linq late-stage cleanups: reducer shapes, adapter hygiene, match.das AST patterns (+ preflight pdflatex gate)

CLAUDE.md

@@ -286,6 +286,7 @@ Full migration table (when reading older docs that say `var inscope` or `<-` for
 | `for (s in A) { B \|> push(s) }` / `push_clone(s)` (iter-var only) | `B \|> push_from(A)` / `push_clone_from(A)` | PERF022: the bulk overload in builtin.das reserves combined capacity up front. Single name `push`/`push_clone` is overloaded between single-element and bulk (ambiguous when destination is `array<T[]>`); the `_from` suffix names the bulk intent. Source must be `array<T>` or C-array — range/iterator sources are not flagged. `emplace` is out of scope (const iter-var can't be moved) |
 | `var a : array<T>; for (x in SRC) { if (COND) { a \|> push(EXPR) } }` (or `table<K;V>` + `insert`/`a[k]=v`) | `var a <- [for (x in SRC); EXPR; where COND]` (or `\{for (...); k => v; where ...\}`) | STYLE027: var with empty default-init followed by a for-loop that only push/insert into it. Accepts depth ≤ 2 nested fors and if-filters at any depth. `emplace` excluded — move-source-zeroing differs from comprehension element-construction. Iterator-comprehension form (`[$f ...]`) NOT suggested |
 | `var X = clone_expression(E); ... $e(X) ...` (only-uses-are-qmacro-splice) | drop the pre-clone, inline `$e(E)` at each splice site | PERF023: `qmacro`/`qmacro_block`/`qmacro_expr`/`qmacro_block_to_array` go through `apply_template` (templates_boost.das:251), which calls `clone_expression` on every substitution input. Pre-cloning is wasted work. Detection: post-expansion `$e(X)` becomes `add_ptr_ref(X)` inside an `ExprMakeBlock`; visitor tracks splice-wrapper depth via preVisitExprCall/visitExprCall counter on `add_ptr_ref`, classifies each candidate `ExprVar` reference as "safe" when depth>0. Fires only when ALL uses are safe AND ≥1 is observed. Multi-clone-of-same-source flagged too — apply_template clones each substitution independently |
+| hand-rolled `is X` / `as X` / null-guard / `ExprRef2Value`-peel ladders in macro code | `qmatch(e, $e(a) + $e(b))` for source-syntax shapes; `match (e) { if (ExprField(name = "key", value = ExprVar(...))) { ... } }` for node-class shapes | both matchers peel `ExprRef2Value` automatically; `\|\|` alternation, `&&` guards, and `match_expr(local)` cover most ladders. Limits + the qmatch↔match division of labor: `skills/das_macros.md` "`match` (daslib/match)" |
 
 For path/filename ops use `fio` helpers (`base_name`/`dir_name`/`path_join`/etc.) — see `skills/filesystem.md`. Never hand-roll `rfind("/")` / slice — misses Windows separators.
 

benchmarks/sql/LINQ_TO_TABLE.md

@@ -243,13 +243,27 @@ PR1 findings:
 
 End of arc: `skills/linq.md` + linq docs mention the table source.
 
-## Late stage (planned) — reducer shapes & general code hygiene
+## Late stage (IN PROGRESS, 2026-06-11) — reducer shapes & general code hygiene
 
 Cross-source cleanups; none are table-specific. Items 1–2 are user-facing reducer-shape fixes,
 items 3–4 are codebase hygiene investigations (the linq_fold surface is workable but "a tad too
 unwieldy" — the table adapter took several stages, and many fuses read as "add this hook, because
 reasons" rather than falling out of the architecture).
 
+Status: **items 1+2 DONE** (selector overloads `sum/min/max/average(src, selector)`, the
+`_select`-macro bucket-element type stamping, the 2-arg recognizer arm with identity
+canonicalization — branch `bbatkin/linq-reducer-shapes`). **Item 4 partially DONE** (4A
+upstream-join validation dedup + 4B `loop_source_expr`/`loop_source_name` recontract — branch
+`bbatkin/linq-adapter-hygiene`; reverse hooks kept as-is per audit, stringly-Captures →
+typed ChainView deferred, per-source dispatch can't become a registry — macro modules compile
+into separate contexts). **Item 3 DONE with scope notes** (key-probe matchers + `join_keyb_is_bare_key`
+converted to `daslib/match` class patterns — n.b. the AST conversions use BOTH `daslib/ast_match`
+(qmatch) and `daslib/match`, each where it fits; prereq landed = ExprRef2Value transparency in
+match.das. Declined: `is_bucket_reducer_call` (statement-shaped match doesn't fit a
+tuple-returning recognizer) and `extract_decs_bridge` (match.das array patterns reject
+das-vector scrutinees — revisit if the library grows them). Toolbox doc:
+`skills/das_macros.md` "`match` (daslib/match)".
+
 1. **Identity-lambda reducers**: `_._1 |> max($(v) => v)` (also `min`/`sum`/`average`) fails with
    30303 today — the untyped lambda can't infer on the tier-2 lazy-bucket surface, and
    `recognize_reducer_specs` has no identity arm either. Fix both ends: recognize the identity