feat: establish read-only DocForge MCP foundation

SLICE_HISTORY.md

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+# Completed slices
+
+## DFG-0 contract freeze and DFG-1 standalone read-only core
+
+### Changed
+
+- Created the standalone DocForge repository and versioned the project, node, edge, result, and
+  reserved changeset contracts.
+- Added one-root project descriptors with confined canonical, authority, cache, and index paths.
+- Added generic Markdown front matter and TOML node loading, stable IDs, typed relationships,
+  authority classes, limits, deterministic ordering, dependency-cycle validation, and hashes.
+- Added atomic SQLite FTS5 indexes with project-root fingerprints, source revisions, logical row
+  validation, stale rejection, and preservation of the previous index when rebuilds fail.
+- Added exact lookup, bounded search and filtering, backlinks, dependencies, impact traversal, and
+  cited token-budgeted context compilation with explicit omissions.
+- Added deterministic JSON CLI commands for project information, validation, index operations,
+  retrieval, traversal, and context compilation.
+- Added two unrelated generic fixtures. No Worldforge or AssetForge vocabulary entered the core.
+
+### Verification
+
+- Ruff lint and format checks passed.
+- Python compilation passed.
+- All 13 unit and integration tests passed.
+- Tests covered root and symbolic-link escapes, unknown configuration, cache overlap, duplicate and
+  broken graph state, dependency cycles, source-set changes, stale indexes, tampered rows,
+  cross-project cache reuse, query-time source changes, deterministic retrieval, and bounded context.
+- Installed CLI proof built and checked a temporary project index, returned the expected search
+  result, selected the required node and dependency, used 153 of 180 estimated tokens, and reported
+  the omitted proof node.
+
+### Limits
+
+- No MCP server exists yet.
+- No changeset or write operation exists.
+- No project adapter or renderer exists.
+- The token estimator is deliberately conservative and lexical; measured project adoption remains a
+  later gate.
+
+### Next gate
+
+DFG-2: expose only the proven read operations through a project-bound local stdio MCP server.
+
+## DFG-2 project-bound read-only MCP server
+
+### Changed
+
+- Pinned the official stable MCP Python SDK to the compatible `mcp>=1.28,<2` release line.
+- Added a local standard input/output server bound to one immutable project root at startup.
+- Exposed eleven read tools for project health, contract boundaries, exact lookup, search, metadata
+  filtering, backlinks, dependencies, impact, bounded context, source validation, and render status.
+- Added project identity, root fingerprint, revision, source hash, adapter version, staleness, server
+  version, and an untrusted-content warning to tool results.
+- Added structured domain failures for missing nodes, stale indexes, and oversized results without
+  returning partial content.
+- Exposed no write, proposal, arbitrary file, shell, Git, build, deployment, publication, or
+  project-switching operation.
+- Kept cache rebuilding as an explicit CLI integration action. MCP queries fail closed when the
+  derived index is missing or stale.
+
+### Verification
+
+- Ruff lint and format checks passed.
+- Python compilation passed.
+- All 19 core, CLI, and MCP tests passed with `ResourceWarning` treated as an error.
+- Protocol tests called all eleven tools through the official in-memory MCP transport.
+- A separate subprocess test initialized the server through real stdio transport and retrieved only
+  its configured fixture project.
+- Tests proved the exact read-only tool surface, fixed project identity, structured missing and stale
+  failures, output limits, explicit omissions, safe fallback when passive Git revision detection is
+  unavailable, and the absence of canonical write tools.
+
+### Limits
+
+- The server cannot create changesets or proposals yet.
+- The server cannot rebuild its own index.
+- Render status reports `not_configured` until DFG-4 defines renderer orchestration.
+- Worldforge and AssetForge adapters remain unopened.
+
+### Next gate
+
+DFG-3: add isolated, hash-bound proposal changesets without canonical write authority.