test(deepseek): stop pinning Node's one-shot zstd decoder to the first frame

docs/deepseek-integration.md

@@ -235,9 +235,10 @@ worker's first answer reads as an answer. Three things about the file shaped the
 reader (`src/deepseek-transcript.ts`):
 
 - **It is one zstd FRAME per append, not one zstd stream.** `zstd -dc` decodes all
-  of them, Node's `zlib` zstd decoder stops at the first: a real 56-line
-  transcript came back as 1 line. The reader walks frame headers itself. On a Node
-  older than 22.15 (no zstd at all) the mode falls back to the pane, as before.
+  of them, Node's `zlib` zstd decoder before 24.22 and 26.10 stops at the first:
+  a real 56-line transcript came back as 1 line. The reader walks frame headers
+  itself, which stays correct on a Node that decodes every frame
+  (nodejs/node#65865). On a Node older than 22.15 (no zstd at all) the mode falls back to the pane, as before.
 - **Not every `user/message` is the user.** Each turn also records a
   plugin-sourced runtime-context snapshot; only `source.kind === 'user'` is a
   prompt.

src/deepseek-transcript.ts

@@ -26,10 +26,11 @@
  * **1. One zstd FRAME per append, not one zstd stream.** The file is
  * `session.jsonl.zstd`, and dsh appends by compressing each batch of lines into
  * its own frame and writing it at the end. `zstd -dc` handles that (frames
- * concatenate by definition), but Node's `zlib.zstdDecompress()` and
- * `createZstdDecompress()` both stop at the first frame end: measured on a real
- * 56-line transcript, Node returned 158 bytes / 1 line where the CLI returned
- * 43,747 bytes / 56 lines. That is a silent truncation to the session header —
+ * concatenate by definition), but before Node 24.22 and 26.10
+ * (nodejs/node#65865) `zlib.zstdDecompress()` and `createZstdDecompress()` both
+ * stop at the first frame end, and the supported range still includes those
+ * versions: measured on a real 56-line transcript, Node returned 158 bytes /
+ * 1 line where the CLI returned 43,747 bytes / 56 lines. That is a silent truncation to the session header —
  * every call would have reported "no answer yet" forever. `decodeZstdFrames()`
  * below walks the frame headers itself and decompresses each frame, and
  * `test/deepseek-transcript.test.ts` pins it against multi-frame fixtures.

test/deepseek-transcript.test.ts

@@ -4,10 +4,11 @@
  * Two of these assertions exist because the obvious implementation was measured
  * to be wrong against real files:
  *
- * - dsh appends ONE ZSTD FRAME PER WRITE, and Node's `zlib` zstd decoder stops
- *   at the first frame end. A 56-line transcript decoded as 1 line / 158 bytes,
- *   which reads as "the worker never answered" rather than as an error. The
- *   multi-frame fixtures below are the guard.
+ * - dsh appends ONE ZSTD FRAME PER WRITE, and Node's `zlib` zstd decoder
+ *   before 24.22 and 26.10 stops at the first frame end. A 56-line transcript
+ *   decoded as 1 line / 158 bytes, which reads as "the worker never answered"
+ *   rather than as an error. Newer Node decodes every frame (nodejs/node#65865),
+ *   so the multi-frame fixtures below pin the walker itself, not Node's decoder.
  * - a fresh worker in a case directory that had been used before answered its
  *   first `last-response` with the PREVIOUS session's reply. Session-to-
  *   transcript pairing is therefore its own describe block.
@@ -67,10 +68,6 @@ describe.skipIf(!zstdSupported())('zstd frame walking', () => {
     const lines = Array.from({ length: 40 }, (_, i) => JSON.stringify({ type: 'noise', seq: i }));
     const buf = framed(lines);
 
-    // The one-shot decoder is what this module had to replace.
-    const oneShot = (zlib as unknown as { zstdDecompressSync?: (b: Buffer) => Buffer }).zstdDecompressSync!(buf);
-    expect(oneShot.toString('utf8').trim().split('\n')).toHaveLength(1);
-
     expect(zstdFrameRanges(buf)).toHaveLength(40);
     expect(decodeZstdFrames(buf).trim().split('\n')).toHaveLength(40);
   });