---

name: "viral-product-evaluator" description: "Review a product codebase and landing page against 32 viral principles and produce a Virality Score plus ranked fixes. Use to audit virality or prioritize growth. Don't use for SEO, ASO, copywriting, or code review." license: MIT effort: high dependencies:

• browse metadata: version: 1.7.0 author: "Luong NGUYEN luongnv89@gmail.com"

---

Viral Product Evaluator

Grade a product against the 32 principles of viral products. Two inputs — a codebase and a landing page — produce one output: a scored report of what's already satisfied and, in priority order, what to do next to make it more viral.

When to Use

Trigger when the user wants to:

• Make a product, SaaS, or indie app "more viral" or more shareable
• Score / audit a landing page against viral-marketing or conversion principles
• Get a prioritized, ordered list of changes to improve a product's pull

Do not use for: technical SEO (seo-ai-optimizer), App Store ASO (aso-marketing), turning a README into a page (landing-page-generator), or bug-hunting code review (code-review).

Prerequisites

• Read access to the target codebase directory.
• Landing page signal: public URL, local file, auto-detectable in the tree, or an orchestrator's evidence-dir.
• The skill's references/*.md files present.

Missing prerequisites after the one ask in Edge cases → stop with a BLOCKED response (references/final-report.md) before gathering evidence.

What this skill does and does not touch

It reads the codebase, fetches the landing page, and writes one report file (viral-evaluation.md) — it never edits source, changes copy, or commits. Applying fixes is a separate task for a copy/frontend skill; this skill stops at the prioritized plan.

Dependency Preflight (mandatory)

This skill invokes /browse (frontmatter dependencies), and only on the live URL path; every other input needs nothing installed. Run once, before the first fetch:

if test -f "$HOME/.claude/skills/browse/SKILL.md"; then
  echo "browse_mode=installed browse_skill=$HOME/.claude/skills/browse/SKILL.md"
elif test -f "$HOME/.agents/skills/browse/SKILL.md"; then
  echo "browse_mode=installed browse_skill=$HOME/.agents/skills/browse/SKILL.md"
elif command -v asm >/dev/null && asm deps --help >/dev/null 2>&1; then
  asm deps discover viral-product-evaluator --json || echo "discover failed; acquire still runs" >&2
  echo "browse_mode=lease"
else
  echo "Missing skill: browse. Install: asm install github:garrytan/gstack:browse -p claude -s global --yes" >&2
  echo "No asm yet: npm install -g agent-skill-manager@latest" >&2
  echo "browse_mode=none"
fi
printf 'vpe_session=%s\n' "viral-product-evaluator-$(date +%s)-$"   # record it; reuse it verbatim

The install-path tests run first because gstack may install /browse without asm knowing.

1. browse_mode=installed: read the recorded browse_skill path.
2. browse_mode=lease: run asm deps acquire browse --session <vpe_session> --json; read the returned skillMdPath directly.
3. browse_mode=none, or step 2 failed: fail-soft — print the install lines, then ask the user for a local file or saved HTML of the page. Never score a URL you could not load.
4. Release in finally. If step 2 ran, run asm deps release --session <vpe_session> --json once at every terminal outcome, stops included.

Repo Sync Before Edits (mandatory)

Phase 3 writes viral-evaluation.md. An inline-only run never syncs or stashes a checkout. When the output path is inside a git worktree, follow references/repo-sync.md: confirm with the user, then stash, sync and pop before the write.

Inputs

1. Landing page — resolve in this order:
   • an orchestrator's evidence-dir → read its page.html + head.json; no /browse.
   • a live URL → run the Dependency Preflight, confirm the fetch with the user, then load it with the /browse skill (headless). Capture rendered copy, headline, CTAs, pricing section, testimonials, nav, and <head> meta (og:image, twitter:image, description, <title>).
   • a local file (index.html, a JSX/TSX/MDX page, a built dist/) → read it directly.
   • auto-detect from the codebase → search the common spots (index.html, app/page.tsx, pages/index.*, src/App.*, landing/, marketing/, public/). If exactly one candidate is found, use it. If none or several are found, ask the user.
2. Codebase — a path to the repo (defaults to the current working directory). Used for the pricing/paywall principles, the feature surface, and landing-page auto-detection.
3. Extra instructions (optional) — strategic context such as "we keep a free tier on purpose". Honor these when interpreting a verdict (note the deliberate deviation) but still score the principle as written so the number stays comparable.

Pipeline (3 phases, in order)

Phase 1 — Resolve inputs & gather evidence

1. Resolve the landing page per Inputs.
2. Locate the codebase (default: the current working directory).
3. Grep it for price, plan, tier, checkout, subscription, free, trial, stripe, paddle and read the matches.
4. Record the monetization evidence section A of the rubric lists (references/principles.md). When nothing matches, record "no billing evidence found" — that is itself evidence.
5. Skim routes, nav items and top-level modules; record a one-line feature inventory.
6. When the codebase is too large for the context budget, delegate steps 3–5 to a one-off Agent task scoped to pricing and feature evidence.
7. Note any extra instructions from the user.

Phase 2 — Evaluate against the 32 principles

1. Read references/principles.md — the full rubric.
2. Score every principle PASS / PARTIAL / FAIL; never skip one. Absence of a thing a viral product would ship (pricing, testimonials, demo) is a real FAIL, not "unknown".
3. Quote product-specific evidence for each verdict — the actual headline, the actual tier, the file/line. Generic findings are not acceptable.
4. Tag every judgment/visual principle (hero punch, emotional headline, OG-image design, founder presence, novelty, price-vs-competitor) low-confidence and record what a human must eyeball. When a principle's evidence source was unavailable (no codebase access, a failed fetch), tag it low-confidence as well and say why.
5. Compute the Virality Score with scripts/virality_score.py — pass every verdict as {"verdicts": {"<n>": "PASS|PARTIAL|FAIL", ...}} (contract in references/principles.md → Scoring). Do not tally or round in prose.

Phase 3 — Prioritize fixes & write the report

1. Read references/report-template.md and build the report in that exact shape: verdict block → scorecard (all 32) → top fixes → what's working → caveats.
2. Order the top fixes by impact × ease, hero/paywall/headline/proof/single-CTA first; merge principles sharing a root cause into one fix.
3. Make each fix concrete enough to act on — the actual proposed headline, the tier to cut, the CTA label — quoting Now and Change.
4. Print the verdict block and top fixes inline, then ask the user to confirm writing the report. One confirmation covers the write and, when the output path is inside a git worktree, the sync.
5. On confirmation: run references/repo-sync.md when needed, then write viral-evaluation.md to output-dir, else the repo root, else the current working directory.
6. When the user declines, return the full report inline and mark the run PARTIAL.
7. Close with the final response from references/final-report.md, including its status rule.

Orchestrated Runs

With orchestrated-by, evidence-dir, skip-checks or output-dir lines, follow references/orchestrated-runs.md; without them nothing changes. All 32 principles are always scored.

Honest evaluation

This is a critique tool — its value is candor. The full candor rules are in references/honest-evaluation.md.

Step Completion Reports

After each phase, emit the report from references/step-reports.md — Gather Evidence, Evaluate, Prioritize & Report.

Acceptance Criteria

• All 32 principles scored with product-specific evidence quoted.
• Virality Score and tier come from scripts/virality_score.py over all 32 verdicts; verdicts and evidence remain model-owned.
• Top fixes are concrete, prioritized by impact×ease, with before/after suggestions.
• Report written to viral-evaluation.md after the user's confirmation, or returned inline when declined; Step Completion Reports emitted per phase.
• The final response follows references/final-report.md: Result: PASS | PARTIAL | BLOCKED first, then Evidence, Uncertainty and Decision.
• Reader checks: main result findable in the first line, facts separated from assumptions, claims traceable to evidence, next decision clear.
• Negative-trigger domains respected (no SEO/ASO/copy/code-review work).

Expected output

A viral-evaluation.md report (plus an inline summary and a Result:-first final response) containing:

• Overall verdict + Virality Score (e.g. 68 — Promising)
• Scorecard table for all 32 principles
• Top 5-8 prioritized fixes with exact copy or code recommendations
• What's already working
• Caveats / low-confidence items

Edge cases

• No landing page: ask once for a URL or file; if the user confirms none exists, score codebase-only (LP principles FAIL with a caveat); without an answer, end BLOCKED. Never fabricate a page.
• /browse missing for a live URL: fail-soft per the Dependency Preflight.
• Strategic deviation (e.g. no testimonials by design): score as written, note the trade-off in caveats.
• Partial evidence (a fetch failed mid-run): mark affected principles low-confidence, never guess a PASS.
• User declines the report write: return the report inline; the run is PARTIAL.
• Output path inside a git worktree: confirm, then sync per references/repo-sync.md before writing.

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Reference files

• references/principles.md — the 32-principle rubric: per-principle checks, evidence source, PASS/PARTIAL/FAIL bars, confidence flags, and the scripts/virality_score.py scoring contract. Load every run.
• references/report-template.md — the exact report shape, with a calibration example.
• references/final-report.md — the final chat response: status rule (PASS / PARTIAL / BLOCKED), response shapes, and the reader-check criteria.
• references/repo-sync.md — the confirm-first sync procedure for an output path inside a git worktree.
• references/step-reports.md — Step Completion Report formats for the three phases.
• references/honest-evaluation.md — the candor rules: no inflation, no invented flaws, labelled low-confidence.
• scripts/virality_score.py — deterministic Virality Score + tier helper (tests/ holds its stdlib fixtures).