fix: make session ordering follow activity lifecycle

Session lists now promote a conversation when it starts working and again when it settles, instead of reacting to every streaming timestamp update. This keeps ordering responsive without bringing back the sidebar churn removed by the recent performance work.

Apply the same user-visible order across Recent, project and worktree groups, session switchers, mobile navigation, widgets, the command palette, and the desktop tray. Preserve pinned priority, freeze timestamp fallback ordering, and keep child-session activity scoped to siblings under the same parent so it never moves the root conversation.

Seed reconnect snapshots without synthetic jumps, clear ephemeral ranks on deletion and runtime changes, and cover lifecycle transitions, mixed root/child trees, metadata-only updates, and project-group ordering with regression tests.

packages/ui/src/sync/DOCUMENTATION.md

@@ -44,6 +44,7 @@ So:
 | `ChildStoreManager` and child directory stores | Priority-scheduled directory bootstrap plus `session`, `message`, `part`, `permission`, `question`, etc. | One runtime and one store per directory |
 | `SessionMessageLoader` | Initial message loading, pagination, prefetch, retries, load state, and optimistic reconciliation | One runtime, directory, and session ID |
 | `global-session-status.ts` | Incremental non-idle session status index reconciled from events and authoritative directory snapshots | All known directories in the active runtime |
+| `session-ordering.ts` | Ephemeral lifecycle rank used by every user-visible session list | All known sessions in the active runtime |
 | `session-ui-store.ts` | Session selection, draft lifecycle, abort prompts, worktree metadata, SDK-facing action entrypoints | App UI state |
 | `useGlobalSessionsStore.ts` | Global active sessions, global archived sessions, `sessionsByDirectory` | All opened project/worktree session lists |
 | `viewport-store.ts` | Scroll anchors, session memory, loading indicators | App UI state |
@@ -125,6 +126,8 @@ Current consumers:
 
 Cross-directory selectors subscribe to the narrow child-store field they aggregate. Session aggregation listens to `state.session`. Live busy/retry state is also maintained in `global-session-status.ts`, where each row subscribes to one session ID instead of scanning every child store. Events update the index incrementally; authoritative per-directory status snapshots seed it, clear sessions omitted as idle, and reconcile missed events. Unrelated streaming events such as `message.part.delta` must not trigger global session/status scans.
 
+Session display order is independent from streaming-frequency `time.updated` publications. `session-ordering.ts` promotes a session exactly when its authoritative activity phase crosses `settled` (`idle`/`error`) and `active` (`busy`/`retry`) in either direction. Repeated busy/retry or idle/error events are no-ops. The first authoritative status snapshot establishes a baseline without synthetic promotions; later snapshots reconcile missed transitions. Root sessions compare lifecycle rank only with other roots, while child sessions compare lifecycle rank only with siblings sharing the same `parentID`, so child activity never moves its root conversation. Pins remain the first ordering bucket. The timestamp/creation fallback is frozen when a session first participates in ordering, so later metadata-only updates cannot reorder it; creation time and ID provide deterministic ties. Runtime switches clear all phases, baselines, and ranks.
+
 Imperative cross-directory session lookups use the cached ID index from `getAllSyncSessionMap()`. The index is rebuilt only when a child store's `state.session` reference changes; permission lineage checks must reuse it instead of rebuilding a full session map per call.
 
 VS Code does not run the server permission-auto-accept runtime. The extension host persists and broadcasts authoritative policy, while its foreground UI runtime resolves missing child-session lineage through the OpenCode API before deciding whether to suppress and answer a `permission.asked` event. Enabling the policy and reconnect/bootstrap both reconcile pending requests in the session directory, including requests inherited by child sessions. Unknown lineage and exhausted reply retries fail closed and leave the request available for manual action. A later `permission.replied` event invalidates any older deferred ask so the async policy check cannot resurrect a resolved request. With every OpenChamber webview closed or suspended no responder runs; this is an intentional VS Code limitation. Other runtimes remain fully server-owned.
@@ -134,7 +137,7 @@ VS Code does not run the server permission-auto-accept runtime. The extension ho
 `useGlobalSessionsStore` is kept correct by:
 
 1. shared global fetch/reconciliation via `loadSessions()` / `refreshGlobalSessions()`
-2. session create/update/delete events; recency-only updates for existing sessions are retained latest-per-session and committed once on `session.idle`/`session.error`, while structural updates and create/delete remain immediate and runtime switching discards pending updates
+2. session create/update/delete events; recency-only updates for existing sessions are retained latest-per-session and committed once on `session.idle`/`session.error`, while structural updates and create/delete remain immediate and runtime switching discards pending updates. Display ordering reacts separately to active/settled lifecycle transitions, not to these recency publications
 3. direct mutation from session actions after successful SDK calls:
    - create
    - title update