gstack/docs/gbrain-sync.md

Cross-machine memory with GBrain sync

gstack writes a lot of useful state to ~/.gstack/ — learnings, retros, CEO plans, design docs, developer profile. By default, all of that dies when you switch laptops. GBrain sync pushes a curated subset to a private git repo so your memory follows you across machines and becomes indexable by GBrain.

What you get

• Work on machine A, pick up seamlessly on machine B.
• Your learnings, plans, and designs are visible in GBrain (if you use it).
• A clean off-ramp (gstack-brain-uninstall) that never touches your data.
• No daemon, no system service, no background process.

What does NOT leave your machine

By design, these stay local even when sync is on:

• Credentials: .auth.json, auth-token.json, sidebar-sessions/, security/device-salt, consumer tokens in config.yaml
• Machine-specific state: Chromium profiles, ONNX model weights, caches, eval-cache, CDP-profile, one-time prompt markers (.welcome-seen, .telemetry-prompted, .vendoring-warned-*, etc.)
• Question-preferences: per-machine UX preferences (question-preferences.json, question-log.jsonl, question-events.jsonl).

The exact allowlist lives in ~/.gstack/.brain-allowlist. The CLI manages it; you can append your own entries below the marker line.

First-run setup (30–90 seconds)

gstack-brain-init

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, self-hosted.
3. Pushes an initial commit with just the config.
4. Writes ~/.gstack-brain-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.

After init, the next skill you run will ask you ONE question about privacy mode:

• Everything allowlisted (recommended): learnings, reviews, plans, designs, retros, timelines, and developer profile all sync.
• Only artifacts: plans, designs, retros, learnings — skip behavioral data (timelines, developer profile).
• Decline: keep everything local. You can turn sync on later with gstack-config set gbrain_sync_mode full.

Your answer is persisted. You won't be asked again.

Cross-machine workflow

On machine A: run gstack-brain-init once. That's it — every skill invocation now drains the sync queue at its start and end boundaries (~200–800 ms network pause per skill).

On machine B:

1. Copy ~/.gstack-brain-remote.txt from machine A to machine B (password manager, dotfile repo, USB stick — your call).
2. Run any gstack skill. The preamble sees the URL file and prints:

   BRAIN_SYNC: brain repo detected: <url>
   BRAIN_SYNC: run 'gstack-brain-restore' to pull your cross-machine memory
   

3. Run gstack-brain-restore. That clones the repo, rehydrates your learnings/plans/retros, and re-registers the git merge drivers.
4. Re-enter consumer tokens (they're machine-local and NOT synced — gstack-config set gbrain_token <your-token>).
5. Next skill: your yesterday-on-machine-A learning surfaces. That's the magical moment.

Status, health, and queue depth

gstack-brain-sync --status

Shows: last successful push, pending queue depth, any sync blocks, and the current privacy mode.

Every skill run prints a BRAIN_SYNC: line near the top of the preamble output. Scan it for problems.

Privacy modes in detail

Mode	What syncs
off	Nothing (default).
artifacts-only	Plans, designs, retros, learnings, reviews. Skips timelines + developer-profile.
full	Everything in the allowlist, including behavioral state.

Change anytime with:

gstack-config set gbrain_sync_mode full
gstack-config set gbrain_sync_mode off

Secret protection

Every commit is scanned for credential-shaped content before it leaves your machine. Blocked patterns include:

• AWS access keys (AKIA…)
• GitHub tokens (ghp_, gho_, ghu_, ghs_, ghr_, github_pat_)
• OpenAI keys (sk-…)
• PEM blocks (-----BEGIN …-----)
• JWTs (eyJ…)
• Bearer tokens in JSON ("authorization": "…", "api_key": "…", etc.)

If a scan hits, sync stops, the queue is preserved, and your preamble prints:

BRAIN_SYNC: blocked: <pattern-family>:<snippet>

To remediate:

1. Review the offending file.
2. If the match is a false positive on content you explicitly want to sync, run gstack-brain-sync --skip-file <path> to permanently exclude that path.
3. Otherwise, edit the file to remove the secret and re-run any skill.

There's a defense-in-depth hook at ~/.gstack/.git/hooks/pre-commit that runs the same scan if you manually git commit against the repo.

Two-machine conflicts

If you write on machine A and machine B the same day, both will push append commits. Git's default would conflict at the file tail, but the .jsonl and markdown files are registered with custom merge drivers:

• JSONL files use a sort-and-dedup driver that orders appends by ISO timestamp (falls back to SHA-256 hash of each line for determinism).
• Markdown artifacts (retros, plans, designs) use a union merge driver that concatenates both sides.

You shouldn't see conflict prompts. If you do (a real semantic conflict, like two machines editing the same plan), git will stop and prompt.

Cross-machine pull cadence

The preamble runs git fetch + git merge --ff-only once per 24 hours (cached via ~/.gstack/.brain-last-pull). You don't need to think about this — it happens automatically at the first skill invocation each day.

Uninstall

gstack-brain-uninstall

This:

• Removes ~/.gstack/.git/ and all .brain-* config files.
• Clears gbrain_sync_mode in gstack-config.
• Does NOT touch your learnings, plans, retros, or developer profile.

Add --delete-remote to also delete the private GitHub repo (GitHub only, uses gh repo delete).

Re-init anytime with gstack-brain-init.

Troubleshooting

See gbrain-sync-errors.md for an index of every error message gstack-brain may print, with problem / cause / fix for each.

Under the hood

For the architectural decisions behind this feature (allowlist vs denylist, daemon vs preamble-boundary sync, JSONL merge driver, privacy stop-gate), see the approved plan in the gstack plans directory.