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
• 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-artifacts-init

The command:

1. Turns ~/.gstack/ into a git repo.
2. Asks for a remote URL (default: gh repo create --private 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. 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:

• 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 artifacts_sync_mode full.

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

Cross-machine workflow

On machine A: run gstack-artifacts-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-artifacts-remote.txt from machine A to machine B (password manager, dotfile repo, USB stick — your call; the legacy ~/.gstack-brain-remote.txt name is still recognized).
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. Next skill: your yesterday-on-machine-A learning surfaces. That's the magical moment.

Status, health, and queue depth

gstack-brain-sync --status

Shows: the status (ok, idle, held, collision, blocked, push_failed, error), files held back by the secret scan with their fixes, files held because their path differs only by letter case from another path (case_held, case_names; see troubleshooting), the drainable count, the last sync and push times, pending queue depth, and the current privacy mode.

Every skill run prints an ARTIFACTS_SYNC: line near the top of the preamble output. When the sync is stuck it adds an ARTIFACTS_SYNC: attention: line; the table of those lines and their fixes is in gbrain-sync-errors.md.

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 artifacts_sync_mode full
gstack-config set artifacts_sync_mode off

Removed and moved files

By default the sync never publishes a removal: delete a synced design doc, or move a project directory (a project slug migration does), and the old path stays on the remote, where the brain keeps indexing it next to the new copy. To publish removals too:

gstack-config set artifacts_sync_removals on

Each sync then commits the removal of synced files that are gone from disk. Transcript pages are left alone, and a decision log and its active snapshot go only together. A sync that would remove more than 20 files at once publishes none of them: that looks like a loss, not a cleanup. Review and publish those yourself, whatever the setting:

gstack-brain-sync --publish-removals        # list them
gstack-brain-sync --publish-removals --yes  # commit and push their removal

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, only the flagged file is held back (with any file coupled to it); everything else syncs. The held file stays queued and is re-scanned at every sync, and skill start prints:

ARTIFACTS_SYNC: attention: status=held held=1. The secret scan is holding back 1 file(s); everything else still syncs. See which files and how to fix them: <bin> --status

To remediate:

1. Run gstack-brain-sync --status (the line prints its absolute path). Each entry under held names the file, the scanner rule and both fixes.
2. If the match is a false positive on content you never want synced, run gstack-brain-sync --skip-file <path> to permanently exclude that path; gstack-brain-sync --unskip-file <path> undoes it.
3. Otherwise, edit the file to remove the secret; the next skill run syncs it.

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.

Separately (v1.63.0.0+), every push writes a tamper-evident receipt to the egress ledger (~/.gstack/security/egress.jsonl) before anything is sent, fail-closed: if the receipt can't be written, the push is refused and the queue is preserved. Inspect the ledger with gstack-egress list and verify its hash chain with gstack-egress verify.

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.

Historical note (#2516): that daily pull refreshed only ~/.gstack itself — NOT the detached worktree at ~/.gstack-brain-worktree that gbrain actually indexes, so the brain silently served stale pages until the next setup-gbrain/sync-gbrain run. Since this fix, the daily sync also advances the brain worktree (gstack-gbrain-source-wireup --advance-only, throttled via ~/.gstack/.brain-worktree-last-advance); a failed advance warns instead of failing silently, and never force-resets a dirty worktree.

Uninstall

gstack-brain-uninstall

This:

• Removes ~/.gstack/.git/ and all .brain-* config files.
• Clears artifacts_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-artifacts-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

The architectural decisions behind this feature: allowlist over denylist (unknown files stay local by default), preamble-boundary sync over a daemon (no background process to babysit), a JSONL merge driver so concurrent machines union their queues instead of conflicting, and a privacy stop-gate that asks once before anything syncs.