Chat improvements (#22823)

* Add score fusion helpers for find_similar_objects chat tool

* Add candidate query builder for find_similar_objects chat tool

* register find_similar_objects chat tool definition

* implement _execute_find_similar_objects chat tool dispatcher

* Dispatch find_similar_objects in chat tool executor

* Teach chat system prompt when to use find_similar_objects

* Add i18n strings for find_similar_objects chat tool

* Add frontend extractor for find_similar_objects tool response

* Render anchor badge and similarity scores in chat results

* formatting

* filter similarity results in python, not sqlite-vec

* extract pure chat helpers to chat_util module

* Teach chat system prompt about attached_event marker

* Add parseAttachedEvent and prependAttachment helpers

* Add i18n strings for chat event attachments

* Add ChatAttachmentChip component

* Make chat thumbnails attach to composer on click

* Render attachment chip in user chat bubbles

* Add ChatQuickReplies pill row component

* Add ChatPaperclipButton with event picker popover

* Wire event attachments into chat composer and messages

* add ability to stop streaming

* tweak cursor to appear at the end of the same line of the streaming response

* use abort signal

* add tooltip

* display label and camera on attachment chip

frigate/api/chat_util.py

@@ -0,0 +1,135 @@
+"""Pure, stateless helpers used by the chat tool dispatchers.
+
+These were extracted from frigate/api/chat.py to keep that module focused on
+route handlers, tool dispatchers, and streaming loop internals. Nothing in
+this file touches the FastAPI request, the embeddings context, or the chat
+loop state — all inputs and outputs are plain data.
+"""
+
+import logging
+import math
+import time
+from datetime import datetime
+from typing import Any, Dict, Generator, List, Optional
+
+from frigate.embeddings.util import ZScoreNormalization
+from frigate.models import Event
+
+logger = logging.getLogger(__name__)
+
+
+# Similarity fusion weights for find_similar_objects.
+# Visual dominates because the feature's primary use case is "same specific object."
+# If these change, update the test in test_chat_find_similar_objects.py.
+VISUAL_WEIGHT = 0.65
+DESCRIPTION_WEIGHT = 0.35
+
+
+def chunk_content(content: str, chunk_size: int = 80) -> Generator[str, None, None]:
+    """Yield content in word-aware chunks for streaming."""
+    if not content:
+        return
+    words = content.split(" ")
+    current: List[str] = []
+    current_len = 0
+    for w in words:
+        current.append(w)
+        current_len += len(w) + 1
+        if current_len >= chunk_size:
+            yield " ".join(current) + " "
+            current = []
+            current_len = 0
+    if current:
+        yield " ".join(current)
+
+
+def format_events_with_local_time(
+    events_list: List[Dict[str, Any]],
+) -> List[Dict[str, Any]]:
+    """Add human-readable local start/end times to each event for the LLM."""
+    result = []
+    for evt in events_list:
+        if not isinstance(evt, dict):
+            result.append(evt)
+            continue
+        copy_evt = dict(evt)
+        try:
+            start_ts = evt.get("start_time")
+            end_ts = evt.get("end_time")
+            if start_ts is not None:
+                dt_start = datetime.fromtimestamp(start_ts)
+                copy_evt["start_time_local"] = dt_start.strftime("%Y-%m-%d %I:%M:%S %p")
+            if end_ts is not None:
+                dt_end = datetime.fromtimestamp(end_ts)
+                copy_evt["end_time_local"] = dt_end.strftime("%Y-%m-%d %I:%M:%S %p")
+        except (TypeError, ValueError, OSError):
+            pass
+        result.append(copy_evt)
+    return result
+
+
+def distance_to_score(distance: float, stats: ZScoreNormalization) -> float:
+    """Convert a cosine distance to a [0, 1] similarity score.
+
+    Uses the existing ZScoreNormalization stats maintained by EmbeddingsContext
+    to normalize across deployments, then a bounded sigmoid. Lower distance ->
+    higher score. If stats are uninitialized (stddev == 0), returns a neutral
+    0.5 so the fallback ordering by raw distance still dominates.
+    """
+    if stats.stddev == 0:
+        return 0.5
+    z = (distance - stats.mean) / stats.stddev
+    # Sigmoid on -z so that small distance (good) -> high score.
+    return 1.0 / (1.0 + math.exp(z))
+
+
+def fuse_scores(
+    visual_score: Optional[float],
+    description_score: Optional[float],
+) -> Optional[float]:
+    """Weighted fusion of visual and description similarity scores.
+
+    If one side is missing (e.g., no description embedding for this event),
+    the other side's score is returned alone with no penalty. If both are
+    missing, returns None and the caller should drop the event.
+    """
+    if visual_score is None and description_score is None:
+        return None
+    if visual_score is None:
+        return description_score
+    if description_score is None:
+        return visual_score
+    return VISUAL_WEIGHT * visual_score + DESCRIPTION_WEIGHT * description_score
+
+
+def parse_iso_to_timestamp(value: Optional[str]) -> Optional[float]:
+    """Parse an ISO-8601 string as server-local time -> unix timestamp.
+
+    Mirrors the parsing _execute_search_objects uses so both tools accept the
+    same format from the LLM.
+    """
+    if value is None:
+        return None
+    try:
+        s = value.replace("Z", "").strip()[:19]
+        dt = datetime.strptime(s, "%Y-%m-%dT%H:%M:%S")
+        return time.mktime(dt.timetuple())
+    except (ValueError, AttributeError, TypeError):
+        logger.warning("Invalid timestamp format: %s", value)
+        return None
+
+
+def hydrate_event(event: Event, score: Optional[float] = None) -> Dict[str, Any]:
+    """Convert an Event row into the dict shape returned by find_similar_objects."""
+    data: Dict[str, Any] = {
+        "id": event.id,
+        "camera": event.camera,
+        "label": event.label,
+        "sub_label": event.sub_label,
+        "start_time": event.start_time,
+        "end_time": event.end_time,
+        "zones": event.zones,
+    }
+    if score is not None:
+        data["score"] = score
+    return data