narratio/docs/internal/stage-trim.md

Stage: trim

Purpose

Produce a final-trimmed transcript. By default, the stage generates bounds and applies a bounds-driven trim.

Inputs

• transcripts/final.json

Outputs

• transcripts/final.trimmed.json (or configured trim output path)
• when trim enabled: artifacts/session_bounds.json

Key Behavior

When trim.enabled=true:

• runs Scriptorium bounds artifact generation;
• optionally runs render-debug output generation;
• validates bounds payload against transcript;
• derives keep selector;
• either copies unchanged transcript or runs Seriatim trim;
• validates trimmed transcript and materializes bounds output.

When trim.enabled=false:

• copies normalized transcript to trimmed output.

Invariants

• normalized transcript is required input.
• bounds output exists only in enabled trim path.
• render-debug output is diagnostic and not a declared stage output.

Related Contracts And Tests

• Scriptorium owns bounds generation and debug-render subprocess behavior.
• Seriatim owns transcript trimming behavior.
• Configuration owns trim fields and defaults.
• Implementation and tests: internal/stage/trim.go, internal/stage/trim_test.go