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 or because they are not valid JSON, 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.)
• Stripe live secret and restricted keys (sk_live_…, rk_live_…)
• Slack tokens (xoxb-…, xoxp-… and the other xox?- forms)
• npm tokens (npm_…)
• Database URLs with a password (postgres://app:<password>@host, and the same for MySQL, MongoDB, Redis and AMQP)

The last four follow gstack's redaction rules, so placeholders such as sk_live_EXAMPLE…, ${DB_PASSWORD} or postgres:postgres@localhost are not held.

The scan reads the whole staged diff twice: once as git diff shows it to you (your diff.context and any textconv driver apply), and once as raw text with three unchanged lines around each edit. A match in either reading holds the file. Both readings include file names. Each added line is also scanned with its JSON strings decoded, so a secret written with \u escapes or inside an escaped JSON string is still caught. Each edited block is also read as the new file text, so a key on an unchanged line and a value added under it are matched together, whatever your git diff.context setting is. Files git treats as binary (a NUL byte, UTF-16 text) are scanned by their bytes, read plainly, without NULs and as UTF-16. If git still reports a file as binary instead of showing its bytes, the file is held as binary-not-scanned. Bytes that none of these readings turn into text, such as a compressed file, are not held unless a pattern matches them.

Because unchanged and removed lines are scanned too, a file that already holds a flagged line is held on every edit while that line is in the diff. If the flagged line was never synced, delete it and the next sync goes through. If it is already committed in ~/.gstack, deleting it leaves it on a removed line of the next diff, so the file stays held and only --skip-file clears it. Skipping stops syncing the file, so a copy that was already pushed stays on the remote; if it was pushed, treat the secret as exposed.

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. Sync is holding back 1 file(s) that the secret scan flagged or that are not valid JSON; 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. If that line was never synced, the next skill run syncs the file. If it is already committed in ~/.gstack, the file stays held and only --skip-file clears it; if it was pushed, treat the secret as exposed.

There's a defense-in-depth hook at ~/.gstack/.git/hooks/pre-commit that runs the same scanner (bin/gstack-brain-secret-scan.py) if you manually git commit against the repo. gstack-artifacts-init and gstack-brain-restore install it and copy the scanner next to it, so the hook keeps working if gstack moves. A hook written by an older gstack checks only the first six patterns; rerun gstack-artifacts-init to refresh it.

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.

When a push is rejected, brain-sync fetches and merges the other machine's commits itself. Local edits to files that merge would change are set aside and put back afterward, and a failed merge is aborted, so ~/.gstack never holds conflict markers. If a local edit conflicts with the other machine's change, the other machine's version stays in the working tree and your edit is kept in a git stash; gstack-brain-sync --status names the stash and the git -C ~/.gstack --literal-pathspecs restore --source=<stash> -- <path> command that brings it back.

JSON files such as developer-profile.json have no merge driver, so a merge can leave conflict markers in them. The sync parses every staged .json file and holds back one that does not parse (status held, rule invalid-json) until you repair it, and gstack-doctor warns when a synced profile or decision snapshot holds conflict markers.

A project's decision snapshot, decisions.active.json, is never merged: it is rebuilt from that project's decisions.jsonl, which merges like any other .jsonl file. When two machines each log a decision between pushes, their snapshots conflict; if every conflict in brain-sync's merge is such a snapshot, brain-sync rebuilds each one from the merged log, commits the merge and pushes, whether or not your .gitattributes predates this. The one exception is a log that lost lines on either side since the machines last agreed, as gstack-decision-log --compact does to redacted decisions: the merged log is the union of both sides, so a rebuild would bring the redacted decision back, and brain-sync aborts that merge as before. Repositories set up by gstack-artifacts-init also mark the snapshot merge=binary, so a merge you run by hand keeps your side without conflict markers; finish it with gstack-decision-log --rebuild-snapshot <project-slug> and git add -f the snapshot before committing.

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.