feat: global activity feed + session digest

Ops "Executions" tab showed raw target UUIDs, alphabetical (not
recency) order, and a stale status vocabulary from an earlier schema
iteration — never actually usable as a live "what's happening" view.
Replaced with a new recency-ordered /api/v1/activity/recent endpoint
and matching table (human-readable action summaries, risk/status
badges, duration, inline error preview).

Also added /api/v1/activity/session/{id} + a collapsible SessionDigest
panel in the chat rail, answering "what did this session actually do"
(executions by status, entities touched, knowledge written) — the
missing piece for proactive outcome reporting to be visible in the UI,
not just in the chat transcript.

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

web/src/pages/Chat.svelte

@@ -2,6 +2,7 @@
   import { messages, streaming, sendMessage, cancelStream, error } from '$lib/stores/chat'
   import SessionRail from '$lib/components/SessionRail.svelte'
   import SessionGraph from '$lib/components/SessionGraph.svelte'
+  import SessionDigest from '$lib/components/SessionDigest.svelte'
   import ToolCallGroup from '$lib/components/ToolCallGroup.svelte'
   import InlineApproval from '$lib/components/InlineApproval.svelte'
   import { Button } from '$lib/components/ui/button'
@@ -188,8 +189,11 @@
             : 'bg-border group-hover/rz:bg-primary/50'}"
         ></span>
       </button>
-      <div class="min-w-0 flex-1">
-        <SessionGraph />
+      <div class="flex min-w-0 flex-1 flex-col">
+        <SessionDigest />
+        <div class="min-h-0 flex-1">
+          <SessionGraph />
+        </div>
       </div>
     </div>
   {/if}

web/src/pages/Ops.svelte

@@ -3,10 +3,10 @@
   import {
     fetchApprovals,
     decideApproval,
-    fetchExecutions,
+    fetchRecentActivity,
     cancelExecution,
     type Approval,
-    type Execution
+    type ActivityItem
   } from '$lib/api'
   import { liveEvents, subscribeEvents } from '$lib/stores/events'
   import * as Tabs from '$lib/components/ui/tabs'
@@ -16,30 +16,55 @@
   import { toast } from 'svelte-sonner'
 
   let approvals = $state<Approval[]>([])
-  let executions = $state<Execution[]>([])
+  let activity = $state<ActivityItem[]>([])
   let deciding = $state<string | null>(null)
 
   async function loadApprovals() {
     approvals = await fetchApprovals()
   }
-  async function loadExecutions() {
-    executions = await fetchExecutions()
+  async function loadActivity() {
+    activity = await fetchRecentActivity()
   }
 
   onMount(() => {
     loadApprovals()
-    loadExecutions()
+    loadActivity()
     const unsubscribe = subscribeEvents()
-    return unsubscribe
+    // The activity feed has no dedicated SSE event type yet — a light poll
+    // keeps it live without waiting for that wiring. Cheap: one query, only
+    // while this page is open.
+    const interval = setInterval(loadActivity, 5000)
+    return () => {
+      unsubscribe()
+      clearInterval(interval)
+    }
   })
 
   $effect(() => {
     const ev = $liveEvents[0]
     if (!ev) return
     if (ev.type.startsWith('approval.')) loadApprovals()
-    if (ev.type.startsWith('execution.')) loadExecutions()
+    if (ev.type.startsWith('execution.')) loadActivity()
   })
 
+  function fmtDuration(ms: number | null): string {
+    if (ms == null) return '—'
+    if (ms < 1000) return `${ms}ms`
+    const s = Math.round(ms / 1000)
+    if (s < 60) return `${s}s`
+    return `${Math.floor(s / 60)}m ${s % 60}s`
+  }
+
+  function fmtWhen(iso: string): string {
+    const d = new Date(iso).getTime()
+    if (!d) return ''
+    const s = Math.round((Date.now() - d) / 1000)
+    if (s < 60) return 'just now'
+    if (s < 3600) return `${Math.floor(s / 60)}m ago`
+    if (s < 86400) return `${Math.floor(s / 3600)}h ago`
+    return `${Math.floor(s / 86400)}d ago`
+  }
+
   async function decide(id: string, decision: 'approve' | 'deny') {
     deciding = id
     const result = await decideApproval(id, decision)
@@ -56,22 +81,26 @@
     const result = await cancelExecution(id)
     if (result) {
       toast.success('Execution cancelled')
-      loadExecutions()
+      loadActivity()
     } else {
       toast.error('Cancel failed')
     }
   }
 
   function riskVariant(risk: string): 'default' | 'secondary' | 'destructive' {
-    if (risk === 'high' || risk === 'critical') return 'destructive'
-    if (risk === 'medium') return 'secondary'
+    if (risk === 'destructive') return 'destructive'
+    if (risk === 'config_mutation') return 'secondary'
     return 'default'
   }
 
+  // Real status vocabulary (internal/httpapi/phase3.go, cmd/nomos): the
+  // previous version checked statuses ('proposed', 'auto_approved',
+  // 'verified', 'executing'...) that don't exist anywhere in the actual
+  // schema — this table was never actually color-coding correctly.
   function execStatusVariant(status: string): 'default' | 'secondary' | 'destructive' | 'outline' {
-    if (['failed', 'timed_out', 'rollback_failed', 'denied'].includes(status)) return 'destructive'
-    if (['verified', 'auto_approved'].includes(status)) return 'default'
-    if (['executing', 'verifying'].includes(status)) return 'secondary'
+    if (['failed', 'denied', 'revoked', 'cancelled'].includes(status)) return 'destructive'
+    if (status === 'completed') return 'default'
+    if (['running', 'approved'].includes(status)) return 'secondary'
     return 'outline'
   }
 
@@ -87,7 +116,7 @@
       <Tabs.Trigger value="approvals">
         Approvals {#if pendingApprovals.length}<Badge variant="destructive" class="ml-1">{pendingApprovals.length}</Badge>{/if}
       </Tabs.Trigger>
-      <Tabs.Trigger value="executions">Executions</Tabs.Trigger>
+      <Tabs.Trigger value="executions">Activity</Tabs.Trigger>
     </Tabs.List>
 
     <Tabs.Content value="approvals" class="flex-1 overflow-auto">
@@ -168,31 +197,39 @@
             <Table.Row>
               <Table.Head>Target</Table.Head>
               <Table.Head>Action</Table.Head>
+              <Table.Head>Risk</Table.Head>
               <Table.Head>Status</Table.Head>
-              <Table.Head>Correlation</Table.Head>
-              <Table.Head>Started</Table.Head>
+              <Table.Head>Duration</Table.Head>
+              <Table.Head>When</Table.Head>
               <Table.Head class="text-right">Actions</Table.Head>
             </Table.Row>
           </Table.Header>
           <Table.Body>
-            {#each executions as execution (execution.id)}
+            {#each activity as item (item.id)}
               <Table.Row>
-                <Table.Cell class="font-mono text-xs">{execution.target ?? '—'}</Table.Cell>
-                <Table.Cell>{execution.action}</Table.Cell>
-                <Table.Cell><Badge variant={execStatusVariant(execution.status)}>{execution.status}</Badge></Table.Cell>
-                <Table.Cell class="font-mono text-xs text-muted-foreground">{execution.correlation_id}</Table.Cell>
-                <Table.Cell class="text-xs text-muted-foreground"
-                  >{execution.started_at ? new Date(execution.started_at).toLocaleString() : '—'}</Table.Cell
-                >
+                <Table.Cell class="font-mono text-xs">{item.target ?? '—'}</Table.Cell>
+                <Table.Cell>
+                  <div>{item.verb}</div>
+                  {#if item.summary}
+                    <div class="text-xs text-muted-foreground">{item.summary}</div>
+                  {/if}
+                  {#if item.error}
+                    <div class="text-xs text-destructive">{item.error}</div>
+                  {/if}
+                </Table.Cell>
+                <Table.Cell><Badge variant={riskVariant(item.risk_class)}>{item.risk_class}</Badge></Table.Cell>
+                <Table.Cell><Badge variant={execStatusVariant(item.status)}>{item.status}</Badge></Table.Cell>
+                <Table.Cell class="text-xs text-muted-foreground">{fmtDuration(item.duration_ms)}</Table.Cell>
+                <Table.Cell class="text-xs text-muted-foreground">{fmtWhen(item.created_at)}</Table.Cell>
                 <Table.Cell class="text-right">
-                  {#if ['proposed', 'approved', 'auto_approved', 'executing'].includes(execution.status)}
-                    <Button size="sm" variant="outline" onclick={() => cancel(execution.id)}>Cancel</Button>
+                  {#if ['pending_approval', 'approved', 'running'].includes(item.status)}
+                    <Button size="sm" variant="outline" onclick={() => cancel(item.id)}>Cancel</Button>
                   {/if}
                 </Table.Cell>
               </Table.Row>
             {:else}
               <Table.Row>
-                <Table.Cell colspan={6} class="text-center text-muted-foreground">No executions yet.</Table.Cell>
+                <Table.Cell colspan={7} class="text-center text-muted-foreground">No activity yet.</Table.Cell>
               </Table.Row>
             {/each}
           </Table.Body>