packages/swarm-ui/src/shell/Shell.tsx

@@ -39,7 +39,6 @@ import './Shell.css';
 const NAV_ITEMS: { href: string; label: string; accent: string }[] = [
   { href: '/', label: 'hives', accent: 'var(--purple)' },
   { href: '/agents', label: 'agents', accent: 'var(--green)' },
-  { href: '/create-agent', label: 'new agent', accent: 'var(--cyan)' },
   { href: '/jobs', label: 'jobs', accent: 'var(--pink)' },
   { href: '/components', label: 'components', accent: 'var(--blue)' },
 ];

frontend/packages/swarm-ui/src/ui/dialog/Dialog.css

@@ -0,0 +1,47 @@
+/* <Dialog> — native `<dialog>` styling. Sized to comfortably hold the
+   create-agent form's own two-panel layout (which wraps to single-
+   column below its existing 16em-per-column threshold — see
+   CreateAgentForm.css — so this doesn't need to special-case that). */
+.ui-dialog {
+  position: relative;
+  width: 90vw;
+  max-width: 44em;
+  max-height: 85vh;
+  overflow: auto;
+  padding: 1.5em;
+  border: 1px solid var(--border);
+  border-radius: 0.6em;
+  background: var(--bg-elev);
+  color: var(--fg);
+}
+.ui-dialog::backdrop {
+  background: rgba(0, 0, 0, 0.5);
+}
+.ui-dialog-close {
+  position: absolute;
+  top: 0.75em;
+  right: 0.75em;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 2.2em;
+  height: 2.2em;
+  border: 1px solid transparent;
+  border-radius: 0.4em;
+  background: none;
+  color: var(--fg);
+  font-size: 1em;
+  line-height: 1;
+  cursor: pointer;
+}
+.ui-dialog-close:hover {
+  border-color: var(--border);
+  background: var(--bg);
+}
+.ui-dialog-body {
+  /* Clears the close button's own box (0.75em inset + 2.2em size) with
+     room to spare — verified against a real screenshot; a smaller value
+     let wide content (e.g. the create-agent form's two-panel layout)
+     render directly under the button instead of beside it. */
+  padding-right: 3.25em;
+}

frontend/packages/swarm-ui/src/ui/dialog/Dialog.tsx

@@ -0,0 +1,76 @@
+// <Dialog> — a generic modal overlay, native `<dialog>` element rather
+// than a hand-rolled focus-trap + backdrop: `showModal()` gives focus
+// trapping, Escape-to-close, and a real `::backdrop` for free, and
+// `@hive/shared`'s own shadow-DOM `hive-dialog` custom element isn't an
+// option here — swarm-ui's esbuild config can't consume those custom
+// elements at all (a separate, already-tracked gap).
+// No opinion on content beyond a close button; the caller's own markup
+// supplies whatever heading/layout it needs (its first real caller,
+// the create-agent form, already has an established two-panel layout
+// from its former life as a standalone route — reusing that unchanged
+// is simpler and lower-risk than re-deriving a modal-specific layout
+// for content mara has already reviewed).
+import { useEffect, useRef } from 'preact/hooks';
+import type { ComponentChildren } from 'preact';
+import './Dialog.css';
+
+export function Dialog({
+  open,
+  onClose,
+  label,
+  children,
+}: {
+  open: boolean;
+  onClose: () => void;
+  // `aria-label` only, no visible title row — see file-top comment on
+  // why content owns its own heading.
+  label: string;
+  children: ComponentChildren;
+}) {
+  const ref = useRef<HTMLDialogElement>(null);
+
+  // Drives the native open/closed state from the `open` prop rather
+  // than mounting/unmounting the element — `showModal()`/`close()` are
+  // imperative, there's no declarative `<dialog open>` equivalent that
+  // also gets you the backdrop + focus trap.
+  useEffect(() => {
+    const el = ref.current;
+    if (!el) return;
+    if (open && !el.open) el.showModal();
+    else if (!open && el.open) el.close();
+  }, [open]);
+
+  // The dialog's own `close` event fires on Escape (and would fire on
+  // a native <form method="dialog"> submit, unused here) — syncing it
+  // back to the caller's state keeps `open` truthful even when nothing
+  // in this component's own JS drove the close.
+  useEffect(() => {
+    const el = ref.current;
+    if (!el) return;
+    function handleClose() {
+      onClose();
+    }
+    el.addEventListener('close', handleClose);
+    return () => el.removeEventListener('close', handleClose);
+  }, [onClose]);
+
+  return (
+    <dialog
+      ref={ref}
+      class="ui-dialog"
+      aria-label={label}
+      // A click lands on the `<dialog>` element itself (not any child)
+      // exactly when it's outside the rendered content box — inside
+      // the box, the click target is always some descendant. Standard
+      // "click the backdrop to close" trick for native `<dialog>`.
+      onClick={(e) => {
+        if (e.target === ref.current) onClose();
+      }}
+    >
+      <button type="button" class="ui-dialog-close" aria-label="close" onClick={onClose}>
+        ✕
+      </button>
+      <div class="ui-dialog-body">{children}</div>
+    </dialog>
+  );
+}