[SchrodingersCattt]

Summary

Part of #228.

agent-state-poll could still publish a snapshot that was frozen before the browser switched scenes or edited. Sidebar drafts already visible in that request stayed put (#229). Groups, transforms, polyhedra, selection, and the filled-scene guard did not.

This covers the remaining high-severity checkbox on #228: agent-state-poll races user edits and tab switches (the rename box and in-flight sidebar path are already handled by #226 and #229).

• Each browser records the scene it selected and the interaction generation of its latest edit. A poll for a scene that browser has left, or for an older generation, returns no update. It does not move the filled-scene guard and does not drop a queued snapshot it cannot publish.
• The browser drops a pure state-poll response that arrives after a tab switch or edit, and a poll that was sent while that callback is still unacknowledged. A tab switch or upload batched into the same request still applies. camera-state-store stays untouched on the poll path.
• The first Dash callback runs at generation 0. That generation still releases the in-flight count, so a later edit does not leave state polls blank. Those polls are what copy a server projection onto the view radio and refresh the controls stamp.
• Calls that do not send the fence (existing direct tests) keep the previous contract, including in-flight sidebar drafts and the rename box.

This does not address #163. The figure-settle latency item on #228 remains.

Test plan

• python3 -m pytest tests/app/test_poll_interaction_fence.py
• Local Camera WebGL suite: the six previously red settle cases pass. tests/app/test_camera_browser_regression.py, tests/app/test_real_app_browser_regression.py, and tests/app/test_layout_responsive.py — 25 passed, and test_two_browsers_keep_separate_scenes_during_upload passed on a rerun after one isolated miss in the full local run.

  

[SchrodingersCattt]

Review @ 39305c28 (Part of #228)

Verdict: approve-ready pending remaining CI (COMMENT only; no self-APPROVE).

What looks right

• Covers the open high Latency checkbox after #226/#229: server-side scene + interaction-generation fence (poll_request_is_stale / claim_poll_publish) plus browser poll_fence.js for responses that race an in-flight tab switch/edit.
• Pure poll vs batched tab-switch/upload distinction is clear; camera store left alone on the poll path; rename / in-flight sidebar drafts left as #226/#229.
• Wording avoids GitHub auto-close keywords for #163 (does not address #163).
• Focused tests in tests/app/test_poll_interaction_fence.py; agent reported local 1990 passed / 70 skipped.

CI at review time

5/9 green (build, bench smoke, fast×2, CPU smoke). Still running: Full tests 3.10/3.11/3.12 + Camera WebGL. Agent says WebGL path untouched — still wait for green before merge.

Hold

Do not squash-merge until all 9 checks are green. Figure-settle / busy-pill remains on #237.