Merge remote-tracking branch 'origin/main' into fix/library-concept-midnight

Three checks in workspace-activity.spec.mjs waited on wall-clock timers:

- "lost server": waitForTimeout(2500), then at most 2 list reads. The read
  after the one that found the restart must be the periodic poll, so the
  test now waits for it and asserts the gap is at least POLL_MS (less
  100 ms for late request reporting). Any extra read lands in that gap.
- "200-row cap note" (review M12): waitForTimeout(1500), then no detail
  read. The page's timers are now Playwright's clock. The test runs one
  read-throttle interval out, so any read the counter update scheduled is
  sent before the log opens. Once the log's read has answered, exactly one
  read must be listed.
- "busy start" (review M14): waitForTimeout(7000), then the link toast is
  still visible. The test now runs the page's clock 7 s on, which fires a
  6.5 s clear however slowly the runner got there.

RED, each against a temporary product change: POLL_MS 3000 (gap 3004 ms,
expected at least 14900), detail re-read on new log lines while the log is
closed (an unexpected read), LINK_TOAST_MS 6500 (toast link gone), and
BACKOFF_FIRST_MS 200 for the earlier backoff check (gap 407 ms, expected at
least 1900).

tests/browser/concept-inventory.mjs

@@ -78,6 +78,17 @@ export async function seedConcept(request,data={}) {
     return response.json();
 }
 
+/**
+ * Seed the concept fixture and fix the browser's clock at the fixture's own instant (`manifest.now`), so the page and
+ * the fixture read one "now": a prompt used now reads "Used today" and the caption names the fixture's day even when
+ * the run crosses midnight between seeding and rendering. Timers keep running; only `Date` stands still.
+ */
+export async function seedConceptAt(page,request,data={}) {
+    const manifest=await seedConcept(request,data);
+    await page.clock.setFixedTime(new Date(manifest.now*1000));
+    return manifest;
+}
+
 /**
  * Save `tags` as the current image tag set of the listed file at `path` (root 0) through the real observe and tag
  * routes (#249 PR C), releasing the capture afterwards; returns the receipt's saved names.

tests/browser/images-concept.spec.mjs

@@ -1,7 +1,7 @@
 import {writeFile} from 'node:fs/promises';
 import {test,expect} from './fixtures.mjs';
 import {captureCanonicalState} from './history-canonical-comparison.mjs';
-import {SIZES,THEMES,MOTIONS,seedConcept,openConcept,openProduction,inventoryOf,diffInventory,mutate,stripExact,countCopy,reflow,withoutItems} from './concept-inventory.mjs';
+import {SIZES,THEMES,MOTIONS,seedConceptAt,openConcept,openProduction,inventoryOf,diffInventory,mutate,stripExact,countCopy,reflow,withoutItems} from './concept-inventory.mjs';
 
 // Task C7 of #249: the production Images page against the immutable concept, on the concept-shaped real fixture (24
 // images of the concept's six prompts, its seeds, sizes and favorites). Heading, toolbar, filter row, caption, grid,
@@ -85,7 +85,7 @@ function listInfo(card,actionsWidth) {
 /** Recorded Images deviations only (spec §8); everything else in the concept inventory must equal production. */
 const nocase=(a,b)=>{const x=a.toLowerCase(),y=b.toLowerCase();return x<y?-1:x>y?1:a<b?-1:a>b?1:0;};
 
-export function mapImagesConcept(reference,{manifest,now=new Date()}) {
+export function mapImagesConcept(reference,{manifest,now=new Date(manifest.now*1000)}) {
     const paths=new Map(manifest.images.map(image=>[image.filename,image.path]));
     // D14: the sort appends production's two sorts. Save view is the concept's own (saved views, #249 D16 retired).
     const toolbar={...reference.toolbar};
@@ -318,7 +318,7 @@ async function behaviorsOf(page,scope) {
     return {hover,opened,viewerTitle,focusAfterViewer,selected,layouts,search,single};
 }
 
-test.beforeEach(async({request},testInfo)=>{testInfo.manifest=await seedConcept(request);});
+test.beforeEach(async({page,request},testInfo)=>{testInfo.manifest=await seedConceptAt(page,request);});
 
 for(const [width,height] of SIZES)for(const theme of THEMES)test(`images page geometry, tokens, controls and behaviors match the concept ${width}x${height} ${theme}`,async({page,request},testInfo)=>{
     test.setTimeout(240_000);
@@ -348,7 +348,7 @@ for(const [width,height] of SIZES)for(const theme of THEMES)test(`images page ge
             importDiff:diffInventory(mapImportConcept(referenceImport),actualImport),referenceBehaviors,actualBehaviors};
     }
     // Load more in production: a fixture past one listing page appends one batch and shows the concept's toast.
-    testInfo.manifest=await seedConcept(request,{extra_images:LOAD_MORE_EXTRA});
+    testInfo.manifest=await seedConceptAt(page,request,{extra_images:LOAD_MORE_EXTRA});
     for(const motion of MOTIONS) {
         const total=FIXTURE_IMAGES+LOAD_MORE_EXTRA;
         await openProductionLoaded(page,theme,motion,total);
@@ -514,7 +514,7 @@ test('one appended image reads in the singular',async({page,request})=>{
     test.setTimeout(120_000);
     await page.setViewportSize({width:1600,height:1100});
     const total=PRODUCTION_BATCH+1;
-    await seedConcept(request,{extra_images:total-FIXTURE_IMAGES});
+    await seedConceptAt(page,request,{extra_images:total-FIXTURE_IMAGES});
     await openProductionLoaded(page,'dark','no-preference',total);
     await expect(page.locator('.infinite-continuation > p').first()).toHaveText(countCopy(`${PRODUCTION_BATCH} of ${total} images · more load as you scroll`));
     // A dispatched press: scrolling the button into view lets the page's own observer load the one image first.
@@ -530,7 +530,7 @@ test('one image appended by scrolling reads in the singular',async({page,request
     test.setTimeout(120_000);
     await page.setViewportSize({width:1600,height:1100});
     const total=PRODUCTION_BATCH+1;
-    await seedConcept(request,{extra_images:total-FIXTURE_IMAGES});
+    await seedConceptAt(page,request,{extra_images:total-FIXTURE_IMAGES});
     await openProductionLoaded(page,'dark','no-preference',total);
     await expect(page.locator('#result-count')).toHaveText(new RegExp(`^${PRODUCTION_BATCH} of ${total} images`));
     await page.locator('.infinite-continuation').scrollIntoViewIfNeeded();
@@ -551,7 +551,7 @@ test('one footer height for the collection (D3)',async({page,request})=>{
     const reference=await inventoryOf(page,'#main');
     expect(reference.grid.columns).toBe(2);
     expect(reference.cards.every(card=>card.info.p.height>parseFloat(card.info.p.lineHeight))).toBe(true);
-    const manifest=await seedConcept(request,{seedless_images:2,short_seedless:true});
+    const manifest=await seedConceptAt(page,request,{seedless_images:2,short_seedless:true});
     await openProductionLoaded(page,'dark','no-preference',FIXTURE_IMAGES+2);
     const actual=await inventoryOf(page,'#workspace-main');
     const box=card=>({left:card.left,top:card.top,width:card.width,height:card.height});

tests/browser/library-concept.spec.mjs

@@ -1,7 +1,7 @@
 import {writeFile} from 'node:fs/promises';
 import {test,expect} from './fixtures.mjs';
 import {captureCanonicalState} from './history-canonical-comparison.mjs';
-import {SIZES,THEMES,MOTIONS,seedConcept,openConcept,openProduction,inventoryOf,diffInventory,mutate,stripExact,countCopy,reflow} from './concept-inventory.mjs';
+import {SIZES,THEMES,MOTIONS,seedConceptAt,openConcept,openProduction,inventoryOf,diffInventory,mutate,stripExact,countCopy,reflow} from './concept-inventory.mjs';
 
 // Task E3 of #249: the production Prompt library shelf against the immutable concept (app.js renderLibrary a572–586,
 // style.css s648–708), on the concept-shaped real fixture (the concept's six prompts with their negatives, categories,
@@ -37,7 +37,8 @@ export function mapLibraryConcept(reference) {
         // D43: tag chips come in the store's alphabetical order; the row flows again from the concept's own chips.
         tags:sortedTags(card.tags),
         // D23: the stars are aria-hidden, with a visually hidden "Rated N out of 5" spoken in their place. The fixture's
-        // run_count (4) and last_used_at (now) give the concept's own "4 runs" and "Used today". The two-line clamp is
+        // run_count (4) and last_used_at (its own "now", where the page's clock stands) give the concept's own "4 runs"
+        // and "Used today". The two-line clamp is
         // applied below through `clampedCards`, measured on the concept with `CLAMP_CSS` (its samples wrap at 390px).
         footer:{...card.footer,facts:{...card.footer.facts,spoken:card.footer.facts.spoken.replace(/^(★+)/,stars=>`Rated ${stars.length} out of 5`)}}}));
     return {...reference,library:{...library,toolbar,
@@ -238,7 +239,8 @@ async function openHost(context) {
 }
 
 test.beforeEach(async({page,request},testInfo)=>{
-    testInfo.manifest=await seedConcept(request);
+    // The page's clock stands at the fixture's own "now", so its last use reads "Used today" on either side of midnight.
+    testInfo.manifest=await seedConceptAt(page,request);
     // Both documents copy through the clipboard; the stub records what they wrote.
     await page.addInitScript(()=>{window.copied=[];Object.defineProperty(navigator,'clipboard',{configurable:true,value:{writeText:async text=>{window.copied.push(text);}}});});
 });
@@ -322,6 +324,27 @@ for(const theme of THEMES)test(`library grid and cards match the concept 1800x11
     expect(compare(reference,actual,{sections:['library'],library:['grid','cards','trailing']})).toEqual([]);
 });
 
+// PR #284's CI run: the fixture recorded the last use at 23:59:5x UTC and the shelf rendered at 00:00:05, so production
+// read "Used yesterday" against the concept's "Used today". Here the browser's wall clock starts at 23:59:58 UTC, the
+// fixture records its use at that instant, and midnight passes before either document opens.
+const BEFORE_MIDNIGHT=Date.UTC(2026,9,22,23,59,58);
+const PAST_MIDNIGHT_MS=5_000;
+test('a run that crosses midnight still reads the concept fixture\'s day',async({page,request})=>{
+    await page.setViewportSize({width:1800,height:1100});
+    await page.clock.install({time:BEFORE_MIDNIGHT});
+    const manifest=await seedConceptAt(page,request,{now:BEFORE_MIDNIGHT/1000});
+    expect(manifest.now*1000,'the fixture\'s now').toBe(BEFORE_MIDNIGHT);
+    const used=(await (await request.get('/prompt_manager/library')).json()).items.map(item=>Date.parse(item.last_used_at));
+    expect(used,'every last use at the fixture\'s now').toEqual(Array(CONCEPT_PROMPTS).fill(BEFORE_MIDNIGHT));
+    await page.clock.fastForward(PAST_MIDNIGHT_MS);
+    await openConceptLibrary(page,'dark','no-preference');
+    const reference=await conceptInventory(page);
+    await openProductionLibrary(page,'dark','no-preference');
+    const actual=await inventoryOf(page,'#workspace-main');
+    expect(actual.library.cards.map(card=>card.footer.facts.text.replace(/^★+ · /,''))).toEqual(Array(CONCEPT_PROMPTS).fill('Used today'));
+    expect(compare(reference,actual,{sections:['library'],library:['grid','cards','trailing']})).toEqual([]);
+});
+
 // The comparison is only worth something if it notices a change (spec §7 mutation check): one CSS mutation (the footer
 // padding) and one DOM mutation (the negative-variants chip removed), each applied after an exact match.
 test('library comparison detects mutations',async({page})=>{

tests/browser/server.py

@@ -23,6 +23,7 @@ from tests.browser.workspace_activity_fixture import register_activity_commands
 from tests.browser.workspace_concept_fixture import (
     MAX_EXTRA_IMAGES as CONCEPT_MAX_EXTRA_IMAGES,
     MAX_SEEDLESS_IMAGES as CONCEPT_MAX_SEEDLESS_IMAGES,
+    MAX_EPOCH_SECONDS as CONCEPT_MAX_EPOCH_SECONDS,
     seed_workspace_concept,
 )
 from tests.browser.workspace_visual_fixture import seed_workspace_visual
@@ -489,8 +490,17 @@ def create_app(root: Path) -> web.Application:
         if (
             request.query
             or not isinstance(data, dict)
-            or set(data) - set(limits) - {"short_seedless"}
+            or set(data) - set(limits) - {"short_seedless", "now"}
             or not isinstance(data.get("short_seedless", False), bool)
+            # A chosen "now" (epoch seconds) pins every time the fixture writes.
+            or (
+                "now" in data
+                and (
+                    isinstance(data["now"], bool)
+                    or not isinstance(data["now"], (int, float))
+                    or not 0 < data["now"] < CONCEPT_MAX_EPOCH_SECONDS
+                )
+            )
             or any(
                 isinstance(data.get(key, 0), bool)
                 or not isinstance(data.get(key, 0), int)
@@ -510,6 +520,7 @@ def create_app(root: Path) -> web.Application:
                 extra_images=data.get("extra_images", 0),
                 seedless_images=data.get("seedless_images", 0),
                 short_seedless=data.get("short_seedless", False),
+                now=data.get("now"),
             )
         )
         return web.json_response({"success": True, **manifest})

tests/browser/workspace-activity.spec.mjs

@@ -2,6 +2,13 @@ import { startCoverage, saveCoverage } from '../../tools/vendor/browser-coverage
 import { test, expect } from './fixtures.mjs';
 import { seedConcept, openConcept, openProduction } from './concept-inventory.mjs';
 
+// The Activity store's periodic list read (activity-store.mjs POLL_MS) and the detail view's read throttle
+// (activity-job-view.mjs DETAIL_INTERVAL_MS).
+const POLL_MS = 15_000;
+const DETAIL_INTERVAL_MS = 1_000;
+// A request is reported to the test a little after the browser sends it; that delay is not a shorter wait.
+const REPORT_SLACK_MS = 100;
+
 // Activity (#249 Activity-1): the concept's Activity page (app.js renderActivity 732–738), its top-bar button
 // (index.html 51–52) and sidebar row (app.js ~341), with the recorded D52 (counts of running jobs), D53 (the progress
 // pill) and D54 (real job items). Fake jobs come from tests/browser/workspace_activity_fixture.py.
@@ -278,6 +285,8 @@ test('reload during a scan reattaches to the running job', async ({ page, reques
 });
 
 test('lost server clears the pill and marks jobs ended', async ({ page, request }) => {
+    // A poll interval after the restart, then failed re-reads backing off for 1 + 2 + 4 s.
+    test.setTimeout(90_000);
     await page.setViewportSize({ width: 1600, height: 1100 });
     const job = await startJob(request);
     await step(request, job.id, { processed: 4000 });
@@ -294,9 +303,12 @@ test('lost server clears the pill and marks jobs ended', async ({ page, request
     await expect(items(page).first().locator('p')).toHaveText(LOST);
     await expect(items(page).first().locator('progress, .row-actions')).toHaveCount(0);
     await expect(navRow(page).locator('.nav-count')).toHaveCount(0);
-    // One re-read found the restart; there is no retry storm and no finish toast for a job that only vanished.
-    await page.waitForTimeout(2500);
-    expect(reads.length).toBeLessThanOrEqual(2);
+    // One re-read found the restart; there is no retry storm and no finish toast for a job that only vanished. The
+    // read after it is the periodic one, a whole poll interval later: any extra read lands in that gap and fails it.
+    const found = reads.length;
+    expect(found, 'reads that found the restart').toBeGreaterThanOrEqual(1);
+    await expect.poll(() => reads.length, { timeout: POLL_MS + 10_000 }).toBeGreaterThan(found);
+    expect(reads[found] - reads[found - 1], 'the next read waits for the poll').toBeGreaterThanOrEqual(POLL_MS - REPORT_SLACK_MS);
     await expect(toast(page)).toHaveText('');
 
     // A server that cannot be read at all also ends the running job, then is read again with a growing backoff.
@@ -308,9 +320,12 @@ test('lost server clears the pill and marks jobs ended', async ({ page, request
     await expect(await request.post('/__test__/jobs/restart')).toBeOK();
     await expect(pill(page)).toBeHidden();
     await expect(items(page).filter({ hasText: LOST })).toHaveCount(1);
-    await page.waitForTimeout(3500);
-    // 1 s, then 2 s: at most two re-reads in 3.5 s.
-    expect(failed.length).toBeLessThanOrEqual(2);
+    // 1 s, then 2 s, then 4 s: each failed re-read waits twice as long as the one before. The gaps between the
+    // reads themselves are the evidence, so a slow runner noticing the ended job late cannot add a read to a window.
+    await expect.poll(() => failed.length, { timeout: 20_000 }).toBeGreaterThanOrEqual(3);
+    const gaps = failed.slice(1, 3).map((at, index) => at - failed[index]);
+    expect(gaps[0]).toBeGreaterThanOrEqual(2000 - REPORT_SLACK_MS);
+    expect(gaps[1]).toBeGreaterThanOrEqual(4000 - REPORT_SLACK_MS);
     await page.unroute('**/prompt_manager/jobs**');
     expect(second.id).not.toBe(job.id);
 });
@@ -607,6 +622,8 @@ test('filter narrows the selected outcome', async ({ page, request }) => {
 
 test('job view renders 200-row cap note', async ({ page, request }) => {
     await page.setViewportSize({ width: 1600, height: 1100 });
+    // The page's timers are Playwright's, running at real speed, so the M12 check below can run a read throttle out.
+    await page.clock.install();
     const job = await startJob(request);
     await step(request, job.id, { processed: 260, bulk: { group: 'added', count: 250 }, records: [
         ...Array.from({ length: 10 }, (_, index) => ({ group: 'no_metadata', path: `misc/plain_${index}.png`, detail: 'No prompt metadata in the file' })),
@@ -646,11 +663,15 @@ test('job view renders 200-row cap note', async ({ page, request }) => {
     page.on('request', item => { if (new URL(item.url()).pathname === `/prompt_manager/jobs/${job.id}`) reads.push(Date.now()); });
     await step(request, job.id, { processed: 300, bulk: { group: 'added', count: 40 } });
     await expect(tiles(page).first().locator('dd')).toHaveText('290');
-    await page.waitForTimeout(1500);
+    // Every read the counter update could have scheduled is due within one throttle interval: run it out, so any such
+    // read is sent before the log opens. Requests reach the test in the order they were sent, so once the log's read
+    // has answered, a read sent before it would already be listed.
+    await page.clock.runFor(DETAIL_INTERVAL_MS);
     expect(reads).toEqual([]);
     await scanLog(page).locator('summary').click();
     await expect.poll(() => reads.length).toBe(1);
     await expect(scanLog(page).locator('pre')).toContainText('bulk/file_00039.png');
+    expect(reads, 'only the log\'s own read').toHaveLength(1);
 });
 
 test('cancel scan ends cancelled with partial counts', async ({ page, request }) => {
@@ -705,14 +726,17 @@ test('a held legacy job shows no Cancel in the list or its view', async ({ page,
 
 test('busy start names the running job', async ({ page, request }) => {
     await page.setViewportSize({ width: 1600, height: 1100 });
+    // The page's timers are Playwright's, so the toast's lifetime below is run out rather than waited for.
+    await page.clock.install();
     const running = await startJob(request, { title: 'Database maintenance', kind: 'maintenance' });
     await startFromImport(page);
     await expect(toast(page)).toHaveText('Another job is running: Database maintenance.');
     await expect(toast(page).getByRole('link', { name: 'Database maintenance', exact: true })).toHaveAttribute('href', `#/activity/${running.id}`);
     await expect(page).toHaveURL(/#\/images$/);
     expect((await listed(request)).map(item => item.id)).toEqual([running.id]);
-    // Review M14: a toast with a link outlasts the plain 6.5 s, so the link stays reachable.
-    await page.waitForTimeout(7000);
+    // Review M14: a toast with a link outlasts the plain 6.5 s, so the link stays reachable. Running the page's timers
+    // 7 s on fires a 6.5 s clear for certain, however slowly this runner reached this line.
+    await page.clock.runFor(7000);
     await expect(toast(page).getByRole('link', { name: 'Database maintenance', exact: true })).toBeVisible();
     await toast(page).getByRole('link', { name: 'Database maintenance', exact: true }).click();
     await expect(heading(page).locator('h1')).toHaveText('Database maintenance');

tests/browser/workspace-images.spec.mjs

@@ -907,6 +907,10 @@ test('browser Back closes the open Images dialog and leaves the next page usable
 
 test('count line shows images and positive prompts', async ({ page, request }) => {
     await page.addInitScript(() => { window.IntersectionObserver = undefined; });
+    // D17's "Today" is the newest file's day: the page's clock stands at that file's mtime, so the fixture's day and
+    // the page's agree on either side of midnight.
+    const { images } = await (await request.get('/prompt_manager/images/output?mode=workspace&limit=40')).json();
+    await page.clock.setFixedTime(new Date(Math.max(...images.map(image => image.modified_time)) * 1000));
     await page.goto(workspace);
     await expect(cards(page)).toHaveCount(2);
     await expect(caption(page).locator('#result-count')).toHaveText('2 of 2 images · 2 positive prompts');

tests/browser/workspace-library.spec.mjs

@@ -610,7 +610,9 @@ test('card matches the concept and never wraps the category mid-word',async({pag
     await expect(await request.post('/prompt_manager/bulk/category',{data:{prompt_ids:[dual.id],category:''}})).toBeOK();
     // A long saved title fills the title row, so only the chip's own min-content keeps "Uncategorized" and "asian" whole.
     const wide='A remarkably long saved positive prompt title that fills the whole card title row';
-    await patchShelf(page,item=>item.id===cat.id?{run_count:4,last_used_at:new Date().toISOString(),rating:5}:item.id===dual.id||item.id===dog.id?{title:wide,run_count:1,last_used_at:null,rating:null}:{});
+    // One "now" for the patched last use and the page's clock, so it reads "Used today" on either side of midnight.
+    const usedAt=new Date();await page.clock.setFixedTime(usedAt);
+    await patchShelf(page,item=>item.id===cat.id?{run_count:4,last_used_at:usedAt.toISOString(),rating:5}:item.id===dual.id||item.id===dog.id?{title:wide,run_count:1,last_used_at:null,rating:null}:{});
     for(const [width,height] of [[1600,1100],[390,844]]) {
         await page.setViewportSize({width,height});await page.goto(route);await expect(cards(page)).toHaveCount(3);
         const card=page.locator(`article[data-prompt-id="${cat.id}"]`);

tests/browser/workspace_concept_fixture.py

@@ -11,6 +11,7 @@ the same sidebar counts (24 images, 6 prompts, 15 tags). Nothing is mocked.
 from __future__ import annotations
 
 from dataclasses import dataclass
+import datetime
 import json
 import math
 import os
@@ -157,6 +158,8 @@ CONCEPT_MODEL = "illustrative-model.safetensors"
 MAX_EXTRA_IMAGES = 120
 # Unlinked, seedless images (D11 "W × H · PNG") newer than the concept's, for D3 checks.
 MAX_SEEDLESS_IMAGES = 2
+# A test's chosen "now" (epoch seconds) stays before the year 3000.
+MAX_EPOCH_SECONDS = 32_503_680_000
 SEEDLESS_SIZE = (1536, 1152)
 # The same 4:3 shape with a short "96 × 72 · PNG" subtitle that stays on one line at
 # 390px beside the card's Info and Tag (the D3 footer check).
@@ -342,6 +345,17 @@ def _bounded(name: str, value: int, maximum: int) -> None:
         raise ValueError(f"{name} is out of range")
 
 
+def _instant(now: float | None) -> float:
+    """The fixture's one "now": ``now`` itself, or the wall clock when omitted."""
+    if now is None:
+        return time.time()
+    if isinstance(now, bool) or not isinstance(now, (int, float)):
+        raise TypeError("now must be a number of epoch seconds")
+    if not 0 < now < MAX_EPOCH_SECONDS:
+        raise ValueError("now is out of range")
+    return float(now)
+
+
 def seed_workspace_concept(
     api: PromptManagerAPI,
     root: Path,
@@ -349,9 +363,16 @@ def seed_workspace_concept(
     extra_images: int = 0,
     seedless_images: int = 0,
     short_seedless: bool = False,
+    now: float | None = None,
 ) -> dict:
     """Replace this server's disposable rows and files with the concept's data.
 
+    Every relative time the fixture writes (the prompts' last use, the files'
+    mtimes, the runs' observation times) is taken from one instant, ``now``
+    (epoch seconds, the wall clock when omitted), returned as ``manifest["now"]``.
+    A browser whose clock is fixed at that instant reads the concept's "Used
+    today" and caption day however close to midnight the run starts.
+
     ``extra_images`` continues the concept's rounds (same prompts, dimensions and
     seed rule) after its 24 images, for bounded-rendering and Load more checks.
     ``seedless_images`` adds unlinked PNGs without metadata, newest of all;
@@ -361,6 +382,10 @@ def seed_workspace_concept(
         raise TypeError("short_seedless must be a boolean")
     _bounded("extra_images", extra_images, MAX_EXTRA_IMAGES)
     _bounded("seedless_images", seedless_images, MAX_SEEDLESS_IMAGES)
+    now = _instant(now)
+    used_at = datetime.datetime.fromtimestamp(now, datetime.timezone.utc).isoformat(
+        timespec="microseconds"
+    )
     _clear(api, root)
     db = api.db
     epoch = db.get_execution_epoch()
@@ -385,8 +410,15 @@ def seed_workspace_concept(
         db.update_prompt_pair_metadata(pair_ids[0], title=first_name)
         for name, text in prompt.negatives[1:]:
             pair_ids.append(db.save_prompt_pair(prompt.positive, text, title=name))
-        # Real queue-hook counting (D23): four runs, the last one now.
+        # Real queue-hook counting (D23): four runs, the last one now, at the
+        # fixture's own instant rather than the database's later wall clock.
         db.record_prompt_use(positive_id, times=CONCEPT_RUN_COUNT)
+        with db.model.get_connection() as conn:
+            conn.execute(
+                "UPDATE prompts SET last_used_at = ? WHERE id = ?",
+                (used_at, positive_id),
+            )
+            conn.commit()
         prompts.insert(
             0, {"id": prompt.id, "positive_id": positive_id, "pair_ids": pair_ids}
         )
@@ -400,7 +432,6 @@ def seed_workspace_concept(
     favorite_root = _favorite_root_key(list(api._get_all_output_dirs())[0])
     total = len(CONCEPT_PROMPTS) * CONCEPT_IMAGE_ROUNDS + extra_images
     rounds = math.ceil(total / len(CONCEPT_PROMPTS))
-    now = time.time()
     images, runs = [], []
     slots = [
         (round_index, prompt_index, prompt)
@@ -484,6 +515,8 @@ def seed_workspace_concept(
     api.invalidate_gallery_cache()
     return {
         "epoch": epoch,
+        # The fixture's "now" (epoch seconds), for the browser's fixed clock.
+        "now": now,
         # The newest file's mtime (epoch seconds), for the D17 caption date.
         "newest_modified": now - 10 if seedless_images else now - 60,
         "seedless": seedless,

tests/test_workspace_concept_fixture.py

@@ -1,7 +1,9 @@
 """The concept fixture files carry the concept inspector facts (app.js:400-414)."""
 
 import json
+import math
 import tempfile
+import time
 import unittest
 from pathlib import Path
 
@@ -15,6 +17,8 @@ except ImportError:  # discovered with tests/ as the top-level directory
 from tests.browser.workspace_concept_fixture import (
     CONCEPT_MODEL,
     CONCEPT_PROMPTS,
+    MAX_EPOCH_SECONDS,
+    _instant,
     write_concept_png,
 )
 from utils.prompt_inspector import inspect_prompt_evidence, read_inspection_file
@@ -80,5 +84,29 @@ class TestWorkspaceConceptFixture(unittest.TestCase):
             self.assertEqual((image["width"], image["height"]), size)
 
 
+class TestConceptFixtureInstant(unittest.TestCase):
+    """One "now" for every relative time the fixture writes (PR #284's midnight)."""
+
+    def test_a_chosen_instant_is_kept(self):
+        self.assertEqual(_instant(1_792_713_598), 1_792_713_598.0)
+        self.assertEqual(_instant(1_792_713_598.25), 1_792_713_598.25)
+
+    def test_the_wall_clock_when_omitted(self):
+        before = time.time()
+        now = _instant(None)
+        self.assertLessEqual(before, now)
+        self.assertLessEqual(now, time.time())
+
+    def test_a_non_number_is_refused(self):
+        for value in (True, "1792713598", [1]):
+            with self.subTest(value=value), self.assertRaises(TypeError):
+                _instant(value)
+
+    def test_an_instant_out_of_range_is_refused(self):
+        for value in (0, -1, MAX_EPOCH_SECONDS, math.inf, math.nan):
+            with self.subTest(value=value), self.assertRaises(ValueError):
+                _instant(value)
+
+
 if __name__ == "__main__":
     unittest.main()