fix(schemas): use enum types as field types + enforce symbol length

- Replace all Literal[...] type annotations with corresponding enum classes
  (TickerAction, TimeHorizon, MarketOutlook, VideoStatus, TranscriptSource)
  for MeetKevinTickerMention, MeetKevinAnalysis, and API response models
  (VideoSummary, VideoDetail, StockMention, StockSummary, TimelineBucket)
- Add min_length=1, max_length=10 validation to MeetKevinTickerMention.symbol
- Split test_conviction_edge_cases into two separate boundary tests
- Strengthen test_valid_ticker_mention with assertions for all 6 fields
- Trim no-information docstrings from TranscriptSegment, StockTimeline
- All 60 schema tests pass

shared/schemas/meet_kevin.py

@@ -77,17 +77,15 @@ class MeetKevinTickerMention(BaseModel):
     """
 
     symbol: str = Field(
-        ..., description="Stock ticker symbol (A-Z, 1-6 chars, auto-uppercased)"
+        ..., min_length=1, max_length=10, description="Stock ticker symbol (A-Z, 1-6 chars, auto-uppercased)"
     )
-    action: Literal["buy", "sell", "hold", "watch", "avoid"] = Field(
+    action: TickerAction = Field(
         ..., description="Recommendation action"
     )
     conviction: float = Field(
         ..., ge=0.0, le=1.0, description="Confidence in recommendation (0.0-1.0)"
     )
-    time_horizon: Literal[
-        "intraday", "days", "weeks", "months", "long_term", "unspecified"
-    ] = Field(..., description="Time horizon for the recommendation")
+    time_horizon: TimeHorizon = Field(..., description="Time horizon for the recommendation")
     rationale_quote: str = Field(
         ..., description="Short verbatim or paraphrased quote from video"
     )
@@ -110,7 +108,7 @@ class MeetKevinAnalysis(BaseModel):
     Used as tool-input for the LLM analyzer and persisted as kevin_analyses.
     """
 
-    market_outlook_direction: Literal["bullish", "neutral", "bearish", "mixed"] = (
+    market_outlook_direction: MarketOutlook = (
         Field(..., description="Overall market sentiment direction")
     )
     market_outlook_reasoning: str = Field(
@@ -136,8 +134,6 @@ class MeetKevinAnalysis(BaseModel):
 
 
 class TranscriptSegment(BaseModel):
-    """Single segment from a video transcript with timing."""
-
     start_seconds: float = Field(..., description="Segment start time in seconds")
     end_seconds: float = Field(..., description="Segment end time in seconds")
     text: str = Field(..., description="Segment text content")
@@ -153,7 +149,7 @@ class VideoSummary(BaseModel):
     title: str = Field(..., description="Video title")
     published_at: datetime = Field(..., description="Publication timestamp")
     thumbnail_url: str = Field(..., description="Thumbnail image URL")
-    status: Literal["discovered", "captioned", "analyzed", "failed", "skipped"] = (
+    status: VideoStatus = (
         Field(..., description="Processing status")
     )
     failure_reason: str | None = Field(
@@ -176,13 +172,13 @@ class VideoDetail(BaseModel):
     published_at: datetime = Field(..., description="Publication timestamp")
     duration_seconds: int | None = Field(default=None, description="Video duration")
     thumbnail_url: str = Field(..., description="Thumbnail image URL")
-    status: Literal["discovered", "captioned", "analyzed", "failed", "skipped"] = (
+    status: VideoStatus = (
         Field(..., description="Processing status")
     )
     failure_reason: str | None = Field(
         default=None, description="Failure reason if status=failed"
     )
-    transcript_source: Literal["captions_manual", "captions_auto", "none"] | None = (
+    transcript_source: TranscriptSource | None = (
         Field(default=None, description="Source of captions")
     )
     transcript_segments: list[TranscriptSegment] = Field(
@@ -204,15 +200,13 @@ class StockMention(BaseModel):
     video_id: int = Field(..., description="Database ID of video")
     youtube_video_id: str = Field(..., description="YouTube video ID for linking")
     published_at: datetime = Field(..., description="Video publication date")
-    action: Literal["buy", "sell", "hold", "watch", "avoid"] = Field(
+    action: TickerAction = Field(
         ..., description="Recommendation action"
     )
     conviction: float = Field(
         ..., ge=0.0, le=1.0, description="Confidence in recommendation"
     )
-    time_horizon: Literal[
-        "intraday", "days", "weeks", "months", "long_term", "unspecified"
-    ] = Field(..., description="Time horizon for recommendation")
+    time_horizon: TimeHorizon = Field(..., description="Time horizon for recommendation")
     rationale_quote: str = Field(
         ..., description="Quote or summary of rationale"
     )
@@ -224,14 +218,12 @@ class StockMention(BaseModel):
 
 
 class StockSummary(BaseModel):
-    """Summary of a stock across all mentions."""
-
     symbol: str = Field(..., description="Stock ticker")
     mention_count: int = Field(..., description="Total mention count")
     last_mentioned_at: datetime = Field(
         ..., description="Timestamp of last mention"
     )
-    latest_action: Literal["buy", "sell", "hold", "watch", "avoid"] = Field(
+    latest_action: TickerAction = Field(
         ..., description="Most recent recommendation"
     )
     avg_conviction: float = Field(
@@ -251,10 +243,8 @@ class StockSummary(BaseModel):
 
 
 class TimelineBucket(BaseModel):
-    """Single time bucket in a sentiment timeline."""
-
     bucket_date: str = Field(..., description="Date string (YYYY-MM-DD or YYYY-Www)")
-    action: Literal["buy", "sell", "hold", "watch", "avoid"] | None = Field(
+    action: TickerAction | None = Field(
         default=None, description="Most common action in bucket"
     )
     avg_conviction: float = Field(
@@ -268,8 +258,6 @@ class TimelineBucket(BaseModel):
 
 
 class StockTimeline(BaseModel):
-    """Timeline of mentions for a single stock ticker."""
-
     symbol: str = Field(..., description="Stock ticker")
     buckets: list[TimelineBucket] = Field(
         default_factory=list, description="Time-bucketed data"

tests/test_schemas.py

@@ -593,7 +593,7 @@ class TestTokenResponse:
 
 class TestMeetKevinTickerMention:
     def test_valid_ticker_mention(self) -> None:
-        from shared.schemas.meet_kevin import MeetKevinTickerMention
+        from shared.schemas.meet_kevin import MeetKevinTickerMention, TickerAction, TimeHorizon
 
         mention = MeetKevinTickerMention(
             symbol="AAPL",
@@ -604,7 +604,11 @@ class TestMeetKevinTickerMention:
             video_timestamp_seconds=120,
         )
         assert mention.symbol == "AAPL"
+        assert mention.action == TickerAction.BUY
         assert mention.conviction == 0.85
+        assert mention.time_horizon == TimeHorizon.MONTHS
+        assert mention.rationale_quote == "Strong earnings growth expected"
+        assert mention.video_timestamp_seconds == 120
 
     def test_symbol_auto_uppercases(self) -> None:
         from shared.schemas.meet_kevin import MeetKevinTickerMention
@@ -642,28 +646,29 @@ class TestMeetKevinTickerMention:
                 rationale_quote="Negative conviction",
             )
 
-    def test_conviction_edge_cases(self) -> None:
+    def test_conviction_boundary_zero_valid(self) -> None:
         from shared.schemas.meet_kevin import MeetKevinTickerMention
 
-        # Test 0.0
-        m1 = MeetKevinTickerMention(
+        m = MeetKevinTickerMention(
             symbol="GOOG",
             action="avoid",
             conviction=0.0,
             time_horizon="unspecified",
             rationale_quote="No confidence",
         )
-        assert m1.conviction == 0.0
+        assert m.conviction == 0.0
 
-        # Test 1.0
-        m2 = MeetKevinTickerMention(
+    def test_conviction_boundary_one_valid(self) -> None:
+        from shared.schemas.meet_kevin import MeetKevinTickerMention
+
+        m = MeetKevinTickerMention(
             symbol="MSFT",
             action="buy",
             conviction=1.0,
             time_horizon="long_term",
             rationale_quote="Maximum confidence",
         )
-        assert m2.conviction == 1.0
+        assert m.conviction == 1.0
 
     def test_timestamp_optional(self) -> None:
         from shared.schemas.meet_kevin import MeetKevinTickerMention