Triage remaining documented API gaps into roadmap priorities or explicit non-goals #256

Context

The feature-first, TypeScript-first roadmap tracks the main current API workstreams, but docs/api-coverage.md and docs/compatibility.md still describe several residual gaps that do not have a clear active roadmap item. Some are intentional escape-hatch boundaries; others may be worthwhile balanced-scope follow-ups. They should be explicitly prioritized or declared out of scope rather than remaining orphaned in prose.

Candidates identified in the 2026-11-04 audit

• Export: Solr 10.1 includeStoredFields is exposed but needs version-specific verification.
• Schema: similarity plugin mutation has type/serialization coverage only.
• Errors: Solr-version-specific error payload variants are not exhaustively integration-tested.
• Transport: advanced authentication mechanisms and retry telemetry are listed as remaining work.
• Validation: additional schema adapters and operation-specific examples are listed as remaining work.
• CoreAdmin: several exposed actions have serialization/type coverage only and no runtime evidence.
• Collections: MODIFYCOLLECTION and cluster-wide role actions remain runtime-unverified; SPLITSHARD/MIGRATE are separately tracked by Add opt-in isolated SolrCloud verification for SPLITSHARD and MIGRATE #232.
• Replication: leader/follower fetch is separately tracked by Verify ReplicationHandler leader/follower fetch lifecycle #238.

These candidates are not automatically commitments. Plugin-specific behavior, generic raw endpoints, and deployment-dependent features may remain explicit non-goals.

Scope

• Review each residual item against the TypeScript-first product direction and balanced scope.
• Classify each as: accepted feature work with a focused issue, explicitly deferred with rationale, or intentional non-goal.
• Create focused follow-up issues only for accepted work; avoid one oversized implementation issue.
• Add the resulting priorities/dependencies to the roadmap after the documentation reconciliation in Reconcile roadmap, compatibility matrix, and API inventory after latest coverage changes #255.

Acceptance criteria

• Every material residual gap in API coverage/compatibility has an issue link or explicit non-goal/deferred rationale in docs/api-coverage.md.
• Accepted work is split into focused issues Verify Solr 10.1 Export includeStoredFields behavior #258 (Export includeStoredFields) and Verify ReplicationHandler abort and async fetch lifecycle #259 (ReplicationHandler abort/async lifecycle), each with test and documentation acceptance criteria.
• No issue promises blanket Solr-version compatibility; runtime evidence remains operation- and version-specific.
• Roadmap priorities remain balanced and feature-first; release work stays separate in Prepare v4.0 stable release checklist and changelog #110.

Dependency

Coordinate roadmap updates with #255.

Audit resolution (2026-11-04)

• PR docs: reconcile roadmap and compatibility evidence after #253 #257 is merged and issue Reconcile roadmap, compatibility matrix, and API inventory after latest coverage changes #255 is closed.
• Accepted focused verification: Verify Solr 10.1 Export includeStoredFields behavior #258 (Export includeStoredFields) and Verify ReplicationHandler abort and async fetch lifecycle #259 (ReplicationHandler abort/async lifecycle).
• Deferred with rationale: version-specific error payloads, advanced auth, retry telemetry, additional validation adapters/examples, and runtime verification of destructive/cluster-wide actions.
• Intentional non-goals: plugin-specific Schema/Metrics/Auth contracts and Solr 10 V2 routes while the client explicitly implements V1.
• docs/roadmap.md, docs/api-coverage.md, and docs/compatibility.md are updated in the PR below. This issue is complete when that PR is merged.