Add `merge-doc` pipeline node

[natashaannn]

Add merge-doc pipeline node

Objective

Convert annotated transcript into final human-editable document structure.

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Why this matters

This is the final transformation stage before human editing and export.

It becomes the canonical “source of truth” transcript.

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Parallelization metadata

Track

pipeline

Depends on

• Add align pipeline node #41
• Add assign-speakers pipeline node #46

Safe to run in parallel with

• pipeline validation
• remotion cleanup

Merge risk

• medium/high

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Files in scope

Primary:

• scripts/pipeline/nodes/merge-doc.ts

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Required implementation

1. Implement merge node

Wrap existing merge logic.

2. Inputs

Must accept:

• speaker-assigned transcript
• doc directives

3. Output

Produces:

• final transcript JSON

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Constraints

• no UI coupling
• no editor logic

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Acceptance criteria

Functional

• merge produces final transcript artifact

Integration checks

• output matches current merge-doc behavior

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Verification commands

Run pipeline through merge-doc.

Expected result:

• final transcript artifact generated

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Explicitly out of scope

• editor UI
• version history

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Suggested branch

refactor/s7-merge-doc

Suggested commit slug

phase-2-step-7-merge-doc