From 25b6e75cedef3d8097e46c8ffdad31a0b10e29a3 Mon Sep 17 00:00:00 2001
From: Renaud Laborbe <150821561+BluegReeno@users.noreply.github.com>
Date: Fri, 24 Jul 2026 20:50:21 +0200
Subject: [PATCH] fix(edifice-map-generator): restore deno check on the PNG
 codec
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`main` has been red since 48f89fd. Committing the deployed v10 of this function
(444fa3d) brought in the pure-TS PNG codec, whose stream helpers do not type-check
under Deno 2.x — 2 × TS2345 on `deno check index.ts`. Every PR since then inherits
the failure through its merge with main.

Two type facts, neither cosmetic:

1. CompressionStream / DecompressionStream declare
   `writable: WritableStream<BufferSource>`, wider than Uint8Array — so a
   `TransformStream<Uint8Array, Uint8Array>` parameter asked for something narrower
   than either class provides, and neither was assignable.
2. Since TypeScript 5.7 typed arrays are generic over their backing buffer: bare
   `Uint8Array` means `Uint8Array<ArrayBufferLike>`, which admits SharedArrayBuffer,
   while `BufferSource` requires `ArrayBufferView<ArrayBuffer>`.

Fixed by typing the codec path `Uint8Array<ArrayBuffer>` and widening the transform
parameter to `TransformStream<BufferSource, Uint8Array>`. This states that these
buffers are never shared — already true, every one comes from `new Uint8Array(n)` or
a `Response.arrayBuffer()`. A cast would have silenced the checker without saying so.

Types only: the diff touches three signatures and no executable line, so the
deployed function is unaffected. Verified with the CI's own toolchain
(`denoland/deno` image, `deno check index.ts`): edifice-map-generator goes from
2 errors to clean, hal-mcp stays clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 .../functions/edifice-map-generator/index.ts  | 22 ++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/supabase/functions/edifice-map-generator/index.ts b/supabase/functions/edifice-map-generator/index.ts
index 95ced7f..e2c4866 100644
--- a/supabase/functions/edifice-map-generator/index.ts
+++ b/supabase/functions/edifice-map-generator/index.ts
@@ -304,18 +304,30 @@ function crc32(data: Uint8Array): number {
   return (c ^ 0xFFFFFFFF) >>> 0;
 }
 
-async function zlibDecompress(data: Uint8Array): Promise<Uint8Array> {
+async function zlibDecompress(data: Uint8Array<ArrayBuffer>): Promise<Uint8Array<ArrayBuffer>> {
   return streamTransform(new DecompressionStream("deflate"), data);
 }
 
-async function zlibCompress(data: Uint8Array): Promise<Uint8Array> {
+async function zlibCompress(data: Uint8Array<ArrayBuffer>): Promise<Uint8Array<ArrayBuffer>> {
   return streamTransform(new CompressionStream("deflate"), data);
 }
 
+// Two type facts drive these signatures under Deno 2.x / TypeScript 5.7, and neither is
+// cosmetic:
+//   1. CompressionStream and DecompressionStream declare `writable: WritableStream<BufferSource>`,
+//      which is wider than Uint8Array — so a `TransformStream<Uint8Array, Uint8Array>`
+//      parameter asked for something narrower than either class provides.
+//   2. Since TS 5.7 typed arrays are generic over their backing buffer: bare `Uint8Array`
+//      means `Uint8Array<ArrayBufferLike>`, which admits SharedArrayBuffer, while
+//      `BufferSource` requires `ArrayBufferView<ArrayBuffer>`. So a bare Uint8Array is not
+//      writable to these streams.
+// Hence `Uint8Array<ArrayBuffer>` throughout the PNG codec path: it states that these buffers
+// are never shared, which is already true — every one of them comes from `new Uint8Array(n)`
+// or a `Response.arrayBuffer()`. A cast would have silenced the checker without saying so.
 async function streamTransform(
-  xform: TransformStream<Uint8Array, Uint8Array>,
-  data: Uint8Array,
-): Promise<Uint8Array> {
+  xform: TransformStream<BufferSource, Uint8Array>,
+  data: Uint8Array<ArrayBuffer>,
+): Promise<Uint8Array<ArrayBuffer>> {
   const writer = xform.writable.getWriter();
   const reader = xform.readable.getReader();
   const chunks: Uint8Array[] = [];