feat: add in-product survey system (#2008)

* feat: add in-product survey system

- SurveyManager: event-based trigger, Space API communication
- Trigger on first successful non-WebSocket response
- Backend API: /api/v1/survey/{pending,respond,dismiss}
- Frontend: floating survey widget with progressive questions
- Flat radio/checkbox style (not dropdown Select)

* fix: persist triggered survey events to disk across restarts

Store triggered events in data/survey_triggered_events.json so that
restarting the process doesn't re-query Space for already-triggered events.

* fix: use metadata table for survey event persistence instead of file

Store triggered events in the existing metadata KV table
(key='survey_triggered_events') instead of a standalone JSON file.

* fix: ruff format and prettier fixes

src/langbot/pkg/survey/__init__.py

@@ -0,0 +1 @@
+"""Survey module for in-product surveys triggered by events."""

src/langbot/pkg/survey/manager.py

@@ -0,0 +1,148 @@
+"""Survey manager: tracks events, communicates with Space to fetch/submit surveys."""
+
+from __future__ import annotations
+
+import asyncio
+import json
+import typing
+import httpx
+import sqlalchemy
+
+from ..core import app as core_app
+from ..entity.persistence.metadata import Metadata
+from ..utils import constants
+
+SURVEY_TRIGGERED_KEY = 'survey_triggered_events'
+
+
+class SurveyManager:
+    """Manages survey lifecycle: event tracking, pending survey fetch, submission."""
+
+    def __init__(self, ap: core_app.Application):
+        self.ap = ap
+        self._triggered_events: set[str] = set()
+        self._pending_survey: typing.Optional[dict] = None
+        self._space_url: str = ''
+
+    async def initialize(self):
+        space_config = self.ap.instance_config.data.get('space', {})
+        self._space_url = space_config.get('url', '').rstrip('/')
+        await self._load_triggered_events()
+
+    async def _load_triggered_events(self):
+        """Load previously triggered events from metadata table."""
+        try:
+            result = await self.ap.persistence_mgr.execute_async(
+                sqlalchemy.select(Metadata).where(Metadata.key == SURVEY_TRIGGERED_KEY)
+            )
+            row = result.first()
+            if row:
+                self._triggered_events = set(json.loads(row[0].value))
+        except Exception:
+            self._triggered_events = set()
+
+    async def _save_triggered_events(self):
+        """Persist triggered events to metadata table."""
+        try:
+            value = json.dumps(list(self._triggered_events))
+            result = await self.ap.persistence_mgr.execute_async(
+                sqlalchemy.select(Metadata).where(Metadata.key == SURVEY_TRIGGERED_KEY)
+            )
+            if result.first():
+                await self.ap.persistence_mgr.execute_async(
+                    sqlalchemy.update(Metadata).where(Metadata.key == SURVEY_TRIGGERED_KEY).values(value=value)
+                )
+            else:
+                await self.ap.persistence_mgr.execute_async(
+                    sqlalchemy.insert(Metadata).values(key=SURVEY_TRIGGERED_KEY, value=value)
+                )
+        except Exception as e:
+            self.ap.logger.debug(f'Failed to save survey triggered events: {e}')
+
+    def _is_space_configured(self) -> bool:
+        space_config = self.ap.instance_config.data.get('space', {})
+        if space_config.get('disable_telemetry', False):
+            return False
+        return bool(self._space_url)
+
+    async def trigger_event(self, event: str):
+        """Called when an event occurs. Checks Space for a pending survey."""
+        if event in self._triggered_events:
+            return
+        if not self._is_space_configured():
+            return
+
+        self._triggered_events.add(event)
+        await self._save_triggered_events()
+
+        # Check for pending survey asynchronously
+        asyncio.create_task(self._fetch_pending_survey(event))
+
+    async def _fetch_pending_survey(self, event: str):
+        """Fetch pending survey from Space for this event."""
+        try:
+            url = f'{self._space_url}/api/v1/survey/pending'
+            payload = {
+                'instance_id': constants.instance_id,
+                'event': event,
+            }
+            async with httpx.AsyncClient(timeout=httpx.Timeout(10)) as client:
+                resp = await client.post(url, json=payload)
+                if resp.status_code == 200:
+                    data = resp.json()
+                    if data.get('code') == 0 and data.get('data', {}).get('survey'):
+                        self._pending_survey = data['data']['survey']
+                        self.ap.logger.info(f'Survey pending: {self._pending_survey.get("survey_id")}')
+        except Exception as e:
+            self.ap.logger.debug(f'Failed to fetch pending survey: {e}')
+
+    def get_pending_survey(self) -> typing.Optional[dict]:
+        """Return the current pending survey (if any) for the frontend to display."""
+        return self._pending_survey
+
+    def clear_pending_survey(self):
+        """Clear the pending survey (after user responds or dismisses)."""
+        self._pending_survey = None
+
+    async def submit_response(self, survey_id: str, answers: dict, completed: bool = True) -> bool:
+        """Submit a survey response to Space."""
+        if not self._is_space_configured():
+            return False
+        try:
+            url = f'{self._space_url}/api/v1/survey/respond'
+            payload = {
+                'survey_id': survey_id,
+                'instance_id': constants.instance_id,
+                'answers': answers,
+                'metadata': {
+                    'version': constants.semantic_version,
+                },
+                'completed': completed,
+            }
+            async with httpx.AsyncClient(timeout=httpx.Timeout(10)) as client:
+                resp = await client.post(url, json=payload)
+                if resp.status_code == 200:
+                    self.clear_pending_survey()
+                    return True
+        except Exception as e:
+            self.ap.logger.warning(f'Failed to submit survey response: {e}')
+        return False
+
+    async def dismiss_survey(self, survey_id: str) -> bool:
+        """Dismiss a survey."""
+        if not self._is_space_configured():
+            return False
+        try:
+            url = f'{self._space_url}/api/v1/survey/dismiss'
+            payload = {
+                'survey_id': survey_id,
+                'instance_id': constants.instance_id,
+            }
+            async with httpx.AsyncClient(timeout=httpx.Timeout(10)) as client:
+                resp = await client.post(url, json=payload)
+                if resp.status_code == 200:
+                    self.clear_pending_survey()
+                    return True
+        except Exception as e:
+            self.ap.logger.warning(f'Failed to dismiss survey: {e}')
+        return False