feat(tui): add /handoff to fold context and start the next turn (#1153)

* feat(tui): add /handoff to fold context and start the next turn

Compact stops after the fold; handoff pivots, so the optional trailing instructions arm the shared operator fold and the same submit delivers the pivot as the next inbound turn.

* fix(compaction): cancel failed handoff without biasing later folds

* fix(compaction): restore idle arming and prior fold guidance on cancel

* fix(compaction): no-op cancelManual once the handoff fold is spent

Restoring snapshots after the fold (or after a noop arm) wiped sticky
extras and re-armed a second idle compact.

* fix(compaction): spend operator arming on overflow recovery

Overflow compact left /handoff armed, so the pivot folded a
second time. Keepers pin empty-trailing cancel, noop-after-idle
cancel, and TUI uncertain noop.

* test(compaction): name overflow keeper by handoff sequence

Author: TheGreatAxios

docs/PRODUCT.md

@@ -105,7 +105,7 @@ the file path and parse details.
 
 ## Slash Commands (TUI)
 
-The TUI has an extensible slash-command framework. Built-ins include `/help` (shortcut + command overlay), `/model` (models-only picker for connected accounts; **Alt+A** or `/connect` adds a provider), `/settings`, `/permissions`, `/plugins`, `/clear`, `/new`, `/compact` (fold conversation context now, optional trailing instructions to the summarizer; does not wait for the 60% occupancy governor; idle success shows the fold and does not start a new turn), `/mcp` (enable, disable, or remove servers), and `/yolo` (persists as the user-global skip-permissions default; `--dangerously-skip-permissions` still forces this process; secret-guard and authz still apply; `/yolo [on|off|toggle]`, bare `/yolo` toggles), plus a `/<name>` command per available workflow. When a session starts with the persisted default already on, the TUI shows a startup notice ("Permission prompts are disabled by your saved default…") so the silent machine-wide default is never invisible; `corbits exec` prints the equivalent warning to stderr. Plugins can register additional commands.
+The TUI has an extensible slash-command framework. Built-ins include `/help` (shortcut + command overlay), `/model` (models-only picker for connected accounts; **Alt+A** or `/connect` adds a provider), `/settings`, `/permissions`, `/plugins`, `/clear`, `/new`, `/compact` (fold conversation context now, optional trailing instructions to the summarizer; does not wait for the 60% occupancy governor; idle success shows the fold and does not start a new turn), `/mcp` (enable, disable, or remove servers), `/handoff [optional instructions]` (folds context through the shared operator pipeline, then immediately starts the next turn with the instructions as the inbound content — default copy when omitted; unlike `/compact`, which stops after the fold, handoff always re-infers, so the operator can pivot goals without `/clear`; a handoff issued mid-tool-batch queues behind the in-flight batch and whichever boundary fires first runs the single fold), and `/yolo` (persists as the user-global skip-permissions default; `--dangerously-skip-permissions` still forces this process; secret-guard and authz still apply; `/yolo [on|off|toggle]`, bare `/yolo` toggles), plus a `/<name>` command per available workflow. When a session starts with the persisted default already on, the TUI shows a startup notice ("Permission prompts are disabled by your saved default…") so the silent machine-wide default is never invisible; `corbits exec` prints the equivalent warning to stderr. Plugins can register additional commands.
 
 **Default skills** exist out of the gate as first-party slash **actions**, not director names: `/implement`, `/plan`, `/refactor`, `/review`, `/pull-request-review`, `/create-issue`, `/scribe`, `/interview`, `/ast-grep`, `/lexicon`. Each one is a how-to playbook — the slash sends the skill body to the primary, which follows the steps. Skills do not assign identity or route the fleet; that stays on director system prompts. `/review` classifies the target first, then dispatches a selected fleet; `/pull-request-review` is worktree checkout plus a surface pass, loading `/review` for quality rules only; `/scribe` is how to maintain PRODUCT / ARCHITECTURE / IMPLEMENTATION; `/implement` is the per-commit review/build/critique loop — it does not steal planning from `/plan`. Substantial Builder work consumes a counsel / `/plan` plan first; tiny parent-DIY stays plan-optional. `/plan` authors an eng change plan (files, AC, non-goals, risks, ordered steps) and does not implement. `/create-issue` remains the tracker command: Linear MCP when available; otherwise it `ask_operator`s for the platform (GitHub etc.) and persists `Preferred issue tracker` in `.corbits/MEMORY.md` (GitHub via `gh issue create`). `/lexicon` owns director-prompt drift and size against the agents repo at a pinned commit. There is no first-party dispatch skill — Skywalker orchestrates natively. `git-rebase`, `linear-issue-workflow`, `style`, `philosophy`, `native-integration`, `typescript`, `ponytail`, and `opsh` stay `use_skill` only (`user-invocable: false`). Bake-only bars such as `idiot-proof` and `native-runtime` are not slashes and are not listed for `use_skill`. Draper and emil are not slashes; they remain closed directors via `spawn_agent(agent=…)`. There is no catch-all worker. Slash names are also available to the model via `skill_search` (descriptions) then `use_skill` (body). Disable the catalog in `/plugins` (`corbits-skills`) if you want them gone.