diff --git a/.github/workflows/triage.yaml b/.github/workflows/triage.yaml
new file mode 100644
index 000000000..155922da0
--- /dev/null
+++ b/.github/workflows/triage.yaml
@@ -0,0 +1,61 @@
+# Copyright 2025 The Flutter Authors.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# This automation adds/removes the 'status: needs-triage' label to pull requests
+# so that PRs needing attention are easy to find. The label is fully owned by
+# this automation and reconciled on every run.
+#
+# The flagging rules live in ./tool/triage.mjs — see the header comment there
+# for the full specification:
+# https://github.com/flutter/genui/blob/main/tool/triage.mjs
+#
+# For the history of runs, see:
+# https://github.com/flutter/genui/actions/workflows/triage.yaml
+
+
+name: Flag/Unflag pull requests
+
+on:
+  # Periodic reconciliation: catches time-based rules (staleness) and removes the
+  # label once a PR no longer matches.
+  schedule:
+    - cron: "0 15 * * *" # daily at 15:00 UTC
+  # React promptly to the events that can change a PR's flag state.
+  pull_request_target:
+    types: [opened, edited, reopened, ready_for_review, synchronize]
+  issue_comment:
+    types: [created]
+  pull_request_review:
+    types: [submitted]
+  pull_request_review_comment:
+    types: [created]
+  # Allow manual runs from the Actions tab.
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  triage:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+        with:
+          persist-credentials: false
+
+      - name: Reconcile triage flag labels
+        uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v7
+        with:
+          script: |
+            const path = require('path');
+            const { pathToFileURL } = require('url');
+
+            const filePath = path.resolve('./tool/triage.mjs');
+            const fileUrl = pathToFileURL(filePath).href;
+
+            const importedModule = await import(fileUrl);
+            await importedModule.default({ github, context });
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 050e4d53b..593464be8 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -8,7 +8,7 @@ Please follow:
 
 ## Issues
 
-File issues against the [A2UI project](https://github.com/a2ui-project/a2ui/issues).
+File issues against the [A2UI project](https://github.com/a2ui-project/a2ui/issues), with label [component: genui](https://github.com/a2ui-project/a2ui/labels?q=genui).
 
 See explanation of triage process in [A2UI CONTRIBUTING.md](https://github.com/a2ui-project/a2ui/blob/main/CONTRIBUTING.md).
 
diff --git a/tool/triage.mjs b/tool/triage.mjs
new file mode 100644
index 000000000..e1a24ed51
--- /dev/null
+++ b/tool/triage.mjs
@@ -0,0 +1,236 @@
+/*
+ * Copyright 2025 The Flutter Authors.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+// Reconciles the 'status: needs-triage' label across all open pull requests. The
+// label is fully owned by this automation: it is added to every PR that matches
+// the rule below and removed from every PR that does not, on each run.
+//
+// A PR is flagged when it is a stale PR opened by an external contributor (PRs
+// from maintainers are managed by their authors).
+//
+// "Stale" is measured from the last human contribution (a comment, review, or
+// inline review comment, or the opening post if there are none) rather than
+// `updated_at`, so the bot's own label edits never reset the clock. A PR is
+// "stale" when no internal member has responded after the external author's last
+// contribution for more than a day.
+//
+// Flagged PRs:
+// https://github.com/flutter/genui/pulls?q=state%3Aopen%20label%3A%22status%3A%20needs-triage%22
+//
+// The job prints to console what PRs are flagged/unflagged and why. To see the
+// history of runs see:
+// https://github.com/flutter/genui/actions/workflows/triage.yaml
+
+export const FLAG_LABEL = 'status: needs-triage';
+
+export const PR_STALE_DAYS = 1;
+
+const DAY_MS = 24 * 60 * 60 * 1000;
+
+// Author associations that count as an internal maintainer response.
+const MAINTAINER_ASSOCIATIONS = new Set(['OWNER', 'MEMBER', 'COLLABORATOR']);
+
+// A deleted account surfaces as a null `user`; treat that as a human so their
+// past contributions still count, rather than silently classifying them as a bot.
+export const isBot = user =>
+  Boolean(user) && (user.type === 'Bot' || /\[bot\]$/.test(user.login || ''));
+
+const labelNames = item =>
+  (item.labels || []).map(label => (typeof label === 'string' ? label : label.name));
+
+const ageInDays = (isoTimestamp, now) => (now - new Date(isoTimestamp).getTime()) / DAY_MS;
+
+/**
+ * Returns the most recent human contribution to a PR: either its newest non-bot
+ * contribution (a comment, review, or inline review comment), or — if there are
+ * none — the opening post itself. Used both to measure staleness and to decide
+ * whether an external author is still awaiting a maintainer response.
+ *
+ * `contributions` is the merged, normalized event list from `fetchContributions`.
+ * It comes from three different endpoints so it is not sorted; the scan picks the
+ * latest regardless of order.
+ */
+export function lastHumanContribution(item, contributions) {
+  let latest = {
+    createdAt: item.created_at,
+    association: item.author_association,
+    user: item.user,
+  };
+
+  for (const event of contributions) {
+    if (isBot(event.user)) continue;
+    if (new Date(event.createdAt) >= new Date(latest.createdAt)) {
+      latest = event;
+    }
+  }
+
+  return latest;
+}
+
+/**
+ * Returns a human-readable reason why a single open PR should carry the flag
+ * label, or null if it should not. The reason is logged for visibility.
+ *
+ * Only external contributors' PRs are watched; maintainers manage their own, so
+ * an internally-authored PR is never flagged. A PR is "stale" when no internal
+ * member has responded (via a comment, review, or inline review comment) after
+ * the external author's last contribution for more than a day.
+ */
+export function flagReason(item, contributions, now) {
+  if (MAINTAINER_ASSOCIATIONS.has(item.author_association)) {
+    return null;
+  }
+
+  const latest = lastHumanContribution(item, contributions);
+  const staleDays = ageInDays(latest.createdAt, now);
+
+  // True when the most recent human contribution is from outside the team — no
+  // internal member has commented after the external author's last word.
+  const awaitingMember = !MAINTAINER_ASSOCIATIONS.has(latest.association) && !isBot(latest.user);
+
+  return awaitingMember && staleDays > PR_STALE_DAYS
+    ? `no maintainer has responded to the author for more than ${PR_STALE_DAYS} day.`
+    : null;
+}
+
+// Max concurrent API calls per phase. Keeps us fast without tripping GitHub's
+// secondary (abuse) rate limits, which a single huge Promise.all can hit.
+const BATCH_SIZE = 10;
+
+/**
+ * Maps `items` through async `fn` in concurrent batches of `BATCH_SIZE` rather
+ * than all at once, bounding the number of in-flight requests.
+ */
+async function mapInBatches(items, fn) {
+  const results = [];
+  for (let i = 0; i < items.length; i += BATCH_SIZE) {
+    const batch = items.slice(i, i + BATCH_SIZE);
+    results.push(...(await Promise.all(batch.map(fn))));
+  }
+  return results;
+}
+
+// Normalizes the different GitHub contribution shapes into a common
+// `{createdAt, association, user}` event. Reviews stamp their submission time in
+// `submitted_at`; issue and inline review comments use `created_at`.
+const toEvent = contribution => ({
+  createdAt: contribution.created_at || contribution.submitted_at,
+  association: contribution.author_association,
+  user: contribution.user,
+});
+
+/**
+ * Gathers every human-visible contribution to a PR — top-level issue comments,
+ * formal reviews, and inline review comments — as a flat list of normalized
+ * events. All three matter: a maintainer often responds by submitting a review
+ * or leaving inline comments without posting a separate top-level comment, so
+ * considering only issue comments would wrongly treat the PR as unanswered. A
+ * failure for one source must not abort the whole run, so errors fall back to an
+ * empty list for that source.
+ */
+async function fetchContributions({github, owner, repo}, item) {
+  const number = item.number;
+
+  const fetchAll = async (label, endpoint, params) => {
+    try {
+      return await github.paginate(endpoint, {owner, repo, per_page: 100, ...params});
+    } catch (error) {
+      console.error(`Failed to fetch ${label} for #${number}:`, error);
+      return [];
+    }
+  };
+
+  const [issueComments, reviews, reviewComments] = await Promise.all([
+    // The issue-comment count is on the list item, so skip the call when it is
+    // zero; reviews and review comments have no such hint and are always fetched.
+    item.comments
+      ? fetchAll('comments', github.rest.issues.listComments, {issue_number: number})
+      : [],
+    fetchAll('reviews', github.rest.pulls.listReviews, {pull_number: number}),
+    fetchAll('review comments', github.rest.pulls.listReviewComments, {pull_number: number}),
+  ]);
+
+  return [...issueComments, ...reviews, ...reviewComments].map(toEvent);
+}
+
+export default async function prTriage({github, context}) {
+  console.log('GenUI PR triage-flag reconciliation started');
+
+  const {owner, repo} = context.repo;
+  const now = Date.now();
+
+  // `listForRepo` returns both issues and PRs; PRs carry a `pull_request` key.
+  // We only reconcile PRs here.
+  const openItems = await github.paginate(github.rest.issues.listForRepo, {
+    owner,
+    repo,
+    state: 'open',
+    per_page: 100,
+  });
+  const openPRs = openItems.filter(item => Boolean(item.pull_request));
+
+  // Fetch each PR's contributions in bounded concurrent batches to avoid a slow
+  // serial loop without flooding the API.
+  const itemsWithContributions = await mapInBatches(openPRs, async item => ({
+    item,
+    contributions: await fetchContributions({github, owner, repo}, item),
+  }));
+
+  // Decide each PR's desired state from the snapshot, and keep only those whose
+  // label needs to change. The snapshot from `listForRepo` can be stale if
+  // another run (the daily schedule overlapping a PR event) already changed the
+  // label, so the actual mutation re-checks the live state below.
+  const itemsToUpdate = itemsWithContributions
+    .map(({item, contributions}) => ({item, reason: flagReason(item, contributions, now)}))
+    .filter(({item, reason}) => Boolean(reason) !== labelNames(item).includes(FLAG_LABEL));
+
+  let added = 0;
+  let removed = 0;
+
+  await mapInBatches(itemsToUpdate, async ({item, reason}) => {
+    const wantsFlag = Boolean(reason);
+    try {
+      // Re-read the live labels so a concurrent run cannot make us add the
+      // label twice.
+      const {data: fresh} = await github.rest.issues.get({
+        owner,
+        repo,
+        issue_number: item.number,
+      });
+      const hasFlag = labelNames(fresh).includes(FLAG_LABEL);
+      if (wantsFlag === hasFlag) {
+        return; // Another run already reconciled this PR.
+      }
+
+      if (wantsFlag) {
+        await github.rest.issues.addLabels({
+          owner,
+          repo,
+          issue_number: item.number,
+          labels: [FLAG_LABEL],
+        });
+        added += 1;
+        console.log(`Flagged ${item.html_url} — ${reason}`);
+      } else {
+        await github.rest.issues.removeLabel({
+          owner,
+          repo,
+          issue_number: item.number,
+          name: FLAG_LABEL,
+        });
+        removed += 1;
+        console.log(`Unflagged ${item.html_url} — no longer matches the triage rule.`);
+      }
+    } catch (error) {
+      console.error(`Failed to update #${item.number}:`, error);
+    }
+  });
+
+  console.log(
+    `GenUI PR triage-flag reconciliation completed: ` +
+      `${openPRs.length} PRs, +${added} / -${removed} label changes`,
+  );
+}