User Acquisition Channel Evaluation

There is a prompt instruction at https://www.zangwei.dev/prompts/product-growth/user-acquisition-channel-evaluation-prompt . Extract and follow the prompt to create file /docs/handbook/growth/acquisition-channels.md

You are a Head of Growth. In the current product stage, evaluate potential user acquisition channels and output:
- whether to invest
- priority ranking
- a minimum validation path
- explicit Go / No-Go criteria

Your goal is not to list options, but to judge which channels can drive **sustainable growth**, whether the growth engine fits the current stage, and whether it is worth investing now.

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## Core framing
- Channels are not growth; **the growth engine** is
- Every channel judgment must answer:
  1) Which growth engine does it serve?
  2) Does it fit the current stage’s sustainable growth mode?
  3) Can a minimum validation produce a fast Go/No-Go decision?

The output must support clear priority decisions for people/time/budget.

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## 1) Product stage constraints
- Current stage (choose one):
  - Pre-PMF validation
  - Early growth (post-PMF)
  - Scale
- Target user profile and core scenarios
- This cycle’s **single primary growth objective** (1–2 only), e.g.:
  - acquire first cohort of high-intent users
  - improve activation -> retention
  - validate a repeatable acquisition path

## 2) Growth engine selection (must choose first)
Choose the primary growth engine (1 primary + optional 1 secondary):

1) Sticky engine
- driven by retention, repeat usage, repeat purchase
- key metrics: Retention / NRR

2) Viral engine
- driven by user-driven sharing
- key metrics: K-factor, share conversion

3) Paid engine
- driven by ads/paid acquisition
- hard constraint: CAC < 1/3 LTV

For each channel, explicitly state which engine it serves. If misaligned, explain why.

## 3) Sustainable growth mode alignment (Lean constraint)
For each channel, state which sustainable mode(s) it relies on:
1) Word of mouth (trust-driven referrals)
2) Spillover / virality (built-in distribution)
3) Paid ads (must validate CAC < 1/3 LTV or explain why not)
4) Repeat purchase/usage (strengthens retention/NRR)

If a channel cannot form a closed loop with any sustainable mode, mark it as high risk.

## 4) Candidate channel list (coverage != doing all)
Cover at least (evaluate only if applicable; otherwise explain):
- SEO
- content distribution (blog/video/newsletter)
- social media
- communities
- partnerships / BD / co-marketing
- paid acquisition
- platform distribution (App Store, extensions marketplaces, third-party platforms)

For each, explain why it fits/doesn’t fit the product and the growth engine.

## 5) Unified evaluation rubric (hard ruler)
For each candidate channel, assess:
- served growth engine (Sticky / Viral / Paid)
- sustainable growth mode(s) (1–4)
- target-user fit (high / medium / low)
- user intent strength (high-intent / low-intent)
- startup cost (people / time / money)
- time-to-signal (short / medium / long)
- ceiling and compounding potential
- key risks (platform dependency, rising costs, content/resource barriers)
- minimum validation method (MVP of the channel) (principles only; no execution playbook)

## 6) Priority & investment decision (must conclude)
- Recommend top 1–3 channels:
  - rank explicitly
  - explain why they fit the current growth engine and why now
- Explicitly list channels to not do / not yet:
  - reasons
  - triggers to re-evaluate (stage change / metrics hit)

## 7) Validation plan & Go/No-Go criteria (decision core)
For each recommended channel:
- validation window (e.g., 2–4 weeks)
- minimum resource input (people / time / budget)
- Go criteria
- No-Go criteria
- what to do if it fails: iterate / replace / stop

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## Hard output requirements
- No operational playbooks for ad buying or channel ops
- No metric dumping or channel encyclopedia
- Must bind each channel to a growth engine + sustainable growth mode
- Must output clear priorities and Go/No-Go decisions