feat(temporal): created_at als Meta-Anker — multiple anchors per block

User-Prinzip (Session 20): "der blockinhalt kann ja auch zeiten
referenzieren. ergo kann ein block mehrere temporale anker haben".

Vorher: ein Block bekam temporale Dimensionen NUR aus Datums-
Erwaehnungen im Content. Ohne Date-Match im Text: nur _none Sentinel.
Bloecke mit abstraktem Inhalt waren temporal unauffindbar.

Jetzt: jeder Block hat MINDESTENS einen temporalen Anker (created_at).
Content-Anchors + Meta-Anchor koexistieren als Union. Ein Block mit
"Meeting am Dienstag" erstellt am Freitag hat:
  - weekday=2 (content, semantic)
  - weekday=5 (created_at, meta)

Beide Signale tragen unabhaengige Dimensionen bei.

Go:
- PopulateTemporal(..., createdAt time.Time) als neuer Pflicht-Parameter
- allTimes = [createdAt] + contentTimes (SQL ON CONFLICT handelt Overlap)
- isZero-Check als defensiver Fallback
- BackfillTemporal: SELECT erweitert um cb.created_at
- 3 Handler-Caller (context_store, context_manage, ingest) passen
  block.CreatedAt durch
- Branch "len(times) > 0" entfernt — createdAt ist immer da

Migration 021:
- Backfill: 8 Dimensionen pro aktivem Block aus created_at via
  EXTRACT(YEAR/MONTH/WEEK/ISODOW/QUARTER/DAY/DOY/HOUR)
- LATERAL + VALUES statt 8 separate INSERTs
- Cleanup: _none Sentinels entfernt wo echte Dimensionen existieren
- Archivierte Bloecke bleiben mit _none (nicht retrieved anyway)

Verifikation:
- 158 → 603 Dimensionen pro Dimension-Typ (+281% Coverage)
- 28 _none verbleibend (nur archivierte Bloecke)
- "abends"-Query: blocks_with_dims 46 → 98 (alle aktiven Bloecke
  mit daily-Dim via created_at.Hour())
- test.sh 16/16, eval.sh 43/43, keine Regression
- Retrieval P95: 64ms

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: GottZ

go/internal/handler/context_manage.go

@@ -272,10 +272,9 @@ func (h *ManageHandler) handleUpdate(w http.ResponseWriter, r *http.Request, ar
 		if err := store.UpdateContentTimes(ctx, h.pool, block.ID, times); err != nil {
 			slog.Error("manage: content_times update failed", "error", err, "block_id", block.ID, "request_id", reqID)
 		}
-		if len(times) > 0 {
-			if err := store.PopulateTemporal(ctx, h.pool, block.ID, times); err != nil {
-				slog.Error("manage: temporal populate failed", "error", err, "block_id", block.ID, "request_id", reqID)
-			}
+		// Always populate: createdAt is included as meta-anchor even without content times.
+		if err := store.PopulateTemporal(ctx, h.pool, block.ID, times, block.CreatedAt); err != nil {
+			slog.Error("manage: temporal populate failed", "error", err, "block_id", block.ID, "request_id", reqID)
 		}
 	}
 

go/internal/handler/context_store.go

@@ -166,10 +166,9 @@ func (h *StoreHandler) HandleStore(w http.ResponseWriter, r *http.Request) {
 		if err := store.UpdateContentTimes(bgCtx, h.pool, block.ID, times); err != nil {
 			slog.Error("store: content_times update failed", "error", err, "block_id", block.ID, "request_id", reqID)
 		}
-		if len(times) > 0 {
-			if err := store.PopulateTemporal(bgCtx, h.pool, block.ID, times); err != nil {
-				slog.Error("store: temporal populate failed", "error", err, "block_id", block.ID, "request_id", reqID)
-			}
+		// Always populate: createdAt is included as meta-anchor even without content times.
+		if err := store.PopulateTemporal(bgCtx, h.pool, block.ID, times, block.CreatedAt); err != nil {
+			slog.Error("store: temporal populate failed", "error", err, "block_id", block.ID, "request_id", reqID)
 		}
 	}()
 

go/internal/handler/ingest.go

@@ -260,11 +260,10 @@ func (h *IngestHandler) processChunk(ctx context.Context, reqID string, chunk In
 			slog.Error("ingest: content_times update failed",
 				"error", err, "block_id", block.ID, "request_id", reqID)
 		}
-		if len(times) > 0 {
-			if err := store.PopulateTemporal(bgCtx, h.pool, block.ID, times); err != nil {
-				slog.Error("ingest: temporal populate failed",
-					"error", err, "block_id", block.ID, "request_id", reqID)
-			}
+		// Always populate: createdAt is included as meta-anchor even without content times.
+		if err := store.PopulateTemporal(bgCtx, h.pool, block.ID, times, block.CreatedAt); err != nil {
+			slog.Error("ingest: temporal populate failed",
+				"error", err, "block_id", block.ID, "request_id", reqID)
 		}
 	}()
 

go/internal/store/temporal.go

@@ -125,9 +125,26 @@ func BuildTemporalBatch(blockID string, times []time.Time, links ...[]string) (*
 }
 
 // PopulateTemporal replaces all temporal dimensions for a block.
-// Deletes existing rows, then batch-inserts new dimensions for each timestamp.
-func PopulateTemporal(ctx context.Context, pool *pgxpool.Pool, blockID string, times []time.Time) error {
-	batch, queryCount := BuildTemporalBatch(blockID, times)
+// Deletes existing rows, then batch-inserts new dimensions.
+//
+// A block can have multiple temporal anchors simultaneously:
+//   - contentTimes: timestamps mentioned/extracted from block content (semantic)
+//   - createdAt: the block's creation timestamp (meta anchor)
+//
+// Both sources contribute INDEPENDENT dimensions. A block created on Friday
+// whose content says "Meeting am Dienstag" gets weekday=2 (content) AND
+// weekday=5 (meta) — enables retrieval for both signals. SQL-level dedup
+// via ON CONFLICT handles timestamp overlap between sources.
+//
+// If createdAt is zero, only contentTimes is used (defensive fallback).
+func PopulateTemporal(ctx context.Context, pool *pgxpool.Pool, blockID string, contentTimes []time.Time, createdAt time.Time) error {
+	allTimes := contentTimes
+	if !createdAt.IsZero() {
+		allTimes = make([]time.Time, 0, len(contentTimes)+1)
+		allTimes = append(allTimes, createdAt)
+		allTimes = append(allTimes, contentTimes...)
+	}
+	batch, queryCount := BuildTemporalBatch(blockID, allTimes)
 
 	br := pool.SendBatch(ctx, batch)
 	defer func() { _ = br.Close() }()
@@ -240,7 +257,7 @@ func BackfillTemporal(ctx context.Context, pool *pgxpool.Pool) (int, error) {
 
 	for {
 		rows, err := pool.Query(ctx,
-			`SELECT cb.id, cb.content
+			`SELECT cb.id, cb.content, cb.created_at
 			 FROM context_blocks cb
 			 WHERE NOT cb.is_archived
 			   AND NOT EXISTS (SELECT 1 FROM context_temporal ct WHERE ct.block_id = cb.id)
@@ -252,13 +269,14 @@ func BackfillTemporal(ctx context.Context, pool *pgxpool.Pool) (int, error) {
 		}
 
 		type blockRow struct {
-			ID      string
-			Content string
+			ID        string
+			Content   string
+			CreatedAt time.Time
 		}
 		var blocks []blockRow
 		for rows.Next() {
 			var b blockRow
-			if err := rows.Scan(&b.ID, &b.Content); err != nil {
+			if err := rows.Scan(&b.ID, &b.Content, &b.CreatedAt); err != nil {
 				rows.Close()
 				return processed, fmt.Errorf("store: temporal: backfill scan: %w", err)
 			}
@@ -282,9 +300,9 @@ func BackfillTemporal(ctx context.Context, pool *pgxpool.Pool) (int, error) {
 				continue
 			}
 
-			// Always populate temporal — for blocks without times this inserts
-			// a sentinel (_none) so NOT EXISTS doesn't re-select them.
-			if err := PopulateTemporal(ctx, pool, b.ID, times); err != nil {
+			// Always populate temporal — createdAt is passed as meta-anchor.
+			// Blocks without content times still get dimensions from their creation time.
+			if err := PopulateTemporal(ctx, pool, b.ID, times, b.CreatedAt); err != nil {
 				slog.Warn("backfill: populate temporal failed",
 					"block_id", b.ID, "error", err)
 				continue

go/migrations/021_created_at_anchors.sql

@@ -0,0 +1,58 @@
+-- =============================================================================
+-- 021_created_at_anchors.sql — Backfill created_at as meta-anchor dimensions
+-- Part of ctx by GottZ (https://github.com/GottZ/ctx)
+-- =============================================================================
+-- User decision (Session 20, 2026-04-05): "der blockinhalt kann ja auch
+-- zeiten referenzieren. ergo kann ein block mehrere temporale anker haben".
+--
+-- Every block has a natural temporal anchor: its created_at timestamp. This
+-- is independent from any dates mentioned in the content. A block about
+-- "Meeting am Dienstag" written on Friday has TWO legitimate anchors:
+--   - weekday=2 (content, semantic)
+--   - weekday=5 (created_at, meta)
+--
+-- Both signals should contribute dimensions. Before M021, only content-
+-- derived times were extracted — blocks without date mentions had no
+-- temporal dimensions at all (only '_none' sentinel).
+--
+-- This migration backfills all 8 dimensions for every non-archived block's
+-- created_at. ON CONFLICT DO NOTHING handles overlap with existing content-
+-- derived dimensions. The '_none' sentinel is NOT removed — future content
+-- updates via PopulateTemporal will clean it up via DELETE+INSERT pattern.
+-- =============================================================================
+
+-- =============================================================================
+-- Backfill all 8 temporal dimensions from created_at for every active block
+-- =============================================================================
+WITH block_times AS (
+    SELECT id, created_at
+    FROM context_blocks
+    WHERE NOT is_archived
+)
+INSERT INTO context_temporal (block_id, dimension, value, source_time)
+SELECT id, dimension, value, created_at
+FROM block_times,
+LATERAL (VALUES
+    ('year',     EXTRACT(YEAR FROM created_at)::TEXT),
+    ('month',    EXTRACT(MONTH FROM created_at)::TEXT),
+    ('week',     EXTRACT(WEEK FROM created_at)::TEXT),
+    ('weekday',  EXTRACT(ISODOW FROM created_at)::TEXT),
+    ('quarter',  EXTRACT(QUARTER FROM created_at)::TEXT),
+    ('monthday', EXTRACT(DAY FROM created_at)::TEXT),
+    ('seasonal', EXTRACT(DOY FROM created_at)::TEXT),
+    ('daily',    EXTRACT(HOUR FROM created_at)::TEXT)
+) AS dims(dimension, value)
+ON CONFLICT DO NOTHING;
+
+-- =============================================================================
+-- Clean up '_none' sentinel rows for blocks that now have real dimensions
+-- =============================================================================
+-- After the backfill, every non-archived block has at least 8 dimensions
+-- from its created_at. The '_none' sentinel is obsolete for these blocks.
+DELETE FROM context_temporal ct
+WHERE ct.dimension = '_none'
+  AND EXISTS (
+      SELECT 1 FROM context_temporal ct2
+      WHERE ct2.block_id = ct.block_id
+        AND ct2.dimension != '_none'
+  );