Adding rewound as an explicit named kwarg on MemoryManager.on_session_switch
broke existing tests that assert exact equality on the extra kwargs dict
captured by providers (test_manager_fans_out_to_all_providers,
test_manager_reset_flag_preserved).

The MemoryProvider base class still documents rewound as a known kwarg,
but the manager now passes it through **kwargs like any other forwarded
flag. The CLI rewind handler already passes rewound=True keyword-style,
so behavior is identical.

…ousResearch#21910)

Adds the TUI half of the /rewind feature so the Ink terminal UI gets
the same affordance as the prompt_toolkit CLI.

Python side (tui_gateway/server.py):
- /rewind added to _PENDING_INPUT_COMMANDS so slash.exec rejects it
  and the TUI falls through to command.dispatch (the only path with
  access to live session state + memory hooks).
- New command.dispatch branch for name == "rewind":
  v1 auto-picks the most recent user turn (Claude-Code-style single-
  step undo), calls SessionDB.rewind_to_message, refreshes the
  in-memory history, fires _memory_manager.on_session_switch with
  rewound=True, and returns the new "prefill" payload.
- A dedicated picker overlay (multi-step rewind) is tracked as a
  follow-up to NousResearch#21910.

TS side (ui-tui/src/):
- New "prefill" variant on CommandDispatchResponse + asCommandDispatch
  validator. Mirrors "send" but does NOT auto-submit; the client drops
  the message into the composer for editing.
- createSlashHandler renders the optional notice via sys() and calls
  ctx.composer.setInput(d.message), letting the user edit-and-resubmit
  the rewound turn — the core UX promised by the issue.

Tests:
- 7 new tui_gateway tests covering prefill payload shape, in-memory
  history truncation, DB soft-delete, memory-provider notification
  (rewound=True), busy-session refusal, missing-session error, and
  registry placement in _PENDING_INPUT_COMMANDS.
- Extended asCommandDispatch vitest covering the new prefill variant
  (with + without notice, and rejection of malformed payloads).

Out of scope for v1 (tracked as NousResearch#21910 follow-up):
- Dedicated picker overlay in Ink (the multi-step rewind UI). v1 auto-
  picks the most recent user turn, matching the most common case.
- Gateway platforms (Telegram, Discord, etc.) — issue scopes v1 to
  CLI + TUI only.

…ousResearch#21910)

Adds nullable columns to messages for gateway outbound-message tracking
so /rewind v2 can best-effort delete the bot's public posts when the
in-memory context is truncated:

  outbound_platform   TEXT  — e.g. 'discord', 'telegram'
  outbound_chat_id    TEXT  — platform chat/channel id
  outbound_thread_id  TEXT  — thread/topic id (nullable for flat platforms)
  outbound_message_id TEXT  — the platform message id to delete

New SessionDB primitives:

  set_outbound_ids(row_id, *, platform, chat_id, thread_id, message_id)
      Stamp coordinates onto a persisted assistant row.  Silent no-op
      when message_id is falsy.

  get_inactive_outbound_ids(session_id, *, since_message_id, chat_id, thread_id)
      Lookup helper used by the gateway rewind code path to drive
      best-effort platform.delete_message calls.  Filters scope to
      caller's (chat, thread) so a single rewind never deletes
      messages in a sibling thread.

  rewind_to_message(..., *, require_thread_scope=(chat_id, thread_id))
      Optional kwarg that refuses cross-thread rewinds with ValueError.
      v1 callers (CLI/TUI, no kwarg) stay green — the guard only fires
      when explicitly passed.  Rows missing outbound coordinates are
      not subject to the guard (NULL bypass).

Migration v12 → v13:

  - Declarative reconcile adds the columns transparently.
  - Partial index idx_messages_outbound on (session_id, outbound_chat_id)
    WHERE outbound_message_id IS NOT NULL — created after reconcile so
    legacy DBs don't trip on the missing column.

Tests:
  - test_rewind_v2_state.py: 12 new (schema, set/get roundtrip,
    chat/thread filtering, active-row exclusion, thread-scope guard
    refuse/accept/NULL-bypass/backward-compat, full v12→v13 migration).
  - test_hermes_state.py: bump 3 version-pin asserts to 13.

…ng seam

Two additions to BasePlatform for /rewind v2 (NousResearch#21910):

1. can_delete_messages(chat_id) -> Optional[bool]
   Best-effort permission probe.  Tri-state return:
   - True   adapter has (or always has) deletion in this chat
   - False  known not to have permission / no delete API
   - None   unknown — caller falls back to optimism
   Default returns None.  Adapters that can cheaply probe (Discord
   channel reachability, Telegram bot connectedness) override.

2. _record_outbound_ids_for_send(event, result)
   Universal seam wired into _process_message_background's
   _record_delivery closure.  Stamps (platform, chat_id, thread_id,
   message_id) onto the most recent assistant row in SessionDB after
   every successful send_with_retry — so when a user runs /rewind in
   a Discord thread or Telegram topic, the gateway knows which
   platform messages to attempt to delete.

   Best-effort and defensively wrapped: any failure (no session
   store, no SessionDB, no message_id, no recent assistant row) is
   logged at debug and swallowed.  A DB hiccup must never break
   message delivery.

   Multi-bubble responses stamp the last-visible id onto the same
   row — acceptable for v2 since the rewind UI is binary
   (delete-attempted vs. not); continuation_message_ids tracking
   is a v3 follow-up.

Also extends delete_message docstring with the v2 use case.

Discord (gateway/platforms/discord.py):
  - delete_message: discord.Message.delete via REST DELETE.  The bot
    can delete its own messages without manage_messages perms, which
    covers the /rewind v2 use case (a wrong-thread bot post the user
    wants retracted).  Failures (gone, perms, rate limit) return False
    so callers degrade gracefully.
  - can_delete_messages: probes channel reachability.  Returns True
    when the channel resolves, False when it clearly doesn't (bot
    kicked, channel deleted), None when the probe itself errors.

Telegram (gateway/platforms/telegram.py):
  - can_delete_messages: bot can always delete its own messages
    within 48h via Bot API deleteMessage, so returns True whenever
    the bot is connected.  Aging-out is handled by the existing
    delete_message implementation returning False.

Closes the platform-adapter slice of /rewind v2 (NousResearch#21910).  Other
platforms (Slack, Matrix, WhatsApp, etc.) inherit the base defaults
(can_delete_messages -> None, delete_message -> False) and can opt
in incrementally with the same pattern.

…lete

Wires /rewind into the gateway slash dispatch next to /branch.  The
gateway version mirrors v1 TUI's single-step auto-pick behavior — a
multi-message picker overlay is a v3 follow-up.

Per-turn flow:
  1. Resolve target = most-recent user message in active transcript.
  2. SessionDB.rewind_to_message(..., require_thread_scope=(chat, thread))
     soft-deletes everything at-or-after that turn.  Refuses with a
     user-visible 'Rewind refused' notice if any in-scope row was
     posted into a different (chat_id, thread_id) — keeps the blast
     radius predictable per the v2 spec.
  3. Probes adapter.can_delete_messages once.  When False (adapter
     reports no perms), surfaces a 'Skipped N platform deletes' notice
     instead of spamming the platform's logs.  When True/None, iterates
     adapter.delete_message over every recorded outbound id in scope.
  4. Aggregates deleted/attempted counts into the reply notice.
  5. Evicts cached agent and fires _memory_manager.on_session_switch
     (..., rewound=True) per v1's hook contract.

Closes the gateway slice of /rewind v2 (NousResearch#21910).  Discord (the
motivating wrong-channel-post case) is fully covered; other platforms
degrade gracefully — they keep the in-memory rewind but skip the
delete step until their adapter overrides delete_message.