docs(plan): schedule the orphan tmux session client parity work

The server half shipped 2026-07-30 as feature A (4892fa7/f6ef19e/d39a0ab) and
both native clients are at zero. This is NOT a regression — OrphanSessionInfo is
deliberately a separate type rather than a flag on LiveSessionInfo, and
src/server.ts:600 names the reason: the clients decode /live-sessions, so a
variant shape there would have broken them.

It is worth planning anyway because SessionManager.shutdown only detaches the
tmux client for tmux-backed sessions (manager.ts:410-417), so a server restart
or a desktop-app quit turns every session into an orphan. The web launcher lists
them and re-adopts on tap; the phone still shows an empty list — which is the
walk-away case this product exists for.

The plan doc carries the eleven traps a client implementer will hit, each one a
shipped review finding or a documented server subtlety — notably that preview
returns cols/rows of literally 0 (both clients currently size thumbnails from
that response), that a 429 must not collapse to "no orphans", and that the
destructive confirmation must come from count-idle rather than card count (that
one nearly ended 33 shells while the dialog said 24).

Also corrects two now-false claims found while cross-referencing: the ROADMAP
row for tmux discovery was half-stale, and ANDROID_CLIENT_PLAN's do-not-consume
list still listed POST /projects/worktree (both clients consume it now) and
GET /sessions (iOS consumes it, Android does not — so "match iOS" now argues
for building it, not against).

docs/ROADMAP.md

@@ -152,7 +152,7 @@ Consciously punted in the planning docs; several become cheap once the two unloc
 | Cross-session cost rollup / trends | `FEATURE_WALKAWAY_WORKBENCH.md §B2.6` | Bounded ring beside the latest-only field + `GET /telemetry/summary` + dashboard panel. Overlaps the budget-guard quick win. **M.** |
 | Mission Control: cross-session feed + durable run log | (no cockpit persistence today) | Merged reverse-chron feed + append-only on-disk tail (reuse `subscription-store.ts` JSONL/atomic write, byte-capped) so overnight runs survive restart. The "while you were away" digest is its first slice. **M–L.** |
 | Per-project task backlog | task tracking unbuilt | Per-repo TODO store mirroring `prefs-store.ts`; one tap spawns Claude pre-filled. Local state, **not** a GitHub Issues sync (YAGNI). **M.** |
-| Host tmux session discovery + attach | user request (this is not raw-iTerm; needs tmux) | We already run as a tmux client on the user's default tmux server (sessions `web_<id>`), so `tmux ls` already sees manual/iTerm tmux sessions. Add a discovery list + "attach external tmux session" entry in the launcher → spawn a client PTY `tmux attach -t <name>`, wrapped in the session model. **S–M.** |
+| Host tmux session discovery + attach | user request (this is not raw-iTerm; needs tmux) | **Half shipped 2026-07-30** as feature **A** (`4892fa7`/`f6ef19e`/`d39a0ab`): the server enumerates its own untracked `web_<id>` tmux sessions (`GET /orphan-sessions` + 4 routes) and the web launcher shows them in a "可恢复" section — one tap re-adopts via the existing `attach(id)` path. **Remaining (a) — iOS + Android consume it:** see [`plans/w7-orphan-session-clients.md`](./plans/w7-orphan-session-clients.md). **M.** **Remaining (b) — the original ask, still unbuilt:** *foreign* tmux sessions (manual/iTerm, not named `web_*`) are still invisible; feature A deliberately only catalogues our own. **S–M.** |
 
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