Add trim configuration contract

architecture.md

@@ -94,6 +94,25 @@ Adapter behavior:
 
 `pipeline.scriptorium` is optional. Existing pipelines without Scriptorium continue to work.
 
+`pipeline.trim` is optional. Existing pipelines without trim config continue to work.
+
+When `pipeline.trim` is present:
+
+- `enabled` is optional and defaults to `false` when omitted
+- relative `output_path`, `bounds.output_path`, and `bounds.render_output_path` values are session-workdir-relative paths
+- do not store secrets in trim config values
+
+When `pipeline.trim.enabled: true`:
+
+- `output_path` is required and non-empty
+- `bounds.prompt_id` is required and non-empty
+- `bounds.transcript_input_name` is required and non-empty
+- `bounds.output_path` is required and non-empty
+- `bounds.timeout` must parse as a Go duration when provided
+- `bounds.render_debug: true` requires non-empty `bounds.render_output_path`
+- `bounds.profile_id` may be empty to use the prompt default profile
+- prompt IDs are config values, not hardcoded stage logic
+
 When `pipeline.scriptorium` is present:
 
 - `binary` is required and non-empty
@@ -116,6 +135,24 @@ For each artifact definition:
 
 Prompt IDs and profile IDs are configuration values, not hardcoded stage logic.
 
+Trim scaffold config shape:
+
+```yaml
+trim:
+  enabled: true
+  output_path: "transcripts/trimmed.json"
+  bounds:
+    prompt_id: "dnd_session.bounds"
+    profile_id: ""
+    transcript_input_name: "transcript"
+    output_path: "artifacts/session_bounds.json"
+    timeout: "10m"
+    render_debug: false
+    render_output_path: "artifacts/session_bounds.render.json"
+  seriatim:
+    report: false
+```
+
 ## 6. Analyze Stage (Current Implementation)
 
 The current real analyze implementation supports only `scriptorium.artifacts.session_recap`.