Columnar rendering: complete migration (Prompts 2.3–10.1)

log.md

@@ -0,0 +1,28 @@
+# Columnar Rendering: Work Log
+
+| # | Prompt | Status | Date |
+|---|--------|--------|------|
+| 1 | 0.1: Introduce ColumnarCollection type alias and ColumnarBundle | Done | 2026-03-24 |
+| 2 | 0.2: Columnar ↔ Vec conversion utilities | Done | 2026-03-24 |
+| 3 | 1.1: Persist source emits columnar collections | Done | 2026-03-24 |
+| 4 | 2.1: Negate operator propagates columnar collections | Done | 2026-03-24 |
+| 5 | 2.2: Union operator propagates columnar collections | Done | 2026-03-24 |
+| 6 | 2.3: Constant operator emits columnar collections | Done | 2026-03-25 |
+| 7 | 3.1: Columnar as_collection_core with Get/Mfp wiring | Done | 2026-03-25 |
+| 8 | 4.1: Columnar FlatMap accepts columnar input, emits columnar output | Done | 2026-03-25 |
+| 9 | 5.1: Columnar input to arrangements via ensure_collections | Done | 2026-03-25 |
+| 10 | 6.1: Columnar Reduce input via ensure_vec_collection | Done | 2026-03-25 |
+| 11 | 6.2: Columnar TopK input via ensure_vec_collection | Done | 2026-03-25 |
+| 12 | 6.3: Columnar Threshold input — verified, no changes needed | Done | 2026-03-25 |
+| 13 | 7.1: Columnar Linear Join input via ensure_vec_collection | Done | 2026-03-25 |
+| 14 | 7.2: Columnar Delta Join output when inputs have columnar | Done | 2026-03-25 |
+| 15 | 8.1: Columnar sink input via ensure_vec_collection | Done | 2026-03-25 |
+| 16 | 9.1: Audit Vec paths; remove redundant Vec from sources; add logging | Done | 2026-03-25 |
+| 17 | 9.2: Remove collection field and ensure_vec_collection from CollectionBundle | Done | 2026-03-25 |
+| 18 | 10.1: Investigate columnar arrangement spines — research complete | Done | 2026-03-25 |
+| 19 | 11.1: Columnar flat_map — iterate &RowRef directly without Vec conversion | Done | 2026-03-25 |
+| 20 | 11.2: Columnar as_specific_collection — identity path returns columnar directly | Done | 2026-03-25 |
+| 21 | 11.3: Columnar as_collection_core — verified, identity avoids round-trip | Done | 2026-03-25 |
+| 22 | 11.4: Columnar Reduce input — verified, flat_map uses &RowRef directly | Done | 2026-03-25 |
+| 23 | 11.5: Columnar FlatMap — direct &RowRef processing via unary_fallible on Column | Done | 2026-03-25 |
+| 24 | 11.6: Columnar ArrangeBy — arrange_columnar_collection iterates &RowRef directly | Done | 2026-03-25 |