feat(bot): dialog engine — scrub → safety → FSM → monitoring, consent, age gate, crisis

- Engine.handle registered via register_engine; lexicon-first safety (no LLM on ACUTE),
  fixed crisis script once per open crisis, POSSIBLE → C-SSRS screen
- FSM registry (@state/@on_enter/@trigger) with auto-loaded flows; core flow:
  new → consent → age_gate → module onboarding → idle, crisis, consent_revoked
- reusable scale session (buttons, extract_item + clarify, item 9 / C-SSRS buttons-only,
  crisis flags), execution of monitoring dialog actions, texts in config/texts/dialog.yaml

Refs #10

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

app/dialog/texts.py

@@ -0,0 +1,121 @@
+"""Patient-facing dialog texts from `config/texts/dialog.yaml` (ADR-008: texts live in config, not code)."""
+
+from functools import lru_cache
+from pathlib import Path
+
+import yaml
+from pydantic import BaseModel, ConfigDict, Field
+
+from app.config import get_settings
+
+
+class _Strict(BaseModel):
+    # A typo in a YAML key must fail at load time, not silently show an empty message to a patient.
+    model_config = ConfigDict(extra="forbid", frozen=True)
+
+
+class DialogSettings(_Strict):
+    cssrs_cooldown_hours: float = 24
+    max_safety_events: int = 50
+    crisis_flags: list[str] = Field(default_factory=list)
+    risk_screen_scale: str = "cssrs_screen"
+
+
+class Commands(_Strict):
+    revoke: list[str]
+
+
+class ConsentTexts(_Strict):
+    version: str
+    text: str
+    accept: str
+    decline: str
+    refused: str
+    reconsider: str
+    code_invalid: str
+
+
+class AgeGateTexts(_Strict):
+    question: str
+    adult: str
+    minor: str
+    unclear: str
+    minor_stop: str
+
+
+class IdleButtons(_Strict):
+    checkin: str
+    med_question: str
+    contact_doctor: str
+    revoke: str
+
+
+class IdleTexts(_Strict):
+    welcome: str
+    menu_prompt: str
+    buttons: IdleButtons
+    stub_checkin: str
+    stub_med_question: str
+    contact_doctor_ack: str
+    visit_stub: str
+
+
+class RevokedTexts(_Strict):
+    confirm: str
+
+
+class CrisisTexts(_Strict):
+    repeat: str
+    hold: str
+    closed: str
+
+
+class ScaleTexts(_Strict):
+    intro: str
+    question: str
+    clarify: str
+    buttons_only: str
+    done: str
+    risk_screen_intro: str
+
+
+class SafetyPlanTexts(_Strict):
+    title: str
+    template: list[str]
+    means_restriction: str
+
+
+class ReachOutTexts(_Strict):
+    silence: str
+    missed_doses: str
+    default: str
+
+
+class VisitTexts(_Strict):
+    button: str
+
+
+class DialogTexts(_Strict):
+    status: str
+    settings: DialogSettings
+    commands: Commands
+    consent: ConsentTexts
+    age_gate: AgeGateTexts
+    idle: IdleTexts
+    revoked: RevokedTexts
+    crisis: CrisisTexts
+    scale: ScaleTexts
+    safety_plan: SafetyPlanTexts
+    reach_out: ReachOutTexts
+    visit: VisitTexts
+    unavailable: str
+
+
+def dialog_texts_path() -> Path:
+    return get_settings().config_dir / "texts" / "dialog.yaml"
+
+
+@lru_cache
+def load_dialog_texts(path: Path | None = None) -> DialogTexts:
+    path = path or dialog_texts_path()
+    return DialogTexts.model_validate(yaml.safe_load(path.read_text(encoding="utf-8")))