feat: GBrain v0.1.0 — Postgres-native personal knowledge brain (#1)

* chore: add CLAUDE.md with project context and gstack skill routing rules

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: initialize project with Bun + TypeScript

package.json with dependencies (postgres, pgvector, openai, anthropic,
MCP SDK, gray-matter). TypeScript config targeting ESNext with bundler
module resolution.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: add foundation layer — engine interface, Postgres engine, schema

BrainEngine pluggable interface with full PostgresEngine: CRUD, search
(keyword + vector), links, tags, timeline, versions, stats, health,
ingest log, config. Trigger-based tsvector spanning pages +
timeline_entries. Markdown parser with frontmatter, compiled_truth /
timeline splitting, and round-trip serialization. 19 tests passing.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: add 3-tier chunking and embedding service

Recursive delimiter-aware chunker (5-level hierarchy, 300-word chunks,
50-word overlap). Semantic chunker with Savitzky-Golay boundary detection
and recursive fallback. LLM-guided chunker via Claude Haiku with sliding
window topic detection. OpenAI embedding service with batch support,
exponential backoff, and rate limit handling.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: add hybrid search with RRF fusion, expansion, and 4-layer dedup

Hybrid search merges vector (pgvector HNSW) + keyword (tsvector) via
Reciprocal Rank Fusion. Multi-query expansion via Claude Haiku generates
2 alternative phrasings. 4-layer dedup pipeline: by source, cosine
similarity, type diversity (60% cap), per-page cap.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: add GBRAIN_V0 spec, pluggable engine architecture, SQLite engine plan

GBRAIN_V0.md: full product spec with architecture decisions, CLI commands,
schema, search architecture, chunking strategies, first-time experience,
and future plans. ENGINES.md: pluggable engine interface, capability matrix,
how to add new backends. SQLITE_ENGINE.md: complete SQLite implementation
plan with schema, FTS5 setup, vector search options, and contributor guide.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: add CLI with all commands

Full CLI dispatcher with 25+ commands: init (Supabase wizard), get, put,
delete, list, search, query (hybrid RRF), import (bulk with progress bar),
export (round-trip), embed, stats, health, tag/untag/tags, link/unlink/
backlinks/graph, timeline/timeline-add, history/revert, config, upgrade,
serve, call. Smart slug resolution on reads. Version snapshots on updates.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: add MCP stdio server with all brain tools

20 MCP tools mirroring CLI operations: get/put/delete/list pages,
search (keyword), query (hybrid RRF + expansion), tags, links with
graph traversal, timeline, stats, health, version history, and revert.
Auto-chunks and embeds on put_page. CLI and MCP share the same engine.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: add 6 skill files and ClawHub manifest

Fat markdown skills for AI agents: ingest (meetings/docs/articles with
timeline merge), query (3-layer search + synthesis + citations), maintain
(health checks, stale detection, orphan audit), enrich (external API
enrichment), briefing (daily briefing compilation), migrate (universal
migration from Obsidian/Notion/Logseq/markdown/CSV/JSON/Roam).
ClawHub manifest for skill distribution.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: add README, CONTRIBUTING, update CLAUDE.md test references

README with quickstart, commands, architecture, library usage, MCP setup,
and links to design docs. CONTRIBUTING with setup, project structure,
and guides for adding commands and engines. CLAUDE.md updated to reference
actual test files instead of planned-but-unwritten import test.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: address adversarial review findings — 5 critical/high fixes

- revertToVersion: add page_id check to prevent cross-page data corruption
- traverseGraph: use UNION instead of UNION ALL for cycle safety
- embedAll: preserve all chunks when embedding stale subset only
- embedding: throw on retry exhaustion instead of returning zero vectors
- putPage: validate slugs to prevent path traversal on export

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: bump version and changelog (v0.1.0)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: expand README with schema, install, search architecture, and motivation

Why it exists, how search works (with ASCII diagram), full database schema
with all 9 tables and index details, chunking strategies explained, storage
estimates, setup wizard walkthrough, knowledge model with example page,
library usage with more examples, expanded skills table.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: add MIT license (Copyright 2026 Garry Tan)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: add OpenClaw install flow as primary option in README

OpenClaw users just say "install gbrain" and the orchestrator handles
everything: package install, Supabase setup wizard, skill registration.
Shows the conversational interface for querying, ingesting, and briefings.
ClawHub and standalone CLI paths follow as alternatives.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: add prerequisites and explicit OpenClaw install instructions

Prerequisites table listing Supabase, OpenAI, and Anthropic dependencies
with links. Environment variable setup. Explicit step-by-step prompt for
OpenClaw users showing exactly what to tell the orchestrator. Note that
search degrades gracefully without API keys (keyword-only without OpenAI,
no expansion without Anthropic).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: scrub named references, add PG essay demo section to README

Replace all Pedro/Brex/Jensen Huang/River AI examples with Paul Graham
essay examples using the kindling corpus. Add "Try it" section to README
showing the power of hybrid search on PG essays in 90 seconds. Update
test fixtures to use concept pages instead of person pages.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

skills/maintain/SKILL.md

@@ -0,0 +1,59 @@
+# Maintain Skill
+
+Periodic brain health checks and cleanup.
+
+## Workflow
+
+1. **Run health check.** `gbrain health` to get the dashboard.
+2. **Check each dimension:**
+
+### Stale pages
+Pages where compiled_truth is older than the latest timeline entry. The assessment hasn't been updated to reflect recent evidence.
+- `gbrain query "stale pages"` or check health output
+- For each stale page: read timeline, determine if compiled_truth needs rewriting
+
+### Orphan pages
+Pages with zero inbound links. Nobody references them.
+- Review orphans: are they genuinely isolated or just missing links?
+- Add links from related pages or flag for deletion
+
+### Dead links
+Links pointing to pages that don't exist.
+- Remove dead links with `gbrain unlink`
+
+### Missing cross-references
+Pages that mention entity names but don't have formal links.
+- Read compiled_truth, extract entity mentions, create links
+
+### Tag consistency
+Inconsistent tagging (e.g., "vc" vs "venture-capital", "ai" vs "artificial-intelligence").
+- Standardize to the most common variant
+
+### Embedding freshness
+Chunks without embeddings, or chunks embedded with an old model.
+- `gbrain embed --stale` to backfill
+
+### Open threads
+Timeline items older than 30 days with unresolved action items.
+- Flag for review
+
+## Quality Rules
+
+- Never delete pages without confirmation
+- Log all changes via timeline entries
+- Run `gbrain health` before and after to show improvement
+
+## Commands Used
+
+```
+gbrain health
+gbrain list [--type T]
+gbrain get <slug>
+gbrain backlinks <slug>
+gbrain link <from> <to> --type <type>
+gbrain unlink <from> <to>
+gbrain tag <slug> <tag>
+gbrain untag <slug> <tag>
+gbrain embed --stale
+gbrain timeline <slug>
+```