Resolve canonical parties with campaign configuration

docs/integrations/README.md

@@ -21,6 +21,7 @@ focused stage documents.
 - [Audita](./audita.md): transcript polishing (`audita process`).
 - [Notarius](./notarius.md): complete pipeline execution and safe JSON bundle
   discovery (`notarius run`).
+- [Party](./party.md): canonical campaign roster input.
 - [Seriatim](./seriatim.md): merge, normalize, trim, and render operations.
 - [Scriptorium](./scriptorium.md): artifact generation and debug rendering
   (`scriptorium run|render`).

docs/integrations/party.md

@@ -0,0 +1,49 @@
+# Canonical Party Input
+
+`party.yml` is a campaign-owned roster input. Narratio recognizes the
+versioned `narratio.party.v1` document below when it resolves a pipeline,
+campaign, and session together.
+
+```yaml
+schema_version: narratio.party.v1
+
+characters:
+  arannis:
+    player:
+      name: Eric
+    character:
+      name: Arannis
+      alias:
+        - Ari
+        - The Grey Owl
+      classes:
+        - name: wizard
+          level: 8
+```
+
+`characters` is a non-empty mapping. Each key is a stable character ID using
+the configured-artifact key grammar: a lowercase ASCII letter followed by zero
+or more lowercase ASCII letters, digits, or underscores. Character order is
+preserved where roster order matters.
+
+Every entry has `player.name`, `character.name`, and a non-empty
+`character.classes` list. Class entries require a non-empty `name` and may
+include a positive integer `level`. The optional, intentionally singular
+`character.alias` field is a list. Names, aliases, and class names must be
+non-empty, trimmed display strings without control characters. Character names
+and aliases must be unique across the full roster under Unicode-aware
+case-insensitive comparison; player names may repeat.
+
+The document has exactly one YAML document and accepts no unknown fields. A
+wrong or malformed `schema_version` is an error.
+
+## Legacy migration boundary
+
+An unversioned party input remains supported only as opaque legacy reference
+material while campaigns migrate. It requires a separate `players_file` and
+retains the existing session override behavior. It cannot be mixed with a
+canonical party: canonical campaigns must omit `players_file`, and sessions
+must not override their party or players inputs.
+
+Use the canonical document for new campaigns. The configuration rules and
+source-relative path behavior are defined in the [Configuration Reference](../config.md).