fix(memory-ingest): strip NUL bytes from transcript body before put

[billy-armstrong]

Summary

gstack-memory-ingest builds a rendered transcript body, then calls gbrain put over stdin. When the body contains a NUL byte (0x00 / �), Postgres rejects it with invalid byte sequence for encoding "UTF8": 0x00, which surfaces from the brain server as an opaque internal_error. The error is then truncated by gbrainPutPage to the first 300 chars of the first line, hiding the root cause.

NUL bytes show up in the wild from user-pasted binary blobs, terminal escape sequences, screen-recorder output, and the like — anything that landed in a ## User or ## Assistant section of a Claude Code transcript.

This sanitizes at write time, one line + a comment block, in bin/gstack-memory-ingest.ts right before the execFileSync("gbrain", ["put", ...]) call. The regex matches a literal NUL character (/�/g).

Repro before this fix

A first-run --bulk ingest of ~86 transcripts on a fresh thin-client setup fails some of them with:

[put-error] transcripts/claude-code/_unattributed/...: Remote tool put_page failed: {

…and the truncated error hides the actual root cause. Adding a temporary stderr-dump to gbrainPutPage surfaces the real message:

{"error":"internal_error","message":"invalid byte sequence for encoding \"UTF8\": 0x00"}

In my case, 2 of 86 transcripts had user-pasted content with embedded NULs. The 1-line strip fixes it cleanly without touching anything else in the pipeline.

After this fix

$ bun bin/gstack-memory-ingest.ts --incremental
[1] transcripts/claude-code/_unattributed/2026-04-30-0f15bc90-57a
[2] transcripts/claude-code/_unattributed/2026-04-30-5d3bf8aa-6cd
Ingest pass complete (incremental):
  written:               2
  failed:                0

Test plan

• Manual: ingested 86 transcripts (2 of which contained NULs) on a fresh thin-client setup → 86/86 written, 0 failed
• Unit test: not added — happy to add one if you want, but I didn't see existing in-process unit tests on gbrainPutPage paths

🤖 Generated with Claude Code

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