diff.py

"""
Diff Mode
---------
Compares two competitive briefs for the same product — typically
across different time periods — and surfaces what changed strategically.

This is for tracking competitor momentum over time. The output isn't
a line-by-line diff; it's a structured change analysis that answers
the questions a PM actually cares about:
  - Did their threat level change?
  - What new features or moves appeared?
  - Did pricing shift?
  - Are they moving closer to your ICP?
  - Did anything de-escalate?

Usage:
    python diff.py --before briefs/notion-ai-jan.md --after briefs/notion-ai-apr.md
    python diff.py --before briefs/notion-ai-jan.md --after briefs/notion-ai-apr.md --target "Notion AI"
    python diff.py --before briefs/notion-ai-jan.md --after briefs/notion-ai-apr.md --output diff.md
"""

import anthropic
import argparse
import sys
from datetime import datetime
from pathlib import Path

MODEL = "claude-sonnet-4-20250514"
MAX_TOKENS = 2048

# ── Diff Prompt ───────────────────────────────────────────────────────────────

DIFF_SYSTEM = """You are a senior competitive intelligence analyst. 
You will be given two competitive briefs for the same product, written at different points in time.

Your job is to produce a structured strategic change analysis — not a line-by-line diff.
Focus on what matters to a Product Manager making roadmap and positioning decisions.

Structure your output as clean Markdown with these sections:

## Threat Trajectory
Did the competitor become more or less dangerous? Why? Lead with a clear verdict:
↑ Escalating / → Stable / ↓ De-escalating

## What's New
Specific new features, product launches, pricing changes, partnerships, or strategic moves
that appear in the newer brief but not the older one.

## What Changed
Things that existed before but have materially shifted — pricing, positioning, ICP, 
AI capabilities, enterprise readiness, etc.

## What Disappeared
Things present in the older brief that are notably absent in the newer one.
(Could signal pivots, failures, or de-prioritization.)

## ICP Drift
Is the competitor moving toward or away from your target customer? Be specific.

## AI Maturity Delta
How has their AI integration changed between the two briefs?

## Strategic Implications
What should a competing PM do differently based on these changes?
Concrete, actionable, no hedging.

## Confidence
Flag anything where the difference might be due to research quality rather than
real product changes. Rate overall confidence: High / Medium / Low.

Be direct. A PM reading this brief doesn't have time for caveats on every sentence.
Flag uncertainty at the end, not throughout."""


# ── Core Diff Function ────────────────────────────────────────────────────────

def diff_briefs(
    target: str,
    before_text: str,
    after_text: str,
    before_label: str = "Earlier brief",
    after_label: str = "Later brief",
    verbose: bool = True,
) -> str:
    """
    Runs a strategic diff between two competitive briefs.
    Returns a structured Markdown change analysis.
    """
    client = anthropic.Anthropic()

    if verbose:
        print(f"\n🔄 Diffing briefs for: {target}")
        print(f"   Before: {before_label}")
        print(f"   After:  {after_label}\n")

    response = client.messages.create(
        model=MODEL,
        max_tokens=MAX_TOKENS,
        system=DIFF_SYSTEM,
        messages=[
            {
                "role": "user",
                "content": (
                    f"Target product: {target}\n\n"
                    f"---\n\n"
                    f"## {before_label}\n\n"
                    f"{before_text}\n\n"
                    f"---\n\n"
                    f"## {after_label}\n\n"
                    f"{after_text}"
                ),
            }
        ],
    )

    return response.content[0].text


def format_diff(target: str, diff: str, before_label: str, after_label: str) -> str:
    """Wraps the diff with header and metadata."""
    return f"""# Competitive Change Analysis: {target}

> **Generated by PM Research Agent** | {datetime.now().strftime("%B %d, %Y")}  
> *Comparing: "{before_label}" → "{after_label}"*  
> *This is a strategic diff, not a line-by-line comparison.*

---

{diff}

---

*Generated by [PM Research Agent](https://github.com/dvmukul/pm-research-agent)*
"""


# ── CLI ───────────────────────────────────────────────────────────────────────

def main():
    parser = argparse.ArgumentParser(
        description="Diff two competitive briefs to surface strategic changes over time"
    )
    parser.add_argument("--before", required=True, help="Path to the earlier brief .md file")
    parser.add_argument("--after", required=True, help="Path to the more recent brief .md file")
    parser.add_argument("--target", default=None, help="Competitor name (inferred from filename if omitted)")
    parser.add_argument("--output", default=None, help="Save diff to a markdown file")
    parser.add_argument("--quiet", action="store_true", help="Suppress progress output")
    args = parser.parse_args()

    before_path = Path(args.before)
    after_path = Path(args.after)

    for p in [before_path, after_path]:
        if not p.exists():
            print(f"❌ File not found: {p}")
            sys.exit(1)

    # Infer target from the "after" filename if not provided
    target = args.target or after_path.stem.replace("-", " ").replace("_", " ").title()

    # Use filenames as labels (strip path and extension)
    before_label = before_path.stem
    after_label = after_path.stem

    before_text = before_path.read_text(encoding="utf-8")
    after_text = after_path.read_text(encoding="utf-8")

    try:
        raw_diff = diff_briefs(
            target=target,
            before_text=before_text,
            after_text=after_text,
            before_label=before_label,
            after_label=after_label,
            verbose=not args.quiet,
        )
    except anthropic.AuthenticationError:
        print("\n❌ Error: ANTHROPIC_API_KEY is missing or invalid.")
        sys.exit(1)
    except Exception as e:
        print(f"\n❌ Unexpected error: {e}")
        sys.exit(1)

    final_diff = format_diff(target, raw_diff, before_label, after_label)

    print(final_diff)

    if args.output:
        output_path = Path(args.output)
        output_path.write_text(final_diff, encoding="utf-8")
        print(f"\n💾 Diff saved to: {output_path.resolve()}\n")


if __name__ == "__main__":
    main()