FAQ and troubleshooting

Platform spec article

FAQ and troubleshooting

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Spec standingStandard

Owner

Piotr Mikstacki pmikstacki@cybernomad.it

Submitter

Piotr Mikstacki pmikstacki@cybernomad.it

Current document

ADRs (2)

1. 0014-cargo-features-not-abi-version Cargo features are separate from ABI version Accepted

   Optional runtime capabilities toggle code paths without bumping BESKID_RUNTIME_ABI_VERSION.

   Context

   CI and VSIX builds enable different beskid_runtime features. Confusing feature gates with ABI bumps breaks compatibility checks.

   Decision

   Concept	Rule
   BESKID_RUNTIME_ABI_VERSION	Changes only on breaking layout/signature per D-EXEC-ABI-0002
   Cargo features	metrics, arrays_backing, sched — build-time toggles
   Additive exports	New feature-gated symbols may ship without ABI bump if old artifacts never import them
   Shipped binaries	Must document enabled features in release notes
   Tests	Compiler tests enable features explicitly when validating optional paths

   Consequences

   Mismatch (test expects arrays_backing, default runtime does not) fails logically without ABI version inequality.

   Verification anchors

   beskid_runtime/Cargo.toml; design model feature table.

   Open full ADR page

2. 0015-arrays-backing-feature arrays_backing gates array element storage Accepted

   Without the feature, array_new may emit header-only arrays with null backing.

   Context

   Array lowering depends on whether the linked runtime allocates element storage behind BeskidArray headers.

   Decision

   arrays_backing	Behavior
   Enabled	array_new allocates element storage; ptr non-null when length > 0
   Disabled	Header-only arrays; ptr may be null
   ABI	Symbol list unchanged; semantics differ by build — document in release matrices
   Alignment	Shipped CLI/VSIX should enable arrays_backing for reference user workflows

   Consequences

   Conformance and doc tests must pin feature set when asserting array behavior.

   Verification anchors

   beskid_runtime array_new; runtime JIT tests with feature flags.

   Open full ADR page

Articles

• Contracts and edge cases MUST/SHOULD rules for optional runtime features and toolchain alignment. article Standard Reviewed Fri May 22
• Design model Cargo feature gates, runtime build capabilities, and compiler alignment expectations. article Standard Reviewed Fri May 22
• Examples Building runtime with features, array backing expectations, and engine extern_dlopen. article Standard Reviewed Fri May 22
• FAQ and troubleshooting Optional runtime features vs ABI version, array backing surprises, and CI alignment. article Standard Reviewed Fri May 22
• Flow and algorithm Selecting runtime features at build time and validating behavior at run time. article Standard Reviewed Fri May 22
• Verification and traceability Cargo feature definitions, conditional compilation gates, and CI matrix expectations. article Standard Reviewed Fri May 22

History

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Completeness

OKfeature · 2 SpecSection(s) · 1 H2 heading(s)

Section id	Required	Found
what-this-feature-specifies	yes	yes
implementation-anchors	yes	yes

Full tree: run pnpm verify:platform-spec-layout (writes src/generated/platform-spec-layout-report.json).

Related spec docs

• Feature
  Runtime feature flags

  Parent feature hub

FAQ

Do feature flags change beskid_runtime_abi_version?

No when behavior is backward compatible (RFF-001). Adding new optional symbols without old compilers calling them does not require a bump.

Why is array_new pointer null in the debugger?

Default builds omit arrays_backing. Enable the feature for tests that touch elements.

Where is extern_dlopen documented?

Under Extern dispatch and policy — it is an engine feature, not a runtime Cargo feature.

Can users toggle features at run time?

No. Selection is compile-time for the linked beskid_runtime artifact. CLI flags choose execution mode, not arrays_backing.

Troubleshooting

Symptom	Fix
Array element segfault	Build runtime with arrays_backing or stop dereferencing ptr
Missing rt_metrics_* at link	Enable metrics on runtime and ensure codegen emits calls
Extern works locally, fails in CI	CI engine lacks extern_dlopen — use link-time externs
VSIX vs local CLI array difference	Compare release matrices for runtime features

Related topics

• Examples
• FAQ ABI versioning