Program entry

A build selects a source runtime, an application module, foreign exports, and optional retained functions. Loader entry selection is independent. The compiler treats application calls as ordinary Silk calls; it has no specially shaped main declaration or generated invocation adapter. See artifact roots and native requirements.

ENTRY-001 — Runtime source chooses a visible application function

Status: Confirmed

A selected runtime imports Intrinsic.application. That binding resolves to the canonical application module with ordinary visibility rules. Source runtime code chooses which function to call, passes arguments, and handles its result. A runtime descriptor names the runtime module, without an invoke field. Foreign C exports and explicit retained declarations seed runtime reachability.

The installed executable defaults call public app.main. A custom runtime may choose another visible function, including one with parameters. The name main has no compiler privilege.

import Intrinsic.application
export "C" fn enter() -> i32 as "main" { return application.answer(42) }

Diagnostics: Missing or private application members, invalid arguments, and unsupported results are ordinary source errors at the runtime import or call. Explicit libraries, objects, and runtime-none profiles acquire no default startup or execution-storage component.

ENTRY-002 — Source startup owns execution

Status: Confirmed

The hosted executable default is silk/native_start. Its source C main(argc, argv) snapshots process inputs, creates a bounded lexical diagnostic observer, owns an Execution, and drives the application to completion. It accepts ordinary integer or unit results, or an Effect producing unit with no requirements or one mutable HostInput requirement. The HostInput requirement is satisfied by an ordinary source provider backed by the owned snapshot.

The standalone WebAssembly default is silk/wasm_start. Its C export is main() -> i32; it owns an Execution and accepts integer, unit, or requirement-free Effect-unit results. It installs no native host-input provider or diagnostic reporter and publishes no silk_main adapter.

Both source runtimes require a NonParking application body. Nested transfers complete inside their Execution; external parking requires a custom source runtime with an explicit scheduling policy. An unexpected suspended completion is handled as a startup failure rather than silently completing.

Diagnostics: The selected source runtime's interface and NonParking obligations are checked through ordinary specialization. No compiler entry-shape diagnostic or implicit scheduler exists.

ENTRY-003 — Source policy handles unhandled outcomes

Status: Confirmed

Hosted startup drops an unhandled owned typed-failure payload before observing its diagnostic context. Its bounded source reporter preserves the primary identity and available origin/path/cause information. Reporting allocation refusal or write failure does not replace the application failure. Unhandled typed failure and startup failure return status one. Unit and Effect success return zero; an ordinary integer result is the returned status.

Standalone Wasm drops an unhandled typed-failure payload and returns one without host reporting. Fatal traps remain abnormal termination and promise no cleanup; without a lexical source observer, Wasm retains bare machine traps. A custom source composition may define its own status and reporting policy using the same ordinary Effect, ownership, observer, and foreign-boundary operations.

Boundary: Diagnostic metadata travels through lexical observers and owned outcomes. No generated C report policy, process-global failure state, or compiler-owned fixed report buffer is involved.

ENTRY-004 — Source composition resolves application requirements

Status: Confirmed

Requirement rows retain ordinary Effect meaning. Hosted default startup supplies only its documented mutable HostInput contract. It does not infer other services from the operating system. Applications resolve remaining requirements through ordinary source providers, or select a custom runtime whose source performs the required composition. Standalone Wasm defaults require a closed application Effect and do not provide native services.

Runtime-none and library artifacts may retain ordinary functions with their own signatures; they have no implicit application execution or entry-result conversion. Foreign export contracts still apply independently at the C boundary.

ENTRY-005 — Foreign exports define the platform entry ABI

Status: Confirmed

Hosted native startup uses the platform C entry ABI and libc startup. Standalone Wasm exports a zero-parameter C main returning i32. Raw Linux startup instead selects its source _start, reads the validated initial stack, calls the application, and terminates through the kernel; see raw Linux.

Custom runtimes define their own C exports and loader entry according to the selected artifact and target contracts. The compiler preserves those exports and validates their ABI, while source calls and interfaces implement application adaptation. Empty libraries and retention-only objects are valid and need no C export or loader entry.

Evidence: hosted startup conformance, execution storage conformance, and raw Linux conformance.