Release XX (v0.51.668): WebUI<->Desktop session reconciliation (#4834, fixes #4833)

[nesquena-hermes]

Release XX (v0.51.668) — WebUI stays in sync after the Desktop app continues a session

Ships #4834 (@franksong2702, T1) — fixes #4833. Anchor-B (continue a WebUI session from the official Hermes Desktop app) + Anchor-A (session state is core).

What it fixes

After the Desktop app continues a WebUI-origin session (appending settled rows to the shared Agent state.db) and you return to WebUI, the sidebar/detail showed a stale/incomplete transcript and the next WebUI turn's context missed the externally-appended settled messages. Fix: batch-read state.db count+max-ts in the sidebar override helper + overlay newer WebUI-origin state.db onto stale sidecar rows only when the DB strictly grew; make /api/sessions cache stamps observe state.db even when CLI sessions are hidden (active-stream hold-down preserved). Read-only, metadata-only — no Desktop change, no live-stream mirroring.

Gate (converged after a prior bounce)

The reconciliation LOGIC was already validated SAFE by the prior dual-gate (read-only/content-free overlay). The bounce was a parallel test-isolation regression (test_session_list_cache_follower_wait_stage_when_rebuild_inflight failed under xdist because the always-on state.db stamp perturbed shared cache state). The re-push isolated the cache tests + a try/int() coercion fix.

• Codex: SAFE TO SHIP — test-isolation fix is test-only (autouse cache-clear fixture + stable-stamp pin); the two prod-behavior changes are the intended feature (guard removal) + a legitimate stale-while-revalidate consequence (traced); overlay metadata-only, gated state_db_source=='webui' + strictly-grew (no resurrection), full transcript still via append-only reconciliation.
• Opus: SHIP IT — same conclusions, confirmed prior SAFE finding holds at HEAD.
• Full xdist suite: 10631 passed (the prior failing follower_wait regression test now PASSES under the full parallel run; 1 unrelated known order-flake passes in isolation).
• Pre-merge head re-check: gated == live (3ec1da6).

Credit @franksong2702.

[greptile-apps]

Greptile Summary

This PR keeps WebUI session views in sync after Desktop appends settled messages. The main changes are:

• Sidebar metadata now reads message count and latest timestamp from state.db.
• WebUI-origin sidebar rows can overlay newer settled state.db counts.
• Session-list cache stamps now observe state.db while CLI sessions are hidden.
• Missing sidecar rows can be recovered into the sidebar index.
• Tests cover cache isolation, stale follower reuse, Desktop append reconciliation, and full-load deduplication.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
api/models.py	Adds read-only state.db sidebar metadata, guarded WebUI-origin overlays, and recovery for sidecars missing from the index.
api/routes.py	Updates session-list cache behavior so stale follower payloads can be reused and hidden-CLI views still notice state.db changes.
tests/test_session_sidebar_cache.py	Adds cache-state isolation and tests for singleflight and stale follower behavior.
tests/test_streaming_session_sidebar.py	Adds coverage for recovering a messageful sidecar that is missing from the sidebar index.
tests/test_webui_state_db_context_reconciliation.py	Adds persistence checks for externally appended messages included in the next WebUI turn.
tests/test_webui_state_db_reconciliation.py	Adds tests for sidebar overlay counts, Desktop append reconciliation, and full session-load deduplication.
CHANGELOG.md	Adds the release note for v0.51.668.

_{Reviews (1): Last reviewed commit: "Release XX (v0.51.668): WebUI<->Desktop ..." | Re-trigger Greptile}