emrg: GUI disconnected event per-sid isolation — P3 finalize (GUI multi-session rant P3)

[argszero]

Summary

P3 finalize of the GUI multi-session rant (2026-08-10T15:07:19): make the disconnected event fully per-sid — a background session's connection drop must not disturb the global UI (no banner/red dot), while the active session's disconnect keeps the global banner. Completes the P3 event-routing spec after slices 0-2 (#630 chat isolation, #632 sessionsBySid, #634 per-session containers).

Changes

renderer/js/app.js

• sidState entries gain disconnected: false (per-sid disconnect flag, cleared on reconnect).
• disconnected handler: marks the event-sid entry disconnected; global banner + red dot only when the disconnected session is the active one (or sid-less single-session transition — legacy behavior preserved, G89 input restore kept); adds .disconnected to the session's registered container only (guarded by Chat.hasContainer so the fallback chain can't mislabel the active container).
• status connected: clears all disconnected flags and removes .disconnected classes from containers.
• switchSession: switching into a disconnected session shows an i18n notice ("connection lost — reconnecting automatically") while keeping input usable (G89).

renderer/js/chat.js — new hasContainer(sid) API (registered-container check distinct from chatContainer's fallback chain).

renderer/js/i18n.js — app.sessionDisconnected zh/en.

renderer/css/layout.css — .session-view.disconnected visual (dimmed + hatch overlay).

test/renderer.smoke.test.js — +3 tests (bg disconnect no global banner + container marked; reconnect clears flags/classes; unregistered-sid disconnect doesn't mislabel + switch-to-disconnected notice). GUI 153→156 (renderer smoke 43→46); README/README.cn/Agent.md counts synced; 680 pytest green; node --check clean.

Verification

• GUI: 156 tests pass (43+17+22+46+15+7+3+3)
• Python: 680 pytest pass; doc-count guard passes
• node --check clean on touched JS

[argszero]

✅ LGTM — cycle 20260810-173604 (author). P3 finalize: disconnected per-sid isolation; 156 GUI + 680 pytest green.

[pm25coder]

Tested this PR end-to-end on Windows — P3 finalize (disconnected event per-sid isolation) verified.

[argszero]

✅ LGTM — cycle 20260810-174555

Verified on head b006aed: GUI suite 156/156 (renderer smoke 46 — bg session disconnect no global banner/red dot + container .disconnected marker via hasContainer guard; reconnect clears all disconnected flags + container classes; unregistered-sid disconnect doesn't mislabel active container; switch-to-disconnected shows i18n notice while input stays usable G89), 680 pytest green, CLI OK, node --check clean. Doc-count guard synced (156 = 43+17+22+46+15+7+3+3).

[argszero]

✅ LGTM — cycle 20260810-174109

Verified locally on the PR head: GUI suite 156/156 (46 renderer smoke — bg session disconnect no global banner/red dot + container .disconnected marker via hasContainer guard; reconnect clears all disconnected flags + container classes; unregistered-sid disconnect doesn't mislabel the active container (fallback chain guard); switch-to-disconnected shows the i18n notice while keeping input usable), 680 pytest green, doc-count guard passes (156 = 43 dc + 17 cm + 46 renderer smoke + 22 + 15 + 7 + 3 + 3 synced in Agent.md/README/README.cn), node --check clean.

Code review: sidState entries gain disconnected flag (cleared on status connected); global banner + red dot only for active (or sid-less legacy) session; container marked only when Chat.hasContainer(sid) — correctly guards against the chatContainer fallback chain mislabeling; switchSession shows app.sessionDisconnected zh/en notice with G89 input restore; CSS .session-view.disconnected dimmed + hatch overlay. Completes the P3 event-routing spec cleanly on top of #630/#632/#634.