Add mm_attribution capture on Agent Wallet docs

[hieu-w]

Description

Park last-touch UTMs and ad click IDs from /agent-wallet docs landings (including the quickstart) in the shared mm_attribution cookie (Domain=.metamask.io). This matches metamask.io so a later sign-in on developer.metamask.io can still attribute the campaign.

• Only writes when the path includes /agent-wallet and the URL has at least one whitelisted UTM or click ID (utm_source, utm_medium, utm_campaign, utm_term, utm_content, plus gclid / twclid / fbclid / msclkid / ttclid / li_fat_id)
• Last-touch merge: new URL params take the 10-key budget first; leftover slots keep earlier tags so a UTM-only visit does not drop a prior gclid
• Sanitizes and caps keys/values to the same limits as the developer dashboard reader and backend
• Cookie: 90 days, Secure, SameSite=Lax

This is site JS, not a documentation content change.

Issue(s) fixed

N/A

Preview

• Agent Wallet quickstart

To verify: open the preview with ?utm_source=google&utm_medium=cpc&gclid=abc and confirm mm_attribution is set for .metamask.io. Localhost will not keep the cookie because of the shared domain.

Checklist

• If this PR updates or adds documentation content that changes or adds technical meaning, it has received an approval from an engineer or DevRel from the relevant team.
• If this PR updates or adds documentation content, it has received an approval from a technical writer.

External contributor checklist

• I've read the contribution guidelines.
• I've created a new issue (or assigned myself to an existing issue) describing what this PR addresses.

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Note

Medium Risk
Introduces cross-subdomain marketing cookies and consent-dependent persistence; behavior is aligned with existing dashboard contracts but affects privacy-sensitive tracking flows.

Overview
Adds client-side last-touch campaign attribution for Agent Wallet docs so UTMs and ad click IDs from /agent-wallet URLs (e.g. quickstart with query params) are stored in the shared mm_attribution cookie on Domain=.metamask.io, matching metamask.io and readable later on developer.metamask.io.

A new Docusaurus client module runs on route updates and calls writeAttributionCookie, which only acts when the path includes /agent-wallet and the URL has whitelisted UTMs or click IDs (gclid, etc.). Values are sanitized and capped to dashboard/backend limits; merges prefer incoming URL params over an existing cookie so new tags are not dropped. Writes are gated on Osano MARKETING consent (immediate if already accepted, otherwise deferred until consent is saved); local dev without Osano does not persist the cookie.

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Project	Deployment	Actions	Updated
metamask-docs	Ready	Preview	Sep 24, 2026 10:29am UTC

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