Writer Persona

Writer Persona

Extract your writing persona from real conversations. Measure how accurately AI can mimic you. Then let it write as you.

Usage

/writer-persona                        # Show persona status (score, last backtest)
/writer-persona --bootstrap            # Extract persona from 100+ real messages
/writer-persona --backtest             # Measure accuracy (default: last 24h)
/writer-persona --backtest --days 7    # Measure over last 7 days
/writer-persona --calibrate            # Manual tuning with your feedback
/writer-persona --write "context"      # Write as you in a given situation
/writer-persona --write                # Interactive: ask for context, then write

Execution

Default (no args): Status

1. Read persona file at persona.md in this skill's directory
2. If exists, display:

`` Writer Persona: {user_name} Score: {last_score}/100 (ceiling: {ceiling_score}) Messages analyzed: {sample_count} Last updated: {last_updated} ``

1. If no persona file: "No persona yet. Run /writer-persona --bootstrap to get started."

---

Phase 0: Setup & Persona Load

1. Read persona file at persona.md in this skill's directory (or path configured in frontmatter)

• If the file doesn't exist, copy persona.template.md from this skill's directory

1. Check frontmatter:

• sample_count: 0 or file missing → auto-enter Phase B (bootstrap)
• --bootstrap flag → force Phase B (overwrites existing persona)

1. If user_name or data_source is empty → enter First Run Setup (below)

First Run Setup (interactive)

Ask the user these questions using AskUserQuestion, one at a time:

1. "What name should I use for the persona?"

• Store as user_name in frontmatter

1. "What language do you primarily write in?"

• Examples: English, Korean, Japanese, Spanish...
• Store as language in frontmatter

1. "How should I collect your messages? Describe your data source."

• Explain: "I need access to 100+ of your real messages for bootstrap, and recent conversations for backtesting. This could be Slack (via MCP), email, Discord, Teams, a text file, or anything your MCP tools can access."
• Examples to offer:
• "Slack — I have mcp-slack tools available"
• "I'll paste messages manually"
• "I have a file with exported messages"
• "Email — I have an email MCP"
• Other (describe)
• Store the description as data_source in frontmatter

1. "What tool or method should I use to search/collect your messages?"

• Ask for specifics based on their answer:
• For Slack: "What's your Slack username or user ID? Which MCP tool should I use to search messages?"
• For manual: "Please provide a file path, or I'll ask you to paste messages during bootstrap."
• For other: "Describe the MCP tool name and how to query it, or how you'll provide messages."
• Store as data_source_config in frontmatter (freeform object)

1. "Are there any situation categories specific to your work?"

• Default categories: Technical Q&A, Work coordination, Feedback/review, Casual chat, Formal/leadership
• User can customize (e.g., add "Client communication", remove "Leadership")
• Store in frontmatter as situation_categories

Save the configured persona file and proceed to Phase B.

---

Phase B: Bootstrap (Initial Construction)

Goal: Analyze 100+ real messages to build the persona definition.

Use Task tool with model: "sonnet".

Include in the agent prompt:

• The full persona.template.md content
• The user's data_source_config (how to collect messages)
• The language setting
• Instructions below:

B-1. Message Collection

Collect 100+ messages written by the user, using whatever data source they configured.

• Aim for the last 30 days to capture current style
• Ensure diversity: different channels/contexts, different recipients, different times of day
• If using an MCP tool, paginate as needed to reach 100+
• If manual input, ask the user to provide messages (or read from a specified file)

Message format (normalize all sources to this):

CONTEXT: [channel/thread/email subject]
TO: [recipient(s)]
DATE: [ISO date]
---
[message text]
===

B-2. Message Classification

Classify each message into the configured situation categories. If a message doesn't fit any category, assign "Other" and note the pattern — this may indicate a missing category.

B-3. 8-Axis Analysis

For each axis, analyze patterns across all collected messages. See references/evaluation-rubric.md for axis definitions.

Analyze in the user's configured language. Adapt axis-specific features to the language:

• Korean: Track 합쇼체/해요체/해체, ㅋㅎ patterns, particle omission
• English: Track contractions, hedging phrases, slang density, register markers
• Japanese: Track keigo levels, sentence-final particles, kanji/kana ratio
• Other languages: Identify the equivalent formality/register markers

Produce:

1. Lexical Choice: Top 30 characteristic words/phrases, avoided expressions, abbreviation patterns, foreign word ratio
2. Function Words: Particle/preposition preferences, conjunction patterns, high-frequency function words (Top 20)
3. Sentence Structure: Average sentence length (chars ± SD), word/sentence counts, simple:complex ratio
4. Formality / Register: Distribution across formality levels (% breakdown), context-specific switching rules
5. Tone / Sentiment: Base tone keywords, positive/negative/neutral ratio, emotion expression frequency
6. Formatting: Emoji usage rate, favorites, laugh markers, punctuation density, line break patterns
7. Discourse Patterns: Greeting/closing style, question rate, response structure, context referencing method

B-4. Situational Tone Map

For each situation category, document: typical tone, register level, and one example message.

B-5. Self-Similarity Ceiling

1. Randomly select 20 message pairs from the same situation category
2. Score each pair on 8 axes using the Phase 3 scoring method ("do these look like the same person?")
3. Average of 20 pairs = ceiling score (this becomes the "100 point" baseline)
4. Record standard deviation
5. Typical range: 65-85 (people vary naturally)

B-6. Golden Set

Select 2 representative messages per situation category = ~10 example messages. Choose messages that best exemplify the user's style in each context.

B-7. Save Persona

Write all analysis results to the persona file following the template structure. Update frontmatter: sample_count, last_updated, ceiling_score, ceiling_stddev. Add to Update History: "Initial bootstrap (N messages, last 30 days)"

Completion message: "Writer Persona ready! Analyzed N messages. Self-similarity ceiling: XX. Try /writer-persona --backtest to measure accuracy, or /writer-persona --write to write in your voice."

---

Phase 1: Mention/Conversation Collection

Goal: Find recent conversations where the user responded, and extract context + actual response.

Use Task tool with model: "sonnet".

Include in the agent prompt:

• The user's data_source_config
• Period: --days N (default: 1)
• Instructions:

1. Search for conversations where the user was mentioned or participated, within the specified period

• Use whatever data source the user configured
• Look for messages directed at the user, threads the user replied to, or conversations the user participated in

1. For each conversation, extract:

• situation_context: All messages before the user's response (the setup)
• actual_reply: The user's actual response
• channel_name: Where the conversation happened (channel, email thread, DM, etc.)
• participants: Who else was in the conversation
• timestamp: When the user responded

1. Filter out:

• Responses that are 1 word or less
• Emoji-only reactions
• Minimal acknowledgments ("ok", "sure", "got it", "ㅇㅇ", "ㅋㅋ")

1. Return: Array of {situation_context, actual_reply, channel_name, participants, timestamp}

Minimum: 5 cases required. If fewer, suggest extending the period (e.g., "Only N cases in 24h. Try --backtest --days 3.")

---

Phase 2: Draft Generation (Parallel, Information-Isolated)

Process up to 5 cases in parallel using separate Task agents.

Each agent (Task tool, model: "sonnet"):

CRITICAL: The draft generation agent must NEVER see the actual_reply. This is the core fairness guarantee of the backtest. Only provide situation_context.

Prompt for each agent:

You are writing as "{user_name}" based on the persona definition below.

## Persona Definition
{full persona file content}

## Situation
Channel/Context: {channel_name}
Participants: {participants}
Conversation so far:
{situation_context}

## Instructions
Write the response that {user_name} would send in this situation.
- Follow the persona's vocabulary, tone, register, and formatting patterns exactly
- Match the situational tone map for this type of conversation
- Infer what {user_name} would say based on their role and expertise
- Write in {language}
- Output ONE message only (in the platform's message format)
- Output the message only. No explanations, labels, or meta-commentary.

---

Phase 3: Scoring

Score each {draft, actual_reply} pair. This phase uses the default model (opus-level recommended) — complex judgment required.

3-1. Structural Analysis (Direct Calculation)

Compare the two texts numerically:

• Sentence count difference
• Average sentence length difference (chars)
• Formality/register marker matching
• Emoji count difference
• Laugh marker count difference (lol/haha/ㅋㅋ/www etc.)
• Line break count difference
• Total character count difference (%)

3-2. LLM-as-Judge (8-Axis Scoring)

Scoring prompt:

You are an expert in writing style analysis. Evaluate whether two texts appear to be written by the same person, across 8 linguistic axes.

## Self-Similarity Ceiling
Even the same person varies across messages.
Self-similarity ceiling for this user: {ceiling_score} points.
This ceiling IS the 100-point baseline. Score relative to it:
"Within the range of natural variation for this person" = full marks on that axis.

## Actual Response (ground truth)
{actual_reply}

## AI Draft
{draft}

## Situation Context
{situation_context}

## Structural Analysis
{Phase 3-1 metrics}

## Evaluation Language
Evaluate in {language}. Use language-appropriate criteria for each axis.

## Score each axis (0-100, normalized to ceiling)

Output JSON:
{
  "lexical": { "score": N, "note": "one-line rationale" },
  "function_words": { "score": N, "note": "..." },
  "sentence_structure": { "score": N, "note": "..." },
  "formality": { "score": N, "note": "..." },
  "tone": { "score": N, "note": "..." },
  "formatting": { "score": N, "note": "..." },
  "semantic": { "score": N, "note": "..." },
  "discourse": { "score": N, "note": "..." },
  "weighted_total": N,
  "top_gaps": ["axis names with lowest scores, 1-2"],
  "persona_fix": "How to modify the persona definition to close this gap"
}

Weights: semantic 25%, tone 20%, formality 15%, discourse 15%, lexical 10%, function_words 5%, sentence_structure 5%, formatting 5%

---

Phase 4: Report Generation

Aggregate all case scores into a report.

Output path: {skill_directory}/reports/YYYY-MM-DD-backtest.md (Create the reports/ directory if it doesn't exist)

Report format:

---
tags: [writer-persona, backtest]
score: {weighted_total_average}
cases: {N}
period: {description}
---

# Writer Persona Backtest — {YYYY-MM-DD}

> Overall: **{XX}/100** | Cases: {N} | Period: last {N} days | Ceiling: {ceiling_score}

## Summary

| Axis | Score | Weight | Note |
|------|-------|--------|------|
| Semantic Fidelity (25%) | {XX} | | {note} |
| Tone / Sentiment (20%) | {XX} | | |
| Formality / Register (15%) | {XX} | | |
| Discourse Patterns (15%) | {XX} | | |
| Lexical Choice (10%) | {XX} | | |
| Function Words (5%) | {XX} | | |
| Sentence Structure (5%) | {XX} | | |
| Formatting (5%) | {XX} | | |
| **Weighted Total** | **{XX}** | | |

## Key Findings

{2-3 bullet points summarizing the most important patterns}

## Case Details

### Case {N}: {channel_name} — {one-line summary}

**Situation**: {1-2 line context}
**Actual response**:
> {actual text}

**AI draft**:
> {draft text}

**Score**: {XX}/100
**Main gap**: {one line}

---

{repeat for each case}

## Persona Corrections {only if score < 80}

### Modified
- **{axis name}**: {before} → {after}
  - Evidence: {N} cases flagged this pattern

### Verify Next Run
- {specific thing to check}

---
_Generated by [writer-persona](https://github.com/cosmos-makers/writer-persona)_

---

Phase 5: Auto-Correction (Conditional)

Trigger: Weighted total score < 80

1. Collect all persona_fix suggestions from Phase 3
2. Find common patterns: Same axis flagged in 2+ cases
3. Modify at most 2 axes (highest gap first)
4. Edit the persona file's corresponding sections
5. Update frontmatter: last_updated, last_score
6. Add to Update History: what changed, why, which cases provided evidence

Overfitting prevention:

• Maximum 2 axes per run (prevents overcorrection)
• If the same axis has been corrected 3 consecutive times in the same direction WITHOUT score improvement → stop auto-correcting that axis
• Mark in report: "Auto-correction paused for {axis} — use --calibrate for manual tuning"
• Record before/after values for every change (enables rollback)

---

--calibrate Mode

Manual persona tuning with user feedback.

1. Load the most recent backtest report from {skill_directory}/reports/
2. For each case, show side by side:

• The situation context
• The actual response
• The AI draft

1. Ask the user:

• "Which sounds more like you — the actual or the draft?"
• "What specifically feels off about the draft?"

1. Apply feedback to the persona file
2. Can unblock axes that auto-correction paused

---

--write Mode

Write a message in the user's voice.

1. Load persona (refuse if sample_count: 0 → guide to --bootstrap)
2. Get context from the user:

• If argument provided (--write "reply to John's email about the deadline"): use that as context
• If no argument: ask interactively:
• "Who are you writing to?"
• "What's the situation/context?"
• "What do you want to communicate?"
• "What platform is this for?" (email, Slack, DM, etc.)

1. Determine situation category from the context → select matching register/tone from persona
2. Generate draft using the same prompt template as Phase 2:

• Full persona definition
• Situation context from user input
• Matching situational tone map entry

1. Output the draft to the user
2. Ask: "Want me to adjust anything? (tone, length, formality, content)"

• If yes: regenerate with the adjustment
• If no: done

The --write mode is the payoff of all the extraction and calibration work. The better the persona score, the better the drafts.

---

Important Rules

Do

• Run message collection and draft generation as separate agents (information isolation — draft agents never see actual responses)
• Always measure and apply the self-similarity ceiling
• Exclude trivial responses (1-word, emoji-only, minimal acks)
• Record all persona changes with diffs and evidence
• Use the strongest available model for scoring (complex multi-axis judgment)
• Adapt all analysis to the user's configured language

Don't

• Start backtesting without bootstrap (sample_count: 0 → refuse, guide to --bootstrap)
• Modify 3+ axes simultaneously
• Judge scores without ceiling context (raw scores are meaningless without the baseline)
• Expose actual responses outside the local environment
• Show actual responses to draft-generation agents (br

…

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: cosmos-makers
• Source: cosmos-makers/writer-persona
• License: MIT

Install and usage instructions live in the source repository linked above.