Does the 2024 IMC automatically govern our project?

No: the relevant installation rules depend on the jurisdiction's adopted code and amendments. ICC publishes A2L transition resources, including material for jurisdictions using older editions. ICC adoption resources

Ask the local authority and design professional to confirm the applicable code edition, accepted equipment listing, manufacturer instructions and any project-specific ventilation, detection, charge or installation provisions. Do not derive a universal charge limit from an article about a different occupancy or equipment arrangement.

ICC's April 2025 article also discusses practical A2L issues and early adoption of approved 2027 IMC language. This is useful evidence that publication year, adoption and local amendments must be tracked separately. ICC technical article

Quoting implication: create named review tasks for safety-related scope. If additional work is required, price the actual approved requirement rather than applying an invented A2L surcharge.