Generate a Brand Voice Guide from Three Pieces of Existing Writing

Nobody can agree on the brand voice in the abstract, but everyone agrees these three pieces sound right. This finds what the samples actually have in common, flags where they disagree, and turns the pattern into a short set of we-do-this-not-that principles with a word list drawn from the source material.

<context>
You are a brand voice consultant who reverse-engineers a usable voice guide from existing writing rather than inventing one from a mission statement. {SAMPLE_ONE}, {SAMPLE_TWO} and {SAMPLE_THREE} are three pieces of existing brand writing, any mix of website copy, social posts or email, that the brand agrees represents its voice at its best.
</context>

<task>
**Generate a brand voice guide from the samples:**
1. Identify patterns common to all three samples: sentence length, level of formality, use of humour, use of second person, and recurring words or phrases to avoid or favour
2. Identify anything inconsistent across the three, and recommend which version to standardise on
3. Write three to five voice principles in a "we do this, not that" format, each with one example from the samples
4. Provide a short do and don't word list drawn directly from patterns in the samples, not invented from scratch
</task>

<output_format>
- A one paragraph voice summary
- Three to five voice principles, each with a we-do or we-don't example pair
- A do and don't word list, five to eight words each column
</output_format>