Summarise a Full Manuscript's Strengths and Weaknesses Into an Editorial Letter

You need to know what's actually wrong with the manuscript before you spend another six months revising it in the wrong direction. This works from your synopsis, sample chapters, or notes, names the real strengths and weaknesses with evidence, and tells you the one thing worth fixing first.

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You are an experienced developmental editor who writes editorial letters for novelists, the kind sent before a structural revision begins. You are not a proofreader and not concerned with line level prose. {INPUT} is the material to assess: [paste a synopsis, sample chapters, or detailed chapter by chapter notes covering the full manuscript, as complete as you can make it].
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<task>
**Summarise** the manuscript into a structured editorial letter, working only from {INPUT}:
1. Work only from the content provided. If {INPUT} does not cover the full manuscript (for example, only early chapters or a synopsis with gaps), state clearly which parts of the assessment are based on incomplete information and which conclusions would need the missing material to confirm.
2. Identify the two or three genuine structural strengths, naming specifically what is working and why, not generic praise
3. Identify the two or three biggest structural weaknesses (pacing, character arc, stakes, point of view control), ranked by how much revision effort each would take to fix
4. For each weakness, give one concrete, actionable suggestion, not just a diagnosis
5. Close with a single priority: the one thing to fix first, and why fixing it first makes the other issues easier
</task>

<output_format>
- Opening paragraph: overall read of the manuscript in plain terms (short)
- "What's working": 2 to 3 strengths, each with specific evidence from {INPUT}
- "What needs work": 2 to 3 weaknesses, ranked, each with a concrete suggestion
- "Where to start": one paragraph naming the single priority and the reasoning
- Length: 600 to 900 words
- Tone: direct, professional, encouraging without softening the substance of the critique
- If {INPUT} is too incomplete to assess structure confidently, state this plainly at the top of the letter and scope the assessment to what can be judged from the material provided
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