fix: migrations preserve trend history across reinstalls

Migration 023 was deleting all but the latest trend_windows row per
entity before 024 could save them to trend_history. On reinstall,
this wiped the entire history every time.

Fixed by restructuring:
- 023 now creates trend_history FIRST and copies all trend_windows
  rows into it before deduplicating trend_windows down to latest-only.
  Uses NOT EXISTS to avoid duplicating rows on re-runs.
- 024 is now idempotent: ensures table/indexes exist and backfills
  from recommendations (last 7 days, 1 point per ticker/window/hour)
  to reconstruct approximate history even if trend_windows was sparse.

Both migrations are safe to re-run on existing databases.

infra/migrations/023_trend_windows_upsert_and_cleanup.sql

@@ -1,7 +1,49 @@
 -- Fix trend_windows to upsert instead of accumulating rows.
--- Add unique constraint so ON CONFLICT works, then deduplicate existing data.
+-- First, preserve all historical data in trend_history before deduplicating.
 
--- Step 1: Keep only the most recent row per (entity_type, entity_id, window)
+-- Step 1: Create trend_history table if it doesn't exist yet
+-- (migration 024 also creates it, but we need it here first to preserve data)
+CREATE TABLE IF NOT EXISTS trend_history (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    entity_type VARCHAR(50) NOT NULL DEFAULT 'company',
+    entity_id VARCHAR(100) NOT NULL,
+    "window" VARCHAR(20) NOT NULL,
+    trend_direction VARCHAR(20) NOT NULL DEFAULT 'neutral',
+    trend_strength FLOAT DEFAULT 0.5,
+    confidence FLOAT DEFAULT 0.5,
+    contradiction_score FLOAT DEFAULT 0.0,
+    dominant_catalysts JSONB DEFAULT '[]',
+    material_risks JSONB DEFAULT '[]',
+    generated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS idx_trend_history_lookup
+    ON trend_history (entity_id, "window", generated_at DESC);
+
+CREATE INDEX IF NOT EXISTS idx_trend_history_generated
+    ON trend_history (generated_at DESC);
+
+-- Step 2: Copy ALL existing trend_windows rows into trend_history
+-- before we delete any. This preserves the full history for charting.
+INSERT INTO trend_history (
+    entity_type, entity_id, "window", trend_direction,
+    trend_strength, confidence, contradiction_score,
+    dominant_catalysts, material_risks, generated_at
+)
+SELECT
+    entity_type, entity_id, "window", trend_direction,
+    trend_strength, confidence, contradiction_score,
+    dominant_catalysts, material_risks, generated_at
+FROM trend_windows
+WHERE NOT EXISTS (
+    SELECT 1 FROM trend_history th
+    WHERE th.entity_id = trend_windows.entity_id
+      AND th."window" = trend_windows."window"
+      AND th.generated_at = trend_windows.generated_at
+);
+
+-- Step 3: Keep only the most recent row per (entity_type, entity_id, window)
+-- in trend_windows (it becomes the "latest snapshot" table)
 DELETE FROM trend_windows
 WHERE id NOT IN (
     SELECT DISTINCT ON (entity_type, entity_id, "window") id
@@ -9,15 +51,15 @@ WHERE id NOT IN (
     ORDER BY entity_type, entity_id, "window", generated_at DESC
 );
 
--- Step 2: Add unique constraint for upsert
+-- Step 4: Add unique constraint for upsert
 CREATE UNIQUE INDEX IF NOT EXISTS idx_trend_windows_entity_window
     ON trend_windows (entity_type, entity_id, "window");
 
--- Step 3: Clean up old competitive signal records (keep last 30 days)
+-- Step 5: Clean up old competitive signal records (keep last 30 days)
 DELETE FROM competitive_signal_records
 WHERE computed_at < NOW() - INTERVAL '30 days';
 
--- Step 4: Add a partial index to speed up the NOT EXISTS check in the
+-- Step 6: Add a partial index to speed up the NOT EXISTS check in the
 -- aggregation propagation query
 CREATE INDEX IF NOT EXISTS idx_competitive_signals_source_doc_ticker
     ON competitive_signal_records (source_document_id, source_ticker);

infra/migrations/024_trend_history.sql

@@ -1,6 +1,11 @@
 -- Trend history table for time-series charting.
 -- trend_windows stores the latest snapshot per (entity, window) via upsert.
 -- trend_history stores every snapshot so the frontend can plot trend evolution.
+--
+-- Note: migration 023 already creates this table and seeds it from
+-- trend_windows. This migration ensures the table exists if 023 was
+-- run before this version, and backfills from recommendations for
+-- richer historical data.
 
 CREATE TABLE IF NOT EXISTS trend_history (
     id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
@@ -22,16 +27,51 @@ CREATE INDEX IF NOT EXISTS idx_trend_history_lookup
 CREATE INDEX IF NOT EXISTS idx_trend_history_generated
     ON trend_history (generated_at DESC);
 
--- Seed history from existing trend_windows so charts aren't empty
+-- Backfill from recommendations if trend_history is sparse.
--- on first deploy. This gives at least one data point per ticker/window.
+-- This reconstructs approximate trend history from the recommendation
+-- records that were generated throughout the day, giving one data point
+-- per ticker per window per hour.
 INSERT INTO trend_history (
     entity_type, entity_id, "window", trend_direction,
     trend_strength, confidence, contradiction_score,
     dominant_catalysts, material_risks, generated_at
 )
 SELECT
-    entity_type, entity_id, "window", trend_direction,
+    'company',
-    trend_strength, confidence, contradiction_score,
+    r.ticker,
-    dominant_catalysts, material_risks, generated_at
+    CASE
-FROM trend_windows
+        WHEN r.time_horizon LIKE 'intraday%' THEN 'intraday'
-ON CONFLICT DO NOTHING;
+        WHEN r.time_horizon LIKE 'swing_1d_3d%' THEN '1d'
+        WHEN r.time_horizon LIKE 'swing_1d_10d%' THEN '7d'
+        WHEN r.time_horizon LIKE 'position_10d_30d%' THEN '30d'
+        WHEN r.time_horizon LIKE 'position_30d_90d%' THEN '90d'
+        ELSE '7d'
+    END,
+    CASE
+        WHEN r.action = 'buy' THEN 'bullish'
+        WHEN r.action = 'sell' THEN 'bearish'
+        WHEN r.action = 'hold' THEN 'neutral'
+        ELSE 'mixed'
+    END,
+    r.confidence * 0.8,
+    r.confidence,
+    CASE WHEN r.risk_classification = 'high' THEN 0.4
+         WHEN r.risk_classification = 'very_high' THEN 0.6
+         WHEN r.risk_classification = 'moderate' THEN 0.2
+         ELSE 0.1
+    END,
+    '[]'::jsonb,
+    '[]'::jsonb,
+    r.generated_at
+FROM (
+    SELECT DISTINCT ON (ticker, time_horizon, date_trunc('hour', generated_at))
+           ticker, action, confidence, time_horizon, risk_classification, generated_at
+    FROM recommendations
+    WHERE generated_at >= NOW() - INTERVAL '7 days'
+    ORDER BY ticker, time_horizon, date_trunc('hour', generated_at), generated_at DESC
+) r
+WHERE NOT EXISTS (
+    SELECT 1 FROM trend_history th
+    WHERE th.entity_id = r.ticker
+      AND th.generated_at = r.generated_at
+);