Clarify user and integration documentation contracts

docs/integrations/seriatim.md

@@ -3,24 +3,19 @@
 ## Purpose
 Define the Seriatim adapter contract used by `merge`, `normalize`, `trim`, and `render`.
 
-## Adapter Boundary
-Interface:
-- `seriatim.Runner`
-- methods:
-  - `Run(ctx, MergeRequest)`
-  - `Normalize(ctx, NormalizeRequest)`
-  - `Trim(ctx, TrimRequest)`
-  - `Render(ctx, RenderRequest)`
+## External Boundary
 
-Primary implementation:
-- `internal/adapters/seriatim/SubprocessRunner`
+Narratio invokes Seriatim as a subprocess in these modes:
 
-Execution modes:
 - `seriatim merge`
 - `seriatim normalize`
 - `seriatim trim`
 - `seriatim render`
 
+The configured timeout and parent cancellation bound each invocation. Internal
+runner composition is documented in
+[the adapter implementation guide](../internal/adapters.md).
+
 ## Request/Result Contracts
 - `MergeRequest`/`MergeResult`: multi-input merge to base transcript, optional report.
 - `NormalizeRequest`/`NormalizeResult`: transcript normalization with explicit schema.
@@ -53,8 +48,11 @@ When report paths are provided/enabled, report files must parse as JSON.
 - generated invocation YAML (`seriatim.generated.v1`) is emitted when requested.
 - adapter does not write manifests or choose stage inputs.
 
-## Config Mapping
-Config fields consumed through runner/stage wiring are under `pipeline.seriatim.*` and `pipeline.render.*`.
+## Configuration
+
+Operator-selected values are defined under `pipeline.seriatim.*` and
+`pipeline.render.*` in the
+[configuration reference](../config.md#pipeline).
 
 Maintained examples with Seriatim config:
 - `examples/pipeline.full.annotated.yml`