Simplify downstream tool configuration

architecture.md

@@ -247,17 +247,18 @@ Archive publishing behavior (implemented):
 
 `pipeline.audita` drives the real Audita subprocess adapter for the `polish` stage.
 
-Audita required fields:
+Audita defaulted fields:
 
-- `binary`
-- `timeout`
-- `base_url`
-- `model`
+- `binary` defaults to `audita`
+- `timeout` defaults to `3h`
+- `report` defaults to `true`
 
 Audita optional fields:
 
 - `llm_api_key_env` (enforced only when configured)
 - `modules` override list (when omitted/empty, Narratio does not pass `--modules`)
+- `base_url` (when omitted, Narratio does not pass `--base-url`)
+- `model` (when omitted, Narratio does not pass `--model`)
 - `transcript_description`
 - `config_path`
 - `output_schema` (`bare-segments` or `audita-v1`)
@@ -266,9 +267,18 @@ Audita optional fields:
 - `proposal_llm_concurrency` (> 0 when provided)
 - `validation_model`
 - `validation_llm_concurrency` (> 0 when provided)
-- `report` (default `true`)
+- `report` override
 
-Narratio passes only configured optional Audita flags; omitted optional values defer to Audita defaults.
+Narratio passes only configured optional Audita flags; omitted optional values defer to Audita runtime defaults/config.
+
+Seriatim defaults:
+
+- `pipeline.seriatim` may be omitted
+- `binary` defaults to `seriatim`
+- `timeout` defaults to `10m`
+- `output_schema` defaults to `seriatim-intermediate`
+- `coalesce_gap` defaults to `3.0`
+- `report` defaults to `true`
 
 When `pipeline.normalize` is omitted, defaults are applied:
 
@@ -302,7 +312,7 @@ When `pipeline.trim.enabled: true`:
 
 When `pipeline.scriptorium` is present:
 
-- `binary` is required and non-empty
+- `binary` defaults to `scriptorium` when omitted
 - `config_path` is optional; when provided it must be non-empty
 - `timeout` is optional; when provided it must parse as a Go duration
 - default `timeout` is `10m`