docs(ffi-linkage): checkpoint — Phase 6.2 (platform) done; next Phase 6.3 (std)

current/CHECKPOINT-EXTERN-EXPORT.md

@@ -5,15 +5,29 @@ Companion to `current/PLAN-EXTERN-EXPORT.md` — one merged plan: **Part A** add
 every commit, one step at a time per the cadence rule.
 
 ## Last completed step
-**Phase 6.1 — migrate `vendors/sqlite` `#foreign`→`extern`** (`refactor` commit
+**Phase 6.2 — migrate `platform/` `#foreign`→`extern`/`export`** (`refactor` commit
+`2cd5d7b`). Pure source rename across uikit/android/android_jni/sdl3 (~64 sites):
+30 fn `… #foreign;`→`… extern;`; 34 import runtime classes
+`#foreign #objc_class/#jni_class("X") {`→`#…_class("X") extern {` (prefix→postfix);
+4 defined `Sx*` obj-c classes `#objc_class("X") {`→`… export {`. Behavior-preserving;
+empty snapshot diff. **Verification (these modules are largely uncompiled by the
+host corpus** — bundle examples import `bundle.sx`, not the runtime modules; android.sx
+only compiles under `OS==.android`): byte-identical `sx ir` on uikit importers 1610 +
+1606 (which DO compile uikit incl. the 4 defined `Sx*` classes on host) and an sdl3
+direct-import probe; android.sx verified by an identical 4-error dedup set (host
+pthread clashes — the keyword-neutral "foreign symbol already bound" dedup message is
+unchanged, and the probe parsed all migrated `extern` jni classes + EGL fns cleanly
+before hitting them). Suite green (647 corpus / 444 unit, 0 failed). Remaining Phase 6
+batches: 6.3 std (~60), 6.4 ffi (~50), 6.5 remainder.
+
+### Prior: Phase 6.1 — migrate `vendors/sqlite` `#foreign`→`extern` (`refactor` commit
 `410a52e`). **PART B PHASE 6 STARTED.** Pure source rename: all 97
 `sqlite3_* … #foreign sqlib "csym";` fn decls → `extern sqlib "csym";` (+ the one
 stale header-comment reference, line 9). The `extern_lib` axis references the `sqlib`
 `#import c` unit identically to `#foreign sqlib`, so IR/output is byte-identical —
 empty snapshot diff (only `sqlite.sx` changed), and example 1624
 (`vendor-sqlite-module`) stdout byte-unchanged. Suite green (647 corpus / 444 unit,
-0 failed). Remaining Phase 6 batches: 6.2 platform (~95), 6.3 std (~60), 6.4 ffi
-(~50), 6.5 remainder.
+0 failed).
 
 ### Prior: Phase 5.1 — annotate A→B gate post-flip + add fn-rename case (`test` commit
 `93e7b6f`). **PHASE 5 COMPLETE → PART B Phase 5 done.** The A→B gate
@@ -170,23 +184,23 @@ AOT), 1227 (export fn rename, AOT), 1348 (objc extern class), 1349 (objc export
 (jni extern class), 1174/1175 (interplay diagnostics).
 
 ## Next step
-**PART B — Phase 6.2 (migrate `library/modules/platform/` `#foreign`→`extern`,
-~95 sites).** Phase 6.1 (sqlite) is COMPLETE.
+**PART B — Phase 6.3 (migrate `library/modules/std/` `#foreign`→`extern`, ~60
+sites).** Phase 6.1 (sqlite) + 6.2 (platform) COMPLETE.
 
-- **Phase 6.2** (`refactor`, snapshot diff must be EMPTY): rewrite
-  `library/modules/platform/` (uikit/android/android_jni/sdl3) `#foreign`→`extern`
-  (fns/globals), `#foreign #objc_class`→`#objc_class … extern`, defined classes →
-  `… export`. ⚠ Unlike sqlite (uniform fn decls), platform mixes Obj-C/JNI runtime
-  CLASSES — those use the **postfix** form (`#objc_class("X") extern { … }` for a
-  reference/import class == `#foreign #objc_class`; `… export` for a defined class ==
-  bare `#objc_class`). Check each `#foreign` site's shape before bulk-replacing; a
-  naive `s/#foreign //` is WRONG for the class-prefix form. Pure SOURCE rename, IR
-  byte-identical; a non-empty diff ⇒ a reader still branches on `foreign_expr`
-  structurally → STOP and coalesce first (don't regen).
-- **Remaining Phase 6 batches:** 6.3 `library/modules/std/`
-  (socket/thread/fs/time/process, ~60), 6.4 `library/modules/ffi/`
-  (objc/raylib/objc_block, ~50), 6.5 remaining `library/`+`vendors/`. Then **Phase 7**
-  migrates examples + issues the same way.
+- **Phase 6.3** (`refactor`, snapshot diff must be EMPTY): rewrite
+  `library/modules/std/` (socket/thread/fs/time/process/…) `#foreign`→`extern`. Mostly
+  libc fn decls (bare `#foreign;` or `#foreign "csym";`); check for any data-global
+  `#foreign` too. These ARE exercised by the host corpus (fs/process/socket examples),
+  so a non-empty snapshot diff catches a regression directly — STOP and coalesce, don't
+  regen. Transform: `s/ #foreign;/ extern;/` for bare, plus the `#foreign "csym"`/
+  `#foreign LIB "csym"` rename forms where present (verify per-file first like 6.2).
+- **Remaining Phase 6 batches:** 6.4 `library/modules/ffi/` (objc/raylib/objc_block,
+  ~50 — has runtime classes, use the postfix shape like 6.2), 6.5 remaining `library/`+
+  `vendors/`. Then **Phase 7** migrates examples + issues the same way.
+- **6.2 verification note (carry forward):** the `platform/` runtime modules
+  (uikit/android/android_jni) are NOT compiled by any marker'd host corpus test — verify
+  future platform-adjacent migrations via direct `sx ir` on importers (1610/1606 compile
+  uikit on host) or import probes, not the corpus alone.
 - **Phases 6–7** (`refactor` batches, empty snapshot diff per batch): migrate the
   stdlib + examples from `#foreign` spelling to `extern`. Because the AST is already
   unified, this is a pure SOURCE rename (`… #foreign LIB "sym";` → `… extern LIB "sym";`
@@ -309,6 +323,13 @@ Part A ratified (bare / postfix / `⇒ callconv(.c)` / lib-separate). Part B:
   deleted at cutover). Affects only diagnostic wording — IR/behavior identical either way.
 
 ## Log
+- (6.2 platform) Migrated `platform/` (uikit/android/android_jni/sdl3, ~64 sites):
+  30 fn `#foreign;`→`extern;`, 34 import classes prefix `#foreign #objc/jni_class`→
+  postfix `… extern {`, 4 defined `Sx*` objc classes → `… export {`. Behavior-
+  preserving, empty snapshot diff. Verified byte-identical `sx ir` on uikit importers
+  1610/1606 + sdl3 probe; android via identical 4-error dedup set (host-only module).
+  Suite green (647/444). `refactor` `2cd5d7b`. NOTE: these runtime modules aren't in
+  the marker'd host corpus — verified out-of-band.
 - (6.1 sqlite) **PHASE 6 STARTED.** Migrated `vendors/sqlite/sqlite.sx`: 97
   `… #foreign sqlib "csym";` fn decls → `extern sqlib "csym";` (+ line-9 comment).
   `extern_lib` references the `sqlib` `#import c` unit like `#foreign sqlib`; IR