Merge branch 'worktree/web-carrier-chain' into worktree/web-ask-user-question

packages/client/connection/src/client/fixture.ts

@@ -24,6 +24,28 @@ function text(t: string): ContentBlock[] {
   return [{ type: 'text', text: t }]
 }
 
+const MARKDOWN_FIXTURE = [
+  '# Markdown fixture',
+  '',
+  'Assistant output renders **strong text**, *emphasis*, and `inline code`.',
+  '',
+  '- first item',
+  '  - nested item',
+  '',
+  '| Surface | State |',
+  '| --- | --- |',
+  '| history | rendered |',
+  '| streaming | stable |',
+  '',
+  '[DeepSeek](https://www.deepseek.com)',
+  '',
+  '```ts',
+  'const markdown = true',
+  '```',
+].join('\n')
+
+const USER_MARKDOWN_LITERAL = '用户字面量：# 不渲染 `code` [link](https://example.com)'
+
 function sid(id: string): SessionId {
   return id as SessionId
 }
@@ -40,7 +62,13 @@ function buildAlphaLog(): SessionEvent[] {
   }
   for (let turn = 0; turn < 60; turn++) {
     push({ type: 'turn/start', data: { turn, trigger: { kind: 'message', source: { kind: 'user' } } } })
-    push({ type: 'user/message', surfaceOp: 'append', data: { content: text(`问题 ${turn}：fixture 历史消息，用于翻页与渲染验收。`), source: { kind: 'user' } } })
+    push({
+      type: 'user/message', surfaceOp: 'append',
+      data: {
+        content: text(turn === 59 ? USER_MARKDOWN_LITERAL : `问题 ${turn}：fixture 历史消息，用于翻页与渲染验收。`),
+        source: { kind: 'user' },
+      },
+    })
     if (turn % 9 === 4) {
       push({ type: 'context/message', surfaceOp: 'append', data: { content: text(`[fixture] 上下文注入（turn ${turn}）`), source: { kind: 'plugin', plugin: 'fixture' } } })
     }
@@ -49,7 +77,7 @@ function buildAlphaLog(): SessionEvent[] {
     const withReasoning = turn % 3 === 1
     const blocks: ContentBlock[] = []
     if (withReasoning) blocks.push({ type: 'reasoning', text: `思考过程 ${turn}：这是一段可折叠的 reasoning 内容。` })
-    blocks.push({ type: 'text', text: `回答 ${turn}：这是 fixture 生成的历史回复正文。` })
+    blocks.push({ type: 'text', text: turn === 59 ? MARKDOWN_FIXTURE : `回答 ${turn}：这是 fixture 生成的历史回复正文。` })
     if (withTool) {
       const callId = `fx-call-${turn}`
       blocks.push({ type: 'tool-call', id: callId, name: 'echo', arguments: `{"text":"turn ${turn}"}` } as ContentBlock)
@@ -377,8 +405,8 @@ export function createFixtureApi(): ApiProxy {
     const step = 0
     append(id, { type: 'step/start', data: { turn, step } })
     append(id, { type: 'assistant/chunk', data: { turn, step, chunk: { type: 'block-start', index: 0, blockType: 'text' } } })
-    /* v8 ignore next -- the ?? arm needs a null match, but replyText is never empty (prompt always prefixes 回声). */
-    const pieces = replyText.match(/.{1,6}/gu) ?? [replyText]
+    /* v8 ignore next -- the ?? arm needs a null match, but every fixture reply is non-empty. */
+    const pieces = replyText.match(/[\s\S]{1,6}/gu) ?? [replyText]
     let i = 0
     const finish = (aborted: boolean): void => {
       replays.delete(id)
@@ -444,7 +472,13 @@ export function createFixtureApi(): ApiProxy {
         setRunning(id, true)
         append(id, { type: 'turn/start', data: { turn, trigger: { kind: 'message', source: { kind: 'user' } } } })
         append(id, { type: 'user/message', surfaceOp: 'append', data: { content, source: { kind: 'user' } } })
-        startReply(id, turn, `回声：${userText}。这是 fixture 的流式回复，用于验证打字机增长与定稿切换。`)
+        startReply(
+          id,
+          turn,
+          userText === 'render markdown'
+            ? MARKDOWN_FIXTURE
+            : `回声：${userText}。这是 fixture 的流式回复，用于验证打字机增长与定稿切换。`,
+        )
         return ok(request, { accepted: true as const })
       },
       cancel: (request) => {

packages/client/connection/tests/fixture.spec.ts

@@ -113,7 +113,7 @@ describe('createFixtureApi', () => {
     const missing = await api.sessions.prompt(req({ sessionId: sid('ghost'), mode: 'queue' as const, content: [{ type: 'text' as const, text: 'x' }] }))
     expect(missing.result).toMatchObject({ ok: false, error: { code: 'session-not-found', details: { sessionId: 'ghost' } } })
     // Real prompt: replay starts (running flips true), cancel freezes it.
-    const accepted = await api.sessions.prompt(req({ sessionId: id, mode: 'queue' as const, content: [{ type: 'text' as const, text: '取消我' }] }))
+    const accepted = await api.sessions.prompt(req({ sessionId: id, mode: 'queue' as const, content: [{ type: 'text' as const, text: 'render markdown' }] }))
     expect(accepted.result).toMatchObject({ ok: true, value: { accepted: true } })
     await new Promise(resolve => setTimeout(resolve, 120)) // a couple of typewriter ticks
     await api.sessions.cancel(req({ sessionId: id }))

packages/client/ui-conversation/src/client/chat/AssistantMarkdown.tsx

@@ -7,7 +7,7 @@
 
 import { memo } from 'react'
 import type { AssistantBlock } from '@deepseek-ai/dsh-client-runtime/client'
-import { IconThinkOutline14, JsonBlock, MessageText } from '@deepseek-ai/dsh-client-ui-primitives'
+import { IconThinkOutline14, JsonBlock, MarkdownText } from '@deepseek-ai/dsh-client-ui-primitives'
 import { ToolRow } from './ToolRow.tsx'
 import css from './AssistantMarkdown.module.css'
 
@@ -44,7 +44,7 @@ export const AssistantMarkdown = memo(function AssistantMarkdown({ blocks, strea
     <div className={css.root} data-streaming={streaming || undefined}>
       {blocks.map((block, i) => {
         switch (block.kind) {
-          case 'text': return <MessageText key={i} text={block.text} />
+          case 'text': return <MarkdownText key={i} text={block.text} />
           case 'reasoning': return <ThinkRow key={i} text={block.text} running={streaming && i === last} />
           // Tool-call heads render as tool rows in the chat view's grouping pass.
           case 'tool-call': return null

packages/client/ui-conversation/tests/chat-view.spec.tsx

@@ -158,6 +158,44 @@ describe('ChatView', () => {
     expect(view.getByText('run a')).toBeTruthy()
   })
 
+  it('renders assistant Markdown across history, streaming, final, and interrupted states while user text stays literal', () => {
+    const markdown = '# Rendered\n\n- **one**\n- `two`'
+    const h = makeHarness({ nodes: [user(1, markdown), assistant(2, markdown)] })
+    const view = render(<h.ChatView {...h.props} />)
+    expect(view.container.querySelectorAll('h1')).toHaveLength(1)
+    const literal = view.getByText((_content, element) => (
+      element?.tagName === 'DIV' && element.childElementCount === 0 && element.textContent === markdown
+    ))
+    expect(literal.querySelector('h1')).toBeNull()
+
+    act(() => {
+      h.set({ partial: { turn: 2, step: 1, blocks: [{ kind: 'text', text: markdown }] } })
+    })
+    expect(view.container.querySelectorAll('h1')).toHaveLength(2)
+    expect(view.container.querySelector('[data-streaming="true"] h1')?.textContent).toBe('Rendered')
+
+    act(() => {
+      h.set({
+        nodes: [user(1, markdown), assistant(2, markdown), assistant(3, markdown)],
+        partial: null,
+      })
+    })
+    expect(view.container.querySelectorAll('h1')).toHaveLength(2)
+    expect(view.container.querySelector('[data-streaming="true"]')).toBeNull()
+
+    act(() => {
+      h.set({
+        nodes: [
+          user(1, markdown),
+          assistant(2, markdown),
+          { ...assistant(3, markdown), interrupted: true },
+        ],
+      })
+    })
+    expect(view.getByText('已停止')).toBeTruthy()
+    expect(view.container.querySelectorAll('h1')).toHaveLength(2)
+  })
+
   it('streaming partial frames re-render only the tail (Profiler count)', () => {
     const h = makeHarness({
       nodes: [user(1, 'q'), assistant(2, 'old answer'), toolResult(3, 'a')],

packages/client/ui-primitives/README.md

@@ -1,6 +1,10 @@
 # @deepseek-ai/dsh-client-ui-primitives
 
-Pure React atoms (zero cordis): StateDot, ic_ds_* icons, Button/Pill/Menu/Input, markdown family (MessageText/JsonBlock). Contract: api-contracts v3 §8.
+Pure React atoms (zero cordis): StateDot, ic_ds_* icons, Button/Pill/Menu/Input, markdown family (MessageText/MarkdownText/JsonBlock). Contract: api-contracts v3 §8.
+
+## Markdown rendering
+
+`MarkdownText` renders GFM from untrusted assistant output through React elements. It omits raw HTML, neutralizes relative and non-HTTP(S)/mailto links, opens HTTP(S) links with safe external-link attributes, and renders image alt text without loading remote resources; `MessageText` remains the literal-text primitive for user-authored content.
 
 ## Model Experience
 
@@ -15,4 +19,3 @@ None; this package neither assembles nor sends a provider request.
 - **Glyph-level icons are redrawn approximations** — the fish logo (and the sparkle held by ui-conversation) come from font glyphs whose vector geometry is not exportable from the local design data; hand-authored recreations stand in until an exact export path exists.
 - **Pill and Input have no design source** — both atoms are self-defined; the sidebar search field and view-tab strip that resemble them are consumer-owned compositions, not these atoms.
 - **StateDot `Active` variant is a hidden placeholder in the design** — not implemented; the four shipped states (done/warning/ongoing/error) are the complete P-I surface.
-- **MessageText renders plain text** — markdown support swaps this component's internals later; consumers must not assume block structure.

packages/client/ui-primitives/package.json

@@ -21,7 +21,9 @@
   "license": "BSD-3-Clause",
   "dependencies": {
     "clsx": "^2.0.0",
-    "react": "^18.2.0"
+    "react": "^18.2.0",
+    "react-markdown": "^10.1.0",
+    "remark-gfm": "^4.0.1"
   },
   "devDependencies": {
     "@deepseek-ai/dsh-invariants": "workspace:^",

packages/client/ui-primitives/src/index.ts

@@ -15,5 +15,6 @@ export type { MenuItem } from './Menu.tsx'
 export { ConnectionBanner } from './ConnectionBanner.tsx'
 export { FishLogo } from './FishLogo.tsx'
 export { JsonBlock } from './markdown/JsonBlock.tsx'
+export { MarkdownText } from './markdown/MarkdownText.tsx'
 export { MessageText } from './markdown/MessageText.tsx'
 export * from './icons/index.tsx'

packages/client/ui-primitives/src/markdown/MarkdownText.module.css

@@ -0,0 +1,123 @@
+.markdown {
+  display: flex;
+  min-width: 0;
+  flex-direction: column;
+  gap: 12px;
+  overflow-wrap: anywhere;
+  font: var(--dsw-font-markdown-base);
+}
+
+.markdown :where(h1, h2, h3, h4, h5, h6, p, ul, ol, blockquote, pre, hr) {
+  margin: 0;
+}
+
+.markdown h1 {
+  font: var(--dsw-font-markdown-h1);
+}
+
+.markdown h2 {
+  font: var(--dsw-font-markdown-h2);
+}
+
+.markdown h3 {
+  font: var(--dsw-font-markdown-h3);
+}
+
+.markdown :where(h4, h5, h6) {
+  font: var(--dsw-font-markdown-h4);
+}
+
+.markdown :where(strong, th) {
+  font-weight: var(--dsw-font-markdown-base-strong-font-weight);
+}
+
+.markdown :where(ul, ol) {
+  padding-inline-start: 24px;
+}
+
+.markdown li + li {
+  margin-block-start: 4px;
+}
+
+.markdown li > :where(ul, ol) {
+  margin-block-start: 4px;
+}
+
+.markdown blockquote {
+  padding-inline-start: 12px;
+  border-inline-start: 3px solid var(--dsw-alias-markdown-citation);
+  color: var(--dsw-alias-label-secondary);
+}
+
+.markdown a {
+  color: var(--dsw-alias-state-business-primary);
+  text-decoration: underline;
+  text-underline-offset: 2px;
+}
+
+.markdown :not(pre) > code {
+  padding: 2px 4px;
+  border-radius: 4px;
+  background: var(--dsw-alias-markdown-inline-code);
+  font: var(--dsw-font-markdown-code);
+}
+
+.markdown pre {
+  max-width: 100%;
+  overflow-x: auto;
+  overscroll-behavior-x: contain;
+  padding: 12px 16px;
+  border-radius: 8px;
+  background: var(--dsw-alias-markdown-code-block);
+  font: var(--dsw-font-markdown-code-block);
+}
+
+.markdown pre code {
+  padding: 0;
+  background: transparent;
+  font: inherit;
+  overflow-wrap: normal;
+  word-break: normal;
+  white-space: pre;
+}
+
+.markdown hr {
+  width: 100%;
+  border: 0;
+  border-block-start: 1px solid var(--dsw-alias-markdown-citation);
+}
+
+.markdown input[type='checkbox'] {
+  margin: 0 8px 0 0;
+  accent-color: var(--dsw-alias-state-business-primary);
+}
+
+.tableScroll {
+  max-width: 100%;
+  overflow-x: auto;
+  overscroll-behavior-x: contain;
+}
+
+.tableScroll table {
+  width: max-content;
+  min-width: 100%;
+  border-collapse: collapse;
+  font: var(--dsw-font-markdown-table);
+}
+
+.tableScroll :where(th, td) {
+  padding: 6px 12px;
+  border: 1px solid var(--dsw-alias-markdown-citation);
+  text-align: start;
+  white-space: nowrap;
+}
+
+.tableScroll th {
+  background: var(--dsw-alias-markdown-code-block-banner);
+  font: var(--dsw-font-markdown-table-head);
+}
+
+.imageAlt {
+  color: var(--dsw-alias-label-tertiary);
+  font-style: italic;
+}

packages/client/ui-primitives/src/markdown/MarkdownText.tsx

@@ -0,0 +1,64 @@
+import ReactMarkdown from 'react-markdown'
+import type { Components, UrlTransform } from 'react-markdown'
+import remarkGfm from 'remark-gfm'
+import css from './MarkdownText.module.css'
+
+const remarkPlugins = [remarkGfm]
+
+function sanitizeUrl(url: string): string {
+  try {
+    switch (new URL(url).protocol) {
+      case 'http:':
+      case 'https:':
+      case 'mailto:':
+        return url
+      default:
+        return ''
+    }
+  } catch {
+    return ''
+  }
+}
+
+const safeUrl: UrlTransform = url => sanitizeUrl(url)
+
+const components: Components = {
+  a: ({ href = '', children }) => {
+    const safeHref = sanitizeUrl(href)
+    if (safeHref === '') return <>{children}</>
+    const external = ['http:', 'https:'].includes(new URL(safeHref).protocol)
+    return (
+      <a
+        href={safeHref}
+        {...(external ? { target: '_blank', rel: 'noopener noreferrer' } : {})}
+      >
+        {children}
+      </a>
+    )
+  },
+  img: ({ alt = '' }) => <span className={css.imageAlt}>{alt}</span>,
+  table: ({ children }) => (
+    <div className={css.tableScroll}>
+      <table>{children}</table>
+    </div>
+  ),
+}
+
+/**
+ * Render untrusted assistant-authored Markdown as semantic React elements.
+ * @param props - Markdown source text preserved by the session projection.
+ * @returns A GFM document with raw HTML, relative links, unsafe protocols, and remote images disabled.
+ */
+export function MarkdownText({ text }: { text: string }) {
+  return (
+    <div className={css.markdown}>
+      <ReactMarkdown
+        remarkPlugins={remarkPlugins}
+        components={components}
+        urlTransform={safeUrl}
+      >
+        {text}
+      </ReactMarkdown>
+    </div>
+  )
+}

packages/client/ui-primitives/src/markdown/MessageText.tsx

@@ -1,4 +1,4 @@
-// MessageText: the single text-block rendering point (Markdown support later = swap this component's internals, zero card-structure changes).
+// MessageText is the literal-text primitive for user and steering content; assistant output uses MarkdownText.
 
 import css from './MessageText.module.css'
 

packages/client/ui-primitives/tests/markdown.spec.tsx

@@ -1,14 +1,93 @@
 // @vitest-environment jsdom
 import { cleanup, fireEvent, render, screen } from '@testing-library/react'
 import { afterEach, describe, expect, it } from 'vitest'
-import { JsonBlock, MessageText } from '@deepseek-ai/dsh-client-ui-primitives'
+import { JsonBlock, MarkdownText, MessageText } from '@deepseek-ai/dsh-client-ui-primitives'
 
 afterEach(cleanup)
 
 describe('MessageText', () => {
   it('renders the text verbatim', () => {
-    const { container } = render(<MessageText text={'line1\nline2'} />)
-    expect(container.textContent).toBe('line1\nline2')
+    const { container } = render(<MessageText text={'# line1\n`line2`'} />)
+    expect(container.textContent).toBe('# line1\n`line2`')
+    expect(container.querySelector('h1')).toBeNull()
+  })
+})
+
+describe('MarkdownText', () => {
+  it('renders CommonMark and GFM elements as semantic DOM', () => {
+    const markdown = [
+      '# Heading',
+      '',
+      'Paragraph with **strong**, *emphasis*, ~~deleted~~, `inline`, and [safe](https://example.com).  ',
+      'Hard break.',
+      '',
+      '> Quote',
+      '',
+      '- parent',
+      '  - child',
+      '',
+      '1. first',
+      '2. second',
+      '',
+      '- [x] done',
+      '- [ ] pending',
+      '',
+      '| Name | Value |',
+      '| --- | --- |',
+      '| alpha | beta |',
+      '',
+      '---',
+      '',
+      '```ts',
+      'const answer = 42',
+      '```',
+      '',
+      '<https://deepseek.com>',
+    ].join('\n')
+    const { container } = render(<MarkdownText text={markdown} />)
+
+    expect(screen.getByRole('heading', { level: 1, name: 'Heading' })).toBeTruthy()
+    expect(container.querySelector('strong')?.textContent).toBe('strong')
+    expect(container.querySelector('em')?.textContent).toBe('emphasis')
+    expect(container.querySelector('del')?.textContent).toBe('deleted')
+    expect(container.querySelector('blockquote')?.textContent?.trim()).toBe('Quote')
+    expect(container.querySelectorAll('ul')).toHaveLength(3)
+    expect(container.querySelector('ol')).not.toBeNull()
+    expect(container.querySelectorAll('input[type="checkbox"]')).toHaveLength(2)
+    expect(container.querySelector('table')?.textContent).toContain('alphabeta')
+    expect(container.querySelector('hr')).not.toBeNull()
+    expect(container.querySelector('pre code')?.textContent).toContain('const answer = 42')
+    expect(container.querySelector('br')).not.toBeNull()
+    expect(screen.getByRole('link', { name: 'safe' }).getAttribute('target')).toBe('_blank')
+    expect(screen.getByRole('link', { name: 'https://deepseek.com' })).toBeTruthy()
+  })
+
+  it('neutralizes raw HTML, unsafe or relative links, and remote images', () => {
+    const markdown = [
+      '<script>globalThis.compromised = true</script>',
+      '<img src="x" onerror="globalThis.compromised = true">',
+      '[script](javascript:alert(1)) [relative](/settings)',
+      '[mail](mailto:dev@example.com) [web](http://example.com) [upper](HTTPS://example.com)',
+      '![remote diagram](https://example.com/private.png)',
+    ].join('\n\n')
+    const { container } = render(<MarkdownText text={markdown} />)
+
+    expect(container.querySelector('script')).toBeNull()
+    expect(container.querySelector('img')).toBeNull()
+    const neutralized = [...container.querySelectorAll('p')]
+      .find(paragraph => paragraph.textContent === 'script relative')
+    expect(neutralized?.querySelector('a')).toBeNull()
+    expect(screen.getByRole('link', { name: 'mail' }).getAttribute('target')).toBeNull()
+    expect(screen.getByRole('link', { name: 'web' }).getAttribute('rel')).toBe('noopener noreferrer')
+    expect(screen.getByRole('link', { name: 'upper' }).getAttribute('target')).toBe('_blank')
+    expect(screen.getByText('remote diagram')).toBeTruthy()
+  })
+
+  it('keeps incomplete streaming Markdown renderable', () => {
+    const { container } = render(<MarkdownText text={'## Streaming\n\n- first\n- **unfinished'} />)
+    expect(screen.getByRole('heading', { level: 2, name: 'Streaming' })).toBeTruthy()
+    expect(container.querySelectorAll('li')).toHaveLength(2)
+    expect(screen.getByText('**unfinished')).toBeTruthy()
   })
 })
 

packages/client/web-react/src/scoped-slots.tsx

@@ -135,6 +135,26 @@ function cachedSessionInject(entry: StoredEntry, cell: SessionCell, actions: obj
   return props
 }
 
+/**
+ * Entry-identity React keys for chain boundaries. A chain outlet renders ONE
+ * elected entry through an error boundary; without a key, a boundary that
+ * failed on entry A would survive a re-election and keep a healthy entry B
+ * blacked out. Keying by entry identity remounts the boundary fresh whenever
+ * the election changes (entries are identity-stable per registration, so the
+ * key is stable while the same entry stays elected).
+ */
+let nextEntryKey = 0
+const entryKeys = new WeakMap<StoredEntry, number>()
+
+function entryKeyOf(entry: StoredEntry): number {
+  let key = entryKeys.get(entry)
+  if (key === undefined) {
+    key = nextEntryKey++
+    entryKeys.set(entry, key)
+  }
+  return key
+}
+
 /**
  * Per-entry isolation: one registrant crashing (component render or inject
  * factory) must not take down siblings. Assembly errors (missing providers)
@@ -265,9 +285,22 @@ function SlotOutlet({ slotKey, ownerProps, opts }: {
     // pass runs per render with zero mount side effects: the first non-null
     // election renders, decliners never mount.
     for (const entry of entries) {
-      // Chain entries always carry select (SlotCore register validation).
-      const matched = (entry.select as (owner: object) => unknown)(ownerProps)
-      if (matched !== null) return guarded(entry, undefined, { ...ownerProps, matched })
+      let matched: unknown
+      try {
+        // Chain entries always carry select (SlotCore register validation).
+        matched = (entry.select as (owner: object) => unknown)(ownerProps)
+      } catch (error) {
+        // A throwing selector is a registrant contract breach (select MUST be
+        // pure and total), but it runs before the entry's SlotErrorBoundary
+        // exists — uncontained it would black out the whole owner region. So
+        // it degrades to a decline: the chain and the fallback stay intact,
+        // and the breach is reported like a crashed entry.
+        console.error(
+          `chain selector crashed in '${slotKey}' (${entry.registrant ?? 'unknown registrant'}), treating as declined:`,
+          error)
+        continue
+      }
+      if (matched !== null) return guarded(entry, entryKeyOf(entry), { ...ownerProps, matched })
     }
     return <>{opts?.fallback ?? null}</>
   }

packages/client/web-react/tests/scoped-slots.spec.tsx

@@ -312,6 +312,55 @@ describe('chain outlets and the renderSlotChain binding', () => {
     expect(declinerBody).not.toHaveBeenCalled()
   })
 
+  it('contains a throwing selector to its entry: reported, treated as declined, chain and fallback intact', () => {
+    const h = makeHost()
+    h.declare('k.chain', CHAIN_ROOT)
+    h.add('k.chain', chainEntryOf({
+      component: () => <span>never</span>,
+      select: () => { throw new Error('selector boom') },
+    }))
+    h.add('k.chain', chainEntryOf({
+      component: ({ matched }: { matched?: string }) => <b>{matched}</b>,
+      select: (owner) => (owner as { pick?: string }).pick ?? null,
+    }))
+    const spy = vi.spyOn(console, 'error').mockImplementation(() => {})
+    const { view } = mountChainRoot(h, { 'k.chain': CHAIN_ROOT }, (renderSlotChain) => <>
+      <main>{renderSlotChain('k.chain', { pick: 'OK' })}</main>
+      <aside>{renderSlotChain('k.chain', {}, { fallback: <i>fb</i> })}</aside>
+    </>)
+    // The breach never escapes to the owner region: later entries still get
+    // tried, and an all-throw/all-null pass still lands on the fallback.
+    expect(view.container.querySelector('main')!.textContent).toBe('OK')
+    expect(view.container.querySelector('aside')!.textContent).toBe('fb')
+    expect(spy.mock.calls.some(([msg]) => String(msg).includes('chain selector crashed'))).toBe(true)
+    spy.mockRestore()
+  })
+
+  it('remounts the boundary on re-election: a failed entry does not black out its replacement', () => {
+    const h = makeHost()
+    h.declare('k.chain', CHAIN_ROOT)
+    h.add('k.chain', chainEntryOf({
+      component: () => { throw new Error('entry A boom') },
+      select: (owner) => (owner as { pick?: string }).pick === 'A' ? {} : null,
+    }))
+    h.add('k.chain', chainEntryOf({
+      component: () => <b>B-ok</b>,
+      select: (owner) => (owner as { pick?: string }).pick === 'B' ? {} : null,
+    }))
+    let pick = 'A'
+    const spy = vi.spyOn(console, 'error').mockImplementation(() => {})
+    const { view } = mountChainRoot(h, { 'k.chain': CHAIN_ROOT },
+      (renderSlotChain) => renderSlotChain('k.chain', { pick }))
+    spy.mockRestore()
+    expect(view.container.querySelector('[data-slot-error]')).not.toBeNull()
+    // Re-elect entry B: the entry-keyed boundary remounts fresh instead of
+    // holding A's failed state over the healthy replacement.
+    pick = 'B'
+    act(() => { h.add('root', { component: () => null }) })   // root bump re-renders the dispatch site
+    expect(view.container.textContent).toBe('B-ok')
+    expect(view.container.querySelector('[data-slot-error]')).toBeNull()
+  })
+
   it('falls to the owner fallback when every selector declines, and re-routes live', () => {
     const h = makeHost()
     h.declare('k.chain', CHAIN_ROOT)