Source Pack

A local-first Model Context Protocol server that turns fetched public web pages into structured research source packs: source-linked candidate facts, quotations, numbers, dates, outbound primary links, coverage signals, and explicit limitations.

Why this exists / strategic value

Agents are good at gathering pages but poor at preserving an auditable research trail. source-pack-mcp converts transient browsing into a durable JSON artifact that another agent, knowledge system, or human reviewer can inspect, search, and reuse.

Its strategic role is the evidence-assembly layer in a local-first agent stack: source material stays on the operator's machine, every extracted item remains attached to its URL, and uncertainty travels with the pack instead of disappearing into a prose answer.

Verification boundaries

This server verifies that content was fetched from the recorded URL at the recorded time. It does not verify that a publisher is authoritative or that an extracted claim is true.

• Facts, numbers, dates, and quotes are candidate evidence extracted with transparent heuristics.
• A fact's confidence describes extraction certainty, not factual truth.
• consistent means similar claims appeared on multiple domains; it is not proof of independent corroboration.
• contested currently flags differing numbers in otherwise similar claims; it is not a complete contradiction detector.
• Discovery is best-effort and may be shallow. Failed fetches and extraction limits are recorded in limitations.
• A stale cached page may be used when a live request fails; retrieved_at retains the original fetch time.

Agents should cite the attached URLs and review consequential claims against primary sources.

Relationship to website-content-mcp

website-content-mcp is the acquisition layer for crawling or capturing content from known websites. source-pack-mcp is the evidence-assembly layer: it organizes selected URLs into a query-specific, persisted pack and compares claim coverage across sources.

Use them together when acquisition needs more control: discover or curate URLs with website-content-mcp, then pass the strongest URLs to pack_add_source. pack_build retains lightweight, best-effort discovery so source-pack-mcp can also run on its own.

MCP tools

Tool	Inputs	Behavior
pack_build	query, max_sources (1-50), search_depth (quick or deep)	Discovers, fetches, extracts, stores, and returns a new source pack.
pack_add_source	pack_id, HTTP(S) url, search_depth	Adds or replaces one URL in a pack and rebuilds its coverage map.
pack_get	pack_id	Returns a stored pack.
pack_list	limit (1-200)	Lists recent pack summaries, newest first.
pack_search	query, limit (1-100)	Searches stored pack text and returns matching snippets.

pack_get, pack_list, and pack_search are read-only. pack_build and pack_add_source write JSON files beneath PACKS_DIR; none of the tools delete data.

Source-pack shape

{
  "pack_id": "uuid",
  "query": "string",
  "created_at": "ISO timestamp",
  "sources": [
    {
      "url": "https://example.com/source",
      "title": "string",
      "domain": "example.com",
      "retrieved_at": "ISO timestamp",
      "facts": [{ "fact": "string", "confidence": "high|medium|low" }],
      "quotes": [{ "text": "string", "context": "string" }],
      "numbers": [{ "value": "string", "unit": "string", "context": "string" }],
      "dates": [{ "date": "string", "event": "string" }],
      "primary_links": ["https://example.org/primary"]
    }
  ],
  "coverage_map": [
    {
      "claim": "string",
      "mentioned_by": ["example.com"],
      "contested_by": [],
      "status": "consistent|contested|isolated"
    }
  ],
  "limitations": ["string"]
}

Install from source

Requirements: Node.js 22+ and npm.

git clone https://github.com/SarutobiSasuke8/source-pack-mcp.git
cd source-pack-mcp
npm ci
npm run check

Build the server:

npm run build

Stdio transport (recommended for local MCP clients)

Register the compiled stdio entry point with an absolute path:

{
  "mcpServers": {
    "source-pack": {
      "command": "node",
      "args": ["/absolute/path/to/source-pack-mcp/dist/src/stdio.js"],
      "env": {
        "PACKS_DIR": "/absolute/path/to/source-pack-data/packs",
        "CACHE_DIR": "/absolute/path/to/source-pack-data/cache"
      }
    }
  }
}

Streamable HTTP transport

npm run start
curl http://127.0.0.1:3225/healthz

The MCP endpoint is http://127.0.0.1:3225/mcp. It intentionally has no application-level authentication and binds to loopback by default; read SECURITY.md before changing HOST or exposing it through a network.

Verify a packed artifact

npm run smoke:mcp
npm run pack:check

smoke:mcp performs a real stdio MCP initialize handshake and asserts the five expected tools. pack:check builds the package and shows the exact files that would be published.

Configuration

Copy .env.example or supply environment variables directly.

Variable	Default	Purpose
MAX_SOURCES_PER_PACK	8	Server-side maximum sources per pack (1-50).
FETCH_TIMEOUT_MS	15000	Timeout for each outbound request.
FETCH_MIN_INTERVAL_MS	1000	Minimum delay between serialized outbound requests.
FETCH_MAX_BODY_BYTES	5242880	Maximum response body size in bytes; larger responses fail with RESPONSE_TOO_LARGE.
SEARCH_API_URL	unset	Optional JSON search endpoint; DuckDuckGo HTML discovery is the fallback.
USER_AGENT	project user agent	User-Agent sent with outbound requests.
CACHE_DIR	.cache	Local fetched-page cache directory.
CACHE_TTL_SECONDS	3600	Fresh-cache lifetime; 0 disables fresh cache hits.
PACKS_DIR	.packs	Local JSON source-pack directory.
HOST	127.0.0.1	HTTP bind host.
PORT	3225	HTTP port.

Relative data paths resolve from the server process's working directory. Use absolute paths in long-lived MCP client configurations.

Pack storage validates records on read and write. Malformed JSON, invalid records and files whose name does not match their pack_id are skipped by listing and search; direct retrieval treats them as unavailable. Their files are left in place for inspection. Updates replace the saved file atomically, so readers see a complete old or new version.

Concurrent pack_add_source calls merge into the latest saved pack through a per-pack write queue. Run only one server process per PACKS_DIR: the queue belongs to that process's shared PackStore, and does not coordinate separate HTTP/stdio processes or external writers.

Error contract

Tool failures keep a human-readable text message for compatibility and also return a stable structuredContent envelope:

{
  "error": {
    "schema_version": "1",
    "code": "PACK_NOT_FOUND",
    "category": "not_found",
    "message": "No pack found with pack_id '...'.",
    "retryable": false,
    "details": { "pack_id": "..." }
  }
}

Current codes are PACK_NOT_FOUND, ROBOTS_DISALLOWED, URL_BLOCKED, RESPONSE_TOO_LARGE, UPSTREAM_HTTP_ERROR, UPSTREAM_NETWORK_ERROR, UPSTREAM_TIMEOUT, and INTERNAL_ERROR. Unknown internal failures are sanitized; upstream errors indicate whether retrying may help.

Testing

Tool tests are hermetic. They load committed fixture directories under test/fixtures/tools/ (HTML pages, search responses, and stored packs) and do not contact the public network.

npm test

npm test builds the project, then runs node --test "dist/test/**/*.test.js". The suite covers every MCP tool:

• pack_build and pack_add_source: packing fixture pages into sources, coverage, and limitations; filtering junk discovery URLs, duplicate URLs, disallowed robots entries, and non-content links; source-count and extraction limits; and upstream, policy, and input errors.
• pack_get, pack_list, and pack_search: reading fixture packs, skipping malformed or misidentified files, honouring list and search limits, and returning not-found or validation errors.

The live integration test stays skipped unless RUN_LIVE_TESTS=1 is set. npm run check runs typecheck, lint, and this test suite. CI runs that check on pull requests.

Development and release checks

npm run typecheck
npm run lint
npm test
npm run check
npm run smoke:mcp
npm run pack:check

The live integration test is opt-in: it is skipped unless RUN_LIVE_TESTS=1 is set, so npm run check and CI are hermetic by default. Outbound fetches are SSRF-guarded: only http/https URLs are allowed, hostnames resolving to loopback, private (RFC1918), link-local, or other reserved addresses are refused (URL_BLOCKED), and redirects are re-validated hop by hop. CI runs the full check, the MCP handshake, the package dry-run, and a high-severity dependency audit. Version tags (v*) produce a tested .tgz workflow artifact; publishing remains an explicit maintainer decision.

License

MIT