feat(KB): status pill + last-activity timestamp on Processing Queue (RFC #883 §5/§10)

Each in-flight (or stuck) embedding job gets a colored health pill,
relative-activity timestamp, and chunk counter so users can tell at a
glance whether ingestion is making progress.

## Health states

- **🟢 Active** — last batch < 2 min ago
- **🟡 Slow** — last batch 2-5 min ago (CPU-paced multi-batch ingestion
  lives here naturally; not always a problem)
- **🔴 Stalled** — last batch > 5 min ago (likely real problem)
- **⚪ Waiting** — queued, no batch started yet
- **🔴 Failed** — job recorded failed status

## What lands

- New backend util `kb_job_health.ts` with pure `computeJobHealth(input)`
  decision function. Time-based thresholds (2 min / 5 min) inlined as
  constants. 9 unit tests pin the boundaries.
- `EmbedJobWithProgress` gains `lastBatchAt`, `startedAt`, `chunks` —
  already set by `EmbedFileJob.handle` on every batch transition, just
  not previously surfaced through `listActiveJobs`.
- Frontend `kb_job_health_display.ts` maps each status to a Tailwind
  dot color, label, and aria-label so backend and UI stay in sync.
- `ActiveEmbedJobs.tsx` renders the pill, "last activity Xs ago", and
  chunk counter above each progress bar. Adds a manual Refresh button
  and "Last updated Xs ago" line — the existing 2s/30s auto-poll
  cadence in `useEmbedJobs` is left intact.
- Live tick at 5s keeps the relative timestamps current without
  re-fetching from the API.

## Not in scope

- Per-card Cancel / Retry / Un-index — separate Phase 2 PR
- Conditional warnings A/B/C — separate Phase 2 PR
- Computing throughput rate (chunks/min) — needs ratio registry consumer
  (Phase 2 follow-up); for now the pill answers the "is it stuck?"
  question directly without a rate estimate.

admin/app/jobs/embed_file_job.ts

@@ -262,13 +262,24 @@ export class EmbedFileJob {
     const queue = queueService.getQueue(this.queue)
     const jobs = await queue.getJobs(['waiting', 'active', 'delayed'])
 
-    return jobs.map((job) => ({
-      jobId: job.id!.toString(),
-      fileName: (job.data as EmbedFileJobParams).fileName,
-      filePath: (job.data as EmbedFileJobParams).filePath,
-      progress: typeof job.progress === 'number' ? job.progress : 0,
-      status: ((job.data as any).status as string) ?? 'waiting',
-    }))
+    return jobs.map((job) => {
+      const data = job.data as EmbedFileJobParams & {
+        status?: string
+        lastBatchAt?: number
+        startedAt?: number
+        chunks?: number
+      }
+      return {
+        jobId: job.id!.toString(),
+        fileName: data.fileName,
+        filePath: data.filePath,
+        progress: typeof job.progress === 'number' ? job.progress : 0,
+        status: data.status ?? 'waiting',
+        lastBatchAt: data.lastBatchAt,
+        startedAt: data.startedAt,
+        chunks: data.chunks,
+      }
+    })
   }
 
   static async getByFilePath(filePath: string): Promise<Job | undefined> {

admin/app/utils/kb_job_health.ts

@@ -0,0 +1,50 @@
+/**
+ * Visual status assigned to an in-flight (or stuck) embedding job, used to
+ * pick the colored status pill in the KB Processing Queue. See RFC #883 §5.
+ *
+ * - `waiting`  — queued, no batch has started yet
+ * - `healthy`  — last batch < 2 minutes ago
+ * - `slow`     — last batch 2-5 minutes ago (CPU-paced multi-batch ingestion
+ *                falls into this band; not necessarily a problem)
+ * - `stalled`  — last batch > 5 minutes ago (likely a real problem)
+ * - `failed`   — job recorded a failed status
+ */
+export type JobHealthStatus = 'waiting' | 'healthy' | 'slow' | 'stalled' | 'failed'
+
+export interface JobHealthInput {
+  /** BullMQ job.data.status — set by EmbedFileJob.handle on transitions. */
+  status: string
+  /** 0-100. 0 means no work observed yet on this job-row. */
+  progress: number
+  /** ms epoch of the last completed batch. Multi-batch ZIMs update this on
+   * every continuation; single-batch jobs leave it unset until completion. */
+  lastBatchAt?: number
+  /** ms epoch of the first batch start. Used as a fallback "last activity"
+   * signal for jobs that haven't yet completed their first batch. */
+  startedAt?: number
+  /** Current ms epoch. Injected for testability. */
+  now: number
+}
+
+const SLOW_THRESHOLD_MS = 2 * 60 * 1000
+const STALLED_THRESHOLD_MS = 5 * 60 * 1000
+
+export function computeJobHealth(input: JobHealthInput): JobHealthStatus {
+  if (input.status === 'failed') return 'failed'
+
+  // No progress recorded and no activity timestamps — job is still queued.
+  if (
+    input.progress === 0 &&
+    input.lastBatchAt === undefined &&
+    input.startedAt === undefined
+  ) {
+    return 'waiting'
+  }
+
+  const lastActivity = input.lastBatchAt ?? input.startedAt ?? input.now
+  const stalenessMs = input.now - lastActivity
+
+  if (stalenessMs > STALLED_THRESHOLD_MS) return 'stalled'
+  if (stalenessMs > SLOW_THRESHOLD_MS) return 'slow'
+  return 'healthy'
+}

admin/inertia/components/ActiveEmbedJobs.tsx

@@ -1,39 +1,101 @@
+import { useEffect, useState } from 'react'
 import useEmbedJobs from '~/hooks/useEmbedJobs'
 import HorizontalBarChart from './HorizontalBarChart'
+import StyledButton from './StyledButton'
 import StyledSectionHeader from './StyledSectionHeader'
+import {
+  JOB_HEALTH_DISPLAY,
+  computeJobHealth,
+  formatTimeAgo,
+} from '~/lib/kb_job_health_display'
 
 interface ActiveEmbedJobsProps {
   withHeader?: boolean
 }
 
 const ActiveEmbedJobs = ({ withHeader = false }: ActiveEmbedJobsProps) => {
-  const { data: jobs } = useEmbedJobs()
+  const { data: jobs, invalidate, dataUpdatedAt } = useEmbedJobs()
+
+  // Live "last refreshed Xs ago" tick. We re-render every 5s purely to keep
+  // the relative timestamp current, without touching React Query state.
+  const [tick, setTick] = useState(() => Date.now())
+  useEffect(() => {
+    const id = setInterval(() => setTick(Date.now()), 5000)
+    return () => clearInterval(id)
+  }, [])
 
   return (
     <>
       {withHeader && (
         <StyledSectionHeader title="Processing Queue" className="mt-12 mb-4" />
       )}
+
+      {/* Refresh row — only shown when at least one job exists so the empty
+          state stays clean. */}
+      {jobs && jobs.length > 0 && (
+        <div className="flex items-center justify-between mb-3 text-sm">
+          <span className="text-text-muted">
+            {dataUpdatedAt > 0
+              ? `Last updated ${formatTimeAgo(dataUpdatedAt, tick)}`
+              : 'Loading…'}
+          </span>
+          <StyledButton variant="ghost" size="sm" icon="IconRefresh" onClick={invalidate}>
+            Refresh
+          </StyledButton>
+        </div>
+      )}
+
       <div className="space-y-4">
         {jobs && jobs.length > 0 ? (
-          jobs.map((job) => (
-            <div
-              key={job.jobId}
-              className="bg-desert-white rounded-lg p-4 border border-desert-stone-light shadow-sm hover:shadow-lg transition-shadow"
-            >
-              <HorizontalBarChart
-                items={[
-                  {
-                    label: job.fileName,
-                    value: job.progress,
-                    total: '100%',
-                    used: `${job.progress}%`,
-                    type: job.status,
-                  },
-                ]}
-              />
-            </div>
-          ))
+          jobs.map((job) => {
+            const health = computeJobHealth({
+              status: job.status,
+              progress: job.progress,
+              lastBatchAt: job.lastBatchAt,
+              startedAt: job.startedAt,
+              now: tick,
+            })
+            const display = JOB_HEALTH_DISPLAY[health]
+            const lastActivityMs = job.lastBatchAt ?? job.startedAt
+            return (
+              <div
+                key={job.jobId}
+                className="bg-desert-white rounded-lg p-4 border border-desert-stone-light shadow-sm hover:shadow-lg transition-shadow"
+              >
+                <div className="flex items-center gap-3 mb-2">
+                  <span
+                    className={`inline-block w-2.5 h-2.5 rounded-full ${display.dot}`}
+                    aria-label={display.ariaLabel}
+                    title={display.ariaLabel}
+                  />
+                  <span className="text-sm font-medium text-text-primary">
+                    {display.label}
+                  </span>
+                  {lastActivityMs !== undefined && (
+                    <span className="text-xs text-text-muted">
+                      · last activity {formatTimeAgo(lastActivityMs, tick)}
+                    </span>
+                  )}
+                  {typeof job.chunks === 'number' && job.chunks > 0 && (
+                    <span className="text-xs text-text-muted">
+                      · {job.chunks.toLocaleString()} chunks
+                    </span>
+                  )}
+                </div>
+                <HorizontalBarChart
+                  items={[
+                    {
+                      label: job.fileName,
+                      value: job.progress,
+                      total: '100%',
+                      used: `${job.progress}%`,
+                      type: job.status,
+                    },
+                  ]}
+                />
+              </div>
+            )
+          })
         ) : (
           <p className="text-text-muted">No files are currently being processed</p>
         )}

admin/inertia/lib/kb_job_health_display.ts

@@ -0,0 +1,63 @@
+import { computeJobHealth, type JobHealthStatus } from '../../app/utils/kb_job_health.js'
+
+export { computeJobHealth, type JobHealthStatus } from '../../app/utils/kb_job_health.js'
+
+/**
+ * Visual presentation for each health status — pill color, dot color, and the
+ * short label rendered alongside the dot. Kept in one place so backend health
+ * decisions (`computeJobHealth`) and frontend rendering stay in sync.
+ */
+export const JOB_HEALTH_DISPLAY: Record<
+  JobHealthStatus,
+  { dot: string; label: string; ariaLabel: string }
+> = {
+  waiting: {
+    dot: 'bg-gray-400 dark:bg-gray-500',
+    label: 'Waiting',
+    ariaLabel: 'Job is queued and waiting to start',
+  },
+  healthy: {
+    dot: 'bg-green-500',
+    label: 'Active',
+    ariaLabel: 'Job is embedding at a normal rate',
+  },
+  slow: {
+    dot: 'bg-yellow-500',
+    label: 'Slow',
+    ariaLabel: 'Job has not made progress for at least 2 minutes',
+  },
+  stalled: {
+    dot: 'bg-red-500',
+    label: 'Stalled',
+    ariaLabel: 'Job has not made progress for at least 5 minutes',
+  },
+  failed: {
+    dot: 'bg-red-700',
+    label: 'Failed',
+    ariaLabel: 'Job failed',
+  },
+}
+
+/**
+ * Format a relative timestamp as "Xs ago", "Xm ago", "Xh ago" with sensible
+ * thresholds for the KB Processing Queue's "Last activity" line.
+ */
+export function formatTimeAgo(timestampMs: number, now: number): string {
+  const seconds = Math.max(0, Math.floor((now - timestampMs) / 1000))
+  if (seconds < 5) return 'just now'
+  if (seconds < 60) return `${seconds}s ago`
+  const minutes = Math.floor(seconds / 60)
+  if (minutes < 60) return `${minutes}m ago`
+  const hours = Math.floor(minutes / 60)
+  return `${hours}h ago`
+}
+
+/**
+ * Convenience wrapper that resolves a job's health status without the caller
+ * having to remember to pass `now`. Mostly for ergonomic frontend use.
+ */
+export function computeJobHealthNow(
+  input: Omit<Parameters<typeof computeJobHealth>[0], 'now'>
+): JobHealthStatus {
+  return computeJobHealth({ ...input, now: Date.now() })
+}

admin/tests/unit/kb_job_health.spec.ts

@@ -0,0 +1,100 @@
+import * as assert from 'node:assert/strict'
+import { test } from 'node:test'
+
+import { computeJobHealth } from '../../app/utils/kb_job_health.js'
+
+const MIN = 60 * 1000
+const NOW = 1_700_000_000_000 // arbitrary fixed epoch for deterministic tests
+
+test('failed status takes precedence over any timing', () => {
+  assert.equal(
+    computeJobHealth({ status: 'failed', progress: 42, lastBatchAt: NOW, now: NOW }),
+    'failed'
+  )
+})
+
+test('no progress + no activity timestamps → waiting', () => {
+  assert.equal(
+    computeJobHealth({ status: 'waiting', progress: 0, now: NOW }),
+    'waiting'
+  )
+})
+
+test('progress > 0 but no lastBatchAt yet → healthy (first batch just started)', () => {
+  assert.equal(
+    computeJobHealth({ status: 'processing', progress: 5, startedAt: NOW, now: NOW }),
+    'healthy'
+  )
+})
+
+test('lastBatchAt 30s ago → healthy', () => {
+  assert.equal(
+    computeJobHealth({
+      status: 'batch_completed',
+      progress: 50,
+      lastBatchAt: NOW - 30 * 1000,
+      now: NOW,
+    }),
+    'healthy'
+  )
+})
+
+test('lastBatchAt 90s ago → still healthy (under 2 min threshold)', () => {
+  assert.equal(
+    computeJobHealth({
+      status: 'batch_completed',
+      progress: 50,
+      lastBatchAt: NOW - 90 * 1000,
+      now: NOW,
+    }),
+    'healthy'
+  )
+})
+
+test('lastBatchAt 3 min ago → slow (CPU-paced ingestion lives here)', () => {
+  assert.equal(
+    computeJobHealth({
+      status: 'batch_completed',
+      progress: 50,
+      lastBatchAt: NOW - 3 * MIN,
+      now: NOW,
+    }),
+    'slow'
+  )
+})
+
+test('lastBatchAt 4:30 ago → still slow (under 5 min stalled threshold)', () => {
+  assert.equal(
+    computeJobHealth({
+      status: 'batch_completed',
+      progress: 50,
+      lastBatchAt: NOW - 4.5 * MIN,
+      now: NOW,
+    }),
+    'slow'
+  )
+})
+
+test('lastBatchAt 5:01 ago → stalled', () => {
+  assert.equal(
+    computeJobHealth({
+      status: 'batch_completed',
+      progress: 50,
+      lastBatchAt: NOW - (5 * MIN + 1000),
+      now: NOW,
+    }),
+    'stalled'
+  )
+})
+
+test('lastBatchAt missing but startedAt 10 min ago → stalled (first-batch-never-finished case)', () => {
+  assert.equal(
+    computeJobHealth({
+      status: 'processing',
+      progress: 5,
+      startedAt: NOW - 10 * MIN,
+      now: NOW,
+    }),
+    'stalled'
+  )
+})

admin/types/rag.ts

@@ -5,6 +5,12 @@ export type EmbedJobWithProgress = {
   progress: number
   status: string
   error?: string
+  /** ms epoch of last completed batch; multi-batch ZIMs update this each batch. */
+  lastBatchAt?: number
+  /** ms epoch of first batch start; used as a fallback when lastBatchAt unset. */
+  startedAt?: number
+  /** Total chunks embedded across this job's batches so far. */
+  chunks?: number
 }
 
 export type ProcessAndEmbedFileResponse = {