fix(webui): order same-key files settles by commit, not start

BUILD-LOG.md

@@ -6312,3 +6312,5 @@ R5 quote fallback room (#797 D3, 2026-11-06, MVP3 lead): r4 review P2 found that
 2026-11-06 UTC | #797 write_record JSON object compatibility — implementation and verification | Before: JSON-encoded requirements and decisions were refused and project-record-invalid detail was lost before the agent. After: strict object parsing preserves object-form bytes, and only record.write project-record-invalid details reach the tool result; docs remain Markdown. Exact-base negative control: seven behavioral failures. Node 26 serial gates: touched file 7/7, project 50/50, harness 316/316, bus excluding project-files 1642/1642, CLI 1204 pass and one federation acceptance skip reproduced on base. An initial candidate focused run failed one test due to a duplicate code prefix; corrected and rerun green. Evidence and handoff: /mnt/storage/scratch/mosaic-lead/mvp3/write-record-object-evidence/ and /mnt/storage/scratch/mosaic-lead/mvp3/write-record-object-report.md. Linked-worktree queue refused; local candidate for independent review, no push or deployment.
 
 2026-11-06 UTC | #797 Files polish — implementation and author verification | Before: caller and Files module each rendered a heading, and request redraws replaced settled content with a loading message. After: callers retain the single heading; cloned DOM content is cached per deduplicated request list or validated thread key, fenced against older mounts and cleared at sign-out. Exact-base negative control: 8 behavioral failures, 3 passes. Node 26 serial authorized browser gate: 91 pass, 0 fail, 0 cancelled, 0 skipped. An initial detached-container test timed out because its fixture awaited its own held request; the same timeout reproduced on base and the fixture was corrected. All evidence and limits: /mnt/storage/scratch/mosaic-lead/mvp3/files-polish-evidence/ and /mnt/storage/scratch/mosaic-lead/mvp3/files-polish-report.md. Local implementation candidate for independent review; no push, merge or deployment.
+
+2026-11-06 UTC | #797 Files polish r2 — review r1 F1/F2 ordering fix | Before (86383a9d1): the per-key sequence fenced only cache writes, so an older same-key read in another live container painted stale files after a newer mount settled (F1), and a pending newer mount kept a completed result out of the cache, so a remount flashed "Reading files…" (F2). After: each mount takes a start order; a settle paints and caches only if no later-started mount for the key has committed, otherwise it shows the newer cached result; a pending mount never blocks an earlier completion. Reviewer probes ported as two tests; on 86383a9d1 they fail 2/13 for behavior, on the fix w15-files-browser 13/13 and the touched caller browser files 93/0/0/0 (Node 26 serial). Evidence: /mnt/storage/scratch/mosaic-lead/mvp3/files-polish-r2-evidence/.

docs/SESSIONS.md

@@ -2103,3 +2103,4 @@ are never rewritten or removed; corrections are new entries.
 2026-11-06 | mvp3-lead-797 (Claude, #797 lane) | project archive r9 WebUI fix on 4c85d3784 for the r8 review P1 | A same-thread refresh that resolves archived or unknown withdraws request-panel and unguarded thread writes before the session read. r8 negative fails for behavior; reviewer probe 4/0; focused 12/12; whole WebUI 661/0/0/0. Evidence: /mnt/storage/scratch/mosaic-lead/mvp3/project-archive-r9-evidence/. Local candidate for independent review; no push, merge or deployment.
 2026-11-06 UTC | Terra implementation sub-agent | #797 write_record JSON object compatibility on fix/write-record-object from 13f81354e | Strict parsed JSON objects and scoped agent-visible validation details; exact-base seven-test negative, Node 26 serial gates and base-reproduced CLI skip recorded in /mnt/storage/scratch/mosaic-lead/mvp3/write-record-object-report.md. Queue refused linked worktree; local commit for independent review, no push or deployment.
 2026-11-06 UTC | Codex implementation sub-agent | #797 Files heading and remount polish on files-polish from 4cc3d05b3 | Single caller heading and fenced sign-out-cleared DOM cache; Node 26 authorized browser gates 91/0/0/0, exact-base behavioral controls and fixture correction recorded in /mnt/storage/scratch/mosaic-lead/mvp3/files-polish-report.md. Queue refused linked worktree; canonical queue reported nothing for this seat. One local candidate for independent review; no push, merge or deployment.
+2026-11-06 UTC | mvp3-lead-797 (Claude, #797 lane) | files-polish r2 on 86383a9d1 for Sol r1 F1/F2 | Per-key commit order fences live paints and caches the newest completed result; reviewer probes ported; r1 negative 11/2, w15-files 13/13, caller browser gate 93/0/0/0. Evidence: /mnt/storage/scratch/mosaic-lead/mvp3/files-polish-r2-evidence/.

packages/webui/src/public/files.js

@@ -4,9 +4,11 @@
   const id = value => typeof value === 'string' && /^[A-Za-z0-9][A-Za-z0-9._-]{0,159}$/.test(value);
   const generations = new WeakMap();
   const cache = new Map();
-  const latest = new Map();
+  // Per key: the start order of the newest mount whose result has been shown and cached.
+  const committed = new Map();
+  let started = 0;
   let signedOut = false;
-  document.addEventListener('mosaic-signed-out', () => { signedOut = true; cache.clear(); latest.clear(); document.querySelectorAll('.mosaic-files').forEach(el => el.replaceChildren()); });
+  document.addEventListener('mosaic-signed-out', () => { signedOut = true; cache.clear(); committed.clear(); document.querySelectorAll('.mosaic-files').forEach(el => el.replaceChildren()); });
   function element(tag, content, className) {
     const node = document.createElement(tag);
     if (content !== undefined) node.textContent = content;
@@ -37,21 +39,28 @@
     container.classList.add('mosaic-files');
     const ids = Array.isArray(requestIds) ? [...new Set(requestIds.filter(id))] : [];
     const cacheKey = typeof key === 'string' && key.length > 0 && key.length <= 320 ? `key:${key}` : `ids:${JSON.stringify(ids)}`;
-    const sequence = {};
-    latest.set(cacheKey, sequence);
+    const order = ++started;
     const previous = !signedOut && !document.body.classList.contains('signed-out') && cache.get(cacheKey);
     container.replaceChildren(...(previous ? previous.map(node => node.cloneNode(true)) : [element('p', 'Reading files…')]));
-    function remember() {
-      if (!signedOut && !document.body.classList.contains('signed-out') && generations.get(container) === generation && latest.get(cacheKey) === sequence) {
-        cache.set(cacheKey, [...container.childNodes].map(node => node.cloneNode(true)));
+    // A settled read paints and caches only if no later-started mount for this key has already
+    // committed; otherwise this container shows that newer result. A pending later mount never
+    // blocks an earlier completion. Callers keep their own fences before calling this.
+    function commit(nodes) {
+      if ((committed.get(cacheKey) || 0) > order) {
+        const newer = cache.get(cacheKey);
+        if (newer) container.replaceChildren(...newer.map(node => node.cloneNode(true)));
+        return;
       }
+      container.replaceChildren(...nodes);
+      if (signedOut || document.body.classList.contains('signed-out')) return;
+      committed.set(cacheKey, order);
+      cache.set(cacheKey, nodes.map(node => node.cloneNode(true)));
     }
     if (ids.length) {
       const config = await read('/api/config');
       if (signedOut || generations.get(container) !== generation) return;
       if (config?.requests !== true) {
-        container.replaceChildren(element('p', 'Files are unavailable.'));
-        remember();
+        commit([element('p', 'Files are unavailable.')]);
         return;
       }
     }
@@ -61,8 +70,8 @@
       return { request, base, state, workspace };
     }));
     if (signedOut || generations.get(container) !== generation || document.body.classList.contains('signed-out')) return;
-    container.replaceChildren();
-    if (!ids.length) { container.append(element('p', 'No request files are available.')); remember(); return; }
+    if (!ids.length) { commit([element('p', 'No request files are available.')]); return; }
+    const nodes = [];
     for (const { request, base, state, workspace } of results) {
       const section = element('section', undefined, 'mosaic-files-request');
       section.append(element('h4', `Request ${request}`), element('h5', 'Reviewed delivery'));
@@ -98,9 +107,9 @@
         }
         if (workspace.truncated) draft.append(element('p', 'The draft list was truncated.'));
       }
-      container.append(section);
+      nodes.push(section);
     }
-    remember();
+    commit(nodes);
   }
   window.MosaicFiles = Object.freeze({ mount });
 })();

packages/webui/tests/w15-files-browser.test.mjs

@@ -228,3 +228,79 @@ test('Files keeps settled read errors visible on refresh', async t => {
   assert.doesNotMatch(text, /old\.html|old-draft\.txt/);
   assert.deepEqual(errors, []);
 });
+
+// Review r1 F1/F2: per-key ordering across live containers (from the reviewer probes).
+async function orderFixture(t) {
+  const fixture = await filesFixture(t);
+  await fixture.b.navigate(fixture.f.base + '/#/');
+  await fixture.b.evaluate(`(() => {
+    const section = document.createElement('section');
+    section.innerHTML = '<h3>Files</h3><div id="review-a"></div><div id="review-b"></div><div id="review-c"></div>';
+    document.querySelector('#main').append(section);
+    window.reviewState = name => ({ version: 1, revision: 1, phase: 'complete', request: 'request-1', delivery: 'delivery-1', delivery_evidence: {id:'delivery-1', request:'request-1', artifact:{path:'output/' + name}} });
+    window.fixtureState = window.reviewState('seed.html');
+    window.fixtureWorkspace = {available:true, entries:[{name:'seed-draft.txt'}], truncated:false};
+    window.reviewFetch = window.fetch;
+    window.reviewMount = (name, options = {}) => MosaicFiles.mount({container:document.querySelector('#review-' + name), requestIds:['request-1'], ...options});
+  })()`);
+  return fixture;
+}
+
+test('Files two live same-key mounts reject a late older on-screen settlement', async t => {
+  const { b, errors } = await orderFixture(t);
+  await b.evaluate("reviewMount('a')");
+  await b.evaluate(`(() => {
+    window.fixtureState = reviewState('stale.html');
+    window.fixtureWorkspace.entries = [{name:'stale-draft.txt'}];
+    let ready;
+    window.reviewOldSnapshot = new Promise(resolve => ready = resolve);
+    let first = true;
+    window.fetch = async (url, init) => {
+      if (String(url) === '/api/requests/request-1' && first) {
+        first = false;
+        const capturedResponse = await window.reviewFetch(url, init);
+        await new Promise(resolve => { window.reviewReleaseOld = resolve; ready(); });
+        return capturedResponse;
+      }
+      return window.reviewFetch(url, init);
+    };
+    window.reviewOld = reviewMount('a');
+  })()`);
+  await b.evaluate('window.reviewOldSnapshot');
+  await b.evaluate(`(async () => {
+    window.fixtureState = reviewState('newest.html');
+    window.fixtureWorkspace.entries = [{name:'newest-draft.txt'}];
+    await reviewMount('b');
+    window.reviewReleaseOld(); await window.reviewOld;
+    window.fetch = async (url, init) => { if(String(url) === '/api/config') await new Promise(resolve => window.reviewReleaseNext = resolve); return window.reviewFetch(url, init); };
+    window.reviewNext = reviewMount('c');
+  })()`);
+  const actual = await b.evaluate(`Object.fromEntries(['a','b','c'].map(id => [id, { connected:document.querySelector('#review-' + id).isConnected, text:document.querySelector('#review-' + id).textContent }]))`);
+  await b.evaluate('(async () => { reviewReleaseNext(); await reviewNext; })()');
+  assert.deepEqual(errors, []);
+  assert.match(actual.b.text, /newest\.html/);
+  assert.match(actual.c.text, /newest\.html/, 'the shared cache correctly retains the newer mount');
+  assert.doesNotMatch(actual.a.text, /stale\.html|stale-draft\.txt/, 'the superseded live mount must not paint an older result');
+});
+
+test('Files a new container for the same key keeps a completed result while a later read is pending', async t => {
+  const { b, errors } = await orderFixture(t);
+  await b.evaluate(`(() => {
+    window.fetch = async (url, init) => { if(String(url) === '/api/config') await new Promise(resolve => window.reviewReleaseFirst = resolve); return window.reviewFetch(url, init); };
+    window.reviewFirst = reviewMount('a');
+  })()`);
+  await b.evaluate(`(() => {
+    window.fetch = async (url, init) => { if(String(url) === '/api/config') await new Promise(resolve => window.reviewReleaseSecond = resolve); return window.reviewFetch(url, init); };
+    window.reviewSecond = reviewMount('b');
+  })()`);
+  await b.evaluate('(async () => { reviewReleaseFirst(); await reviewFirst; })()');
+  await b.evaluate(`(() => {
+    window.fetch = async (url, init) => { if(String(url) === '/api/config') await new Promise(resolve => window.reviewReleaseThird = resolve); return window.reviewFetch(url, init); };
+    window.reviewThird = reviewMount('c');
+  })()`);
+  const actual = await b.evaluate(`({completed:document.querySelector('#review-a').textContent, newMount:document.querySelector('#review-c').textContent})`);
+  await b.evaluate('(async () => { reviewReleaseSecond(); await reviewSecond; reviewReleaseThird(); await reviewThird; })()');
+  assert.deepEqual(errors, []);
+  assert.match(actual.completed, /seed\.html/);
+  assert.match(actual.newMount, /seed\.html/, 'a completed result exists for this request key');
+});