2026-09-26 23:06:16 +02:00
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---
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title: Independent Feature Boundary
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status: draft
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maturity: hypothesis
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families: [composition, execution]
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scales: [L1, L4]
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admission: research-candidate-only
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---
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# Independent Feature Boundary
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Context: a cohesive frontend capability needs a release cadence different from its
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host or neighboring capabilities. Delivery autonomy competes with integration cost,
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shared experience and runtime dependency management.
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Proposed solution: define the capability's public composition contract and package it
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as a separately releasable unit with an explicit activation mechanism. State supported
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host/API/dependency versions, lifecycle and cleanup behavior, route ownership, and
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which shared state may cross the boundary. Validate compatible old/new combinations
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before changing the binding that activates a release.
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Publishing bytes, activating them and retiring the old version are separate actions.
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Plan for cached bindings, lazy loads and running sessions that retain old code. Define
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rollback scope, artifact retention and failure behavior; neither an asset rollback nor
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unmount reverses accepted domain operations. A new incompatible contract may require
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a coordinated migration despite separate pipelines.
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Result: compatible changes can be activated without rebuilding unrelated features,
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but compatibility testing, observability and composition policy add cost. A directory,
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repository, lazy chunk or lifecycle export alone does not provide this independence.
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Shared runtime/startup dependencies can still couple failures. Code in the same browser
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context is not thereby security-isolated. Preserve usable navigation and focus across
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partial loading, replacement and teardown.
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Evidence: [deployment-boundary review](../reviews/FeatureDeploymentBoundaries.md)
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D04–D09 locates runtime binding, lifecycle exports and separate workflow definitions
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in one example family, with documentary alternatives. CI success, actual deployment
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independence and complete-pattern recurrence are unverified. No canonical identity
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or admitted graph relations; hypothesis only.
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Alternative: a coordinated application release with [Vertical Feature Slice](VerticalFeatureSlice.md)
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when separate cadence is unnecessary. Proposed relations: may use
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[Failure Boundary](FailureBoundary.md) for a specified fault scope and
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[URL-addressable State](URLAddressableState.md) for shared route contracts. Neither
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separate activation nor [Islands of Interactivity](IslandsOfInteractivity.md) entails
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the other. Boundaries can coincide without becoming the same pattern.
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Next test: [VC-06](../walkthroughs/VC06-MicrofrontendEstate.md) proposes compatible and
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incompatible feature releases, failed loading and binding rollback across fresh and
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2026-09-26 23:14:34 +02:00
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already-open sessions. A bounded native-module experiment now exercises these cases; see the update below.
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## Executed activation/session evidence — 2026-09-26
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[Feature release experiment](../reviews/FeatureReleaseExperiment.md) meets 14/14
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expected observations across two browsers in an authored native-module fixture.
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Distinguish retained artifact, per-document binding and evaluated module lifetime:
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a fresh session follows activation/rollback while an existing session retains its
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binding; deleting the old artifact can break its delayed first load. A post-import
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API check runs after evaluation and is not a security boundary. A shared startup
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failure can block otherwise separate features. These are bounded mechanism observations,
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not execution of the source examples or proof of full-pattern production independence.
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2026-09-26 23:30:15 +02:00
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## Activation conflict and reload policy — 2026-09-26
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[Follow-up tests](../reviews/ActivationConflictsAndReload.md) demonstrate lost updates
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under blind binding replacement and explicit conflict rejection/refetch for disjoint
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intent. A same-feature stale rollback is not automatically reapplied. Atomicity is
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verified only in the single-process fixture, not a distributed deployment service.
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For unfinished work, distinguish defer, preserve-and-reload and authorized explicit
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discard. Block unsafe progress on storage refusal or unresolved operation outcome;
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read the latest draft after asynchronous checks. Revalidate stored schema in the new
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session because activation can change after preflight. The tested per-tab preservation
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is not native-unload/crash protection or a substitute for retention policy.
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