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Merged
SchrodingersCattt merged 3 commits into from
Oct 26, 2026
Merged

Keep state polls from overwriting newer edits and tab switches #242

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678b613
Keep state polls from publishing over a newer edit or tab
cursoragent Oct 25, 2026
39305c2
Share the poll-fence stores between the two app layouts
cursoragent Oct 25, 2026
e31b32a
Release the poll fence after the first generation
cursoragent Oct 25, 2026
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6 changes: 6 additions & 0 deletions docs/redesign/callbacks.md
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,12 @@ the full reducer migration:
calls `set_props("scene-tabs", ...)`.
- `sync_agent_state` still updates control props on tab switches and agent
polls, but it no longer writes the tab DOM.
- A state poll whose browser has switched scenes, or whose interaction
generation is older than an edit already noted for that browser, does
not write controls or `agent-state-store`. The browser also drops a
poll response that arrives after a tab switch or while that edit's
callback is still unacknowledged. The next poll carries the new
generation. Part of #228.

This is not the final operation reducer, but it establishes the invariant that
the visible scene list has one writer and one source of truth.
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282 changes: 282 additions & 0 deletions frontend/assets/poll_fence.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,282 @@
/* Drop a state-poll response that would land on top of a newer edit or tab.

``sync_agent_state`` preserves sidebar drafts it can see in the request, and
it refuses a poll whose browser has already recorded a newer scene or
generation. This script covers the remaining window: the poll request left
the browser, the user then switched tabs or edited, and the response
arrives afterwards. A poll sent while that edit's callback is still
unacknowledged is dropped too, because the server may have answered from
the pre-edit snapshot. Dash would apply that response directly, including
``agent-state-store`` (groups, transforms, polyhedra, selection) and the
shared sidebar. Rewriting the payload to an empty update leaves the newer
interaction in place. The next poll carries the new generation.

A tab click or upload batched into the same request is that interaction's
own sync and must still apply.
*/
(function (root) {
var MODIFIERS = {Shift: 1, Control: 1, Alt: 1, Meta: 1};

var UNACKED_RELEASE_MS = 800;

function liveFence() {
return {
epoch: Number(root.__mvUiEpoch || 0),
scene: root.__mvSelectedSceneId ? String(root.__mvSelectedSceneId) : "",
unacked: Number(root.__mvUnackedEpoch || 0),
};
}

function sceneIdFromNode(node) {
if (!node || !node.closest) return "";
var select = node.closest(".tab-select");
if (select && select.id) {
try {
var parsed = JSON.parse(select.id);
if (parsed && parsed.scene_id) return String(parsed.scene_id);
} catch (error) {
/* Pattern ids are JSON; a plain id is handled below. */
}
}
var tab = node.closest("[id^='scene-tab-']");
if (!tab || !tab.id || tab.id === "scene-tabs") return "";
if (tab.id.indexOf("scene-tab-close-") === 0) return "";
if (tab.id.indexOf("scene-tab-label-") === 0) {
return tab.id.slice("scene-tab-label-".length);
}
return tab.id.slice("scene-tab-".length);
}

function armUnackedRelease(epoch) {
if (typeof root.setTimeout !== "function") return;
root.setTimeout(function () {
if (Number(root.__mvUnackedEpoch || 0) !== Number(epoch || 0)) return;
if (Number(root.__mvUserWrites || 0) > 0) return;
root.__mvUnackedEpoch = 0;
}, UNACKED_RELEASE_MS);
}

function finishUserWrite(startedEpoch) {
root.__mvUserWrites = Math.max(0, Number(root.__mvUserWrites || 1) - 1);
if (Number(root.__mvUserWrites || 0) > 0) return;
if (Number(root.__mvUiEpoch || 0) !== Number(startedEpoch || 0)) return;
root.__mvUnackedEpoch = 0;
}

function noteInteraction(sceneId) {
root.__mvUiEpoch = Number(root.__mvUiEpoch || 0) + 1;
if (sceneId) root.__mvSelectedSceneId = String(sceneId);
root.__mvUnackedEpoch = root.__mvUiEpoch;
armUnackedRelease(root.__mvUnackedEpoch);
if (root.__mvFenceFlush) return;
root.__mvFenceFlush = true;
var publish = function () {
root.__mvFenceFlush = false;
var clientside = root.dash_clientside;
if (!clientside || typeof clientside.set_props !== "function") return;
if (!root.__mvClientId) {
root.__mvClientId = "mv-" + Math.random().toString(36).slice(2, 12);
clientside.set_props("ui-client-id", {data: root.__mvClientId});
}
clientside.set_props("ui-interaction-epoch", {data: Number(root.__mvUiEpoch || 0)});
};
if (typeof root.Promise === "function") root.Promise.resolve().then(publish);
else publish();
}

function isAgentStatePoll(body) {
if (!body || typeof body !== "object") return false;
var changed = body.changedPropIds || [];
var names = [];
var index;
for (index = 0; index < changed.length; index += 1) {
names.push(String(changed[index]).split(".")[0]);
}
if (names.indexOf("agent-state-poll") === -1) return false;
if (names.indexOf("scene-tabs") !== -1) return false;
if (names.indexOf("native-upload-sync") !== -1) return false;
if (names.indexOf("display-defaults-btn") !== -1) return false;
var rendered = JSON.stringify(body.output == null ? "" : body.output);
return rendered.indexOf("agent-state-store") !== -1
&& rendered.indexOf("scene-tab-rename-input") !== -1;
}

function isBackgroundTick(body) {
if (!body || typeof body !== "object") return false;
var changed = body.changedPropIds || [];
if (!changed.length) return false;
var prefixes = ["agent-state-poll.", "perf-log-poll.", "status-dismiss-timer."];
var index;
var prop;
var prefix;
var matched;
for (index = 0; index < changed.length; index += 1) {
prop = String(changed[index]);
matched = false;
for (prefix = 0; prefix < prefixes.length; prefix += 1) {
if (prop.indexOf(prefixes[prefix]) === 0) {
matched = true;
break;
}
}
if (!matched) return false;
}
return true;
}

function isUserWrite(bodyText) {
if (typeof bodyText !== "string" || !bodyText) return false;
try {
return !isBackgroundTick(JSON.parse(bodyText));
} catch (error) {
return false;
}
}

function requestFence(bodyText, live) {
if (typeof bodyText !== "string" || !bodyText) return null;
var body;
try {
body = JSON.parse(bodyText);
} catch (error) {
return null;
}
if (!isAgentStatePoll(body)) return null;
var snapshot = live || liveFence();
return {
epoch: Number(snapshot.epoch || 0),
scene: snapshot.scene ? String(snapshot.scene) : "",
unacked: Number(snapshot.unacked || 0),
};
}

function responseIsStale(tracked, live) {
if (!tracked) return false;
var now = live || liveFence();
// Sent while an edit or tab callback was still open, or one opened
// before this response could be applied.
if (Number(tracked.unacked || 0) > 0) return true;
if (Number(now.unacked || 0) > 0) return true;
if (Number(now.epoch || 0) !== Number(tracked.epoch || 0)) return true;
var thenScene = tracked.scene ? String(tracked.scene) : "";
var nowScene = now.scene ? String(now.scene) : "";
return Boolean(thenScene && nowScene && thenScene !== nowScene);
}

function blankPollPayload(payload) {
if (!payload || typeof payload !== "object") return payload;
var copy = {};
var key;
for (key in payload) {
if (Object.prototype.hasOwnProperty.call(payload, key)) copy[key] = payload[key];
}
copy.response = {};
if (copy.sideUpdate && typeof copy.sideUpdate === "object") copy.sideUpdate = {};
return copy;
}

function install() {
if (root.__mvPollFenceInstalled) return;
root.__mvPollFenceInstalled = true;
var documentRef = root.document;
if (!documentRef || typeof documentRef.addEventListener !== "function") return;

documentRef.addEventListener("pointerdown", function (event) {
if (!event || event.isTrusted === false) return;
var node = event.target;
if (!node || !node.closest) return;
if (node.closest("#rightclick-target-fallback")) return;
noteInteraction(sceneIdFromNode(node));
}, true);

documentRef.addEventListener("keydown", function (event) {
if (!event || event.isTrusted === false || MODIFIERS[event.key]) return;
var node = event.target;
if (!node || !node.closest) return;
if (!node.closest("input, textarea, select")) return;
if (node.id === "rightclick-target-fallback") return;
noteInteraction(null);
}, true);

function publishIdentity() {
var clientside = root.dash_clientside;
if (!clientside || typeof clientside.set_props !== "function") return false;
if (!root.__mvClientId) {
root.__mvClientId = "mv-" + Math.random().toString(36).slice(2, 12);
}
clientside.set_props("ui-client-id", {data: root.__mvClientId});
clientside.set_props("ui-interaction-epoch", {data: Number(root.__mvUiEpoch || 0)});
return true;
}
if (!publishIdentity() && typeof root.setTimeout === "function") {
var attempts = 0;
var timer = root.setInterval(function () {
attempts += 1;
if (publishIdentity() || attempts > 40) root.clearInterval(timer);
}, 250);
}

if (typeof root.fetch !== "function" || root.fetch.__mvPollFence) return;
var originalFetch = root.fetch;
var wrapped = function (input, init) {
var url = typeof input === "string" ? input : (input && input.url) || "";
var bodyText = init && typeof init.body === "string" ? init.body : "";
var tracked = null;
var userWriteEpoch = 0;
if (String(url).indexOf("_dash-update-component") !== -1) {
var live = liveFence();
tracked = requestFence(bodyText, live);
if (!tracked && isUserWrite(bodyText)) {
userWriteEpoch = Number(live.epoch || 0);
root.__mvUserWrites = Number(root.__mvUserWrites || 0) + 1;
}
}
var pending = originalFetch.apply(this, arguments);
if (userWriteEpoch && pending && typeof pending.then === "function") {
var startedEpoch = userWriteEpoch;
pending = pending.then(function (response) {
finishUserWrite(startedEpoch);
return response;
}, function (error) {
finishUserWrite(startedEpoch);
throw error;
});
} else if (userWriteEpoch) {
finishUserWrite(userWriteEpoch);
}
if (!tracked || !pending || typeof pending.then !== "function") return pending;
return pending.then(function (response) {
if (!response || typeof response.clone !== "function") return response;
return response.clone().json().then(function (payload) {
if (!responseIsStale(tracked, liveFence())) return response;
var headers = new root.Headers(response.headers);
headers.delete("content-length");
headers.delete("content-encoding");
return new root.Response(JSON.stringify(blankPollPayload(payload)), {
status: response.status,
statusText: response.statusText,
headers: headers,
});
}, function () {
return response;
});
});
};
wrapped.__mvPollFence = true;
root.fetch = wrapped;
}

var api = {
noteInteraction: noteInteraction,
sceneIdFromNode: sceneIdFromNode,
isAgentStatePoll: isAgentStatePoll,
requestFence: requestFence,
responseIsStale: responseIsStale,
blankPollPayload: blankPollPayload,
isUserWrite: isUserWrite,
finishUserWrite: finishUserWrite,
install: install,
};
root.MatterVisPollFence = api;
install();
})(typeof window !== "undefined" ? window : globalThis);
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