discover-event-surfaces

Discover Event Surfaces

When to Use

• After running diff-intake and receiving a structured YAML brief
• When auditing a new feature for analytics coverage before it ships
• When a PM asks "are we tracking everything important in this release?"
• When mapping user flows to their corresponding analytics events
• When defining what events need to be added vs. updated vs. deprecated

Core Jobs

1. Receive Brief from Diff-Intake

Accept the YAML brief from diff-intake. If no brief exists, ask for one or invoke diff-intake first.

Verify brief has: new_surfaces, changed_behaviors, technical_context.

2. Check Existing Events (No Duplicates)

Before creating new events, check what already exists in Amplitude:

• Use mcp__Amplitude__get_event_properties to pull existing event schemas
• Use mcp__Amplitude__get_context to understand the project context
• Search for events that may already cover the same action (e.g., checkout_completed may already exist)
• Flag existing events that need property additions rather than new event creation

Rule: always prefer updating an existing event over creating a new one if the semantic intent is the same.

3. Map Each New Surface to Event Candidates

For each item in new_surfaces, derive one or more candidate events:

Surface Type	Primary Event	Secondary Events
New screen	<screen_name>_viewed	—
Button / CTA	<action>_clicked	—
Form	<form_name>_started, <form_name>_submitted	<form_name>_abandoned
Modal / drawer	<modal_name>_opened, <modal_name>_closed	—
API-triggered action	<resource>_<past_tense_verb>	—
Feature toggle	<feature>_enabled, <feature>_disabled	—

4. Apply Naming Convention (Verb-Noun Pattern)

All event names must follow: verb_noun in snake_case.

Valid examples:

• page_viewed ✓
• checkout_completed ✓
• filter_applied ✓
• userClickedCheckout ✗ (camelCase)
• CheckoutCompleted ✗ (PascalCase)
• checkout-click ✗ (kebab-case)

Check technical_context.existing_tracking_file for the project's actual convention — match it if it differs.

5. Identify Required Properties for Each Event

For each candidate event, list the properties needed to answer future analytics questions:

Universal properties (should be on every event):

• user_id, session_id, platform, app_version, timestamp

Contextual properties (what makes this event useful for analysis):

• Screen context: page_name, page_section, referrer_page
• Item context: item_id, item_type, item_name, price
• Action context: button_label, form_fields_completed, error_message
• Experiment context: experiment_id, variant (if A/B test)

Ask: What question would a PM ask about this event in 6 months? Make sure the properties answer it.

6. Flag Funnel-Critical Events

Identify events in the critical business funnel and mark them HIGH priority:

• Acquisition funnel: signup_started → signup_completed → onboarding_completed
• Activation funnel: first meaningful action per your product's activation metric
• Conversion funnel: every step in purchase or upgrade flow
• Retention signals: session started, core feature used, notification engaged

Rule: every conversion step needs tracking; every intermediate step enables drop-off analysis.

Flag any missing step in a funnel as CRITICAL — you can't compute conversion without it.

7. Prioritize by Business Value

Assign priority to each candidate event:

• critical: funnel step, revenue event, or legal/compliance requirement
• high: key feature engagement, activation signal, retention indicator
• medium: secondary engagement, UX feedback signal
• low: diagnostic, debug, or informational event

8. Check Existing Amplitude Schema for Naming Consistency

Query existing events via mcp__Amplitude__get_event_properties to verify:

• No naming conflicts (same action, different name)
• No semantic duplicates (two events that mean the same thing)
• Property names match existing conventions (e.g., user_id vs userId)

9. Output Event Candidate List

Produce a YAML list of candidate events:

candidates:
  - name: checkout_confirmation_viewed
    trigger: "User lands on /checkout/confirmation page"
    priority: critical
    properties:
      - order_id: string
      - order_total: number
      - payment_method: string
      - items_count: number
    status: new  # or: update_existing, deprecate
    existing_event_ref: null  # or: "checkout_complete" if updating

  - name: shipping_address_submitted
    trigger: "User clicks 'Save Address' on ShippingForm"
    priority: high
    properties:
      - address_country: string
      - is_default_address: boolean
    status: new
    existing_event_ref: null

MCP Tools

• mcp__Amplitude__get_event_properties — pull existing event schemas to avoid duplicates and match conventions
• mcp__Amplitude__get_context — get project context (project ID, organization, active events)

Key Concepts

• Event candidate: A proposed analytics event not yet implemented — may become a new event or an update to existing
• Verb-noun pattern: The standard naming convention for analytics events (action_object in snake_case)
• Funnel-critical: An event that, if missing, breaks conversion rate calculation for a key business funnel
• Semantic duplicate: Two events that track the same user action under different names — a taxonomy problem
• Universal property: A property that should appear on every event to enable cross-event analysis

Output Format

A YAML document with candidates array, each entry containing:

name: <snake_case event name>
trigger: <human description of when this fires>
priority: <critical|high|medium|low>
properties: <list of {name: type} pairs>
status: <new|update_existing|deprecate>
existing_event_ref: <existing event name if updating, null if new>

After output, state: "Found N candidate events. Proceed to instrument-events to generate implementation specs, or to taxonomy to validate naming against existing schema."