Ctxd

License: MIT Node.js

A vendor-neutral, release-aware context contract and MCP runtime for reliable data agents. It gives Claude, Codex, and other clients compact metadata, reviewed semantic definitions, approved join paths, and pre-execution validation.

The project deliberately does not replace Metabase, dbt, Cube, or a warehouse. It is the contract, compiler, release gate, and evaluation layer between those systems and an agent.

Install

From npm (CLI + library; requires a C++ toolchain for better-sqlite3):

npm install ctxd
npx ctxd init

From source (recommended for development and contributions):

git clone https://github.com/thisis-gp/ctxd.git
cd ctxd
npm install   # or: corepack enable && yarn install
npm test
npx ctxd init

See CONTRIBUTING.md for the full dev workflow. Report security issues privately — see SECURITY.md.

Agent question
    -> context search / plan / compile
    -> trusted SQL (validated, version-stamped)
    -> user runs SQL in Metabase (their own access)

By default ctxd does not execute production queries. It is the context and SQL compiler for agents; Metabase remains the query surface.

It talks to Metabase via the Metabase API for metadata ingest (and optionally for tech-bot query execution). No direct database credentials. Nightly refresh uses a server-side API key; end users never see it.

Who configures what (plug-and-play)

Role	What they do	What they never need
Tech team	Set Metabase URL/API key on the server, run ctxd refresh, run ctxd serve --http	Per-user Metabase logins for agents
Claude / Codex users	Add MCP URL + their personal token; get trusted SQL for Metabase	Metabase API keys, shared org token, running queries through ctxd

Default product mode is context-only: ctxd helps the LLM find tables/joins/metrics and draft/validate SQL. Users (or Metabase) run the query. Query execution tools stay off unless CTXD_ALLOW_QUERY=true (tech bots only).

Org quickstart (hosted + HTTPS)

# On the server (tech once)
npx ctxd init
# edit .env: METABASE_URL, METABASE_API_KEY, CTXD_ADMIN_TOKEN, CTXD_DOMAIN, ACME_EMAIL

npx ctxd refresh --prune-keep 14   # must run on the SAME host/volume as serve
docker compose up -d --build       # Caddy HTTPS → ctxd

Ops note: Nightly refresh must run where the MCP server reads snapshots (e.g. docker compose run --rm refresh on that host). A GitHub Action that only uploads an artifact does not update the live server — that was the “ops gap.”

15 2 * * * cd /opt/ctxd && docker compose run --rm refresh >> /var/log/ctxd-refresh.log 2>&1

Open https://$CTXD_DOMAIN/admin, sign in with CTXD_ADMIN_TOKEN, and create one token per user. Users paste into Claude/Codex:

{
  "mcpServers": {
    "ctxd": {
      "url": "https://ctxd.example.com/mcp",
      "headers": {
        "Authorization": "Bearer ctxd_USER_SPECIFIC_TOKEN"
      }
    }
  }
}

Health: GET /health. MCP: POST /mcp (per-user Bearer). Admin: /admin.

Local developer (stdio)

npx ctxd serve

Register with a local command entry as in examples/mcp-config.json (ctxd-local).

How it works

A snapshot build queries Metabase once and produces an immutable, per-release snapshot directory:

snapshots/v8.19.0-0/
├── manifest.json          # release, git commit, fingerprint, counts, status
├── entities.jsonl         # databases / schemas / tables / columns (inspectable)
├── relationships.jsonl    # foreign-key edges
├── metabase-assets.jsonl  # questions / models / dashboards + query definitions
├── semantic-definitions.json # versioned metric definitions + SQL templates
├── search.sqlite          # FTS5 full-text index for sub-second retrieval
└── changes.json           # diff vs the previous snapshot

The MCP server then serves focused retrieval from the promoted current snapshot instead of dumping the whole model into the conversation.

Architecture

Layer	Module	Responsibility
Adapter	src/metabase/	Only place that speaks the Metabase HTTP API
Metadata indexer	src/indexer/metadata-indexer.ts	Normalize DB structure into entities + FK relationships
Content indexer	src/indexer/content-indexer.ts	Normalize questions / models / dashboards
Snapshot	src/snapshot/	Deterministic fingerprint, JSONL + SQLite, manifest, diff
Release	src/release/manager.ts	current pointer lifecycle: validate → publish → promote → rollback
Retrieval	src/context-service.ts	Search, entity context, freshness, SQL validation, read-only exec
MCP	src/mcp/server.ts, src/mcp/http.ts	Fourteen context_* tools over stdio or remote HTTP
Adapters	src/adapters/	Import dbt, Cube, and MetricFlow JSON metadata into the same normalized model
Contract draft	src/contract-draft.ts	Generate a reviewable starting contract from a snapshot or adapter export
Evaluation	src/benchmark.ts	Compare direct-schema agent runs with context-layer runs on accuracy, tokens, calls, and time

The adapter boundary is strict: nothing above src/metabase/ sees a raw Metabase response — everything consumes the normalized model in src/model.ts. Swapping the data source later means rewriting only the adapter.

Setup

yarn install
yarn build
node dist/cli.js init      # scaffolds .env from .env.example
# edit .env: set METABASE_URL and METABASE_API_KEY

Building a snapshot

# Build, validate, publish, and promote a release snapshot.
node dist/cli.js snapshot build    --release v8.19.0-0 --git-commit "$(git rev-parse HEAD)"
node dist/cli.js snapshot validate --release v8.19.0-0
node dist/cli.js snapshot publish  --release v8.19.0-0
node dist/cli.js snapshot promote  --release v8.19.0-0   # advances `current`

Or run the whole pipeline (build → validate → publish → deploy/health → promote):

DEPLOY_SCRIPT=./scripts/deploy.sh HEALTHCHECK_SCRIPT=./scripts/healthcheck.sh scripts/release.sh v8.19.0-0 v8.18.0-0

Rollback restores the previous pointer:

node dist/cli.js snapshot rollback

Querying from the terminal

node dist/cli.js search "active user subscriptions"
node dist/cli.js search "invoices" --scope tables
node dist/cli.js join-path public.claim_files public.benefits  # shortest FK join path
node dist/cli.js diff                                          # schema changes vs previous release
node dist/cli.js drift                                         # is the current snapshot stale vs live Metabase?
node dist/cli.js freshness
node dist/cli.js stats            # token/latency savings dashboard from recorded MCP usage
node dist/cli.js query "SELECT COUNT(*) AS claim_count FROM public.claims;"

Importing other metadata tools

The core model is not Metabase-specific. Adapter inputs can be inspected or used to draft a contract:

node dist/cli.js adapters list
node dist/cli.js adapters inspect dbt examples/dbt-manifest-mini.json
node dist/cli.js contract draft --adapter dbt --input examples/dbt-manifest-mini.json --project demo

Supported JSON importers:

Adapter	Input
dbt	manifest.json models/sources + columns
cube	Cube schema JSON with cubes, dimensions, and measures
metricflow	MetricFlow semantic manifest JSON

These importers create the same NormalizedModel that snapshots use, so new connectors do not need a separate agent-facing contract.

Serving to an agent

npx ctxd serve                 # local MCP stdio (developer laptop)
npx ctxd serve --http          # shared org MCP at http://HOST:8787/mcp

Register it with Claude Code / Codex (see examples/mcp-config.json). For --http, users only need the URL and their personal Bearer token (issued at /admin) — not Metabase credentials.

MCP tools

Tool	Purpose
context_search	Top-N tables, columns, and saved questions for a query
context_plan_query	Resolve a question into candidate tables, columns, saved questions, and ambiguity warnings
context_compile_semantic_query	Compile measures/dimensions/filters into SQL (no execution)
context_compile_contract_query	Compile reviewed-contract SQL (no execution)
context_get_entity	One table's columns, relationships, and referencing questions
context_get_relationships	FK edges touching a table
context_get_join_path	Shortest FK join path between two tables
context_find_saved_questions	Reusable Metabase questions/models before writing SQL
context_get_changes	Schema-change diff for a release
context_get_release_context	Inspect a specific release snapshot
context_get_freshness	Snapshot version, fingerprint, deployed-match status
context_validate_sql	Check a statement is read-only (no execution)
context_run_*	Hidden by default. Execute via Metabase only when CTXD_ALLOW_QUERY=true

Every response embeds the source snapshot + release version.

Context contract

context.contract.json is the vendor-neutral project contract. It records entity grain, measures, dimensions, approved joins, fanout risk, and query policies. The contract is reviewed like code and can be validated without credentials:

node dist/cli.js validate-contract context.contract.json
node dist/cli.js benchmark validate examples/benchmark.json examples/benchmark-observations.json
node dist/cli.js benchmark compare examples/benchmark.json examples/benchmark-direct-observations.json examples/benchmark-context-observations.json
node dist/cli.js snapshot validate --release v1.0.0-0 --contract context.contract.json

Cross-entity compilation uses only approved contract joins. Inferred foreign keys remain useful for discovery, but they cannot silently become semantic truth. High-fanout and many-to-many paths fail closed until explicitly modeled.

The benchmark format is intentionally model-neutral. Record each agent's selected measures, dimensions, entities, calls, latency, and answer correctness, then compare them against the same contract. This makes releases measurable on correctness, wrong joins, round trips, latency, and cost instead of relying on token estimates alone.

Release gate

Use one command in CI to block a release when snapshot validation, contract validation, or benchmark validation fails:

node dist/cli.js release-gate \
  --release v1.0.0-0 \
  --contract context.contract.json \
  --benchmark examples/benchmark.json \
  --observations examples/benchmark-observations.json

The example GitHub Actions workflow in .github/workflows/release.yml runs this after snapshot build and before publish/promote.

Demo

Open docs/demo.html for a static overview of the workflow and copyable commands. It does not require credentials or a dev server.

Declarative semantic queries

Agents should prefer semantic queries when a registered metric exists. They declare the measure and optional dimensions/filters; the layer owns the table, canonical formula, default filters, row cap, and read-only execution.

{
  "measures": ["claims.csat_responses"],
  "dimensions": [],
  "limit": 100
}

Use context_compile_semantic_query to get generated SQL, validate with context_validate_sql, then run it in Metabase. Cross-table measures are rejected until a reviewed join graph is registered. (context_run_semantic_query exists only when CTXD_ALLOW_QUERY=true.)

Safety

• API keys come only from env / secret manager, are never logged, and are never written into a snapshot.
• Default: no query execution through ctxd. Agents get context + drafted SQL; users run queries in Metabase under their own access. Set CTXD_ALLOW_QUERY=true only for trusted tech bots.
• When execution is enabled, SQL must start with SELECT/WITH, parse as a single SELECT (fail closed), reject SELECT ... INTO, enforce row/time limits, and validate table/column references against the active snapshot.
• Sensitive tables/fields can be denylisted (DENYLIST env) — they stay indexed but carry no descriptions and cannot be referenced in validated/executed SQL.
• Reviewed semantic and contract definition files may contain raw SQL expressions; treat those files like code.
• Snapshots store metadata and query definitions only, never production rows.
• When execution is enabled, every executed query is appended to audit/queries.jsonl.

Status

Implements the Metabase adapter, indexers, SQLite snapshot + FTS search, MCP server, semantic + contract compilation, release versioning, release gate, benchmark harness, and multi-source metadata adapters (dbt/Cube/MetricFlow). Incremental snapshot refresh (Phase 5 in the BRD) is not yet implemented.