docs: fold the Codex accuracy review of the release docs

Six findings, all verified against source before fixing:

1. 'Every send writes a receipt' overclaimed — fail-open sinks proceed with
   a stderr warning when the receipt write fails, so a fail-open send can go
   unrecorded (lib/egress-receipt.ts:8-14). Descriptive prose now says so;
   the receipted framing keeps 'attempted'.
2. 'Receipts hash the request body' is wrong for subprocess-owned sends —
   git pushes record sha256: null (lib/egress-receipt.ts:71).
3. 'grants shows every consent in force' overclaimed — it reports the four
   standing config settings (bin/gstack-egress:139-181). Reworded in
   README, ARCHITECTURE, and the CHANGELOG entry.
4. 'Zero-exception scanner' vs reality: the new-sink scanner carries a
   reasoned SCANNER_EXEMPT list (user-directed fetches, probes, instruction
   strings, skill prose). CLAUDE.md now names it.
5. Error-catalog cause/fix for the receipt refusal: the writer mkdirs the
   ledger dir itself, so 'missing' isn't a cause and bare chmod fails when
   it is absent — cause reworded, fix is mkdir -p && chmod.
6. gbrain-sync first-run steps described the retired binary's behavior:
   default repo is gstack-artifacts-$USER, and init PRINTS the gbrain
   hookup command (never auto-executes; bin/gstack-artifacts-init:384-419).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/gbrain-sync-errors.md

@@ -103,12 +103,13 @@ made, and the queue is preserved — the next run retries the whole drain.
 `gstack-brain-sync --status` shows `EGRESS_RECEIPT_FAILED` as the failure
 detail.
 
-**Cause.** `~/.gstack/security/` is missing or unwritable, the disk is
-full, or `GSTACK_HOME` points at a read-only location.
+**Cause.** `~/.gstack/security/` is not writable (the receipt writer creates
+it when missing, so absence alone is not the cause), the disk is full, or
+`GSTACK_HOME` points at a read-only location.
 
 **Fix.**
 ```bash
-chmod -R u+w ~/.gstack/security
+mkdir -p ~/.gstack/security && chmod -R u+w ~/.gstack/security
 ```
 Then run any skill (or `gstack-brain-sync --once`) to retry. Inspect the
 ledger with `gstack-egress list`; verify its hash chain with

docs/gbrain-sync.md

@@ -38,18 +38,18 @@ The command:
 
 1. Turns `~/.gstack/` into a git repo.
 2. Asks for a remote URL (default: `gh repo create --private
-   gstack-brain-$USER`). Any git remote works — GitHub, GitLab, Gitea,
+   gstack-artifacts-$USER`). Any git remote works — GitHub, GitLab, Gitea,
    self-hosted.
 3. Pushes an initial commit with just the config.
 4. Writes `~/.gstack-artifacts-remote.txt` (URL-only, no secrets —
    safe to copy to another machine).
-5. Wires the gstack-brain repo into your local gbrain as a federated
-   source (via `gbrain sources add` + `git worktree`) so `gbrain search`
-   can index your synced learnings, plans, and designs. Implementation
-   lives in `bin/gstack-gbrain-source-wireup`. The old
-   `gstack-brain-reader add --ingest-url ...` HTTP path was removed in
-   v1.15.1.0 — it depended on a `/ingest-repo` endpoint gbrain never
-   shipped.
+5. Prints the `gbrain sources add` hookup command for the brain host
+   (never auto-executed — run it yourself, or on your own machine
+   `bin/gstack-gbrain-source-wireup` does the same wiring) so
+   `gbrain search` can index your synced learnings, plans, and designs.
+   The old `gstack-brain-reader add --ingest-url ...` HTTP path was
+   removed in v1.15.1.0 — it depended on a `/ingest-repo` endpoint gbrain
+   never shipped.
 
 After init, the **next skill you run** will ask you ONE question about
 privacy mode: