feat: entity system and temporal graph with Postgres-native search (#249)

* feat: add v2 entity system with Postgres-native search

New entity system built as an independent package alongside the existing
asset system. Zero changes to existing asset code. All search is
Postgres-native — no Elasticsearch dependency for v2.

Core domain (core/entity/):
- Entity: open type system, temporal (valid_from/valid_to), properties JSONB
- Edge: typed, directed, temporal relationships
- Chunk: pgvector embeddings for semantic search
- Service: context assembly, impact analysis, search orchestration
- HybridSearch: keyword + semantic fusion via Reciprocal Rank Fusion
- SearchRepository: Postgres tsvector + pg_trgm (replaces ES)

Storage (store/postgres/):
- EntityRepository: CRUD with temporal support
- EdgeRepository: recursive CTE graph traversal
- ChunkRepository: pgvector cosine similarity search
- EntitySearchRepository: tsvector full-text + pg_trgm fuzzy matching
- Migration 000019: entities, edges, chunks tables with search_vector
  generated column, GIN indexes, trigram indexes

Search architecture (all Postgres):
- Keyword: tsvector with weighted fields (URN/name=A, desc=B, source=C)
- Fuzzy: pg_trgm similarity with automatic fallback
- Semantic: pgvector cosine distance on chunk embeddings
- Hybrid: RRF fusion of keyword + semantic results
- Suggest: pg_trgm similarity-based autocomplete

MCP tools (internal/mcp/):
- search_entities: hybrid search across the entity graph
- get_context: assembled context subgraph
- impact: downstream blast radius analysis

* feat: add entity v2 handler with gRPC/REST endpoints

Generated Go code from proton proto definitions for entity v2 RPCs.
Created handler/entity.go implementing all 12 new RPC methods:

Entity CRUD: GetAllEntities, GetEntityByID, UpsertEntity, DeleteEntity
Search: SearchEntities, SuggestEntities, GetEntityTypes
Context: GetEntityContext, GetEntityImpact
Edges: UpsertEdge, GetEdges, DeleteEdge

Handler accepts entity and edge services via WithEntityService/
WithEdgeService options — no changes to existing handler constructor
signature. Serve function passes options through to handler.

* feat: remove old asset system, discussions, tags — entity-only

Deleted:
- core/asset/ — entire old asset package
- core/discussion/ — discussions and comments
- core/tag/ — tags and tag templates
- store/elasticsearch/ — ES client and discovery repos
- store/postgres/asset_*, lineage_*, discussion_*, comment_*, tag_* repos
- handler/asset.go, discussion.go, comment.go, tag.go, search.go, lineage.go
- All old CLI commands (assets, discussions, lineage, search)
- All old migrations (replaced with single 000001_init_schema.up.sql)

Updated:
- Proto regenerated from proton (entity-only service definition)
- handler.go: simplified — only namespace, star, user, entity, edge services
- bootstrap.go: removed ES, removed all old service wiring
- config.go: removed Elasticsearch config
- star package: updated to use entity.Entity instead of asset.Asset
- CLI: entity commands (list, view, upsert, delete, search, types, context, impact)
- Migration: single fresh schema with namespaces, users, entities, edges, chunks, stars

Schema (6 tables):
- namespaces, users, entities, edges, chunks, stars
- tsvector + pg_trgm + pgvector for search (no ES)
- RLS on all tables

* refactor: cleanup stale deps, fix namespace service, add entity tests

- go mod tidy: removed unused ES and other stale dependencies
- Namespace service: nil-safe DiscoveryRepository (ES removed)
- Deleted stale integration tests (postgres, user, namespace repo tests
  that depended on deleted test infrastructure)
- Fixed last 2 "asset" string references in star errors and CLI
- Added entity unit tests (11 tests):
  - Type validation (open type system)
  - Entity.IsCurrent temporal check
  - Reciprocal Rank Fusion (empty, single, multi-list)
  - Service: Upsert, GetByURN, Delete, GetAll, GetTypes, Search

* chore: remove ES dependency, stale docs, configs, mocks, CI

- Removed elasticsearch from docker-compose.yaml (Postgres-only)
- Removed elasticsearch from config.yaml and config.example.yaml
- Removed elasticsearch service from .github/workflows/test.yml
- Deleted stale guide docs (ingestion, querying, starring, telemetry)
- Deleted stale handler mocks (no tests import them)
- Removed empty test/ directory
- Updated Postgres to v16 in docker-compose
- go mod tidy (cleaned unused indirect deps)

* build: update PROTON_COMMIT to eefb04d (merged entity proto)

* chore: gitignore docs/_drafts

* fix: resolve all lint issues

* fix: remove stale docs and fix sidebars.js

* fix: resolve broken doc links and update concepts overview

Author: ravisuhag

.github/workflows/test.yml

@@ -18,22 +18,6 @@ concurrency:
 jobs:
   test:
     runs-on: ubuntu-latest
-    services:
-      elasticsearch:
-        image: elasticsearch:8.17.1
-        ports:
-          - 9200:9200
-        env:
-          discovery.type: single-node
-          xpack.security.enabled: "false"
-          ES_JAVA_OPTS: "-Xms128m -Xmx128m"
-        options: >-
-          --health-cmd "curl -f http://localhost:9200/_cluster/health"
-          --health-interval 10s
-          --health-timeout 5s
-          --health-retries 10
-    env:
-      ES_TEST_SERVER_URL: "http://localhost:9200"
     steps:
       - uses: actions/checkout@v6
       - uses: actions/setup-go@v6

.gitignore

@@ -28,3 +28,4 @@ vendor/
 compass.yaml
 temp/
 .mcp.json
+docs/_drafts/

Makefile

@@ -3,7 +3,7 @@ COMMIT := $(shell git rev-parse --short HEAD)
 TAG := "$(shell git rev-list --tags --max-count=1)"
 VERSION := "$(shell git describe --tags ${TAG})-next"
 BUILD_DIR=dist
-PROTON_COMMIT := "b9ed2ad"
+PROTON_COMMIT := "eefb04d"
 
 .PHONY: all build clean test tidy vet proto setup format generate lint install