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Compatibility Management

Manage how old and new versions interact so change does not break dependent systems or users.

The Diagnostic Story

Symptom: After a change that seemed local to the version owner, users and dependent systems break. Nobody can tell which version combinations are supported, which are deprecated, and which are forbidden. Legacy users are stranded while maintainers remain trapped by indefinite support obligations. Adapters, workarounds, and informal exceptions accumulate without any governing policy, and new features are blocked because there is no safe way to handle mixed-version operation.

Pivot: Define compatibility rules, migration paths, deprecation policy, support windows, and explicit adapter behavior — making the relationship between old and new versions a governed design decision rather than an implicit assumption.

Resolution: Breaking changes decrease and dependent actors are no longer stranded by surprise. Deprecation and end-of-support become governed events rather than accidental abandonment. Mixed-version operation during rollouts, migrations, or standard revisions becomes safer because the supported combinations are explicit and discoverable.

Reach for this when you hear…

[API platform] “We shipped v2 and half our integrators broke overnight because we did not realize they were using an undocumented behavior we removed.”

[regulatory compliance] “The new rule is in effect but the old forms are still valid for six months — we need a clear policy on what happens when an application references both.”

[medical device] “The firmware update runs fine on new hardware but the legacy implants in patients cannot accept it — we need a version matrix that is actually maintained.”

Mechanisms / Implementations

  • Adapter Layer: A thin translation layer that maps a host's calls, data, and conventions onto the interface the subsystem expects — so the subsystem can consume host capability, and later swap which host provides it, without its own code changing.
  • API Versioning: Exposes a host capability as explicitly versioned interfaces that coexist, so consumers migrate on their own schedule and a change to the host never becomes a forced, simultaneous break for everyone downstream.
  • Backward Compatibility Policy
  • Compatibility Matrix: A pairwise register of which constituents may share a domain and which must be kept apart, each verdict tied to the antagonism condition and the evidence behind it.
  • Compatibility Test Suite: A maintained battery that runs the matrix of supported version, client, and configuration combinations on every change, standing guard that none of them regresses.
  • Migration Guide
  • Protocol Negotiation
  • Rolling Upgrade
  • Schema Migration
  • Semantic Versioning

Abstractions this archetype builds on — directly (a source ingredient) or as a related pattern. Links follow the typed catalog namespace.

Built directly on (2)

Also references 11 related abstractions

Variants

Narrower or domain-specific specializations that share this archetype's core structure. Recognized variants are established; candidate variants are provisional.

Backward Compatibility Management · temporal variant · recognized

Preserves older dependents by ensuring newer versions continue to accept, interpret, or respect older interfaces, records, terms, or expectations.

Forward Compatibility Management · temporal variant · recognized

Allows older versions to tolerate or safely ignore future extensions, fields, terms, or procedures they do not yet fully understand.

Adapter-Mediated Compatibility · implementation variant · recognized

Uses an intermediary adapter, shim, crosswalk, translation layer, or compatibility wrapper to let incompatible versions interact.

Migration Window Compatibility · temporal variant · recognized

Maintains compatibility for a bounded transition period while dependents move from an old version to a new one.

Negotiated Protocol Compatibility · mechanism family variant · recognized

Uses a handshake, negotiation, or selection rule so interacting parties choose a mutually supported version or mode before proceeding.