SagaSmith Narrative MCP

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An authoritative, system-neutral MCP for long-form tabletop narrative play. It depends on sagasmith-core for durable campaigns, transactions, revisions, documents, continuity ledgers, snapshots, and branches.

The base runtime has two phases: lobby and play. A profile may opt into an authoritative conflict phase. Native MCP tools are session-scoped and dynamic; hosts must process tools/list_changed notifications.

The server never guesses rules from prose. A campaign binds an immutable profile version and checksum. Profiles may use Level 0 (explicit Agent/human rulings) or the limited pure Level 1 mechanics in this package. More complex rules require a separate system provider.

Lobby administrators can inspect campaign-scoped profile/Pack drafts through narrative_query. Access changes support grant and revoke operations with last-owner protection; controlled actors can be updated through actor_change. Recovery queries and snapshot/branch mutations are administrator-only. Snapshots remain independently restorable full state documents at the public boundary. Core schema v8 stores each document as one bounded, checksummed zlib-1 record; restore and branch checkout do not replay an ancestor chain.

See Architecture and authority and Profile and Pack lifecycle for the durable product boundary. Three self-authored regression campaigns live in fixtures/ash-harbor, fixtures/moss-road-seasons, and fixtures/echo-manor-voices. The third is a 15-session, five-NPC character-performance campaign with declared goals, private motives, red lines, false beliefs, relationship arcs, voice markers, isolated dialogue, and a recovered alternate ending.

Development

python -m pip install -e ".[dev]"
pytest
ruff check .

Run the original campaign fixtures concurrently through real stdio MCP sessions:

python scripts/regression_parallel_campaigns.py --output .runs/parallel

The runner opens real stdio MCP sessions, uses a separate session identity for each principal, executes every declared route step, follows a focused alternate branch, and emits machine-readable per-campaign timelines and a combined summary. A non-zero exit means the run is not accepted.

The Agent Host integration uses the MCP and Agent repositories' own environments: the test process runs with ../SagaSmith-agent/.venv/Scripts/python.exe, while the spawned MCP server runs with this repository's .venv/Scripts/python.exe:

../SagaSmith-agent/.venv/Scripts/python.exe -m pytest -q tests/test_agent_host_integration.py

Run locally with sagasmith-narrative-mcp. Its independent default home is ~/.sagasmith/narrative-mcp. Set SAGASMITH_NARRATIVE_MCP_HOME to relocate it, SAGASMITH_NARRATIVE_MCP_DATABASE_URL to use an explicit database, and SAGASMITH_NARRATIVE_MCP_BOUND_PRINCIPAL_ID when the transport authenticates one principal.

The server applies Core Alembic migrations at startup and requires the current Snapshot schema v8. Before deployment, stop the server and take a consistent backup of the SQLite database (including a settled WAL), or use the external database's native backup mechanism. There is no database downgrade or dual-protocol mode: rollback restores the database together with matching Core and MCP versions as one unit.

Without SAGASMITH_NARRATIVE_MCP_BOUND_PRINCIPAL_ID, stdio is a trusted single-user local mode; model-supplied principal fields are not multiplayer authentication. A multiplayer deployment must bind one authenticated principal per MCP process through a trusted transport. Shared-principal HTTP exposure is not currently supported and the server must not be published directly to a network.