chore(backlog): TASK-55 all ACs checked + Done

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: 2 people

backlog/tasks/task-55 - Specializer-small-tails-sweep-—-NULL-value-statics-schema-qualified-relations.md

@@ -3,9 +3,10 @@ id: TASK-55
 title: >-
   Specializer small-tails sweep — NULL-value statics + schema-qualified
   relations
-status: In Progress
+status: Done
 assignee: []
 created_date: '2026-07-27 22:10'
+updated_date: '2026-07-27 22:23'
 labels: []
 milestone: m-7
 dependencies:
@@ -29,8 +30,14 @@ Deferred with named rejects: COLUMNS(* REPLACE ...) and fn(COLUMNS(*)) expressio
 
 ## Acceptance Criteria
 <!-- AC:BEGIN -->
-- [ ] #1 Static tables with NULL VALUE columns serve: NULL flows through join lanes (INNER and LEFT, incl. residuals); NULL keys keep dropping; both backends
-- [ ] #2 Schema-qualified driving/joined/comma-joined relations + 3-part column refs bind by suffix match; known-limitations.md §5 + twin suite updated in the same commit
-- [ ] #3 Corpus replay: zero FAILs, match count reported (expect ~+12 to ~517)
-- [ ] #4 Gate green both backends, clippy clean
+- [x] #1 Static tables with NULL VALUE columns serve: NULL flows through join lanes (INNER and LEFT, incl. residuals); NULL keys keep dropping; both backends
+- [x] #2 Schema-qualified driving/joined/comma-joined relations + 3-part column refs bind by suffix match; known-limitations.md §5 + twin suite updated in the same commit
+- [x] #3 Corpus replay: zero FAILs, match count reported (expect ~+12 to ~517)
+- [x] #4 Gate green both backends, clippy clean
 <!-- AC:END -->
+
+## Final Summary
+
+<!-- SECTION:FINAL_SUMMARY:BEGIN -->
+Small-tails sweep shipped: corpus 505 -> 511 of 678, zero FAILs. (1) NULL values in static join tables serve — declared-nullable value columns flatten to (validity i1, payload) pairs in the map layout with zero IR changes; the probe's typed miss-defaults make validity=false free on LEFT misses, and StaticCol ANDs validity into the null lane on both backends (INNER/LEFT/residual all oracle-checked); NULL keys keep the drop rule; the materializer maps NULL -> (false, typed default) with the non-nullable guard kept as a safety net. (2) Schema qualifiers are registry-noise: s1.t1 resolves by table-part suffix match for driving/joined/comma-joined relations, 3-part schema.table.col refs bind; amends the wave-5 main.-only rule, documented as a §5 contract choice (DuckDB's schema-existence errors are unknowable to a schema-less registry); ambiguity still errors. known-limitations.md + twin suite updated in the same commit (NULL-value reject row flipped to served). 3 of the 9 NULL-static corpus cases uncovered second blockers (dup keys / self-joins — stage-B constituency grows again). Gates: 155 Rust + 599 py green, interp identical minus backend-identity guards, clippy clean on touched files. PR #42 (stacked on #41).
+<!-- SECTION:FINAL_SUMMARY:END -->