fix(gui): the collapsed plan hint accounts for parallel active items

Lifting the single-in_progress cap makes a list shape reachable that the
web surfaces never received. Two sites derived their one-line summary with
todos.find(t => t.status === 'in_progress') — the collapsed TodoPanel header
and the todo_write row — which was total under the old cap and silently
dropped every active item but the first once several could match: a plan
with three running tasks collapsed to the name of one. The expanded list
was always correct, so neither PR's tests covered it.

Both sites now take planSummary in contract/todo-plan-model.ts, the
domain-shared face both the skeleton and toolviews domains may import; the
duplicated derivation was why one find could be fixed while the other
stayed wrong. The hint names the first active item and suffixes +<n> for
the rest, so the collapsed line reports how many tasks are running.

The web fixture's todo sample now runs two items in_progress, so the
assembled web transcript replays a parallel plan: the row reads
'1/4 已完成 · 实现 fixture 样本 +1' over the built bundles.

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

@@ -168,14 +168,17 @@ function buildAlphaLog(): SessionEvent[] {
     push({ type: 'turn/end', data: { turn, reason: { kind: 'completed' } } })
   }
   // Turn 65: todo_write sample — the TodoRow toolview in the flow plus the
-  // todo/write snapshot event feeding the TodoPanel plan strip.
+  // todo/write snapshot event feeding the TodoPanel plan strip. Two items are
+  // in_progress: the tool permits several, so both surfaces must render a
+  // parallel plan rather than the first active item alone.
   const fixtureTodos = [
     { content: '梳理需求', status: 'completed' },
     { content: '实现 fixture 样本', status: 'in_progress' },
+    { content: '跑后台构建', status: 'in_progress' },
     { content: '浏览器验收', status: 'pending' },
   ]
   const todoArgs = JSON.stringify({ todos: fixtureTodos })
-  toolTurn(65, 'todo_write', todoArgs, 'Updated todo list: 1 pending, 1 in progress, 1 completed.')
+  toolTurn(65, 'todo_write', todoArgs, 'Updated todo list: 1 pending, 2 in progress, 1 completed.')
   // The real tool appends the snapshot mid-execution — between tool/call and
   // tool/result — so the fixture reproduces that exact ordering (the last
   // toolTurn events run ... tool/call, tool/result, step/end, turn/end).

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

@@ -84,6 +84,10 @@ describe('createFixtureApi', () => {
     const times = events.slice(todoAt - 1, todoAt + 2).map(e => e.time)
     expect(times[0]).toBeLessThanOrEqual(times[1] ?? 0)
     expect(times[1]).toBeLessThanOrEqual(times[2] ?? 0)
+    // The sample is a parallel plan: the tool permits several in_progress, so
+    // the surfaces fed from here are exercised against more than one active item.
+    const snapshot = events[todoAt] as { data: { todos: { status: string }[] } }
+    expect(snapshot.data.todos.filter(t => t.status === 'in_progress')).toHaveLength(2)
   })
 
   it('create adds a session and pushes host/session-added to open host streams', async () => {