refactor(client): isolate trajectory history

packages/client/ui-conversation/src/client/apply.ts

@@ -83,8 +83,8 @@ export function apply(ctx: Context): void {
     },
   }), 'ui-conversation: input standard-kit provider')
 
-  // Resident current-session-optional shell. It constructs the stable
-  // composer frame; the strict session child decides whether Chat mounts it.
+  // Resident current-session-optional shell. It owns the stable Hero/composer
+  // frame while strict session slots fill only their session-bound regions.
   slots.register({
     name: 'conversation',
     children: {
@@ -114,8 +114,8 @@ export function apply(ctx: Context): void {
     }),
   }, ConversationRoot)
 
-  // The strict session subtree owns the per-session store and view content;
-  // the resident parent supplies the composer node through owner props.
+  // The strict session subtree owns only per-session store and view content;
+  // the resident parent keeps Hero and composer layout identity stable.
   slots.register({
     name: 'conversation.session',
     children: { 'conversation.view': { kind: 'list', scope: 'session' } },

packages/client/ui-conversation/src/client/contract/slots.ts

@@ -19,7 +19,7 @@ declare module '@deepseek-ai/dsh-client-ui-slots' {
     'conversation.session': { kind: 'single'; scope: 'session'; owner: ConversationSessionOwnerProps }
     /**
      * The conversation view ring: one list entry per view tab (chat here;
-     * Trajectory from ui-trajectory), rendered one-at-a-time by
+     * trajectory/waterfall from ui-trajectory), rendered one-at-a-time by
      * ConversationRoot via `only: <active id>`. Declared by this package's
      * 'conversation' entry (declaring is claiming). Session scope: views read
      * the conversation snapshot through the standard kit.
@@ -117,8 +117,6 @@ declare module '@deepseek-ai/dsh-client-ui-slots' {
 
 /** Owner share of the strict session content seat. */
 export interface ConversationSessionOwnerProps {
-  /** Composer chain assembled by the resident parent; only Chat mounts it. */
-  composer: ReactNode
 }
 
 /**
@@ -143,7 +141,7 @@ export interface ConvViewOwnerProps {}
 
 /**
  * Owner share of a per-view toolview slot: the call material the rendering
- * view supplies per row. Uniform across views — the Trajectory
+ * view supplies per row. Uniform across views — the trajectory/waterfall
  * toolview slots (same kind/scope/owner, names fixed by the slot-naming
  * discipline) land with their own row render sites; today only the chat slot
  * is declared (RendersCheck rejects a declaration nobody renders).

packages/client/ui-conversation/src/client/skeleton/ConversationRoot.tsx

@@ -118,11 +118,6 @@ export function ConversationRoot({
       {inputBar}
     </div>
   )
-  const composer = renderSlotChain(
-    'conversation.composer',
-    { interactions: pending },
-    { fallback: composerBar, overlay: true },
-  )
 
   return (
     <div className={css.root} data-phase={settling ? 'settling' : hero ? 'hero' : 'active'}>
@@ -130,9 +125,12 @@ export function ConversationRoot({
           renders no chrome while blank but owns the draft-persistence mirror
           bind — unmounting it in the hero would lose pre-first-send text on
           a refresh or scope rebuild. */}
-      {sessionId !== undefined
-        ? renderSlot('conversation.session', { composer })
-        : composer}
+      {sessionId !== undefined && renderSlot('conversation.session', {})}
+      {renderSlotChain(
+        'conversation.composer',
+        { interactions: pending },
+        { fallback: composerBar, overlay: true },
+      )}
     </div>
   )
 }

packages/client/ui-conversation/src/client/skeleton/ConversationSession.tsx

@@ -1,6 +1,6 @@
 /** Strict per-session conversation content: header, view ring, and chat store bindings. */
 
-import { Fragment, useEffect, useSyncExternalStore } from 'react'
+import { useEffect, useSyncExternalStore } from 'react'
 import clsx from 'clsx'
 import { shallowEqual } from '@deepseek-ai/dsh-client-runtime/client'
 import type { SessionId, SessionListState, SessionSummary } from '@deepseek-ai/dsh-client-runtime/client'
@@ -24,7 +24,7 @@ function deriveAncestry(list: SessionListState, id: SessionId): readonly Session
 
 export function ConversationSession({
   sessionId, useSession, useSessions, useInput, inputActions, useStore, actions,
-  renderSlot, views, bindDraftMirror, open, composer,
+  renderSlot, views, bindDraftMirror, open,
 }: ConversationSessionProps) {
   useSyncExternalStore(views.subscribe, views.version)
   const tabs = views.list()
@@ -32,7 +32,6 @@ export function ConversationSession({
   const active = tabs.find(view => view.id === activeId) ?? tabs[0]
   const ancestry = useSessions(s => deriveAncestry(s, sessionId), shallowEqual)
   const composerPhase = useSession(s => s.composerPhase)
-  const hasPending = useSession(s => s.pending.length > 0)
   const blank = useSession(s => s.blank)
   const inputState = useInput(s => s)
   const storedDraft = useStore(s => s.draft)
@@ -45,11 +44,11 @@ export function ConversationSession({
     // the machine mirror, not this seed effect.
   }, [inputActions])
 
-  const blankHero = blank && composerPhase === 'blank'
+  if (blank && composerPhase === 'blank') return null
 
   return (
     <>
-      {!blankHero && <header className={css.header}>
+      <header className={css.header}>
         <div className={css.crumbRow}>
           <nav className={css.crumbs} aria-label="Session hierarchy">
             {ancestry.map((summary, index) => {
@@ -87,13 +86,10 @@ export function ConversationSession({
             ))}
           </div>
         )}
-      </header>}
-      {!blankHero && <div className={css.viewArea}>
+      </header>
+      <div className={css.viewArea}>
         {active !== undefined && renderSlot('conversation.view', {}, { only: active.id })}
-      </div>}
-      {(blankHero || active?.id === 'chat' || hasPending) && (
-        <Fragment key="composer">{composer}</Fragment>
-      )}
+      </div>
     </>
   )
 }

packages/client/ui-conversation/tests/apply-inject.spec.tsx

@@ -34,7 +34,6 @@ function sessionFakeFor() {
   return {
     open: vi.fn(() => Promise.resolve()),
     loadOlder: vi.fn<ISession['loadOlder']>(() => Promise.resolve()),
-    loadAllHistory: vi.fn<ISession['loadAllHistory']>(() => Promise.resolve()),
     prompt: vi.fn<ISession['prompt']>(() => Promise.resolve({ ok: true, value: { accepted: true } })),
     cancel: vi.fn<ISession['cancel']>(() => Promise.resolve({ ok: true, value: { accepted: true } })),
   } satisfies SessionBehaviorOverrides

packages/client/ui-conversation/tests/chat-toolview-slot.spec.tsx

@@ -59,7 +59,6 @@ async function bench(nodes: ToolResultNode[]) {
     snapshot: { nodes },
     session: {
       loadOlder: vi.fn<ISession['loadOlder']>(),
-      loadAllHistory: vi.fn<ISession['loadAllHistory']>(),
       prompt: vi.fn<ISession['prompt']>(async () => ({ ok: true, value: { accepted: true } })),
     },
   })

packages/client/ui-conversation/tests/skeleton.spec.tsx

@@ -18,7 +18,7 @@ import { ConversationSession } from '../src/client/skeleton/ConversationSession.
 import { InputBar } from '../src/client/skeleton/InputBar.tsx'
 import type { InputBarProps } from '../src/client/skeleton/InputBar.tsx'
 import type {
-  ComposerBarOwnerProps, ConversationSessionOwnerProps,
+  ComposerBarOwnerProps,
 } from '../src/client/contract/slots.ts'
 
 /** Machine-backed wiring over a sink spy. */
@@ -88,10 +88,8 @@ function mount(
     slotCalls.push(key)
     if (key === 'conversation.hero.workspace') { pickerOwner = owner; return null }
     if (key === 'conversation.session') {
-      const sessionOwner = owner as ConversationSessionOwnerProps
       return (
         <ConversationSession
-          composer={sessionOwner.composer}
           sessionId={SID}
           SessionProvider={({ children }) => children(SID)}
           useSession={useSession}