Five gaps the examples hit, written down before they are forgotten

NEXT.md

@@ -1,3 +1,46 @@
+## To discuss: five gaps the raylib examples hit and could not close
+
+Found by the lane that ported `core-2d-camera`, `core-scissor-test`, `core-window-flags`,
+`core-world-screen` and `core-window-should-close`. None blocked those five. All five blocked
+something else, and each is a language or checker question rather than a missing binding, which is
+why they are here and not in a binding list.
+
+1. **A `(Ptr T)` returned from C cannot be indexed.** `indexed` in `lib/check.ml` accepts `Array`
+   and `Slice` only, so a C function answering `int*` is readable at element 0 through `deref` and
+   nowhere else. `LoadRandomSequence` is the case that hit it and `core_random_sequence` is
+   unportable until it moves. The question is what the answer should be: a length has to come from
+   somewhere before a pointer can become a slice, and C does not supply one. Possibly a
+   `(slice-from-ptr p n)` where the caller states the length and owns being right about it.
+
+2. **An enum-typed `defstruct` field is refused by the layout check**, even when the representation
+   is identical. The message is `DISAGREES Camera3D: field projection is CameraProjection in the
+   defstruct and i32 (int)`. The check is comparing a Flan enum against the header's `int` and
+   calling that a disagreement, which it is not — an enum is an `i32`. Worked around with an
+   `rl/camera-projection` helper so the call site still takes a checked keyword. Related and
+   probably the same decision: a keyword resolves only where an enum type is expected, so
+   `:perspective` cannot be written into an `i32` field directly.
+
+3. **The header check does not reach `defconst` or `defenum`.** `generate-c`'s claim is that every
+   `defstruct` and every hand-written `declare-c` agrees with the header, and that claim holds. It
+   says nothing about constants. **A wrong flag bit or a wrong enum member is silent** — which is
+   exactly the class of error the header read exists to catch, and the class hardest to see by
+   reading. This lane added 16 `ConfigFlags` constants and four enums by hand off the header, so the
+   values are right today and nothing would notice if they stopped being.
+
+4. **raymath is `static inline`, so there is no symbol to bind.** `Clamp`, `Vector2Add`, `Remap` and
+   the rest exist only in the header. `declare-c` has nothing to name. rlgl's matrix stack is
+   unbound for a different reason. Together they make `core_2d_camera_mouse_zoom` unfaithful rather
+   than merely awkward, so it was skipped. The options are writing the arithmetic in Flan, which is
+   what the prelude would do anyway, or compiling a small C file that re-exports them as real
+   symbols.
+
+5. **Four families are still refused by the importer for want of a `defstruct`.** `FilePathList`
+   (a `char**`, blocks `core_drop_files`), `Model`/`Mesh`/`Ray`/`BoundingBox` (the model and
+   3D-collision families), and **function-pointer parameters** (`SetTraceLogCallback`, which blocks
+   `core_custom_logging`, and the audio stream processors). The first three are ordinary widening —
+   write the `defstruct` and they import. The function-pointer one is not, and is the interesting
+   one: it is the callback direction of the FFI, which nothing has needed yet.
+
 ## Queued, 2026-09-13 (second session) — everything four lanes left behind
 
 Four lanes ran in parallel worktrees and three landed; all are merged into `dev-loop` and `dune test` is green on