diff --git a/server/reflector/db/transcripts.py b/server/reflector/db/transcripts.py
index 2beef845..b3f6d49c 100644
--- a/server/reflector/db/transcripts.py
+++ b/server/reflector/db/transcripts.py
@@ -5,7 +5,7 @@ import shutil
 from contextlib import asynccontextmanager
 from datetime import datetime, timedelta, timezone
 from pathlib import Path
-from typing import Any, Literal
+from typing import Any, Literal, Sequence
 
 import sqlalchemy
 from fastapi import HTTPException
@@ -180,7 +180,7 @@ class TranscriptDuration(BaseModel):
 
 
 class TranscriptWaveform(BaseModel):
-    waveform: list[float]
+    waveform: Sequence[float]
 
 
 class TranscriptEvent(BaseModel):
diff --git a/server/reflector/hatchet/workflows/diarization_pipeline.py b/server/reflector/hatchet/workflows/diarization_pipeline.py
index 224ebcef..b7b0559e 100644
--- a/server/reflector/hatchet/workflows/diarization_pipeline.py
+++ b/server/reflector/hatchet/workflows/diarization_pipeline.py
@@ -16,7 +16,7 @@ import tempfile
 from contextlib import asynccontextmanager
 from datetime import timedelta
 from pathlib import Path
-from typing import Callable
+from typing import Any, Callable, Coroutine, TypeVar
 
 import httpx
 from hatchet_sdk import Context
@@ -162,7 +162,15 @@ def _spawn_storage():
     )
 
 
-def with_error_handling(step_name: str, set_error_status: bool = True) -> Callable:
+R = TypeVar("R")
+
+
+def with_error_handling(
+    step_name: str, set_error_status: bool = True
+) -> Callable[
+    [Callable[[PipelineInput, Context], Coroutine[Any, Any, R]]],
+    Callable[[PipelineInput, Context], Coroutine[Any, Any, R]],
+]:
     """Decorator that handles task failures uniformly.
 
     Args:
@@ -170,9 +178,11 @@ def with_error_handling(step_name: str, set_error_status: bool = True) -> Callab
         set_error_status: Whether to set transcript status to 'error' on failure.
     """
 
-    def decorator(func: Callable) -> Callable:
+    def decorator(
+        func: Callable[[PipelineInput, Context], Coroutine[Any, Any, R]],
+    ) -> Callable[[PipelineInput, Context], Coroutine[Any, Any, R]]:
         @functools.wraps(func)
-        async def wrapper(input: PipelineInput, ctx: Context):
+        async def wrapper(input: PipelineInput, ctx: Context) -> R:
             try:
                 return await func(input, ctx)
             except Exception as e:
@@ -186,7 +196,7 @@ def with_error_handling(step_name: str, set_error_status: bool = True) -> Callab
                     await set_workflow_error_status(input.transcript_id)
                 raise
 
-        return wrapper
+        return wrapper  # type: ignore[return-value]
 
     return decorator
 
@@ -256,7 +266,6 @@ async def get_participants(input: PipelineInput, ctx: Context) -> ParticipantsRe
 
     recording = ctx.task_output(get_recording)
     mtg_session_id = recording.mtg_session_id
-
     async with fresh_db_connection():
         from reflector.db.transcripts import (  # noqa: PLC0415
             TranscriptParticipant,
@@ -264,16 +273,17 @@ async def get_participants(input: PipelineInput, ctx: Context) -> ParticipantsRe
         )
 
         transcript = await transcripts_controller.get_by_id(input.transcript_id)
-        if transcript:
-            # Note: title NOT cleared - preserves existing titles
-            await transcripts_controller.update(
-                transcript,
-                {
-                    "events": [],
-                    "topics": [],
-                    "participants": [],
-                },
-            )
+        if not transcript:
+            raise ValueError(f"Transcript {input.transcript_id} not found")
+        # Note: title NOT cleared - preserves existing titles
+        await transcripts_controller.update(
+            transcript,
+            {
+                "events": [],
+                "topics": [],
+                "participants": [],
+            },
+        )
 
         mtg_session_id = assert_non_none_and_non_empty(
             mtg_session_id, "mtg_session_id is required"
@@ -640,6 +650,8 @@ async def detect_topics(input: PipelineInput, ctx: Context) -> TopicsResult:
 
     async with fresh_db_connection():
         transcript = await transcripts_controller.get_by_id(input.transcript_id)
+        if not transcript:
+            raise ValueError(f"Transcript {input.transcript_id} not found")
 
         for chunk in topic_chunks:
             topic = TranscriptTopic(
@@ -647,7 +659,7 @@ async def detect_topics(input: PipelineInput, ctx: Context) -> TopicsResult:
                 summary=chunk.summary,
                 timestamp=chunk.timestamp,
                 transcript=" ".join(w.text for w in chunk.words),
-                words=[w.model_dump() for w in chunk.words],
+                words=chunk.words,
             )
             await transcripts_controller.upsert_topic(transcript, topic)
             await append_event_and_broadcast(
@@ -697,6 +709,8 @@ async def generate_title(input: PipelineInput, ctx: Context) -> TitleResult:
     async with fresh_db_connection():
         ctx.log("generate_title: DB connection established")
         transcript = await transcripts_controller.get_by_id(input.transcript_id)
+        if not transcript:
+            raise ValueError(f"Transcript {input.transcript_id} not found")
         ctx.log(f"generate_title: fetched transcript, exists={transcript is not None}")
 
         async def on_title_callback(data):
diff --git a/server/reflector/hatchet/workflows/models.py b/server/reflector/hatchet/workflows/models.py
index 748361d9..c2a98901 100644
--- a/server/reflector/hatchet/workflows/models.py
+++ b/server/reflector/hatchet/workflows/models.py
@@ -42,7 +42,7 @@ class RecordingResult(BaseModel):
 
     id: NonEmptyString | None
     mtg_session_id: NonEmptyString | None
-    duration: float
+    duration: int | None
 
 
 class ParticipantsResult(BaseModel):