fix(bot): close dialog engine gaps (C-SSRS repeat, scale intros, button payloads, step timeout)

- No same-day C-SSRS repeat: a risk screen completed within cssrs_cooldown_hours is not queued again
  after PHQ-9 item 9 >= 1 (scale crisis path, rule schedule_scale, scale_due); crisis script and alerts stay.
- Scale intro registry: register_scale_intro(scale_id, text_or_fn); start_scale(intro=None) uses it.
  veteran_daily migrated from per-scale on_enter hooks.
- Prefix triggers "button:<prefix>:*" with trigger_payload(event); medication buttons carry the dose
  (med:taken:<dose_id>, ...), med_pending dropped; payload-less legacy buttons answer as stale.
- Abandoned-step timeout: settings.abandon_after_hours (default 6 h) returns abandonable states
  (daily.*, meds.*, scale.* not in onboarding) to idle before the next event; never in crisis or with intake on.

Refs #56

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/dialog/engine.py

@@ -2,6 +2,10 @@
 
 Pipeline for one incoming event (SPEC §3, guardrails #1, #2, #3):
 
+  0. abandoned step     the FSM sits in a question step (check-in, scale) the patient left more than
+                        `settings.abandon_after_hours` ago → back to idle first (stored answers stay; never in
+                        crisis, never in an onboarding chain), then the event is handled as usual.
+
   text event
     1. scrub()            raw text → ScrubbedText. Raw text is never stored, logged or sent anywhere.
     2. consent gate       no valid consent → no LLM, nothing stored; only the local crisis lexicon runs
@@ -25,7 +29,7 @@ Logs carry only the token, states and event codes (guardrail #8).
 import asyncio
 import logging
 from dataclasses import dataclass, field
-from datetime import datetime
+from datetime import datetime, timedelta
 from typing import Any
 from weakref import WeakValueDictionary
 
@@ -45,7 +49,16 @@ from app.dialog.contracts import Event, Reply, register_engine
 from app.dialog.crisis import crisis_open, no_consent_crisis_text, open_crisis
 from app.dialog.flows import load_flows
 from app.dialog.flows.core import close_crisis, revoke
-from app.dialog.fsm import NO_CONSENT_STATES, RESTING_STATES, Ctx, Step, apply_data, enter_hook_for, handler_for
+from app.dialog.fsm import (
+    NO_CONSENT_STATES,
+    RESTING_STATES,
+    Ctx,
+    Step,
+    apply_data,
+    enter_hook_for,
+    handler_for,
+    is_abandonable,
+)
 from app.dialog.texts import DialogTexts, load_dialog_texts
 from app.llm.gateway import LLMGateway, get_gateway
 from app.services import questionnaire as intake_service
@@ -58,6 +71,8 @@ MAX_ENTER_CHAIN = 8
 _patient_locks = WeakValueDictionary()
 # DB unreachable: answer safely instead of failing the channel (connectivity errors only — bugs must surface).
 _DB_DOWN = (OSError, OperationalError, InterfaceError)
+# dialog_state.data key: when the patient last acted in (or the FSM entered) the current step — abandon timeout.
+STEP_AT = "step_at"
 
 
 @dataclass
@@ -109,6 +124,8 @@ class Engine:
         state_before = ctx.state
         run = _Run()
 
+        if self._abandoned(ctx):
+            await self._apply(ctx, self._abandon(ctx), run)
         await self._apply(ctx, await self._route(ctx, event), run)
 
         if run.notify:
@@ -126,6 +143,9 @@ class Engine:
                 await repo.add_message(
                     session, token=token, direction="out", text=scrub(reply.text), ts=ctx.now, fsm_state=ctx.state
                 )
+        if event.type != "system" or ctx.state != state_before:
+            # System events the step ignores (reminders inside a scale) do not count as the patient being there.
+            ctx.data[STEP_AT] = ctx.now.isoformat()
         await self._save_state(ctx)
         task_id = event.params.get("questionnaire_task")
         if event.type == "system" and task_id and run.replies:
@@ -145,6 +165,24 @@ class Engine:
         )
         return run.replies
 
+    def _abandoned(self, ctx: Ctx) -> bool:
+        """The current question step was left unanswered longer than `abandon_after_hours` (app.core.clock)."""
+        if intake_enabled() or not _consented(ctx) or ctx.state in RESTING_STATES or crisis_open(ctx.data):
+            return False
+        hours = ctx.texts.settings.abandon_after_hours
+        last = ctx.data.get(STEP_AT)
+        if not hours or not last or ctx.now - datetime.fromisoformat(last) < timedelta(hours=hours):
+            return False
+        return is_abandonable(ctx)
+
+    def _abandon(self, ctx: Ctx) -> Step:
+        """Drop the unfinished step's progress (answers already stored in item_responses / daily_checkins stay;
+        an unfinished scale gets no scale_results row) and rest in idle so queued scales may start."""
+        log.info("dialog step abandoned token=%s state=%s", ctx.token, ctx.state)
+        scale_id = scale_session.active_scale(ctx.state)
+        scales = {k: v for k, v in (ctx.data.get("scales") or {}).items() if k != scale_id}
+        return Step(next_state="idle", data={"checkin": None, "scales": scales or None})
+
     async def _route(self, ctx: Ctx, event: Event) -> Step:
         consented = _consented(ctx)
         if event.type == "text":
@@ -307,10 +345,19 @@ class Engine:
         if not pending or ctx.state not in RESTING_STATES:
             return Step()
         screen = ctx.texts.settings.risk_screen_scale
+        dropped: dict[str, Any] = {}
+        if any(p["scale"] == screen for p in pending) and await scale_session.recent_risk_screen(ctx, screen):
+            # Item 9 / rule phq9_item9 / scale_due asked for a C-SSRS the patient completed within the cooldown:
+            # do not repeat the same suicide screen (#56). Crisis script and alerts are unaffected.
+            log.info("dialog risk screen skipped (cooldown) token=%s", ctx.token)
+            pending = [p for p in pending if p["scale"] != screen]
+            dropped = {"pending_scales": pending or None}
+            if not pending:
+                return Step(data=dropped)
         if ctx.state == "crisis":
             pending_screen = [p for p in pending if p["scale"] == screen]
             if not pending_screen:
-                return Step()
+                return Step(data=dropped)
             item = pending_screen[0]
         else:
             item = pending[0]